Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice

on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering

sooner. Effects that scientists had predicted in the past would result from global climate change are now

occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves..Scientists have

high confidence that global temperatures will continue to rise for decades to come, largely due to

greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC),

which includes more than 1,300 scientists from the United States and other countries, forecasts a

temperature rise of 2.5 to 10 degrees Fahrenheit over the next century. According to the IPCC, the extent

of climate change effects on individual regions will vary over time and with the ability of different societal

and environmental systems to mitigate or adapt to change. The IPCC predicts that increases in global mean

temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will

produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over

time as global temperatures increase."Taken as a whole," the IPCC states, "the range of published evidence

indicates that the net damage costs of climate change are likely to be significant and to increase over time." 1