Climatevchangevvulnerability and Mountain Ecosystem

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Climate Change Vulnerability

o Mountain Ecosystemsin the Eastern Himalayas

Climate Change Impact and Vulnerability

in the Eastern Himalayas Synthesis Report


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Climate Change Vulnerability oMountain Ecosystems in the Eastern

Himalayas

International Centre or Integrated Mountain Development, Kathmandu, Nepal, June 2010

Editors

Karma Tse-ring

Eklabya Sharma

Nakul Chettri

Arun Shrestha

Climate Change Impact and Vulnerability

in the Eastern Himalayas Synthesis Report


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Preace

Mountains are among the most ragile environments on Earth. They are also rich repositories o biodiversity and water

and providers o ecosystem goods and services on which downstream communities (both regional and global) rely.

Mountains are home to some o the worlds most threatened and endemic species, as well as to some o the poorest

people, who are dependent on the biological resources. Realising the importance o mountains as ecosystems ocrucial signicance, the Convention on Biological Diversity specically developed a Programme o Work on Mountain

Biodiversity in 2004 aimed at reducing the loss o mountain biological diversity at global, regional, and national levels

by 2010. Despite these activities, mountains are still acing enormous pressure rom various drivers o global change,

including climate change. Under the infuence o climate change, mountains are likely to experience wide ranging

eects on the environment, natural resources including biodiversity, and socioeconomic conditions.

Little is known in detail about the vulnerability o mountain ecosystems to climate change. Intuitively it seems plausible that

these regions, where small changes in temperature can turn ice and snow to water, and where extreme slopes lead to

rapid changes in climatic zones over small distances, will show marked impacts in terms o biodiversity, water availability,

agriculture, and hazards, and that this will have an impact on general human well being. But the nature o the mountains,

ragile and poorly accessible landscapes with sparsely scattered settlements and poor inrastructure, means that research

and assessment are least just where they are needed most. And this is truest o all or the Hindu Kush-Himalayas, with the

highest mountains in the world, situated in developing and least developed countries with ew resources or meeting the

challenges o developing the detailed scientic knowledge needed to assess the current situation and likely impacts o

climate change.

The International Centre or Integrated Mountain Development (ICIMOD) undertook a series o research activities

together with partners in the Eastern Himalayas rom 2007 to 2008 to provide a preliminary assessment o the

impacts and vulnerability o this region to climate change. Activities included rapid surveys at country level, thematic

workshops, interaction with stakeholders at national and regional levels, and development o technical papers by

individual experts in collaboration with institutions that synthesised the available inormation on the region. A summary

o the ndings o the rapid assessment was published in 2009, and is being ollowed with a series o publication

comprising the main vulnerability synthesis report (this publication) and technical papers on the thematic topics climate

change projections, biodiversity, wetlands, water resources, hazards, and human wellbeing.

Clearly much more, and more precise, inormation will be needed to corroborate the present ndings. Nevertheless,

this series o publications highlights the vulnerability o the Eastern Himalayan ecosystems to climate change as a result

o their ecological ragility and economic marginality. It is hoped that it will both inorm conservation policy at national

and regional levels, and stimulate the coordinated research that is urgently needed.

Andreas Schild, PhDDirector General, ICIMOD


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From July 2007 to December 2008, the International

Centre or Integrated Mountain Development (ICIMOD)carried out a rapid Assessment o Climate Change

Vulnerability o Mountain Ecosystems in the Eastern

Himalayas, with support rom the MacArthur Foundation.

This synthesis report is the outcome o this work.

The Eastern Himalayas (EH) lie between 82.70E and

100.31E longitude and 21.95N to 29.45N latitude,

covering a total area o 524,190 sq.km. The region

extends rom the Kaligandaki Valley in central Nepal to

northwest Yunnan in China, and includes Bhutan, parts

o India (North East Indian states, and the Darjeeling hills

o West Bengal), southeast Tibet and parts o Yunnan in

China, and northern Myanmar. These ve countries have

dierent geo-political and socioeconomic systems, as well

as diverse cultures and ethnic groups.

The project undertook various research activities to assess

the climate change vulnerability o mountain ecosystems

in the EH. Activities included surveys at country level,

thematic workshops, interaction with stakeholders at

national and regional levels, and development otechnical papers by individual experts in collaboration

with institutions that synthesised the available inormation

on the region. Available climate models were used to

develop climate predictions or the region based on the

observed data. The ndings are summarised in detail

in this synthesis report, ollowing publications o a briesummary in 2009, preparation o an internal in depth

report, and individual papers, all o which eed into this

synthesis. The six technical papers produced on thematic

areas are being published separately and are included

on a CD-ROM with this synthesis.

Recent scientic opinion led by the Intergovernmental

Panel on Climate Change (IPCC) is that global climate

change is happening and will present practical

challenges to local ecosystems. The analysis and

predictions showing an increase in the magnitude o

climate change with altitude (in terms o both temperature

and variation in precipitation). The study explored the

impact and uture projections o changing climatic

conditions and showed the critical linkages between

biodiversity, ecosystem unctioning, ecosystem services,

drivers o change, and human wellbeing. The study

highlights the regions vulnerability to climate change as a

result o its ecological ragility and economic marginality.

This is in line with the broad consensus on climate change

vulnerability, and need or adaptation o conservationpolicy at national and regional levels.

Many actors contribute to the loss o biodiversity such as

habitat loss and ragmentation, colonisation by invasive

Executive Summary


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species, overexploitation o resources, pollution, nutrient

loading, and global climate change. The threats to

biodiversity arising rom climate change are very acute

in the EH as the region is rich in threatened and endemic

species with restricted distributions. Fragmentation and

loss o habitat directly impinge on the survival o species,

especially those that are endemic to the region. Species

in high altitude areas especially in the transition zone

between sub-alpine and alpine are more vulnerable to

climate change. In addition, the regions wetlands are

being aected by the erratic weather observed in many

parts o the region.

The assessment also looked at the perception o climate

change by the people in the region. People see climate

change as a big threat and challenge. They perceive

climate change to be a result o excessive human

activity and, to a certain extent, natural cyclical climaticvariation. The majority o the respondents rom the region

associated climate change with foods, landslides,

increases in temperature, land degradation, the drying o

water sources, pest outbreaks, and ood shortages.

The assessment revealed a gap in our knowledge on

the climate change vulnerability o mountain ecosystems

in the EH and the inadequacy o human resources

and institutional setups, as well as a lack o policy

imperatives to address the issues. The lack o systematic

research, monitoring, and documentation on the status o

biodiversity in the region was highlighted in all the studies

undertaken or this assessment. The region also lacks

adequate scientic evidence to determine the impact o

climate change on human wellbeing with any certainty.

Equally, the majority o available research ocuses on the

adverse impacts o climate change and overlooks both

the adaptation mechanisms adopted by the local people

and the new opportunities presented. The enormous

challenge or the region is to adapt to the impacts o

climate change by integrating responses and adaptation

measures into local level poverty reduction strategies.

In the process o assessing climate change vulnerabilities

in the EH, ICIMOD has been able to network, initiate,

and advocate or biodiversity conservation with regional

cooperation on critical areas. This assessment is expected

to advance our thinking about climate variability and

change, and the vulnerability and adaptation o important

impact areas, with a view to developing uture strategies

on both conservation and development. It indicatesshortcomings and identies research gaps in relation

to biodiversity, wetland conservation, the resilience o

ecosystems and their services, and hazards assessment,

and points out the unreliability o trends and model

projections due to the lack o country-wise consistent data

related to climate change. The research gaps and lessons

learned provide a good platorm or initiating concrete

projects and activities on biodiversity and climate change

in the Eastern Himalayas. It is also hoped that the rapid

assessment will be helpul in guiding the MacArthur

Foundation, ICIMOD, and their partners in developing

new strategies and plans or research on biodiversity

conservation and enhancing human wellbeing.


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Contents

Preace

Executive Summary

1 Introduction 1Background 1

The Eastern Himalayas Study 1

Knowledge o Climate Change 2

Mountain Ecosystems 5The Eastern Himalayas 6

Drivers o Change, Ecosystem Stresses 8

Analytical Framework 10

2 Climatic Trends and Projections 13Introduction 13

Trends 14

Projections 16

3 Sensitivity o Mountain Ecosystems to Climate Change 23Introduction 23

Sensitivity o Biodiversity 23Sensitivity o Hydrology and Water Resources 26Sensitivity o Human Wellbeing 31

4 Potential Impacts o Climate Change and Implications orBiodiversity and Human Wellbeing 33

Introduction 33

Impacts on Ecosystems and Consequences or Biodiversity 33

Impacts on Water, Wetlands and Hazards, and Consequences or Biodiversity 37

Impacts on Human Wellbeing 43

5 Responses to Climate Change 47Stakeholder Perceptions o Climate Change 47

Vulnerability o Biodiversity to Climatic Threats 49

Vulnerability in the EH 54

Response, Adaptation and Mitigation 60


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6 Gaps and Needs 69Capacity Building and Training Needs 69

Knowledge Gaps and Potential Research Areas 70

Policy and Governance 74

7 Conclusion 77

Reerences 79

Annexes

Annex 1: Protected areas with indicators o vulnerability in order o vulnerability rank 90Annex 2: Ecological region ranked by vulnerability 94

Annex 3: Administrative units ranked by vulnerability 96

Annex 4: Knowledge gaps and research priorities or dierent systems in each country 100

Acronyms and Abbreviations 103

Acknowledgements 104


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Climate Change Vulnerability o Mountain Ecosystems in the EH

1

1 Introduction

Background

Climate and natural ecosystems are tightly coupled,

and the stability o that coupled system is an important

ecosystem service. Chapter 13 o Agenda 21, which

was adopted at the United Nations Conerence on

Environment and Development (UNCED) in Rio de

Janeiro in 1992 (UNEP 1992), explicitly recognises

that mountains and uplands are a major component o

the global environment. The Chapter sets the scene by

stating the role o mountains within the global ecosystemand expresses serious concern about the decline in the

general environmental quality o many mountain areas.

Since Agenda 21, mountains have no longer been on

the periphery o the global debate on development and

environment, but have moved to centre-stage.

The Eastern Himalayas (EH) are considered multiunctional

because they provide a diverse range o ecosystem

services (provisioning, regulating, cultural, supporting);

this also makes them useul or studying the relationshipbetween loss o biodiversity and loss o ecosystem

services. The worlds most diverse mountain orests are

ound among the peaks and valleys o the EH (CEPF

2007). Rapid changes o altitude over relatively short

horizontal distances have resulted in rich biodiversity with

a wide variety o plants and animals, oten with sharp

transitions in vegetation sequences (ecotones), ascending

into barren land, snow, and ice.

The survival o these ecosystems and the wildlie

within them is being threatened by human activitiessuch as timber harvesting, intensive livestock grazing,

agricultural expansion into orestlands, and, above

all, by climate change. Mountain areas are especially

susceptible to global warming, which is the result o rising

concentrations o greenhouse gases (GHGs) generated

by human activity in the atmosphere. At the same time

landscapes and communities in mountain regions are

being aected by rapid socioeconomic changes like

outmigration. Identication and understanding o the key

ecological and socioeconomic parameters o mountain

ecosystems, including their sensitivities and vulnerabilities

to climate changes, has become crucial or planning and

policy making or the environmental management and

sustainable development o mountain regions, as well

as downstream areas (APN 2003). The welare o hal

a billion people downstream is inextricably linked to the

state o natural resources in the Eastern Himalayas.

The Eastern Himalayas Study

The study presented here was concerned with establishing

a correlation between biodiversity, ecosystem unctioning,

and ecosystem services or human wellbeing and wasmotivated by concern about climate change and its

eects on the supply o a range o ecosystem services.

The project was unded by the MacArthur Foundation and

implemented by ICIMOD. This synthesis report provides a

review o the climate change assessment with a ocus on

impact areas considered important or addressing climate

change vulnerability in the mountain ecosystems o the

EH. A brie summary was published in 2009 (Sharma

et al. 2009) and the six technical papers produced on

thematic areas are also being published separately in

this series. The EH is a priority area or the MacArthur

Foundation and the assessment was made to help guide

the MacArthur Foundation, ICIMOD, and their partners

in developing new strategies or biodiversity conservation

and enhancing human wellbeing.

The regional assessment was conducted by an

interdisciplinary team at ICIMOD together with support

and contributions rom various stakeholders, partners,

and the countries concerned. This report synthesises the

assessment sector-by-sector ndings rom the technicalpapers generated as part o this project, and other

documents, using an applied research methodology. As

such, it both collates previous studies and inormation,

and extrapolates toward the specic requirements o

ICIMOD and the MacArthur Foundations biodiversity

and ecosystems assessment. It also attempts to assess the

trends, perceptions and projections o climate change

and variability, as well as the impacts o climate change

on biodiversity conservation, and identies which impacts

might be most important or the EH, taking into account

the degree o uncertainty related to each category o

impact. The ultimate aim is to reach a broad consensus

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Climate Change Impact and Vulnerability in the EH Synthesis Report

2

Box 1: The IPCC

During the course o this century the resilience o many

ecosystems (their ability to adapt naturally) is likelyto be exceeded by an unprecedented combinationo change in climate and change in other globalchange drivers (especially land use change andoverexploitation), i greenhouse gas emissions and

other changes continue at or above current rates. By

2100 ecosystems will be exposed to atmospheric CO2

levels substantially higher than in the past 650,000years, and global temperatures at least among thehighest o those experienced in the past 740,000years. This will alter the structure, reduce biodiversity

and perturb unctioning o most ecosystems, andcompromise the services they currently provide.

Source: IPCC (2007a)

on conservation policies, practices, and governance in

climate change adaptation, with a view to developing

a uture strategy on both conservation and development.

This report also identies actions that could be taken to

reduce the regions vulnerability, and summarises data

and research priorities needed to guide interventions

addressing climate change issues.

Five questions guided the assessment process:

What is the status o mountain ecosystems in the1.

EH, and what are the current stresses and issues that

provide the context or determining the impacts o

climate change?

How might changes in climate and climate variability2.

exacerbate or ameliorate these stresses or create

new ones?

How much will the provision o ecosystem services in3.

the EH change due to the eects o climate change?

What actions might increase the regions resilience4.

to climate variability; and what are the potential

strategies or coping with risk and to take advantage

o new opportunities created by climate change?

What are the priorities or new inormation and5.

policy-relevant research areas to better answer the

above questions?

Underlying the approach in this assessment is the

question: What aspects o ecosystems are important topeople in the EH? Unortunately, our understanding o

how people depend upon ecosystems and how people

value dierent aspects o ecosystems is incomplete.

Aspects o ecosystems that we believe are important

to the people o the EH, based on currently available

inormation, were emphasised.

The ollowing activities were undertaken:

Review o major reports with a general and specic

ocus on the Eastern Himalayan region and otherdiverse proessional contributions

Contact and consultations with regional stakeholders

Downloading and compilation o historical

climatology, time series, and climate change

scenario results or the EH, and synthesis o the broad

trends as documented in recent regional and global

reports

Synthesis and categorisation o climate change

impacts on biodiversity in the EH and biodiversity

management actions that address these impactsIdentication o potential data and knowledge gaps,

and exploration o potential areas o research

This assessment specically ocuses on the ollowing

impact areas considered sensitive to climate change:

biodiversity and impacts o climate change,

water, wetlands and hazards, and

threats to human wellbeing.

This synthesis provides an in depth analysis o the existing

knowledge and inormation on: 1) the current trends,

perceptions and projections o climate variability and

climate change; 2) the potential or major positive or

negative climate change impacts; 3) the vulnerable

aspects and eatures o mountain ecosystems in the EH; 4)

options to make the EH more resilient to climate change;

and 5) priorities or improving such regional assessments

through new research initiatives to close knowledge gaps.

The assessment also attempts to consolidate past eorts

in climate change studies and come out with a clear

perspective on a uture course o action. The synthesiswraps up with possible policy options and governance

mechanisms to address the vulnerabilities associated with

climate change in the priority impact areas. Gaps in our

current knowledge and understanding are translated into

recommendations or research agendas in the Eastern

Himalayas.

Knowledge of Climate Change

There is a growing consensus in the scientic community

that climate change is happening (Box 1). Researchsummarised in the Intergovernmental Panel on Climate

Change (IPCC) Fourth Assessment Report (AR4)

indicates that in the Himalayas global average surace

temperatures are increasing, and snow cover and ice


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3

extent are decreasing (IPCC 2007a). While the absolute

magnitude o predicted changes is uncertain, there is a

high degree o condence in the direction o changes

and in the recognition that climate change eects will

persist or many centuries. The report noted that the

average global surace temperature has increased by

nearly 1C over the past century and is likely to rise by

another 1.4 to 5.8C over the next century. Such simple

statements, however, mask the highly variable, site-

specic, and complex interactions among climate change

eects.

