NOAA NESDIS Technical Reports

Regional Climate Trends and Scenarios for the U.S. National Climate Assessment

142-Regional Climate Trends and Scenarios for the U.S. National Climate Assessment

This document is one of series of regional climate descriptions designed to provide input that can be used in the development of the National Climate Assessment (NCA). There are nine reports in this series, one each for eight regions defined by the NCA, and one for the contiguous U.S. The eight NCA regions are the Northeast, Southeast, Midwest, Great Plains, Northwest, Southwest, Alaska, and Haiwaii/Pacific Islands. While the datasets and simulations in these regional climate documents are not, by themselves, new (they have been previously published in various sources), these documents represent a more complete and targeted synthesis of historical and emission-dependent future climate conditions around the specific regions of the NCA.

There are two components of these descriptions. One component is a description of the historical climate conditions in the region. The other component is a description of the climate conditions associated with two future pathways of greenhouse gas emissions based on IPCC emission scenarios.

Historical Climate

The description of the historical climate conditions was based on an analysis of core climate data (the data sources are available and described in each document). However, to help understand, prioritize, and describe the importance and significance of different climate conditions, additional input was derived from climate experts in each region, some of whom are authors on these reports. In particular, input was sought from the NOAA Regional Climate Centers and from the American Association of State Climatologists. The historical climate conditions are meant to provide a perspective on what has been happening in each region and what types of extreme events have historically been noteworthy, to provide a context for assessment of future impacts.

Possible Future Climates

Information on future climates provides an internally consistent set of climate conditions that can serve as inputs to analyses of potential impacts of climate change. There are no established probabilities for their future realization. They simply represent an internally consistent climate picture using certain assumptions about the future pathway of greenhouse gas emissions. By "consistent" we mean that the relationships among different climate variables and the spatial patterns of these variables are derived directly from the same set of climate model simulations and are therefore physically plausible.

As part of a sustained assessment approach, it is intended that these documents will be updated as new and well-vetted model results are available and as new climate emission scenarios become available. These documents could be of particular interest to decision makers and communities seeking to develop adaptation plans.For more information on these and other scenarios prepared as input for the National Climate Assessment, including downloadable maps and images, please go to