Weather, climate and the greenhouse effect

LSGI1B02Climate Change and Society

Impacts of Climate Change, with special reference to Hong Kong Lecture 92

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Global weirding The weather gets weird. The hots are expected to get hotter, the wets wetter, the dries drier and the most violent storms more numerous. 3

Griedman : Avoid the term global warming. I prefer the term global weirding, because that is what actually happens as global temperatures rise and the climate changes. The weather gets weird. The hots are expected to get hotter, the wets wetter, the dries drier and the most violent storms more numerous.

Its useful to compare fever with global warming because the latter is more than just a rise in temperatureRegional impacts strongest, also hardest to predict.

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National Geographic picturePictorial Examples of worldwide ImpactsSlide 4 -11

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More temperature colours needed for 2013!

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Global Warming Has Increased Monthly Heat Records Worldwide by a Factor of Five, Study FindsJan. 14, 2013 Monthly temperature extremes have become much more frequent, as measurements from around the world indicate. On average, there are now five times as many record-breaking hot months worldwide than could be expected without long-term global warming, shows a study now published in Climatic Change. In parts of Europe, Africa and southern Asia the number of monthly records has increased even by a factor of ten. 80 percent of observed monthly records would not have occurred without human influence on climate, concludes the authors-team of the Potsdam Institute for Climate Impact Research (PIK) and the Complutense University of Madrid.

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Fire are detected by MODIS satellites, only those with wattage > 100MW were retained. Up to July 2012. Note that Daya Bay has two 944 MWe nuclear power plants.

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Air pollution level in Moscow 10 times normal, 2010 forest fire.7

Mar 22, 2010 Hong Kong: As the sandstorm from northern China is moving southward with the northeast monsoon and is now affecting Hong Kong, the Air Pollution Index is expected to reach the 'very high' or 'severe' level," the government said in a statement.Wildfires May Contribute More to Global Warming Than Previously PredictedJuly 9, 2013 Wildfires produce a witch's brew of carbon-containing particles, as anyone downwind of a forest fire can attest. A range of fine carbonaceous particles rising high into the air significantly degrade air quality, damaging human and wildlife health, and interacting with sunlight to affect climate. But measurements taken during the 2011 Las Conchas fire near Los Alamos National Laboratory show that the actual carbon-containing particles emitted by fires are very different than those used in current computer models, providing the potential for inaccuracy in current climate-modeling results.Weve found that substances resembling tar balls dominate, and even the soot is coated by organics that focus sunlight, said senior laboratory scientist Manvendra Dubey, Both components can potentially increase climate warming by increased light absorption.

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Will there be light at the end of the tunnel?Pakistan, 2010

More snowstorms Chinas extreme case in 2008

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9Freezing conditions and abnormal atmospheric conditions led to the worst snow storms since 1954 across large parts of mainland China in the three weeks immediately before (and one week after) the 2008 Lunar New Year holiday. The unfortunate timing, location, considerable extent and persistence of the snow storms combined to result in significant economic damage and disruption, the direct cost of which has been estimated to be at least USD 15.4 billion, and may be as high as USD 21 billion. Market insured losses are much lower however, estimated at between USD 0.28 to 1.2 billion, reflecting the low penetration of insurance in most sectors of the economy.

Meteorological factor: La Nina, blocking high resulting in frequent intrusion of cold air, strong sub-tropical ridge bringing warm moist air aloft.

354,000 houses and buildings collapsed under snow loading (Yiran, 16/02/08), with a further 1.4 million properties damaged (Bloomberg, 16/02/08). Subsequent reports put the total number of collapsed houses at 485,000 (E&EF, 23/02/08; Terra Daily, 24/02/08).

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The polar vortex is an area of low pressure defined by a circulation of strong winds (jet stream) blowing around the centre. The speed of the jet stream depends on the temperature difference between the Arctic and the mid-latitudes. As the Arctic warms faster, the temperature difference narrows, leading to a decrease in wind speed of the jet stream. The effect can be liken to opening the door of the refrigerator, with the cold air spreading out. Places in the south where the Arctic air normally cannot reach is now occasionally affected by polar air hence exceptionally cold weather in US in 2013/2014.

