Can scientists predict changes on a regional level? What will happen in my part of the country? How accurate are local predictions?
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Regional predictions of climate change are still a challenge. Most global climate models track temperature, precipitation, and several other variables for multiple layers of the atmosphere on a three-dimensional grid with horizontal points separated by roughly 60-120 miles (as opposed to 10-20 miles or less for typical weather models). Several research groups are focusing on improving regional modeling.
Meanwhile, some general conclusions can be drawn from the global models. For example:
- Drier to the south. The 2007 IPCC report noted a strengthening consensus among models for decreased precipitation this century across the subtropics, including the southern tier of the contiguous United States. When combined with warmer temperatures, this decrease is expected to have dramatic impacts on water supply, agriculture, wildfire, and drought-sensitive ecosystems.
- Wetter to the north. The northern tier of U.S. states could receive more precipitation overall. In higher latitudes and at higher elevations, the length of time with snow cover in winter is expected to drop, with impacts felt in water management as well as skiing, snowmobiling, and other snow-dependent activities. The global and national trends toward rain and snow falling in heavier bursts when it does fall is also expected to continue.
In 2000, the United States released the National Assessment of Climate Change (see link below). Since then, no comparable study of regional U.S. climate change has been published. The U.S. Climate Change Science Program is preparing a unified synthesis report, Global Climate Change Impacts in the United States, which will update many of the topics covered in the 2000 assessment. Other CCSP reports also include some regional-scale detail. The IPCC’s 2007 assessment from Working Group II includes a summary of recent and future climate-change impacts across North America.
More information: US Climate Change Science Program. Unified Synthesis Product: Global Climate Change in the United States
IPCC Working Group 2: Climate Change Impacts, Adaptation, and Vulnerability. Chapter 14: North America
Highlights from the IPCC Working Group II Summary for Policymakers of “Climate Change 2007: Impacts, Adaptation and Vulnerability.”
The Complexity of Climate Modeling: Components of the NCAR-based Community Climate System Model (CCSM)