Primer on Climate Change and Global Warming – Part II (Impact)

{xtypo_dropcap}T{/xtypo_dropcap}he effects of climate change are already being felt by natural systems in many places. Glaciers in both the northern and southern hemispheres are shrinking, permafrost is thawing, growing seasons are lengthening and animals are shifting their ranges to higher and cooler ground. {sidebar id=34}
While increases in intense rainfall events and heat waves have happened in some regions, there is no clear global trend in smaller-scale severe weather events such as tornadoes, hail or dust storms. Tropical cyclones have increased in intensity since 1970, although there is no clear trend in their numbers.

Climate models indicate that further increases in greenhouse gases will lead to continued global warming, more heatwaves, fewer frosts, less snow and a rise in sea level. Rainfall over most parts of the world may increase, but some places in the mid-latitudes, may become drier. Vulnerable natural systems, such as alpine fauna and coral reefs, are likely to suffer most as a result of climate change. The world’s poor and disadvantaged people and developing countries are likely to be affected much more than developed countries, which have the capacity to adapt to climatic changes.

Projections for the 21st century suggest:
(Adapted from the Intergovernmental Panel on Climate Change Climate Change 2007: Impacts, Adaptation and Vulnerability” WGII)

Ecosystems: In the coming century, many ecosystems will struggle to adapt to changes in climate, flooding, drought, wildfires, insects, pollution & more. With a few degree change in global temperature, many species are likely to face an increased risk of extinction. Beyond this level, major changes in species’ ecological interactions and geographic ranges are expected. All natural systems are vulnerable to invasion by exotic species. Disturbance by climate change is likely to increase vulnerability by increasing the stress on established vegetation. Warmer conditions will increase the likelihood of pests and diseases from tropical and sub-tropical Australia spreading southward. Some weeds may benefit from climate change and from reduced competition as unfavorable conditions weaken native species and perhaps crops. Less snow and a shorter snow season appear likely, threatening alpine ecosystems. In tropical rainforests, even a modest degree of warming is likely to significantly harm high altitude rainforest flora and fauna.

Loss of Biodiversity
– Significant loss of biodiversity is projected to occur by 2020 in some ecologically-rich Australian and New Zealand sites, including the Great Barrier Reef and Queensland Wet Tropics. Other sites at risk include the Kakadu wetlands, SW Australia, Sub-Antartic islands and the alpine areas of both countries.

Species Losses – The great majority of organisms and ecosystems in Europe are predicted to experience difficulties adapting to climate change. Mountainous areas will face extensive species losses – upto 60% in some areas by 2080 if emissions continue to remain high.

Species Extinction – By the middle of this century, Savanna is expected to gradually replace tropical forest in Eastern Amazonia, due to increases in temperature and decreases in soil water. There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America.

Reductions in Sea-Ice
– It’s predictable that the polar regions will experience reductions in the thickness and extent of glaciers and ice sheets. Changes in natural ecosystems will have detrimental effects on many organisms including migratory birds, mammals, and higher predators. In the Arctic, additional impacts include reductions in the extent of sea ice and permafrost increasing coastal erosions and an increase in the depth of seasonal permafrost thawing.

Freshwater Resources:
Warming temperatures are expected to expand areas prone to draught and increase heavy rainstorms, leading to floods. More than 1/6 of the world’s population currently lives in regions supplied by “melt water” from major mountain ranges. As glaciers and snow cover melt, regions that rely on these sources for fresh water will see their supplies dry up.

Receding Glaciers
– Within the next 20 – 30 years, it is projected that Himalayan glacier melt will increase flooding, cause rock avalanches, and affect water resources in Asia. This would be followed by decreased river flow as the glaciers continue to recede. Freshwater availability in many parts of Asia is expected to decrease, potentially affecting more than a billion people by 2050’s.

Drought – More frequent or intense droughts would increase loss of crops, livestock, fisheries and wildlife, and decrease river flows and water quality. It is projected that by 2020 between 75 & 250 million people in Africa will be experiencing stresses on their water supply.

Changes in Precipitation – Changes in rainfall patterns and reduced soil moisture could reduce water supplies for agriculture, domestic and industrial uses, energy generation and biodiversity.

Water shortages
– It is projected that by mid-century, climate change will reduce water resources in many small islands, including those in the Caribbean & Pacific Ocean, where the water sources become insufficient to meet demand during periods of low rainfall.

Freshwater resources in North America
– Warming in the Western mountains of North America is projected to cause decreasing snowpack, more winter flooding, and reduced flows of water in the summer – exacerbating competition for over-allocated water resouces.

Coastal Areas:
By the 2080’s millions of people are projected to be flooded every year with the largest numbers in the mega-deltas of Asia and Africa and the most vulnerable on small islands. In addition rising temperatures are expected to mean widespread coral death and sea-level rise is expected to damage salt marshes and mangroves. Projected global warming will contribute additional stress to coral reefs around the world due to ocean warming (causing coral bleaching), stronger tropical cyclones, sea level rise and higher levels of carbon dioxide which may reduce coral growth rates.

Rising Sea Levels
– Erosion of beaches, coral bleaching, & other deterioration in small islands’ coasts is expected to affect local fisheries & reduce the value of these destinations for tourism. Sea-level rise is expected to exacerbate storm surge, erosion, and other coastal hazards, threatening vital infrastructure & facilities that support the livelihood of island communities.

Severe Storms
– North American communities and habitats will be increasingly stressed by the interaction of climate change impacts with development and pollution. Population growth and the rising value of infrastructure in coastal areas increase vulnerability – with losses projected to increase if the intensity of tropical storms increases.