In addition to intrusion of cold air, the meandering of the jet stream also implies reduced mobility of the wave cold weather condition could last longer than previously.10

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Selection of record-breaking meteorological events since 2000, and the confidence level that the event can be attributed to climate change.12

Source: Turn down the heat a report for the World Bank by the Potsdam Institute for climate impact research and climate analysis, 201212

Basic concepts of climate change impactClimate change impacts 1st order : temperature rise, precipitation shift; 2nd order : sea level rise, increase in vector population, health, hill fire 3rd order : coastal erosion, impact to ecosystem, food production; impacts are the damage report of climate change.Vulnerability : exposure (magnitude, timing, distribution, persistence, likelihood of impacts, climate dynamics) + sensitivity (effect as a function of the magnitude of change; a mixed issue natural and social) + adaptive capacity, largely social issues, except for ecosystems); IPCC definition: vulnerability is the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change, and variability and extremes. Vulnerability is a function of the character, magnitude and rate of climate change and variation to which a system is exposed, its sensitivity, and its adaptive capacity. Resilience in natural and human systems : ability to return to a healthy state following a change or shock.

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Vulnerability: Susceptible to physical or emotional injury, damage etc.

Example: a house building in an low lying area with little drainage (sensitive) but very little rainfall or flood (low exposure)13

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Potential impacts of climate change15

UNEP graphics. Design: Philippe Rekacewicz

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Impact to Asia, IPCC AR5

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Health

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Health - Casual pathways

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ARI acute respiratory infection18

Change of Net Effective Temperature (NET: effect of temperature, wind and RH combined)

Summer NETWinter NET

Mortality due to excessive heat (heat stroke) and daily maximum NET in Summer

Normalized mortalityDaily maximum NET20

The distribution is normalized by dividing the mortality by the corresponding frequency of occurrence of the NET category. From this figure, deaths associated with EHEAT start to occur when the daily maximum NET exceeds 26 and the normalized mortality increases sharply thereafter as NET increases. Thus the mortality associated with EHEAT is expected to rise with the trend of increasing NET. 20

Mortality due to excessive cold (hypothermia) and daily minimum NET in WinterNormalized mortality Daily Minimum NET

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PE-Link: Personal emergency link service () ( )

Senior Citizen Home Safety Association (SCHSA) was founded by a group of passionate individuals in 1996, offering key services including the Personal Emergency Link Service (PE Link Service) and the Elder Ring Hotline Service. During the past 15 years, SCHSA has been developing services for the elderly based on their specific needs, and the PE Link Service has recorded more than 150,000 service users. SCHSA has a vast partnership network and is also the only non-profit making charitable organization in Hong Kong that collaborates with Hospital Authority in transferring electronic patient records of service users to Accident & Emergency (A&E) Department*. 22

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Risk to human health - malaria24

Source: Dr Anthony McMichael, Australian National University24

Impact to HKHealth - Dengue fever

Ovitrap ( ) provides data to study conditions favourable for reproduction (Aedes albopictus)Ovitrap Index = No. of Aedes-positive ovitraps / No. of ovitraps collected from the specific area x 100%25

Ovitrap Index = No. of Aedes-positive ovitraps / No. of ovitraps collected from the specific area x 100%25

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=eaT (bR2 + cR + d) :ovitrap indexT: mean temperature from D-15 to D+6 R: total rainfall from D-15 to D-1 a, b, c, d : constants

Mathematical model for ovitrap index29Air temperature and rainfall are the most important parameters.

Relative humidity is also correlated, but is considered a secondary parameter to temperature and rainfall.

Wind strength/direction affects distribution.

Health problems due to O3 Worst cases are days of high temperature

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Regression was carried out 3 times. In the first time, the entire data set was studied. In the second time, the analysis was repeated using only those records with ozone that exceeded 240g/m3. The third analysis was repeated using only those records with temperature that exceeded 32oC.

when the temperature was below 15C, ozone concentration never exceeded 100 g/m3.Ozone levels higher than 150 g/m3 only occurred when the temperature exceeded 22oC. On the side with high temperature and high ozone level, when temperature exceeded 30oC, very high ozone level was detected. At this high end quadrant, the daily peak ozone concentration has a tendency to increase with temperature. This ozone-temperature correlation was more obvious on exceedance days.

Wackter & Bayly, 1988 reported a linear relationship between ozone and temperature. IPCC also pointed out that the ozone level is highly associated with temperature when the temperature is greater than 32oC.30

Hedley Environmental Index, HKU

31http://hedleyindex.sph.hku.hk/html/en/

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Changes in tick habitat 32

US Global Change Research Program

Tick transmit Lyme disease. Lyme diseaseis abacterial infectiontransmitted by a tick.Lyme diseasewas first recognized in 1975, after researchers investigated why unusually large numbers of children were being diagnosed withjuvenile rheumatoid arthritisin Lyme, Conn., and two neighboring towns.

The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children's first symptoms typically started in the summer months coinciding with the height of the tick season.

Several of the patients reported having a peculiarskin rashjust before developingarthritissymptoms, and many also recalled being bitten by a tick at therashsite.

US Global Change Research Program : http://www.globalchange.gov/browse/multimedia/projected-changes-tick-habitat

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Tick-borne disease in China

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Distribution of tick-borne diseases in China by Xian-Bo Wu1,Ren-Hua Na2,Shan-Shan Wei2,Jin-Song Zhu3andHong-Juan Peng2*, 2013

As an important contributor to vector-borne diseases in China, in recent years, tick-borne diseases have attracted much attention because of their increasing incidence and consequent significant harm to livestock and human health. The most commonly observed human tick-borne diseases in China include Lyme borreliosis (known as Lyme disease in China), tick-borne encephalitis (known as Forest encephalitis in China), Crimean-Congo hemorrhagic fever (known as Xinjiang hemorrhagic fever in China), Q-fever, tularemia and North-Asia tick-borne spotted fever. In recent years, some emerging tick-borne diseases, such as human monocytic ehrlichiosis, human granulocytic anaplasmosis, and a novel bunyavirus infection, have been reported frequently in China. Other tick-borne diseases that are not as frequently reported in China include Colorado fever, oriental spotted fever and piroplasmosis.33

Agriculture & food security

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The world has enough food for everyone, but not everyone has enough food

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Reasons : the food in the wrong place, unaffordable, cant be stored long enough more of a political problem than scientific problem.35

No. of undernourished people% of undernourished people36

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FAO, 201037

Optimum calorie intake for a grown up male adult: around 230037

Key risks for food security, AR5, IPCC

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() Least developed countries39

Plant growth rate vs temperature

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For each plant variety, there is an optimal temperature for vegetative growth, with growth dropping off as temperatures increase or decrease. Similarly, there is a range of temperatures at which a plant will produce seed. Outside of this range, the plant will not reproduce. As the graphs show,corn will fail to reproduce at temperatures above 95F andsoybean above 102F.40

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O3 : 1 ppb = 2.00 g/m3

Being a powerful oxidant, O3 and its secondary by-products damage vegetation by reducing photosynthesis and other important physiological functions (Mills et al., 2009; Ainsworth and McGrath, 2010). This results in stunted crop plants, inferior crop quality, and decreased yields.

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Decrease in productivityNatural disasters - floods, tropical storms, drought are on the increase In many countries, climate changeis exacerbating already adverse natural conditions. Increasingly, the world's fertile farmland is under threat from erosion, salination and desertification. Deforestation by human accelerates the erosion of land.

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Deforestation reduces the critical part trees play in the water cycle. When rainfall is reduced in the region, droughts would become more frequent, bringing about major environmental impacts.

New roads that provide access to settlers and loggers into the Forests of Papua New Guinea can cause widespread fragmentation of rainforests which can no longer support wildlife the same way intact habitats do.42

US sweet corn failure, 2012;Popcorn prices soared from $20 per 50-pound bag to $30 and higher.

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Aug 2012: CHICAGO Some farmers are selling off their livestock herds because they can't afford to buy feed, marking a new level of fallout from the drought that will affect consumers and possibly the entireU.S.economy.43

Queensland drought

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Main issues of food security

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IPCC AR5: Main issues of the chapter. Drivers are divided into climate and non-climate elements, affecting production and non-production elements of food systems, thereafter combining to provide food security. The thickness of the red lines is indicative of the relative availability of refereed publications on the two elements

Being a powerful oxidant, O3 and its secondary by-products damage vegetation by reducing photosynthesis and other important physiological functions (Mills et al., 2009; Ainsworth and McGrath, 2010). This results in stunted crop plants, inferior crop quality, and decreased yields.45

International Food Price 46

Since the AR4, international food prices have reversed historical downward trend.

The plot shows the history of FAO food and cereal price indices (composite measures of food prices), with vertical lines indicating events when a top five producer of a crop had yields 25% below trend line (indicative of a seasonal climate extreme). Australia is included despite not being a top five producer, because it is an important exporter and the drops were 40% or more below trend line. Prices may have become more sensitive to weather-related supply shortfalls in recent years. At the same time, food prices are increasingly associated with the price of crude oil (blue line), making attribution of price changes to climate difficult. Thus, there is clear evidence since AR4 that prices can rise rapidly, but the role of weather in these increases remains unclear. All indices are expressed as percentage of 20022004 averages. Food price and crop yield data from FAO(http://www.fao.org/worldfoodsituation/foodpricesindex and http://faostat.fao.org/) and oil price data from http://www.eia.go46

Estimates of impact of recent climate trend on yields of 4 major crops

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Summary of estimates of the impact of recent climate trends on yields for four major crops.

Studies were taken from the peer-reviewed literature and used different methods (i.e., physiological process-based crop models or statistical models), spatial scales (stations, provinces, countries, or global), and time periods (median length of 29 years).

Some included effects of positive carbon dioxide (CO2 ) trends but most did not.

Number of estimates with different level of impact (% yield per decade). Boxplot of estimates separated by temperate vs. tropical regions, modeling approach, whether CO2 effects were included, and crop. Boxplots indicate the median (vertical line), 25th to 75th percentiles (colored box), and 10th to 90th percentiles (white box) for estimated impacts in each category, and numbers in parentheses indicate the number of estimates. Studies were for China, India, USA, Mexico ,), Australia, Russia, and some studies for multiple countries or global aggregates and Scotland.Values from all studies were converted to percentage yield change per decade. Each study received equal weighting as insufficient information was available to judge the uncertainties of each estimate.47

Simulated changes in yields of 11 crops for 2050, averaged across 3 GHG emission scenarios and 5 GCM (world bank)

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The broad-scale pattern of climate change impacts on crop productivity and production has remained consistent across all of these global studies spanning almost 20 years of research. Crop yields are more negatively affected across most tropical areas than at higher latitudes, and impacts become more severe with an increasing degree of climate change. Furthermore, large parts of the world where crop productivity is expected to decline under climate change, coincide with countries that currently have a high burden of hunger. There is a robust and coherent pattern on a global scale of the impacts of climate change on crop productivity and, hence, on food availability and that climate change will exacerbate food insecurity in areas that already currently have a high prevalence of hunger and undernutrition.48

Yield of maize and wheat against temperature rise49

Yield of maize and wheat begin to decline with 1 2 degrees of warming in the tropics. Temperate maize and tropical rice yields are less clearly affected at these temperatures, but significantly affected with warming of 3 5 degrees.

Percentage simulated yield change as a function of local temperature change for the three major crops and for temperate and tropical regions. Dots indicate where a known change in atmospheric CO2 was used in the study; remaining data are indicated by x. Note that differences in yield value between these symbols do not measure the CO2 fertilization effect, as changes in other factors such as precipitation may be different between studies. Non-parametric regressions (LOESS, span = 1 and degree = 1) of subsets of these data were made 500 times. These bootstrap samples are indicated by shaded bands at the 95% confidence interval. Regressions are separated according to the presence (blue) or absence (red) of simple agronomic adaptation (Table 7-2). In the case of tropical maize, the central regression for absence of adaptation is slightly higher than that with adaptation. This is due to asymmetry in the datanot all studies compare adaptated and non-adapted crops. Figure 7-8 presents a pairwise adaptation comparison. Note that four of the 1048 data points across all six panels are outside the yield change range shown. These were omitted for clarity. Some of the studies have associated temporal baselines, with center points typically between 1970 and 2005. Note that local warming in cropping regions generally exceeds global mean warming (F49

Impact of climate and CO2 change on crop yields for all available crops

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51Summary of projected changes in crop yields, due to climate change over the 21st century

Figure SPM.7: Summary of projected changes in crop yields, due to climate change over the 21st century. The figure includes projections for different emission scenarios, for tropical and temperate regions, and for adaptation and no-adaptation cases combined. Relatively few studies have considered impacts on cropping systems for scenarios where global mean temperatures increase by 4oC or more. For five timeframes in the near-term and long-term, data (n=1090) are plotted in the 20-year period on the horizontal axis that includes the midpoint of each future projection period. Changes in crop yields are relative to late-20th-century levels. Data for each timeframe sum to 100%. 51

Food Security in China if no effective measures are taken, agricultural production in China may decrease by 5 10%, with the three main crops suffering reduction in production (causes: rising temperature, more frequency drought/flood, water shortage etc.)WheatRiceCorn52

National relative yield loss (%) in 2030 (B1 scenario) for (a) soybean, (b) maize and (c) wheat as a result of O3 increases53

Global crop yield reductions due to surface ozone exposure: 2. Year 2030 potential crop production losses and economic damage under two scenarios of O3 pollutionShiri Avnerya, , Denise L. Mauzerallb, , , Junfeng Liuc, , Larry W. HorowitzcSurface ozone (O3) is the most damaging air pollutant to crops and ecosystems (Heagle, 1989). It is produced in the troposphere by catalytic reactions among nitrogen oxides (NOx=NO+NO2), carbon monoxide (CO), methane (CH4), and non-methane volatile organic compounds (NMVOCs) in the presence of sunlight. Ozone enters leaves through plant stomata during normal gas exchange. As a strong oxidant, ozone and its secondary byproducts damage vegetation by reducing photosynthesis and other important physiological functions, resulting in weaker, stunted plants, inferior crop quality, and decreased yields .

M12 and AOT40 are standards to assess potential vegetation damage from ozone exposure .53

Projected impact of climate change on agricultural yield (compared to 2003 levels)54

Source: European Environment Agency

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Water security

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Longitudinally averaged 1950-2000 precipitation56

Longitudinally averaged 21st century precipitation change a redistribution of water resource57

Monsoons - not the same worldwide

American southwest medieval drought (dust bowl was a picnic compared with the drought that cause the demise of Mayan civilization)China highlands - drierSouth Asian monsoon - dry spells increase in frequency and wet spells increase in intensity (Nature Climate Change, 2014) although there is yet no consensus.58

Fig. Change in the mean annual range of precipitation: 1976 to 2003 minus 1948 to 1975 periods (mm per day). Blue/green (red/yellow) colour denotes a decreasing (increasing) annual range of the monsoon rainfall. Grey areas indicate missing values (oceans) or areas with insignificant annual changes. IPCC AR4, 2007

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Water Tower of Asia

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The Roof of the World - The seasonal melting of snowpack and mountain glaciers feeds the seven major rivers of Asia, the Yangtze, the Yellow River, the Ganges, the Indus, the Brahmaputra, the Salween, and the Mekong, providing the fresh water supply to a large portion of the population of Asia. In this regard, the Himalayas and Tibetan Plateau could be aptly called the `Water Tower of Asia'.

In recent years, there has been growing evidence of increased warming, accompanied by early snow melt, and retreat of high mountain glaciers in the Himalayas regions. Particularly in the western and central Himalayas, the rate of retreat has been increasing in recent decades. The early snow melt and rapid retreat of glaciers in the Himalayas pose serious and unprecedented threats to the fresh water supply of the entire Asia population .