Climate change and the Convention on BiologicalDiversity

There has been ongoing interest in the potential impacts

o climate change on biodiversity in the EH over the

past decade or more. All ve countries o the Eastern

Himalayas (Bhutan, China, India, Myanmar, Nepal)are signatories to the 1992 Convention on Biological

Diversity (CBD), and their commitment was renewed

during the World Summit on Sustainable Development

(WSSD) in 2002. In 2004, the CBD adopted the

Programme o Work on Mountain Biological Diversity with

the overall purpose o achieving a signicant reduction o

loss o mountain biological diversity by 2010.

The broad objectives o the CBD and the Ramsar

Convention on Wetlands are mutually compatible(conservation and wise use) and scope exists or close

cooperation between the two agreements at all levels.

Ramsar has been designated as the lead partner o the

CBD in relation to inland water ecosystems. Natural

ecosystems play a critical role in the carbon cycle, and,

hence, act as sources and sinks or greenhouse gases.

They are also extremely vulnerable to the impacts o

climate change. The nature o the national activities in the

CBD ramework may thus have signicance or reducing

global climatic change and adapting to its eects.

Cooperation between countries in the Eastern Himalayasunder these two agreements to address climate change

challenges is, thereore, essential.

Climate change, ecosystem services and humanwellbeing

Atmospheric warming aects other aspects o the climate

system: pressure and composition o the atmosphere;

temperature o surace air, land, water, and ice; water

content o air, clouds, snow, and ice; wind and ocean

currents; ocean temperature, density, and salinity; andphysical processes such as precipitation and evaporation.

Climate aects humans directly through the weather

experienced (physically and psychologically) day to day

and the impacts o weather on daily living conditions,

and indirectly through its impacts on economic, social,

and natural environments. The potential or climate

change to impact on biodiversity has long been noted

by the IPCC, various other bodies (Feenstra et al. 1998),

and research biologists (e.g., Peters and Lovejoy 1992).

Climate change, including variability and extremes,

continues to impact on mountain ecosystems, sometimes

benecially, but requently with adverse eects on the

structure and unctioning o ecosystems. Fortunately,

the unctioning o many ecosystems can be restored i

appropriate action is taken in time. The linkage between

climate and human wellbeing is complex and dynamic as

shown in Figure 1.

The concept o ecosystem services introduced by the

Millennium Ecosystem Assessment (MEA 2005) ormsa useul link between the unctioning o ecosystems and

their role or society, including the dynamics o change

over space and time. Most services can be quantied,

even i no single metric is applied across their entire

range. Impacts o climate change on ecosystem structure,

unctioning, and services have been observed (Parmesan

and Yohe 2003; IPCC 2007a, c) which in turn aect

human society mainly by increasing human vulnerability.

Humans rely on ecosystems, because they depend on

ecosystem services (de Groot 1992; Daily 1997; MEA

2005). Ecosystems oer provisioning services (e.g., ood,

reshwater, uelwood, biochemicals), regulating services

(e.g., climate and disease regulation, pollination),

cultural services (e.g., spiritual, recreational, aesthetic

value, inspirational), and supporting services (e.g., soil

ormation, nutrient cycling, primary production). They

infuence our security, basic materials or a good lie,

health, social relations, and, ultimately, our reedoms and

choices in short, our wellbeing (MEA 2003).

Clearly, the human economy depends upon the services

perormed or ree by ecosystems. Natural ecosystems

also perorm undamental lie-support services without

which human civilisations would cease to thrive. Many

o the human activities that modiy or destroy natural

ecosystems may cause the deterioration o ecological

services the value o which, in the long term, dwars the

short-term economic benets to society. We are bound to

the human perspective, even i we recognise the intrinsic

value o ecosystems and biodiversity. Social systems

and natural systems are inseparable because ecosystemservices weave people into ecosystems (Figure 2).


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4

CLIMATE CHANGE

Temperature Precipitation Atmosphericcomposition

Variabilityandextremes

HUMAN WELLBEINGSecurity

Asafeenvironment Resiliencetoecologicalshocksorstressessuchas

droughts, foods, and pests Securerightsandaccesstoecosystemservices

Basic material or a good lie

Accesstoresourcesforaviablelivelihood(includingood and building materials) or the income to purchasethem

Health

Adequatefoodandnutrition Avoidanceofdisease Cleanandsafedrinkingwater Cleanair

Energyforcomfortabletemperaturecontrol

Good social relations

Realisationofaestheticandrecreationalvalues Abilitytoexpressculturalandspiritualvalues Opportunitytoobserveandlearnfromnature Developmentofsocialcapital Avoidanceoftensionandconictoveradeclining

resource base

Freedom and choice

Abilitytoinuencedecisionsregardingecosystemservices and wellbeing

Opportunitytobeabletoachievewhatanindividual

values doing and being

ECOSYSTEM SERVICES

Provisioning services

Food and odder, bre, uel, timber, pharmaceuticals,biochemicals, genetic resources, reshwater and air

Regulating services

Invasion resistance, herbivory, pollination, seed dispersal,climate regulation, pest and disease regulation, naturalhazard protection, erosion regulation, food regulation,water purication

Cultural services

Spiritual and religious values, knowledge system,education and inspiration, recreation and aesthetic values,sense o place

Supporting services

Primary production, provision o habitat, nutrient cycling,soil ormation and retention, oxygen production, watercycling

BIODIVERSITY (ecosystem, habitat, species)

NumberDistributionAbundanceCompositionInteraction

ECOSYSTEM FUNCTIONS

Figure 1: Linkages between climate change, biodiversity, ecosystem services, and human wellbeing (adapted rom MEA 2003)


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Figure 2: Role o ecosystems in assessment o climate change eects on human wellbeing(modied rom Metzger and Schrter 2006)

Mountain Ecosystems

An ecosystem is an interdependent, unctioning system

o plants, animals, and microorganisms. An ecosystem

can be as large as the Tibetan Plateau or as small as a

waterhole at the ringe o a subtropical orest. Ecosystems

are o undamental importance to environmental

unctioning and sustainability, and they provide manygoods and services critical to individuals and societies.

These goods and services include: i) providing ood,

bre, odder, shelter, medicines and energy; ii) processing

and storing carbon and nutrients; iii) assimilating

waste; iv) puriying water, regulating water runo and

moderating foods; v) building soils and reducing soil

degradation; vi) providing opportunities or recreation

and tourism; and vii) housing the Earths reservoir o

genetic and species diversity. In addition, natural

ecosystems have cultural, religious, and aesthetic value as

well as an intrinsic existence value. Without the support othe other organisms within their own ecosystem, lie orms

would not survive, much less thrive. Such support requires

that predators and prey, re and water, ood and shelter,

clean air and open space remain in balance with each

other and with the environment around them.

Mountain ecosystems are ound throughout the world,

rom the equator almost to the poles, occupying

approximately one-th o the Earths land surace. Beyond

their common characteristics o high relative relie andsteep slopes, mountains are remarkably diverse (Ives et

al. 1997) and globally important as centres o biological

diversity. On a global scale, mountains greatest value

may be as sources o all the worlds major rivers, and

many smaller ones (Mountain Agenda 1998).

Climate is an integral part o mountain ecosystems and

organisms have adapted to their local climate over

time. Climate change has the potential to alter these

ecosystems and the services they provide to each other

and to human society at large. Human societies dependon ecosystem provisioning, regulating, cultural and

supportive services or their wellbeing. The goods and

services provided by mountain ecosystems sustain almost

hal the human population worldwide, and also maintain

the integrity o the Earth system through the provision o

vital environmental regulation and rejuvenation unctions.

Production agriculture and extractive orestry are the

mainstay o ood security and subsistence livelihoods in

mountain regions. Livelihood strategies are built around

indigenous knowledge and traditional practices o

ecological sustainability in natural resources management.

Mountain arming systems integrating arable agriculture,

horticulture, livestock, and silviorestry have moderated

utilisation with conservation ethics to ensure that

ecosystem services are not exploited beyond their

renewable capacities. Unortunately, these practices

are losing their relevance as a result o globalisation, at

the expense o customary rights to ecosystem services.

Without policy support or, and legal recognition o,

traditional practices, mountain communities are conrontedwith limited livelihood options and less incentive to

stay in balance with surrounding ecosystems. Problems

associated with modernisation, like GHG emissions, air

Climate change Ecosystems

Food securityHumanwellbeing

Livelihoods

Health

Water

Biodiversity

Adaptationand

mitigation

Environmental

resilience


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Table 1: Percentage share o the aerial extent o the EasternHimalayas by country

Country Areas % o EH area

India Sikkim, Arunachal Pradesh, Assam,Meghalaya, Nagaland, Mizoram,Manipur, Tripura; and DarjeelingHills o West Bengal

52.03

Myanmar Chin and Kachin states 17.90

Nepal Kaligandaki Valley, Koshi Basin,Mechi Basin

16.08

Bhutan Whole country 7.60

China ZhongDian, DeQin, GongShan,Weixi, FuGong

6.26

pollution, land use conversion, deorestation, and land

degradation, are slowly creeping into mountain regions.