Flooding – Sea-level rise is projected to cause increased risk of flooding in low-lying areas of Latin America. Increase in sea-surface temperature due to climate change are projected to have adverse effects on Mesoamerican coral reefs, and cause shifts in the location of Southeast Pacific fish stocks.

Populations at Risk – Towards the end of the 21st century, projected sea-level rise will affect low-lying African coastal areas with large populations. The cost of adaptation could amount to at least 5 – 10% of GDP. Fisheries and tourism will also be affected as mangroves and coral reefs are projected to be further degraded.

Food and Forests: The net effect of climate change on plant growth is dependent on interactions between carbon dioxide, temperature, nutrients and rainfall. High carbon dioxide concentrations and longer growing seasons due to higher temperatures increase plant productivity. However, reductions in rainfall and increased risk of drought would decrease plant growth as seen during 2002–3 and 2006–7. Globally, the potential for food production is expected to increase with a few degrees warming but to decline when temperatures pass that level. Effects vary from place to place, however, with lower latitudes seeing decreases in crops even for a few degrees change. Increased floods and droughts will be especially difficult for low-latitude areas that depend on local crops for food. Yields of stone fruit such as apricots and nectarines in some locations may be reduced due to inadequate chilling.

Changing Forests in Australia and New Zealand – Due to increased drought and fire, agriculture and forestry production is projected to decline over much of Southern and Eastern Australia, and over parts of Eastern New Zealand by 2030. Yet, initial agriculture and forestry benefits are projected in Western and Southern New Zealand and in areas close to major rivers due to a longer growing season, less frost and increased rainfall.

Reduced Growing Seasons in Africa – Agricultural production in many African countries and regions in expected to be severely compromised by climate change. The area suitable for crops, the length of growing seasons, & the amount of food produced are all expected to decline. In some African countries, yields fro rain-fed agriculture could be reduced by upto 50% by 2020.

Changing yields in Asia – By the mid-21st century, crop yields could increase upto 20% in Eastern and Southeastern Asia, while decrease upto 30% in Central and Southern Asia. The risk of hunger is projected to remain very high in several developing countries.

Increasing yields in North America – In North America, moderate climate change in the early decades of the century is projected to increase yields of rain-fed agriculture by 5 – 20%, but this will vary among regions. Major challenges are projected for crops that are near the warm end of their range or depend on highly-utilized water resources.

Industry and Society: The effects of climate change on industry and society will vary widely across the world, but they will tend to be worse the larger the change. The most vulnerable industries and communities are those very dependent on climate-sensitive resources, and those coastal and river flood plains or areas prone to extreme weather. Poor communities, which have less ability to adapt and are more depending on local food and water resources, will be especially vulnerable.

Unsustainable development
– Climate change is projected to impinge on sustainable development of most developing Asian countries. The changes compound pressures on natural resources and and the environment associated with rapid industrialization, urbanization and economic development.

Reduced Tourism
– Nearly all European regions are expected to be negatively affected by some future impacts of climate change, posing challenges to many economic sectors. Mountainous areas will face reduced snow cover and winter tourism, while southern areas will see decreased summer tourism. In Southern Europe, reduced water availability is expected to reduce the potential for hydroelectric power.

Threatened Cultures – For Arctic communities, impacts resulting from changing snow and ice conditions are projected to be mixed. While reduced heating costs and more navigable Northern Sea routes could benefit the region, some traditional ways of life are being threatened and substantial investments are needed to adapt or re-locate physical structures and communities.

Health: Changes in climate change will affect the health of people around the world differently. Fewer cold and frosty days in higher latitudes would reduce cold stress and cold-related deaths in humans and livestock, and reduce frost damage, but may extend the range of pests and diseases while in other areas more heatwaves could result in heat stress and heat-related deaths in humans and livestock, and damage to crops. While temperate areas are projected to be outweighed by increases in health problems elsewhere, especially in developing countries. Millions of people, especially those with little ability to adapt are expected to be affected by health concerns including increased malnutrition, diarrhea, cardio-respiratory diseases and changing patterns in the spread of infectious diseases.

Increased Diseases – Illness and death due to diarrheal diseases are expected to rise in South and East Asia due to increase in floods and droughts. Rising coastal water temperatures could exacerbate the abundance and/or toxicity of cholera in Southern Asia.

Changing Range of Disease – Climate change is expected to have mixed effects on the range and transmission potential of malaria in Africa.

Heat Waves – In Southern, Central and Eastern Europe, health risks due to heat waves are projected to increase.

A picture says a thousand words. So, here’s some further evidence in these images:

Figure 1: WHO estimates climate change has already caused about 150,000 premature deaths/yr in 2000.

Figure 2: Coastal glaciers are retreating. Shown here is the Muir Glacier in Alaska in August 1941 and August 2004. NSIDC/WDC for Glaciology, Boulder, compiler. Online glacier photograph database. Boulder, CO: National Snow and Ice Data Center.

Figure 3: Sea-level is rising. The average sea-level rise during the period 1993-2003 was ≈ 35 mm which translates to about 3.5 mm/yr. Compare this to the rise during 1910-1990 which was only about 1.5 mm/yr. Arctic Climate Impact Assessment, 2004.

Climate change is coming at us faster, with larger impacts and bigger risks, than even most climate scientists expected as recently as a few years ago. In the 3rd and final part, we will discover what our choices are – mitigation and adaptation.

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