Already glacier melt has led to soil erosion, bursting of glacier lakes, with enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols.

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Hong Kong situation - rainfall, water collected, water imported (1965 2012)

Source: Civic Exchange, http://www.civic-exchange.org/wp/wp-content/uploads/2013/07/201307LiquidAssets4_en.pdf60

The average annual rainfall post-1997 exceeded pre-1997 levels by 6 percent, but the average annual rainfall collected decreased by 12 percent. On average, in the pre-1997 era, the amount of water taken from the Dongjiang was almost equal to the amount of rainfall collected each year. However, post-1997, the amount and proportion of water imported from the Dongjiang each year has increased dramatically.

In 1963, average daily use of 8 gallons (36.4 litres) per person was seen as too much,while in 2011, a study on household water use by the Water Supplies Department showed that each person uses 55.2 litres of water per day on showering alone. The Water Supplies Departments household water use survey in 2011 revealed that average per capita consumption is 124.7 (45 cu m /yr) litres per day.

The production of one kilogram of beef requires 15 thousand litres of water.

The water footprint of a 150-gram soy burger produced in the Netherlands is about 160 litres. A beef burger from the same country costs about 1000 litres.

The water footprint of Chinese consumption is about 1070 cubic meter per year per capita.

Japan with a footprint of 1380 cubic meter per year per capita.

The water footprint of US citizens is 2840 cubic meter per year per capita. About 20% of this water footprint is external. The largest external water footprint of US consumption lies in the Yangtze river basin, China.

The global water footprint in the period 1996-2005 was 9087 Gm3/yr. Agricultural production contributes 92% to this total footprint.

Water scarcity affects over 2.7 billion people for at least one month each year.

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1963

SPI of Heyuan () SPI of Hong Kong1963

The drought has now spread, far across this wasteland, the few now left undead, crawl on the burning sand. The river's dry, the mortals die, it's doomsday's dawn.

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In 1963, average daily use of 36litres per person was seen as too much, while in 2011, a study on household water use by the Water Supplies Department showed that each person uses 55.2 litres of water per day on showering alone.

Standardized Precipitation Index (SPI) for Heyuan ( ) and Hong Kong (1953 2011)

Poem: The Great Drought, by Ryan M

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Species and natural areas

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Loss of habitat63

Unprecedented California Sea Lion Strandings Linked To Warmer PacificReuters:02/18/2015 7:27 pm EST

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The strandings are unusual because the pups, born last June, aren't supposed to be completely weaned until May.

Satellite data show sea lion mothers are foraging in traditional hunting grounds, but likely spending longer periods away, said Sharon Melin, a biologist with NOAA's National Marine Mammal Laboratory in Seattle.

Fish populations are likely being disrupted by a layer of ocean water, some 100 meters (330 feet) deep, that is 2 to 5 degrees warmer than usual this time of year along the Pacific Coast from Baja to Alaska's Aleutian Islands, said NOAA climatologist Nate Mantua.

The change was caused by a weather pattern involving weak northern and strong southern winds that are creating warmer-than-normal conditions.64

Impact to ecosystem an example Coral reefHot spot of biodiversitySupport 500 million people.< 0.5% of global oceanUS10 billion/year65

Coral reef symbiosis (algae and coral) : coral gains oxygen and extra energy for growth, algae gains carbon dioxide and protection

They are hotspots for biodiversity, and while they cover less than 1 percent of the oceans, it is estimated that at least a quarter of all marine life spends at least part of their life on a coral reef. If we lose reefs, then we are losing not just the organisms that inhabit reefs but also those that indirectly depend on reefs for survival.

The polypsof hard corals get most of their nutrition from the sun! Each hard coral polyp has within it many single-celled plants, algae called ZOOXANTHELLAE, which give the coral its color (coral tissue itself is completely colorless). The polyps use these zooxanthellae to make most of their food through photosynthesis (each algal cell makes much more food than it needs, and releases the excess food to the coral polyp through oil droplets, a process called "blebbing"); and the rest of their diet comes from active feeding on a mixture of microorganisms suspended in the water colony (phytoplankton and zooplankton). Because of this feeding strategy, hard corals must have clear, shallow water to grow, so that they can get enough sunlight to remain healthy. Corals also tend to be very temperature sensitive, and when the water temperature drops below 68 F or rises above 86 F, the coral-zooxanthellae relationship breaks down (a process called CORAL BLEACHING, because the coral colony turns white) and the coral colony will usually starve and die. Corals sedentary lifestyle also requires very high water quality, with a constant flow of new nutrients and dissolved oxygen over the reef. Unfortunately, these very specific conditions only occur in a few places on earth, which is the reason that coral reefs only make up 0.5% of the worlds oceans!65

Coral and CO2 concentration

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Source: Hare et al. 2011, Rogelj et al. 2010, Schaeffer et al. 201266

Coral and temperature rise

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Source: limiting global warming to 2C is unlikely to save most coral reefs, Frieler et al, 2012, Nature Climate Change67

Ocean acidification, IPCC AR5

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Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approx. a 30% increase in acidity.68

Impacts to ocean (Upper : ocean acidification; Lower: sea-butterfly in 2100 seawater)

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When carbon dioxide (CO2) is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity.The pteropod, or sea butterfly, is a tiny sea creature about the size of a small pea. Pteropods are eaten by organisms ranging in size from tiny krill to whales and are a major food source for North Pacific juvenile salmon. The photos below show what happens to a pteropods shell when placed in sea water with pH and carbonate levels projected for the year 2100. The shell slowly dissolves after 45 days.69

Impacts to Aquatic ecosystemIncreasing temperature leads to coral reef bleaching;Ocean acidification;Range shifts of fish related to temperature changes;Movement of phankton due to salinity changes;Changes in pathogen and invasive species abundance;Fish migration in lakes and rivers;Decrease diatom abundance;Salinity and temperature changes may shift planetary-scale ocean circulation.70

Oceans are highly nonlinear system.

On a global scale, increased ocean temperatures could make the ocean more stratified. This would cause less mixing and create stronger nutrient limitation and less frequent nutrient pulses. A change like this would select for different sizes of diatoms. If smaller sized diatoms dominate, then carbon sequestration becomes less efficient and there may be more CO2 remaining in the atmosphere, which would exacerbate global warming. - See more at: http://msutoday.msu.edu/news/2009/mighty-diatoms-global-climate-feedback-from-microscopic-algae/#sthash.B2LoHPmS.dpuf

Ocean currents are an important abiotic factor that significantly influences food webs and reproduction of marine organizms and the marine ecosystems that they inhabit. Many species with limited mobility are dependent on this "liquid wind" to bring food and nutrients to them and to distribute larvae and reproductive cells. Even fish and mammals living in the ocean may have their destinations and food supply affected by currents.

Upwelling currents bring cold nutrient-rich waters from the ocean bottom to the surface, supporting many of the most important fisheries and ecosystems in the world. These currents support the growth of phytoplankton and seaweed which provide the energy base for consumers higher in the food chain, including fish, marine mammals, and humans.

In 1988, more than 16% of coral reef died as a result of el nino.

Range shift of fish in ocean cannot liken to shift in trees on land: These changes may mean expanded ranges for warm-temperate and tropical species, but economically-valuable cold-ranging species like lobster, cod, and winter flounder can only shift so far north before they hit the poles and nowhere left to go.

Rivers: A general upstream movement of river zones, particularly affecting species bound to small streams and springs, which can not move further upstream. Most fish of small rivers, especially the salmonids, are cold-adapted and will be particularly affected by rising temperatures.70

Impacts of ecosystemThe resilience of many ecosystems is likely to be exceeded by an unprecedented combination of climate change and its associated disturbances (flooding, drought, wildfire, insects, ocean acidification etc) and other drivers such as land-use change, pollution and over-exploitation of resources multiple exposure20 30% of plant/animal species at increasing risk of extinctionShifting climate zonesVegetation dont shift quickly, but insects move quickly a mismatchSome positive impacts likely (carbon fertilization), but outweighed by extensive forest and woodland decline through wildfire, insects etc.

