Assessing Future Climate Change

The document describes the use of IPCC emissions scenarios (A1fi and B1) and three global climate models (GFDL CM2.1, HadCM3, and PCM) to project climate variables in the U.S. Midwest. It details the distinction between higher-emissions paths, leading to 940 ppm of CO2 by 2100, and lower-emissions paths, leading to 550 ppm. The briefing notes that while these models reproduce historical regional climate features, they may be conservative as they do not capture recent rapid winter warming in the Midwest or the accelerated melting of polar ice sheets.

• The analysis utilizes two IPCC emissions scenarios: a higher-emissions scenario (A1fi) characterized by fossil fuel-intensive growth where atmospheric CO2 reaches 940 ppm by 2100, and a lower-emissions scenario (B1) involving a shift to resource-efficient technologies where CO2 peaks mid-century and reaches 550 ppm by 2100.
• Projections for the U.S. Midwest were generated using three global climate models with varying sensitivities: the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) CM2.1, the UK Met Office Hadley Centre Climate Model version 3 (HadCM3), and the National Center for Atmospheric Research’s Parallel Climate Model (PCM).
• The climate model projections may be conservative because they fail to account for the rapid rate of polar ice sheet decay and melting, as well as the rapid winter warming observed in the Midwest over recent decades.
• To move from global grid-based projections (with cells 50 to 250 miles wide) to higher-resolution regional projections covering tens of miles, researchers applied statistical and dynamical downscaling techniques.

APA

Union of Concerned Scientists (2009). Assessing Future Climate Change. https://www.ucs.org/sites/default/files/2019-09/mw-climate-backgrounder.pdf

Chicago

Union of Concerned Scientists. Assessing Future Climate Change. 2009. https://www.ucs.org/sites/default/files/2019-09/mw-climate-backgrounder.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Assessing Future Climate Change |date=July 2009 |url=https://www.ucs.org/sites/default/files/2019-09/mw-climate-backgrounder.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2009assessing, author = {{Union of Concerned Scientists}}, title = {{Assessing Future Climate Change}}, institution = {Union of Concerned Scientists}, year = {2009}, month = jul, url = {https://www.ucs.org/sites/default/files/2019-09/mw-climate-backgrounder.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }