What's at Stake
The earth is warming. The 1990s were the hottest decade of the entire millennium and 1997, 1998, and 1999 were three of the hottest years ever.
The growing scientific consensus is that this warming is largely the result of emissions of carbon dioxide and other greenhouse gases from human activities including industrial processes, fossil fuel combustion, and changes in land use, such as deforestation. Projections of future warming suggest a global increase of 2ºF to 7ºF by 2100, with warming in the U.S. expected to be even higher. In addition to warming, increases in sea level and changes in precipitation, including more frequent floods and droughts, are likely. These changes, over time, are referred to broadly as "climate change."
Unaddressed, climate change will have significant impacts across the U.S. and around the world. For instance, sea-level rise will add to stresses coastal communities are already facing, including erosion, storms, and pressures from development. In the arid and semi-arid western U.S., relatively modest changes in precipitation can have large impacts on already limited water supplies.
While some of the effects of climate change may be positive, such as longer growing seasons in the northern U.S. and Canada, crop yields in the southern U.S. are likely to decline. And even these positive impacts are unlikely to be sustained as the globe continues to warm. Many developing countries are even more vulnerable to the adverse impacts of climate change and less able to adapt. As nations continue to grow more interdependent, the U.S. may not be immune from impacts experienced elsewhere.
Most projections of future impacts do not address what could happen if warming continues beyond 2100, which is inevitable if steps to reduce emissions are not taken, or if the rate of change accelerates. The possibility of catastrophic events also cannot be ruled out.
Even if we are able to reduce emissions of greenhouse gases, some further warming is unavoidable. We must plan and take action now to adapt to the changes we will face as our climate changes.