The out-migration o the rural workorce has brought

economic activities in some rural areas to a standstill.

Thus, landscapes and communities in mountain regions

are being simultaneously aected by rapid environmental

and socioeconomic threats and perturbations.

With the advent o a globalised world, the mutual

relationship between humans and mountains is now

threatened by a growing population and its increasing

demands on ecosystem services, which are beyond

tolerance thresholds. Traditional resilience is being rapidly

eroded leading to dependence on external inputs and

the overexploitation o selective resources, threatening

their sustainability. Rapid changes to ragile ecosystems

driven by both natural and anthropogenic determinants

pose unprecedented threats, not only to the livelihoodso the local people, wildlie, and culture, but also to the

billions living downstream, and ultimately to the global

environment. Besides demographic and socioeconomic

changes, the political economics o marginalisation

imposes an additional layer o vulnerability. The inherent

environmental ragility o mountain ecosystems and the

socioeconomic vulnerability o mountain people have

brought the issues o mountain ecosystems to the top o

the global sustainability agenda.

The Eastern Himalayas

The EH covers an area o 524,190 sq.km, stretching

rom eastern Nepal to Yunnan in China, between

82.70E and 100.31E longitude and 21.95N and

29.45N latitude. The limits o the region as dened

or the purposes o this study are shown in Figure 3. The

region extends through parts o ve countries (Table 1)

Characteristics

The Eastern Himalayan region (EH), with its mountains,valleys, and food plains, is physiographically diverse

and ecologically rich in natural and crop-related

biodiversity. It is also signicant rom geopolitical,

environmental, cultural, and ethnic perspectives, and in

terms o its ecosystems and the tectonic orogeny o the

encompassing Himalayan mountain system. The lowlands

are characterised by braided rivers emerging rom deeply

dissected oothills and converging into slow meandering

rivers urther downstream. The ecological diversity o

the EH is, in part, a unction o the large variation in

topography, soil, and climate within the region. The

human population is also unevenly distributed: the highest

population densities are ound in the Nepal Terai, West

Bengal, and the Assam Duars, and in dispersed pockets

in the Brahmaputra basin, Meghalaya, Tripura, and

Manipur. During the past 30 years, the human population

o the region has increased at approximately 2.1%

annually (WWF 2005), with higher rates in and aroundurban centres, and low or sometimes negative growth

rates in many o the rural and isolated areas.

The ocus o this study on the EH refects its position as a

globally signicant region or ecosystem biodiversity, and

the enormity o its services command area in geopolitical,

demographic, and socioeconomic terms. A common

eature o the Eastern Himalayan region is the complexity

o its topography. Orographic eatures include rapid

and systematic changes in climatic parameters (e.g.,

temperature, precipitation, radiation) and environmental

actors (e.g., dierences in soil types).

The region lies between China and India, the two

countries with the astest economic growth rates and

largest populations in the world; hence, there is a

great risk o ragmentation o ecosystems as economic

development supersedes environmental concerns. The

region has multiple biogeographic origins, being at

the intersection o the Indo-Malayan Realm, Palearctic

Realm, and the Sino-Japanese Region. It also marksthe rontier o the collision between the monsoonal and

mountain systems associated with intense thunderstorms

and lightning. The region is steeped in metaphors and

held in reverence as the Water Tower o Asia, with the

Himalayas as a whole providing about 8.6 x

106 m3 o water annually to the region and downstream.

It is also reerred to as the Third Pole. The Himalayas

have the largest concentration o glaciers outside the

polar caps covering 33,000 km2 (Dyurgerov and Meier

1997). The EH region also contains numerous hotspots

o biodiversity. For all these reasons and more, the EH

region warrants protection in order to maintain ecosystem

integrity and adaptability (Figure 3).


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Figure 3: The Eastern Himalayan region as defned or the study

Ecoregions

The abundance o terrestrial ecosystems in the region

are grouped into 25 ecoregions, including the category

rock, snow, and ice, based on past biogeographical

studies (WWF 2004). These ecoregions are nested

within two higher-order classications: biomes (7) and

biogeographic realms (2), which together provide

a ramework or comparison among units and the

identication o representative habitats and species

assemblages. The eocregions provide crucial habitatsor wildlie and the vegetation communities are home to

hundreds o endangered plant species.

Flora and auna

The EH contains some o the largest contiguous blocks o

orest habitat in the HKH region with a diverse array o

communities and species. The diversity o trees provides

the basis or the wide range o orested community

types dominated by deciduous as well as evergreen

communities o hardwood orests in the tropics and sub-

tropics; deciduous/evergreen and broad/needle-lea

orests in the temperate zone; and dominant needle-

lea, meadows, scrub, and coniers in the alpine zone.

Extensive stands o riverine evergreen and deciduous

orests orm unique habitats or rare plants and animals on

the Brahmaputra and Koshi foodplains.

Less well known are the Eastern Himalayan broadlea

and conier orest ecoregions, which blanket the lowlands

to the inner valleys o the Himalayas in northern India,

Nepal, and Bhutan (CEPF 2007; WWF 2006a). These

middle-elevation orests are located between 800 and

4000 m.

Temperatures vary widely throughout the year, and rainollows the monsoon season. The weather is warm and

wet rom the rst hailstorms o April to the last monsoon

drizzle sometime in October, and mushrooms grow

everywhere. But, rom the beginning o autumn, the

months may go by with scarcely any rain, although snow

can blanket the high altitude areas anytime during the

winter. These conditions are ideal or broadlea evergreen

trees at the lower elevations, and or deciduous trees and

coniers higher up. At certain elevations, where conditions

are neither too cold nor too dry, the trees themselves are

draped with all kinds o small plants: orchids, lichens,

and erns. The orests here are vibrant with lie and

provide homes or a tremendous diversity o plant and

animal species.


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Among the peaks and valleys o the EH, mammals as

varied as the Bengal tiger, snow leopard, sloth bear,

rhino, elephant, takin, and red panda make their home

in the worlds most diverse sub-tropical and temperate

orests. The EH is home to a number o extraordinary

mammals like the lesser panda, clouded leopard, and

rare golden langur, as well as leeches and orb-weaver

spiders. Many kinds o birds inhabit these orests

some just passing through and others breeding. They

include black-necked cranes, Kashmir fycatchers, striped

laughing thrushes, Blyths tragopans, Himalayan quails,

and iridescent re-tailed sunbirds.

Wetlands and reshwater ecosystems

Wetlands and marshes play a role in nutrient cycling,

water storage, provide crucial sh and wildlie habitats,

and remove pollutants rom water. Several types o

wetlands exist in the EH, rom ephemeral streambeds

to huge lakes ed by either meltwater or precipitation.

Wetlands and marshes provide important ecosystem

services: they contribute to the fow o mountain streams

and river systems, provide habitat or wetland fora

and auna, serve as carbon sinks, regulate foods, and

puriy water. Many o the wetlands in the region are

designated as Ramsar sites and wetlands o signicance

in recognition o their vital role in maintaining natural

processes and providing services.

The importance o reshwater ecosystems to residents o

the EH is dicult to quantiy, in part because o the deep

attachments that many people have to streams, rivers, and

reservoirs in their community. Freshwater resources have

multiple, sometimes conficting, values. These include

shing, swimming, boating, water supply, beauty, food

control, navigation and transportation, and hydropower.

Freshwater ecosystems support aquatic plants and

animals, as well as organisms in wetland and terrestrial

ecosystems that depend upon reshwater. Freshwater

ecosystems, like orest and wetland ecosystems, arestressed by habitat alteration, pollution, and non-native

invasive species. Stream habitat alterations include dams,

road crossings, channelisation, and loss o stream bank

vegetation. Dams are built to supply water or human

uses, to control fooding, and to generate electricity.

Dams also alter stream fow, sedimentation, temperature,

and dissolved oxygen concentrations, impairing the

ability o streams and rivers to support native auna,

especially reshwater sh, aquatic plants, and benthic

microorganisms. The largest electricity-producing structuresare in mountainous areas and in uture dams are likely

to occur in greater numbers in Bhutan, Nepal, and

Arunachal Pradesh.

