At least one researcher cited in the 196-page climate impacts report issued this week by the Obama administration is not impressed with the final product. Roger Pielke of the University of Colorado’s Center for Science & Technology Research has written a blog post critical of the report and in particular, the way in which his work was interpreted. If you’d rather not plow through the entire post, John Tierney has an overview of Pielke’s critique on his blog for the New York Times.

The report was arguably the first to break down both observed and projected effects of climate change into coherent regional summaries. For the purposes of the report, California was considered part of the Southwest region, which included states as far east as Colorado and New Mexico.

Not surprisingly, many of the points raised in the Southwest section (beginning on p. 129) have to do with water supply. Most have been reported or discussed in our Climate Watch coverage, either here or in our radio reports. Selected “highlights” include:

– Past climate records based on changes in Colorado River flows indicate that drought is a frequent feature of the Southwest, with some of the longest documented “megadroughts” on Earth.

– The prospect of future droughts becoming more severe as a result of global warming is a significant concern, especially because the Southwest continues to lead the nation in population growth.

– Human-induced climate change appears to be well underway in the Southwest. Recent warming is among the most rapid in the nation, significantly more than the global average in some areas.

– Projections suggest continued strong warming, with much larger increases under higher emissions scenarios compared to lower emissions scenarios. Projected summertime temperature increases are greater than the annual average increases in some parts of the region, and are likely to be exacerbated locally by expanding urban
heat island effects.

– Water supplies in some areas of the Southwest are already becoming limited, and this trend toward scarcity is likely to be a harbinger of future water shortages. Groundwater pumping is lowering water tables, while rising temperatures reduce river flows in vital rivers including the Colorado.

– Projected temperature increases, combined with river-flow reductions, will increase the risk of water conflicts between sectors, states, and even nations.

– Increasing temperature, drought, wildfire, and invasive species will accelerate transformation of the landscape.

– Under higher emissions scenarios, high-elevation forests in California, for example, are projected to decline by 60 to 90 percent before the end of the century.

– In California, two-thirds of the more than 5,500 native plant species are projected to experience range reductions up to 80 percent before the end of this century under projected warming.

– Projected changes in the timing and amount of river flow, particularly in winter and spring, is estimated to more than double the risk of Delta flooding events by mid-century, and result in an eight-fold increase before the end of the century.

– A steady reduction in winter chilling could have serious economic impacts on fruit and nut production in the region. California’s losses due to future climate change are estimated between zero and 40 percent for wine and table grapes, almonds, oranges, walnuts, and avocados, varying significantly by location.

By the way, Pielke’s critique does not directly address anything in this list, though his work does involve weather-related disasters, which would include floods. Asked by a commentator on his blog if he thinks the entire report should be dismissed based on the flawed interpretation of his research, Pielke replied: “I wouldn’t think so and would certainly hope not. At the same time the section which covers my research does not give me a lot of confidence in the process that led to the report.”