The United Nations’ (UN) International Panel on Climate Change (IPCC) released a draft copy of the “Summary for Policymakers” on 16 November as part of the IPCC’s Fourth Assessment Report. The panel warned that if action is not taken to curb emissions and if the world “does not stabilize carbon dioxide emissions until 2030,” the temperature could increase by as much as 6.3 degrees Fahrenheit above 2000 temperatures. “That level of warming could result in widespread extinctions of species, a slowing of the global currents, decreased food production, loss of 30 percent of global wetlands, flooding for millions of people and higher deaths from heat waves.”

The summary included sections on observed changes in climate and their effects, causes of change, projected climate change and its impacts, adaptation and mitigation options, and a section on the long-term perspective. Without indicating how much warming would be too much, the summary report stated, “it is very likely that: heat waves have become more frequent over most land areas, the frequency of heavy precipitation events has increased over most areas, and since 1975 the incidence of extreme high sea level has increased worldwide.”

The summary report incorporated examples of projected regional impacts on Africa, Asia, Australia and New Zealand, Europe, Latin America, North America, polar regions, and small islands. Examples of potential North American impact include:

  • Warming in western mountains is projected to causes decreased snow pack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources;
  • In the early decades of the century, moderate climate change is projected to increase aggregate yields of rain-fed agriculture by 5-20 percent, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or which depend on highly utilized water resources;
  • During the course of this century, cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts;
  • Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution.

Additionally, the summary report listed examples of possible impacts of climate change on various sectors including agricultures, forestry, and ecosystems; water resources; human health; and industry, settlement, and society. Scientists are “virtually certain” that over most land areas there will be warmer and fewer cold days and nights and warmer and more frequent hot days and nights, which will likely impact agriculture by increasing yields in colder environments, decreasing yields in warmer environments, and increasing insect outbreaks. Other likely trends include heat waves in warmer regions that create water availability and quality problems and heavy precipitation events that increase soil erosion.

The “Summary for Policymakers” provided a variety of adaptation options, organized by sector. Some examples include: expanded rainwater harvesting; water storage and conservation techniques; water re-use; desalination; water-use and irrigation efficiency created by national water policies and integrated water resources management and water-related hazards management. The report also listed potential constraints to these options being implemented. A full list of those examples and the summary report in its entirety can be downloaded by visiting the IPCC website,

The panel is hopeful that given these options, action will be taken. Senator John Kerry (D-MA) remarked, “This will be viewed by all as a definitive report. It is a blueprint for the Bali talks.” Other U.S. Senators will join Kerry at the U.N. Climate Change Conference in Indonesia beginning 3 December.


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