Hazards and disaster

The rate o retreat o glaciers and the thawing o

permarost has rapidly increased in recent times.

The region has witnessed unprecedented melting o

permanent glaciers during the past three decades, with

the vast Himalayan glaciers showing the ast rate o

retreat, resulting in increases in glacial runo and glaciallake outburst foods (GLOFs), and an increased requency

o events such as foods, mudfows, and avalanches

aecting human settlements. GLOFs have occurred in

the EH at various locations in Nepal, India, Bhutan, and

China. GLOF events can have widespread impacts on

socioeconomic systems, hydrology, and ecosystems.

Recent studies suggest that loss o glacier volume, and

eventual disappearance o many glaciers, may cause

water stress to millions o people in India and China. As

glacier mass reduces, the reduced volume o runo will

have serious consequences or downstream hydropower

and land use systems including agriculture.

Other key water-related natural disasters include droughts,

foods, landslides, wildres rom lightning, thunderstorms,

and cloudbursts.

Earthquakes pose another risk in the region and can

ampliy the potential impacts o climate change and

exacerbate vulnerability. Frequent slope ailure, mass

wasting, and landslides along the Himalayan oothillsare evidence o these reinorcing stresses causing

ecological damage and economic losses. The Main

Himalayan Seismic Belt, a 50 km wide zone between

the Main Boundary Thrust and the Main Central Thrust,

is seismically the most active in the region. Massive

earthquakes (M>8) have occurred along the detachment

surace that separates the under-thrusting Indian plate rom

the Lesser Himalaya (1897 Assam, 1905 Kangra, 1934

Bihar-Nepal, 1950 Assam). The regions between the

epicentres o these earthquakes, known as seismic gaps,

are potential sites or uture big earthquakes.

Drivers of Change, EcosystemStresses

Climate change has synergistic eects with many o

the biggest existing impacts on biodiversity. Many

authors stress that potential climate change impacts

on biodiversity will occur in concert with other well-

established stressors. A ew specic examples evident in

the EH are highlighted in Box 2.


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Impacts can be assessed using the concept o proximate

cause (the specic biophysical event that causes the loss

o genetic, species, or ecosystem diversity), intermediate

cause (the human act that triggers the biophysical

event), and ultimate cause (the underlying economic,

social, or policy reason motivating the human act).

Much o our current attention is ocused on proximate

and intermediate causes. Proximate causes tend to be

amenable to technical solutions; ultimate causes generally

require major economic, political, and cultural solutions.

The ultimate causes o biodiversity impact are growth-based economics, excessive personal consumption and

associated waste, and excessive per capita energy use.

However, a great deal o energy is expended in stopgap

solutions to address proximate causes, winning a ew

biodiversity battles, but losing the war.

Ecosystems in the EH are being impaired and destroyed

by a wide variety o human activities. The survival o the

ecosystems and wildlie in the EH is being threatened by

human activities like timber harvesting, intensive grazing

by livestock, and agricultural expansion into orestland.

The EH has environmental and socioeconomic problems,

common to the entire Hindu Kush-Himalayan (HKH)

region in sectors such as water, agriculture, and land

use; ecosystems and biodiversity; and human wellbeing.

The majority o the problems in these sectors are related

to management issues and are exacerbated by the

associated impacts o climate change.

Rapid and unsustainable economic and population

growth in the region is imposing increasing stress

on the natural environment. The economic level o

a country determines to a large extent its resource

requirements, in particular its requirements or energy,

industrial commodities, agricultural products, and

reshwater. Threats to ecosystems are driven by rapid

growth in population, economic production, and social

consumption behaviours, and by the ailure to appreciate

the monetary terms o the services and refect this in scal

policies. The consequence o changes taking place in

the structure and unctioning o ecosystems due to humanimpacts render them more vulnerable to climate change

stresses, as their underlying resiliency and unctional

integrity have been severely eroded by non-climatic

intererence. Threats include the alteration o the Earths

carbon, nitrogen, and other biogeochemical cycles

through the burning o ossil uels and the heavy use

o nitrogen ertiliser; degradation o armlands through

unsustainable agricultural practices; squandering o

reshwater resources; poisoning o land and waterways;

and overharvesting o wild ood, managed orests,

and other theoretically renewable systems. As a result,

environmental deterioration in mountains is driven by

numerous actors, including deorestation, overgrazing by

livestock, and the cultivation o marginal soils leading to

soil erosion, landslides, and the rapid loss o habitat and

genetic diversity. The obvious outcomes are widespread

unemployment, poverty, poor health, and bad sanitation

(Price et al. 2000). These problems are amplied by

the unequal impacts o ecosystem degradation and the

unequal distribution o benets rom ecosystem services.

The latter is a paradox in that ecosystem services avourthe rich and powerul when pristine, and afict the poor

when degraded.

Rising population levels weigh heavily upon the resources

available per capita. Water supply is one o the major

challenges, because o the growing demand or water

driven by high population, increasing urbanisation,

and rapid economic and social development. With the

expansion o human settlements and rapid economic

growth, water has been increasingly used or the

treatment and disposal o waste, exacerbating water

shortages and reducing water quality. The replacement o

orests and wetlands by urban and agricultural ecosystems

generally increases the input o sediment, nutrients, and

Box 2: Synergistic eects o climate change and other

ecosystem stressors in the EH

Habitat loss and ragmentation:1. With temperaturerises and reduced precipitation, alpine meadows andshrubs may migrate to places higher up the mountains.However, this process will be constrained by

environments that do not have soils o sucient depthor anchorage and nutrient storage. Wetlands willshrink in response to high evaporation, which is urtherexacerbated by the expansion o settlements and otherhuman activities.

Invasive species:2. The rising temperature o waterbodies renders them more suitable habitats or

invasive species that outcompete native species andsynergistically interact with climate change to threatennative organisms.

Species exploitation:3. Synergistic action between

commercial harvesting and climate change will havedetrimental impacts on subtropical and temperatetimber orests.

Environmental contamination:4. Nutrient enrichmentrom agricultural runo could act synergistically withwarming water temperatures due to climate change to

enhance eutrophication in reshwater systems.


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toxic chemicals into rivers, streams, lakes, and estuaries.

Drainage (or agricultural and urban purposes) is the main

threat to reshwater wetlands, besides pollution and non-

native invasive species. While non-native invasive species

can orce out more benecial native marsh plants, high

levels o chemical pollutants can accumulate in wetlands

as pollutant carrying sediments are trapped in wetland

vegetation.

The EH suers rom both water overabundance and

extreme water shortages and acute moisture stress during

the dry months, which adversely aect the ecology and

agricultural production. A change in the onset, continuity,

and withdrawal patterns o the southwest monsoon in

recent years has also led to considerable spatial and

temporal variations in rainwater availability. At least hal

o the severe ailures o the Indian summer monsoon since

1871 have occurred during El Nio years (Webster et al.1998).

Forest ecosystems are stressed by habitat change and

ragmentation, which occurs as humans subdivide

orest plots into ever smaller and more isolated sections.

Fragmentation can result in reduced genetic diversity

within populations, loss o species, and increases in

undesirable, non-native, and weedy species. Large

continuous orest patches still exist in the regions

subtropical and warm temperate broadlea areas, but

orests in the regions tropical belts and foodplains are

now heavily ragmented. Forests are also threatened by

the invasion o non-native species. Pollution can also

stress orest trees, especially in urban, industrial, and

heavily populated areas. Non-native ungal diseases

and insect pests can severely stress orests and cause

the eective extinction o previously dominant trees and

threaten others. The most irreversible o human impacts

on ecosystems will most likely be the loss o native

biodiversity.

Stream fows are moderated in vegetated watersheds

because rain is absorbed into the ground and slowly

released into streams. Stream channelisation and wetland

loss increase the EHs vulnerability to precipitation

changes. An increase in the requency or intensity o

storms could exacerbate existing problems. In heavily

paved urban areas, increases in peak fows during

storms scour stream banks, which decreases reproductive

success, while reduced stream fow during dry periods

reduces available habitats or sh and aquatic insects.

According to the IPCC (2007a,b,d) increases inhydrological variability (such as greater foods and

longer droughts) could result in increased sediment

loading and erosion, degraded hillsides and watersheds,

reduced water quality, and reduced stability o aquatic

ecosystems, with the greatest impacts occurring in urban

areas with a high percentage o impervious surace

area. Sediments reduce water clarity, smother bottom

organisms, and clog waterways; excessive nutrient input

causes eutrophication; and toxic chemicals aect plants

and animals. These changes may reduce productivity and

biodiversity in streams and rivers (IPCC 1998).