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Impacts on terrestrial systems

Extinction of many amphibian speciesShifting timing of events and geographical rangeIncreasing growth in some forests, but also surging pest populations coastal erosion marshland degradation72

Amphibian because of thriving of certain fungus which is fatal to amphibians72

Coastal areas

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Sea level rise

Salt encroachment of fresh water lens (salt tide, )Storm surge

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Water lens: For small islands. There are two fluids that in contact. Rain water falls on the island and seeps into the ground. Its fresh, but the water in the surrounding ocean and the water thats already underground are both salty. Salty water is more dense than the fresh so the freshwater will float on top of the salty water creating a thin lens.

How thick is the lens? For every meter that the fresh groundwater is above sea level, there are 40 meters of fresh water below sea level. This is because saltwater has density of about 1.025 g/cm3, while freshwater has a density of about 1.000 g/cm3

The freshwater lens can be a great source of drinking water on these isolated small islands, but like the islands themselves, they are threatened by rising sea levels due to global warming.

2014220143

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Impact to HKStorm surge

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Impact to HKEconomy eco-tourismPotential loss in coastal wetland and damage of mangrove habitat as sea level rises (eroding the outer boundary of wetland, inland retreat of mangrove is prohibited by artificial structures) loss of migratory birds;Emigration of Chinese Dolphin ?;Less diversified flora (trees shifting upward and northward; increase in more invasive species) - negative impact to country park and hiking industry;

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Impact to HKEconomy fishing industry Toxic algae bloom ( warm temperature, heavy rainfall flushing phosphorus fertilizer to sea); Loss of diversity and changes to fish community composition as a result of coral bleaching; Coral-dependent fishes suffer the most rapid population declines as coral is lost; Other species will exhibit long-term declines due to loss of settlement habitat and erosion of habitat structural complexity; Increased ocean temperature will affect the physiological performance and behaviour of coral reef fishes.

Martin Williams, 2011, Cheung Chau77

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Subsiding house foundation at Cheung Chau as a result of erosion due to Typhoon Hagupit

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Typhoon Hagupit passed about 180 km SSW of HK and brought a storm surge of 1.4 m at Victoria Harbour, raising the sea level to a height of 3.53 m above Chart Datum (2nd highest after Typhoon Wanda)

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IPCC Assessment Report No. 5 projects that in the last decades of 21st century, global sea level rises by 0.26-0.82mReturn period (yr)Extreme sea level above chart datum (m)With current sea levelMean sea level rises by 0.26mMean sea level rises by 0.82m22.93.23.753.13.43.9103.33.54.1203.43.64.2503.53.84.4

Storm surge from typhoons

Storm surge risks increase with sea level riseHagupit (50 yr event) becomes an annual/biennial event

Impact of extreme events to Infrastructure

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How humans become exposed to waterborne diseases following inundation82

US Climate Assessment Report 2013

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Impact to HKInfrastructure - Wastewater and sewageRising sea level puts pressure on drainage systems makes waste water and storm water harder to be discharged to the sea, and result in flooding;Putting HKs drainage system under pressure. 83

Effect on weather systems More water vapour the nitro of the atmosphere - heat engineMore stormy84

Typhoons and hurricanesWarmer sea surface more powerful, not necessarily more stormsComplicated - warmer atmosphere may negate the effect of warmer sea surface.Super typhoon Haiyan85

Fig. Expected percent change in the average over period 20812100 relative to 20002019(AR5)

Others

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Key vulnerabilities of citiesConcentrated populationUrban heat island effectInfectious diseasesMassive investment in infrastructureHurricane Katrina and Sandy in USInsured lossesDisconnect between people and food sourceOften centralized system of energy provision, fresh water resources etc.Ripple effectsClimate refugees Stern Review estimates 170 million people displaced by flooding at 3 deg warming, and 300 million more at 4 deg.

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Rippled effect _ developed countries face ethical tough questions about denying livelihood of people displaced by GHG released by these countries.87

Great natural catastrophes worldwide 1950-201188

Economic loss has risen at least 10 folds since 1950s, after accounting for inflation. Part of this is due to growth in population (