Last Friday, scientists from the Intergovernmental Panel on Climate Change (IPCC) released Volume 2 of the Fourth Assessment Report, which explores the impacts of climate change on natural and human systems and the relative ability of these systems to adapt. Entitled "Climate Change Impacts, Adaptation and Vulnerability," this latest volume issues an alarming forecast of human-induced warming, including large-scale biodiversity loss, decreased water and food availability, and new human health threats. This follows the February 2nd release of Volume 1, which determined with 90 percent certainty that global warming is a result of human activities.
To read background information on the IPCC and the Fourth Assessment Report, "Climate Change 2007," read the EarthTrends news post on Volume 1.
Observed Impacts on Natural Systems
The consequences of increased temperatures are already being observed in natural systems around the globe. Much attention has focused on polar systems--where the impacts of global warming have been most measurable and pronounced--with the designation of 2007 as an International Polar Year. The IPCC lists growing numbers of glacial lakes, increasing ground instability in permafrost regions, and changes in Arctic and Antarctic ecosystems as evidence of this change. The IPCC also asserts with "high confidence" (an 8 out of 10 chance) that the following natural systems outside of polar regions are being affected:
- Hydrological systems: Increased run-off from glacier and snow-fed rivers and warming of lakes and rivers.
- Terrestrial biological systems: Earlier spring events (i.e. bird migration) and poleward and elevation shifts in plant and animal ranges.
- Marine and freshwater biological systems: Changes in water temperature, ice cover, salinity, acidity, oxygen levels and ocean circulation. Shifts in algal and fish abundance in oceans and changes in the range and timing of freshwater fish migrations.
Future Consequences for Human Welfare
Human welfare is tightly linked to the health of natural systems. The above-mentioned changes are already creating human impacts, and the IPCC projects greater negative consequences as warming increases. Some of the major findings include:
- Water availability: Even though heavy precipitation events and flooding are very likely to increase in frequency, drought-affected regions will likely increase in extent. Water supplies stored in glaciers and snow cover, which serve more than one-sixth of the world population, will decline.
- Ecosystems: 20-30 percent of plant and animal species are likely to be at risk of extinction if global average temperature increases exceed 1.5-2.5 degrees Celsius. Changes in ecosystem structure and function will have negative consequences for ecosystem goods and services such as water and food supply.
- Food production: Agricultural productivity is projected to increase slightly at mid to high latitudes (for 1-3 degrees warming) but decrease at lower latitudes, creating greater hunger risk in those regions. Regional shifts in the distribution and production of certain fish species will adversely affect aquaculture and fisheries.
- Health: Heat waves, floods, storms, fires and droughts are likely to claim more lives. The burden of cardio-respiratory and diarrheal diseases will increase and the spatial distribution of some infectious disease vectors will shift.
Special Concerns for Africa
Africa is one of the most vulnerable continents to climate variability. Inadequate access to food, water, health care and income will likely be exacerbated by global warming. Furthermore, Africa's adaptive capacity is low due to widespread poverty and poor governance. According to the IPCC:
- Between 75 and 250 million Africans are projected to be exposed to increased water stress by 2020;
- Extent of cultivable land, the length of the growing season, and yield potential are expected to decrease. Yields from rain-fed agriculture, which accounts for over 99 percent of African cropland, could be reduced by up to 50 percent by 2020;
- Rising water temperatures will negatively impact fish production in large lakes; and
- Adapting to sea-level rise could cost between 5-10 percent of GDP and have additional consequences for fisheries and tourism.
Look out for the release of Volume 3, "Mitigation of Climate Change," on May 4th, 2007.
RELATED LINKS:
Summary of Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability (pdf)
The United Nations Framework Convention on Climate Change (UNFCCC)
NASA's Global Change Master Directory
Carbon Dioxide Information Analysis Center
World Resources Institute's Climate Analysis Indicators Tool
Map of Climate Change and Vulnerability in Africa from UNEP/GRID-Arendal
EarthTrends
Climate and Atmosphere Searchable Database
Data Table: Global Climate Trends 2005
Data Table: Carbon Dioxide Emissions by Source 2005
February 2007 Monthly Update: Polar Warming and Its Global Consequences
News Post: IPCC Releases Comprehensive Assessment of Global Climate Change
News Post: Major Climate Science Discoveries of 2007
News Post: Drought in Indonesia Could Intensify with Global Warming
