Summer Heat Records Top Cold Records 13 to 1

A Think Progress article reports that according to a recent Stanford climate study, the tropics and large parts of the Northern Hemisphere will see a permanent rise in summer temperatures in the foreseeable future if greenhouse gas concentrations continue to increase. A clear trend of hotter summer temperatures is emerging in the United States as the number of record high temperatures continues to increase at a much faster pace than record low temperatures. In the past decade, the number of record high temperatures doubled the number of record low temperatures.

“According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years,” said the study’s lead author, Noah Diffenbaugh.

Capital Climate and Think Progress report that according to the National Oceanic and Atmospheric Administration’s (NOAA) National Climatic Data Center (NCDC), “ U.S. heat records in the first 9 days of June have outnumbered cold records by an eye-popping ratio of 13 to 1."

The Bay Area has been no exception to the trend, with cities such as Gilroy, Napa, and San Rafael posting all-time high summer temperatures in the past five years.

Rising summer temperatures could create severe and varied consequences. Human health is certainly at risk - the record heat waves in Europe in 2003 killed 40,000 people. Agricultural production is also threatened; the study projects that increases in summer temperatures in the Midwestern United States could reduce the harvest of staples, such as corn and soybeans, by more than 30 percent.

The fact that areas of the United States, Europe, and China also show permanent emergence by the mid-21st century highlights the fact that nations with developed and emerging economies are also likely to face unprecedented climate stresses even with the relatively moderate warming expected over the next half-century. These results could provide a conservative projection of the timing of permanent emergence of an unprecedented heat regime.