Climate Change

Background

Climate Change is the description of variations from the long term natural climate equilibrium produced by the anthropogenic changes to the atmospheric composition. Global warming, the long-term increase in average temperatures, is the most important manifestation of climate change. Global warming has been predicted and scientifically shown to be caused by the increase of carbon dioxide in the atmosphere by human activities, which enhances the natural greenhouse effect.

Polar bears are one of several species threatened by shrinking sea ice

Source: http://static.guim.co.uk/sys-images/...rbears_276.jpg. Author: Juniors Bildarchiv/Alamy .

According to the IPCC, climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use. Note that the UN Framework Convention on Climate Change (UNFCCC), in its Article 1, defines climate change as: ‘a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’. The UNFCCC thus makes a distinction between climate change attributable to human activities altering the atmospheric composition, and climate variability attributable to natural causes.¹

The scientific consensus, represented in the 2007 technical report of the international body of scientists, the Intergovernmental Panel on Climate Change (IPCC) agrees that global warming is real and that humans are "very likely" to be causing it. The report points out that a warming of about 0.2ºC p per decade for the next two decades is projected and continued greenhouse gas emissions at or above current rates would cause further warming.²

Human activities, such as burning fossil fuels for energy, deforestation, burning of grasslands and forests, land use, and agricultural practices release increasing amounts of heat trapping greenhouse gases, changing the earth's energy balance by keeping in more of the sun's heat. Scientists and communities around the world are already observing changes in our climate , including increasing land and ocean temperatures widespread melting of glaciers, rising sea levels, drought and increasing frequency of severe weather events. Scientists predict that if greenhouse gas emissions are not slowed, these trends will increase catastrophically this century. The impacts of climate change on human communities and natural ecosystems will be severe and dramatic, with the poor disproportionately affected. Information on solutions to mitigate and adapt to climate change can be found in the mitigation and adaptation portals.

In 2008 Gallup Polls surveyed 127 countries. Over a third of the world's population was unaware of global warming, with people in developing countries less aware than those in developed, and those in Africa the least aware.

Climate Change Indicators ³

Greenhouse Gas Concentrations: According to the EPA, in 2005 the world is estimated to have emitted over 38,000 million metric tons of greenhouse gases, expressed as carbon dioxide equivalents. This represents a 26 percent increase from 1990 levels. In 2008, U.S. greenhouse gas emissions totaled 6,957 million metric tons of carbon dioxide equivalents, a 14 percent increase from 1990.

Source: EPA Climate Change Indicators. Author: . Permission: .

Temperature Change: The National Oceanic and Atmospheric Administration Climatic Data Center indicates that global average surface temperatures have risen at an average rate of 0.13°F per decade since 1901 (this is similar to the rate of warming within the lower 48 states). Since the late 1970s, however, the United States has warmed at nearly twice the global rate (0.37°F - 0.51°F per decade). Worldwide, 2000–2009 was the warmest decade on record.

Droughts and Storms: As average global temperatures rise because of climate change, the Earth’s water cycle is expected to speed up and increase evaporation. This makes more water available in the air for precipitation, but contribute to drying over some land masses. As a result, the Earth experiences more extreme weather patterns. Storm-affected areas are likely to experience increased precipitation and increased risk of flooding, while areas located far away from storm zones are likely to experience less precipitation and increased risk of drought. Since the 1970s, drought-affected areas have increased on a global scale—most likely as a result of anthropogenic (human caused) climate change. Drought conditions can slow plant growth and cause crop loss or lower water supply levels in ground water and reservoirs. Similarly, average precipitation has increased worldwide at a rate of 1.9% per century, and eight of the last ten years for extreme one-day precipitation events have occurred since 1990.

Arctic Sea Ice: Compared with the 1979 to 2000 average, the extent of Arctic Sea ice in 2007 was lower by 1 million square miles—an area approximately the size of Alaska and Texas combined. Although 2009 saw an increase in sea ice extent compared with 2007 and 2008, the 2009 sea ice extent was still 24 percent below the 1979 to 2000 historical average.

Glacial Melting: Glaciers are one of the most sensitive indicators of climate change because they advance when the climate cools and retreat when the climate warms. The world glacial inventory tracks over 100,000 glaciers covering 240,000 square kilometers. By tracking these glaciers since 1960, scientists estimate that glaciers worldwide have lost more than 2,000 cubic miles of water, which in turn has contributed to observed changes in sea level. (For more information on glaciers see the climate change security wiki). In South America, shrinking glaciers threaten a large portion of the population that lives west of the Andes. Glaciers in Peru have reduced in size by 25% in the last thirty years, and at current rates, they may disappear. Glaciers in Southeast Asia, the third largest on earth after Antarctica and Greenland, are also shrinking which diminishes water supplies. The Chinese Academy of Sciences estimates that the Tibetan plateau glaciers will shrink by half every decade; this threatens massive water shortages in the future, as less ice is available to melt and fill the Yellow River.⁴

Change in ocean temperature and acidity kill symbiotic zooxanthellae algae which causes coral bleaching shown here

Source: http://jroy.abenaza.com/wp-content/u...leaching-1.jpg.

Sea Level Rise: When averaged over all the world’s oceans, absolute sea level increased at an average rate of 0.06 inches per year from 1870 to 2008. From 1993 to 2008, however, average sea level rose at a rate of 0.11 to 0.13 inches per year. Increasing ice melt will continue to contribute to sea level rise, which may have significant impacts on the security of populations in regions that are just above sea level (see the climate change security wiki).

Sea Surface Temperatures: From 1901 through 2009, temperatures rose at an average rate of 0.12 degrees per decade. Over the last 30 years, sea surface temperatures have risen more quickly at a rate of 0.21 degrees per decade.

Ocean Acidity: Ocean carbon dioxide levels have risen, accompanied by an increase in acidity (that is, a decrease in pH). Ocean acidity has increased globally most notably in the Atlantic.

Health Risks

In an assessment report on health impacts, the IPCC concluded that: "climate change is projected to increase threats to human health, particularly in lower income populations, predominantly within tropical/subtropical countries." This has direct effets (ie. impacts of thermal stress, death/injury in floods and storms) and indirect effects through changes in the ranges of disease vectors (ie. mosquitoes), water-borne pathogens, water and air quality, and food availability. Overall scientists agree that the health impacts of climate change are adverse. According to the "World Health Report 2002" climate change in 2000 was responsible for 2.4% of diarrhea cases and 6% of malaria (higher temperatures and precipitation levels increase the viability of disease-transmitting mosquitoes).⁵

(For more information on the impacts of climate change on health and society, see climate change security)

Policy Responses

Developing and developed countries disagree over who should bear the burden of costs for cutting greenhouse emissions for climate change. Developing countries point to the industrialized countries high per capita emissions, ie. the total emissions of a country divided by its population. Powerful developing countries, namely China, India, and Brazil, believe climate change is due to the profligate and unsustainable lifestyles of those living in rich countries. On the other hand, commentators from developed countries more often point out that it is total emissions that matter. In 2008, developing countries made up around half of the world's total emissions of CO2 from cement production and fossil fuel use. Together the US and China contribute over 40% of world CO2 emissions.

Regulatory Initiatives

Cap-and-trade

Carbon Tax

McKibben-Wilcoxin Hybrid

MacCracken Leveraging Framework