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BIOGEOSPHERIC CHANGE
RESPONSE OF ECOSYSTEM STRUCTURE AND DISTRIBUTION TO ALTERED FORCING
© 2007 T. Kittel
Clarice Bassi - Anavilhanas
DRIVERS OF FUTURE ECOLOGICAL CHANGE: MULTIPLE FACTORS
Climate Change – Anthropogenic forcings:• Greenhouse gas emissions (GHG): CO2, CH4, N20, etc• Sulfate aerosols (SUL), Cloud condensation nuclei (dust, ..)• Landuse change Surface biophysical properties• Stratospheric Ozone
Disturbance – Landuse change:• Deforestation, cropland conversion• Overgrazing, desertification• Invasive species
Direct Chemical Effects:• CO2
• N deposition / acid deposition• Toxic pollution: Tropospheric ozone, Salt accumulation, …
The Source – Anthropogenic ForcingGreenhouse Gas Emissions
Dioxide
Increasing CO2 –
• Fossil fuels• Land conversion• Biomass burning
Effects =• Radiatively-active
Climate effect
• Biologically-active: Increased water and nutrient use efficiency Fertilization
Roads & fires - Amazon
Landcover Change
The Source – Anthropogenic Forcing
Changes in energetics & hydrology of the terrestrial surface
Changes in ecosystem biogeochemistry & emissions
Regional to global climate
Aircraft tracks, Bay of Biscay, E Atlantic
Aerosols – sulfate, dust, soot, sea salt, …
The Source – Anthropogenic Forcing
Haze / Cloud Condensation Nuclei
Changes in radiative properties of the atmosphere
Dust from Gobi Desert embedded in a storm approaching California
Manifestation of Change – Climate
1901-2002 Hemispheric Animation
Surface Air Temperatures
1850-2005
“We are entering a period of consequences” - Winston Churchill
Manifestation of Change - Biosphere
Estimated changes in net primary productivity 1982-1999
• Increased North American NPP
The Future – Climate
• Projected Change – Annual Surface Air Temperature
2020’s 2090’s
Change (°C) relative to 1980-1999
Greatest response in the Northern High Latitudes
The Future – Climate
• Projected Change – Precipitation: Northern Winter
% Change relative to 1980-1999
2090’s
SCIENTIFIC UNCERTAINTIES: CLIMATE SENSITIVITY
• Emission scenarios Business-as-usual Carbon Stabilization
• Climate model differences
= the shaded envelop
Models similar conceptually
Different responses driven by –
Different model representations
Uncertainties in scaling up microphysical processes
– ppt, radiation & clouds
‘The devil is in the details’
Business as Usual
CO2 Stabilization
(http://www.ipcc.ch/present/graphics.htm)
CGCM1
HADCM2SUL MC1LPJ
• Model Uncertainty – Total Ecosystem Carbon
Uncertainty – Sources
“Same Ecology, Different Results”- at the regional level
(1) Very character of regional climates will likely change over the next decades:
• Multivariate Higher surface temperatures – different responses for
Tmin Tmax
Regionally varying changes in precipitation, cloud cover (light regime), wind regimes, etc.
• In means, but in also seasonality and interannual
variability• Trends likely not to be monotonic
As circulation patterns shift, & the system passes thresholds
• Giving rise to novel climates
The Certainties – Climate
“What do we know for sure?”
(2) Probable climate changes are of a magnitude and character to be significant for populations, communities, and landscapes:
• Geographic ranges
• Phenologies/life cycles
• Species interactions out of phase: Foodwebs, competition, pollination
• Ecosystem structure & function Resilience of many ecosystems is likely to be
exceeded
• Giving rise to novel ecosystem types
Certainties – The Biosphere
(3) The magnitude of uncertainties ≥ magnitude of system sensitivity
The magnitude of what’s certain will change everything
Certainties – The Biosphere
ACTION UNDER SUFFICIENT BUT LIMITED KNOWLEDGE?
“Least regrets” policy approach –
Develop policy that doesn’t rely on any single scenario of future change, but which reduces overall system vulnerability
• Maintain or restore integrity of natural systems Large preserves, landscape corridors, Clean Water Act … A focus on ecosystem services
• Develop infrastructure enhancing resiliency of socio-economic systems – to changes in climatic forcing regardless of direction
Landuse policy in areas currently prone to fire, flooding, hurricanes …
Individual Action –Carbon & ecological sustainabilityCommunity involvement
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