Increased temperature is the most-oten cited primary

climate change driver. While this highlights the key role

o temperature and heat accumulation in ecological

systems, it also refects the reality that uture climate

change predictions related to temperature are the most

certain, ollowed by those or precipitation and other

climate variables (e.g., wind patterns, relative humidity,

solar radiation, cloud conditions). There is less certaintyregarding derived variables (e.g., soil moisture, potential

evapotranspiration), i such projections are available at

all.

Changes in long-term climate patterns and climatic

variability are likely to have signicant eects on natural

ecosystems, and a particularly large impact on the

already-stressed ecosystems o the eastern Himalayas.

For example, the traits o successul invasive species tend

to increase their resilience to a variety o disturbances,

including climate and non-climate stresses, and climate

change could work in concert with other stresses to urther

reduce populations o rare and endemic species, while

increasing populations o already abundant, widespread

species. Table 2 describes how climate variability and

change might impact on ecosystems already weakened

by other stresses.

Analytical Framework

Climate change is one o many possible stressors on

biodiversity. Climate change may maniest itsel as a

shit in mean conditions or as changes in the variance

and requency o extremes o climatic variables. These

changes can impact on biodiversity either directly or

indirectly through many dierent impact mechanisms.

Range and abundance shits, changes in phenology,

physiology, and behaviour, and evolutionary change

are the most oten cited species-level responses. At the

ecosystem level, changes in structure, unction, patterns

o disturbance, and the increased dominance o invasive

species is a noted concern. Having a clear understandingo the exact impact mechanisms is crucial or evaluating

potential management actions.


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Range/abundance

shits

Table 2: The potential or adverse ecosystem impacts when changes in climate and climate variability interact with existingstresses

Ecosystem Existing stress Interaction with climatic changes

Multipleecosystems

Non-native invasive species

Air pollution

Climatic changes will probably tend to avour invasive species over rare andthreatened species.Adverse interactions with climatic changes

Forests Fragmentation Fragmentation may hinder the migration o some species, and the loss o geneticdiversity within ragments will reduce the potential or populations to respond tochanging conditions through adaptive evolution.

Wetlands Habitat loss Habitat loss reduces the resilience o wetlands to the negative eects o storms,because wetlands play a role in moderating destructively high stream fows andpollution runo.

Freshwatersystems

Habitat degradation: streamchannelisation, altered streamfows in urban areasPollution: nutrients, sediments,toxic substances

Straightening o stream channels reduces resilience to destructively high fows.Increases in the requency or intensity o storms could exacerbate this problem.Increased precipitation could increase pollution runo.

In this synthesis, the assessment o biodiversity impacts

is structured using an Ecosystems/Species X Terrestrial/

Freshwater ramework, i.e., assessing biodiversity impacts

at ecosystem and species levels within unctional terrestrial

and reshwater systems. In short, this involves making

specic linkages along the continuum rom climate

change stressors to impact mechanisms and biodiversity

management endpoints. Figure 4 presents an overview

o the analytical ramework o climate change impacts on

biodiversity that shape the structure o this synthesis.

Limiting actors

One o the key diculties in any attempt to understand

climate change in the EH is to account or the modiying

eect o the high Himalayan range on weather and

climate, the complexity o the physiographic environment,

and the natural variations and cycles o the large-scale

monsoonal circulation. Despite these climate change

assessment challenges and major uncertainties, certain

conclusions are emerging. O particular relevance to

the EH is the conclusion that climate change eects in

the region are expected to occur aster and be more

pronounced than the global average (IPCC 2007a,d).

Figure 4: Conceptual ramework or the assessment o climate change impacts on biodiversity

mEcosyst iversity

divSpecies rsity

divGenetic ersity

limate change stressors Impact mechanisms Biodiversity

Freshwater Terrestrial

Changes inphenology/physiology

Evolutionarychange


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Table 3: Climatic eects o mountain actors

Factors Primary eects Secondary eects

Altitude Reduced air density, vapour pressure; increased solarradiation receipts; lower temperatures

Increased wind velocity (mid-latitude); increasedprecipitation (mid-latitude); reduced evaporation;physiological stress

Continentality Increased annual/diurnal temperature range; modied cloud/precipitation regimes

Snowline altitude rises

Latitude Seasonal variation in day length and solar radiation totals Snowall proportion increases; annual temperaturesdecrease

Topography Spatial contrasts in solar radiation/ temperature regimes andprecipitation as a result o slope and aspect

Diurnal wind regimes; snow cover related totopography

2 Climate Trends and Projections

Introduction

Due to the complexity o the topography and the

orographic eatures, it is more dicult to understand

climatic characteristics in the mountains than in the

plains. Existing knowledge o the climatic characteristics

o the EH is limited by both paucity o observations and

the limited theoretical attention paid to the complex

interaction o spatial scales in weather and climate

phenomena in mountains. In order to determine the

degree and rate o climatic trends, there is a need orlong-term data sets, which are currently lacking or most

o the EH. Research has tended to ocus on the infuence

o barriers on air fow and on orographic eects on

weather systems, rather than on conditions within the

mountain environment. As much as climate shapes the

mountain environment and determines its constituent

characteristics, so do the mountains in turn infuence

the climate and related environmental eatures through

altitude, continentality, latitude, and topography, each

o which aects several important climate variables. Theroles o these actors are summarised schematically in

Table 3. The mountain ecosystems not only signicantly

infuence atmospheric circulation, they also exhibit a great

deal o variation in local climatic patterns. These climatic

dierences are expressed in vegetation type and cover,

and geomorphic and hydrological eatures.

The Fourth Assessment Report (AR4) o the IPCC

concludes that changes in the atmosphere, the oceans,

and glaciers and ice caps show unequivocally that

the world is warming. It ur ther concludes that majoradvances in climate modelling and the collection

and analysis o data now give scientists very high

condence (higher than what could be achieved in the

Third Assessment Report) in their understanding o how

human activities are contributing to global warming. This

was the strongest conclusion to date, making it virtually

impossible to blame natural orces or global warming.

The average temperature increase across the globe

during the 20th Century has been around 0.74C.

These changes have been accompanied by changes

in precipitation, including an increase in precipitation

at higher latitudes and a decline at lower latitudes, and

an increase in the requency and intensity o extreme

precipitation events. Floods and droughts have also been

observed to be increasing in requency and intensity, and

this trend is likely to continue.

Projections o temperature increases in the 21st Century

have been made on the basis o established and

plausible scenarios o the uture. A warming o about

0.2C is projected or each o the next two decades

and the best estimate o temperature increase by theend o the 21st Century is placed at 1.8C to 4C.

These projections are based on the assumption that no

specic action is taken to mitigate GHG emissions. Hot

extremes, heat waves, and heavy precipitation events will

become more requent, uture tropical cyclones (typhoons

and hurricanes) are likely to become more intense, with

larger peak wind speeds and more heavy precipitation

associated with ongoing increases in tropical sea-surace

temperatures. Increases in the amount o precipitation are

very likely at high-latitudes, while decreases are likely in

most subtropical land regions (by as much as about 20%

in the A1B scenario in 2100) (IPCC 2007a).

limate Change Vulnerability o Mountain Ecosystems in the EH


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A growing number o studies on past climate and model-

based projections have been reported in recent times at

dierent spatio-temporal scales, some o which cover the

EH in part or as a whole. There are several constraints

and issues that need to be resolved at the policy,

institutional, and eld levels to improve the observational

and prediction basis or accurate and conclusive

statements on climate variability and change. There is

a need to probe deeper into the dynamics o mountain

climate systems in search o signs o climate change.

There has been limited coordination in such eorts across

the EH region, and the dierent countries in the region

have interpreted the existing observational and prediction

results within their respective political boundaries only,

despite the act that climate systems are large-scale

processes.

For this vulnerability assessment, it was necessary torefect on climate trends and projections determined at the

country level rom a large compilation o national reports.

In this synthesis, climate variability reers to day-to-day,

year-to-year, and decade-to-decade patterns o weather

and climate; climate change reers to longer trends,

usually measured by temperature and precipitation.

Historical climatic conditions provide the context or

potential uture changes.

Past inormation was consolidated and the latest updates

incorporated, and a synthesis review made with a

reassessment o climate trends and change projections

to the end o this century . The ndings conrm earlier

studies that temperatures will continue to rise and rainall

patterns will be more variable, with both localised

increases and decreases. The gures or the EH are not

a drastic deviation rom the IPCC outcomes or the South

Asian region. Nonetheless, they reinorce the scientic

basis or the contention that the EH is undergoing a

warming trend.

Trends

Few studies provide an exclusive and comprehensive

analysis o the EH. There is a need or a concerted eort

to ormally document the magnitude and direction o

climate trends that have taken place. Dash et al. (2007)

observed that during the last century the maximum

temperature increased over North East India by 1C

during winter and 1.1C during the post-monsoon

months. There have been small increases in rainall

during winter, pre- and post-monsoon seasons. They alsonoted a decreasing trend in high-intensity depressions

and cyclonic storms, but increases in the number o low

pressure areas during the monsoon. Conversely, another

study reported a slightly negative trend o -0.008 to

-0.06C in the annual mean temperature in North East

India rom 1960 to 1990 (APN 2003).

There have been investigations into climate trends and

characteristics in the Himalayan regions o southwest and

northwest China using time series data o varying lengths

(Yunling and Yiping 2005; Yin 2006). In the southwest

region covering the counties o Deqin and Weixi o the

Hengduan mountain range, over the observation period

o 41 years, the mean annual air temperature increased

at the rate o 0.01C/yr to 0.04C/yr. The changes in

precipitation, however, are very dierent and complex.

At some locations, mean annual precipitation decreased

by 2.9 to 5.3 mm/yr, and at others by 5.8 to 7.4 mm/

yr. Trends in air temperature were more signicant in the

dry season than in the rainy season, with precipitation

showing the opposite behaviour. Climate trends dieredrom climate element to climate element, region to region,

and season to season.

Signicant warming has been observed on the Tibetan

Plateau (Liu and Chen 2000), with warming more

pronounced at higher altitude stations, than lower

ones. The unexpected observed decreases in potential

evapotranspiration (PET) in Tibet AR has been linked to

reduced wind speed under the decreasing strength o the

Asian monsoon (Chen et al. 2006).

An increasing rate o warming with elevation was also

observed in a similar study encompassing the whole

physiographic region o Nepal using climatological

data rom 1977 to 2000 (updated rom Shrestha et al.

1999). The altitudinal dependency was less clear during

the post-monsoon period, with the middle mountain

region recording the highest positive trend (Table 4). The

results suggest that the seasonal temperature variability is

increasing and the altitudinal lapse rate o temperature

is decreasing. Unlike temperature, precipitation does notshow any consistent spatial trends. Annual precipitation

changes are quite variable, decreasing at one site and

increasing at a site nearby.

In Bhutan, the analysis o available observations on

surace air temperatures has shown a warming trend o

about 0.5C rom 1985 to 2002, mainly during the non-

monsoon seasons. Temperatures in the summer monsoon

season do not show a signicant trend in any major part

o the country. Rainall fuctuations are largely random

with no systematic change detectable on either an annualor monthly scale (Tse-ring 2003).


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Table 4: Regional mean temperature trends in Nepal 19772000 (C/year)

Seasonal Annual

Regions Winter Pre-monsoon Monsoon Post-monsoon Jan-Dec

Dec-Feb Mar-May Jun-Sep Oct-Nov

Trans-Himalaya 0.12 0.01 0.11 0.10 0.09

Himalaya 0.09 0.05 0.06 0.08 0.06

Middle Mountains 0.06 0.05 0.06 0.09 0.08

Siwalik 0.02 0.01 0.02 0.08 0.04

Terai 0.01 0.00 0.01 0.07 0.04

Source: updated rom Shrestha et al. (1999) and Xu et al. (2007)

Table 5: Changes in primary climate change drivers and climate system responses in the Eastern Himalayasrom 1977-2000

Climate change drivers Biophysical responses to climate changeAverage annual temperature increased by 0.01C in theoothills, 0.02C in the middle mountains, and 0.04C inthe higher HimalayasNight-time temperatures increased across most o the EH inspring and summerAnnual precipitation changes are quite variable, decreasingat one site and increasing at a site nearby

Duration o snow cover reduced and snow disappears earlierLess snowallFlow in river basins reduced/increasedGlacier retreat 20-30 m/yearNet primary production (NPP) increasedWetlands contractEarly spring and late autumn fowering

The technical papers written or this assessment capture

much o the detail on how the climate o the EH changedduring the 20th Century using a set o indicators including

primary climate change drivers (e.g., temperature,

precipitation), climate system responses (e.g., receding

glaciers, hydrological systems, water-related hazards),

and ecosystem responses (e.g., ecotone shits,

phenological changes, ecosystem structure, unction, type

and distribution, decoupled trophic levels). Some o the

changes detected in the primary climate change drivers

and climate system responses are summarised in Table 5.

Examination o observational records rom dierentsites distributed across the region, and an analysis o

the Climate Research Unit, University o East Anglia,

United Kingdom, dataset on global historical time series

(Mitchell et al. 2004) show that the global climate has

already changed signicantly. In the EH, the annual mean

temperature is increasing at a rate o 0.01C/yr (0.01-

0.04C yr-1) or higher. The warming trend has been

greatest during the post-monsoon season and at higher

elevations. Increases in temperature during the period

(1977-2000) have been spatially variable indicatingthe biophysical infuence o the land surace on the

surrounding atmospheric conditions. In general, there is

a diagonal zone with a south-west to north-east trend o

relatively less or no annual and seasonal warming. This

zone encompasses the Yunnan province o China, parto the Kachin State o Myanmar, and the North Eastern

states o India. Eastern Nepal and eastern Tibet record

relatively higher warming trends. Warming in the winter

(DJF) is much higher and more widespread. In addition, a

signicant positive trend with altitude has been observed

throughout the region. High altitude areas have been

exposed to comparatively greater warming eects than

those in the lowlands and adjacent plains.

The temperature trends in the three elevation zones are

given in Table 6. The analysis suggests the ollowingmajor points:

The Eastern Himalayan region is experiencing1.

widespread warming. The warming is generally

higher than 0.01C/yr.

Table 6: Temperature trends by elevation zone or theperiod 19772000 (C/year)

Elevation zone Annual DJF MAM JJA SON

Level 1: ( 4000 m) 0.04 0.06 0.04 0.02 0.03

Source: Shrestha and Devkota (2010)


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Table 7: Perceived changes in primary climate change drivers and climate system responses in the Eastern Himalayas

Climate change drivers Biophysical responses to climate change

Temperatures have been rising across the entire region, with winterand spring temperatures rising more rapidly than those in summerThe daily temperature range has gone downTotal annual precipitation has increased in some areas anddecreased in others

Longer growing seasonReduced snowall in requency and amountTree line moving to higher elevationIce elds contractingBiomass increase in wetlands

The highest rates o warming are occurring in winter2.

(DJF) and lowest or even cooling trends are observed

in summer (JJA).

There is progressively more warming with elevation,3.

with the areas >4000 m experiencing the highest

warming rates.

The results rom the stakeholder workshops and the

questionnaire survey on peoples perceptions o climate

change in the region are presented in the technical

report on biodiversity (Chettri et al 2010). Some o the

perceived changes in primary climate change drivers and

climate system responses are summarised in Table 7.

Projections

A considerable amount o work has been done to predict

uture climates by downscaling General Circulation

Model (GCM) outputs using statistical or dynamic

methods. In most cases, the results are not comparable

due to dierences in the choice o GCMs, spatial and

temporal resolutions, emission scenarios associated with

diverse socioeconomic assumptions, and the ormats

in which the results are published, although all o them

describe plausible models o uture climate meaningul

to the research context. For this assessment, climate

scenarios were reconstructed specically or the EH

domain using data generated by recent model runs

at regional and global levels. The climate scenariosdeveloped are summarised rst to put the remaining

results into perspective.

Regional projections

The current spatial resolution o general circulation models

(GCMs) is generally too crude to adequately represent

the orographic detail o most mountain regions and

inadequate or assessing uture projections in the regional

climate. Since the mid-1990s, the scaling problem

related to complex orography has been addressedthrough regional modelling techniques, pioneered by

Giorgi and Mearns (1991), and through statistical-

dynamic downscaling techniques (e.g., Zorita and von

Storch 1999). The ollowing discussion o potential

ecological responses to changes in climate and climate

variability primarily uses the Indian Institute o Tropical

Meteorology (IITM) regional climate scenarios, which are

based on a transient HadCM3 model downscaled using

HadRM2 and PRECIS (Providing Regional Climates or

Impacts Studies; Hadley Centre) regional climate models

(RCMs) run under two uture GHG emission scenarios

(A2 and B2 o the SRES [Special Report on Emissions

Scenarios]). This approach, which applies general

methods in accordance with the IPCC Data Distribution

Center guidelines on the use o scenario data or impacts

and adaptation assessments (IPCC-TGCIA 1999), allows

us to identiy both potential trends and the range o

uncertainty around them. The discussion is rather general

and presumes no major surprises due to uncertainties

regarding the rate, magnitude, spatial distribution, and

seasonality o temperature and precipitation changes.

In order to accommodate some level o sensitivityanalysis, the RCM simulation runs were supplemented

with data rom the IPCCs SRES runs perormed with

three Coupled General Circulation Models (GCMs), the

HadCM3, CGCM2, and CSIRO Mk2, interpolated to

higher temporal and spatial resolution or the development

o WorldClim (www.worldclim.org) (Hijmans et al.

2005). The GCM results are given as 30-year monthly

mean changes (i.e., no inormation is presented about

changes in inter-annual or inter-daily variability). All

data is extracted as change values, expressed either in

absolute or percentage terms using the 1961 to 1990

model-simulated baseline period. Results are, thereore,

generally reported as the change between the 1961

to 1990 30-year mean period, and the uture 30-year

mean periods (2020s, 2050s or 2080s). These time

periods represent 30-year mean elds centred on the

decade used to name the time period, e.g., the 2020s

represent the 30-year mean period 20102039, the

2050s represent 20402069 and the 2080s represent

20702099. For all the models, the response to the

middle orcing emission scenarios A2 and B2 wasreerred to, and uture climate change was presented or

two 30-year time slices centred on the 2020s and 2050s

or WorldClim using HadCM3, and 2050s and 2080s

or HadRM2 and PRECIS, each relative to the baseline

period 19611990. Among the three models, the

HadCM3 provided the closest match to observed data.


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Figures 5 and 6 show maps o the spatial variation o

mean annual temperature change and mean annual

precipitation change, respectively, or each scenario

at each uture time period based on the interpolatedHadCM3 (2020s and 2050s) and PRECIS (2080s)

simulation runs. By the 2080s, the mean annual

temperature change or all o the EH is shown to be

in the range o +2.9 to +4.3C and the mean annual

precipitation change in the range o 13 to 34%. The

PRECIS simulation indicated a slightly higher warming

in winter than in summer . Changes in monsoon

precipitation showed enormous spatial variability

predicted to range anywhere between minus 20% to plus

50% o the baseline period.

The mean projected annual temperature and precipitation

changes under three GCMs plus PRECIS, three time-slices,

and two SRE scenarios are summarised in Table 8, to

present a wider range o uture climate scenarios. The

dierences across the scenario results reinorces the need

to explicitly recognise and account or the uncertainties

that exist in projections o uture climate. That said, the

results are generally consistent with those reported by

the IPCC or the northern hemisphere (IPCC 2001a)

although the magnitude o climate change is predictedto be greater or the EH than that projected by the IPCC

or the Asia region both or the mid and or the end o

the century. Future winters are likely to experience larger

temperature increases above the current level. Such

increases will be greater under the SRES A2 emission

trajectory, which describes the region as geared towards

economic development with a regional orientation instrategic approaches. Precipitation changes will be

greater in winter and spring, while the monsoon season is

not expected to experience signicant changes in mean

conditions. There are important seasonal dierences

and trends that are not generally refected in these

annual maps. The seasonally dierentiated values are

summarised in Table 9. Any specic impact assessment

that is sensitive to seasonal climate trends would need to

generate maps and data specic to the season o interest.

Temperature scenarios vary across space and over time,but show a clear trend towards warming with average

projected increases rom 0.80 to 0.99C (2020s)

to 2.06 to 2.22C (2050s) across the A2 and B2

scenarios calculated with HadCM3, and rom 0.49

to 1.11C (2020s), and 1.43 to 1.90C (2050s) or

A2 across GCMs, with the greatest increase in the high

altitude area. All the GCMs indicated a higher rate o

warming at higher elevations.

The spatial variation o changes in precipitation wasconsiderable with enormous contradictions between the

models in the pattern o changes. HadCM3 projected

a decrease in precipitation along the northeastern

Table 8: Summary o plausible uture climates considered or the assessment o the Eastern Himalayas in terms o character,magnitude and rate

Time slice Exposure Climate model/SRES scenario

HadCM3/A2 HadCM3/B2 CGCM2/A2 CSIROMk2/A2

2020s T (C) 0.99 0.80 0.49 1.11

P (%) 5.43 4.55 47.05 12.40

2050s T (C) 2.22 2.06 1.43 1.90 P (%) 14.07 6.23 60.80 18.96

2080sa T (C) 4.3 2.9

P (%) 34 13

a Values rom PRECIS RCM runs; T = mean annual temperature change; P = mean annual precipitation change

able 9: Climate change projections for the Eastern Himalayas based on RCM outputs

Temperature change (C) HadRM2 PRECIS (B2) PRECIS (A2) Precipitation change (%) HadRM2 PRECIS (B2) PRECIS (A2)

Winter (DJF) 3.2 3.6 5.3 Winter (DJF) 57 23 35

Spring (MAM) 2.0 2.6 3.8 Pre-monsoon (MAM) 46 8 46

Summer (JJA) 3.0 2.8 3.8 Monsoon (JJA) 17 28

Autumn (SON) 3.2 2.5 4.3 Post-monsoon (ON) 15 12 18

Annual 2.9 2.9 4.3 Annual 18 13 34

Notes: HadRM2 is used for 2050s for 2xCO2

and PRECIS for 2080s for A2 and B2 SRES scenarios.

Source: Shrestha and Devkota (2010)


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Figure 5: Spatial variation o mean annual temperature changes (C) over the EH

2020s

Notes: A2 and B2 scenarios are simulated by HadCM3 (2020 and 2050) and PRECIS (2080).Changes are relative to the 19611990 model-simulated baseline period.Maps in the 2080s row show mean annual and winter temperature changes under the B2 scenario.

0.00 0.110.12 0.220.23 0.340.35 0.450.46 0.570.58 0.680.69 0.800.81 0.820.93 1.031.04 1.151.16 1.261.27 1.381.39 1.491.50 1.611.62 1.721.73 1.85

0.00 0.090.10 0.190.20 0.290.30 0.380.39 0.480.49 0.580.59 0.680.69 0.780.79 0.880.89 0.970.98 1.071.08 1.171.18 1.271.28 1.371.38 1.471.48 1.58

0.00 0.200.21 0.410.42 0.610.62 0.820.83 1.031.04 1.241.25 1.441.45 1.651.66 1.861.87 2.072.08 2.282.29 2.482.49 2.692.70 2.902.91 3.113.12 3.33

0.00 0.190.20 0.390.40 0.590.60 0.790.80 0.991.00 1.191.20 1.391.40 1.591.60 1.791.80 1.992.00 2.192.20 2.392.40 2.592.60 2.792.80 2.993.00 3.20

2080s

2050s

Period

A2

A2

B2

B2

B2

B2


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Figure 6: Spatial variation o mean annual precipitation changes (%) over the EH

Notes: A2 and B2 scenarios are simulated by HadCM3 (2020 and 2050) and PRECIS (2080).Changes are relative to the 1961-1990 model-simulated baseline period.Maps in the 2080s row are or monsoon season (JJA).

-7.03 5.56-5.55 4.07-4.06 2.58-2.57 1.10-1.09 0.390.40 1.871.88 3.363.37 4.844.85 6.336.34 7.817.82 9.309.31 10.79

10.80 12.2712.28 13.7613.77 15.2415.25 16.74

-23.08 -20.10-20.09 -19.10-17.09 -14.11-14.10 -11.12-11.11 -8.13-8.12 -5.14-5.13 -2.15-2.14 0.850.86 3.843.85 6.836.84 9.829.83 12.8112.82 15.8015.81 18.8018.81 21.7921.80 24.79

-14.84 10.94-10.93 7.03-7.02 3.12-3.11 0.790.80 4.704.71 8.628.63 12.5312.54 16.4416.45 20.3520.36 24.2624.27 28.1728.18 32.0932.10 36.0036.01 39.9139.92 43.8243.83 47.74

-10.53 8.77-8.765 7.00-6.99 5.23-5.22 3.46-3.45 1.69-1.68 0.080.09 1.851.86 3.623.63 5.395.40 7.167.17 8.938.94 10.70

10.71 12.4712.48 14.2414.25 16.0116.02 17.79

2020s

2080s

2050s

Period

A2 B2

A2 B2

B2


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ringes o the region, while the CSIRO-Mk2 projected a

decrease along the southeaste

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Climatevchangevvulnerability and Mountain Ecosystem