This is What Global Warming Looks Like
Posted September 16, 2010
UPDATED: New ad-free video link. New NASA data for January-August 2010.
Summer 2010 was the worst summer ever for many Americans and even more Russians, Pakistanis, and Chinese. Today NRDC released a report analyzing U.S. temperatures and a video highlighting weather extremes in the United States, Russia, Pakistan, and China in summer 2010.
The report analyzes summer 2010 (June, July and August) data from 1,218 weather stations in NOAA’s Historic Climatology Network (HCN). The report reveals that 153 locations recorded their hottest summer on record and nearly one in three stations recorded average temperatures among their five hottest on record.
Even more telling: average nighttime low temperatures were the hottest ever recorded at nearly one in four of the HCN weather stations. This means that at 278 stations the average nighttime low temperatures for June, July and August 2010 were hotter than at any time since 1895. More than half the stations recorded average nighttime low temperatures among their five hottest on record.
Nighttime temperatures are more sensitive to the buildup of heat-trapping pollution in the atmosphere than daytime temperatures because increases in atmospheric aerosols and cloud cover have counteracted some of the warming effect of greenhouse gases during the day. Hot, stagnant nights can prove even more harmful than daytime highs as vulnerable populations (particularly the very young and the elderly) are unable to cool down and get relief from the stress of the daytime heat.
In addition to the national overview, for the 37 states that contain weather stations where summer 2010 records were set we have developed state maps showing the name and location of each weather station that set a record and accompanying tables that show for each weather station how summer 2010 compared to all other summers on record. We also have a Google Earth data layer that allows you to zoom in on any part of the country.
Some highlights of the state-by-state analysis:
- In Maryland, 15 of the 16 stations in the Historical Climatology Network reported their hottest average summer on record, and 12 reported their hottest average nighttime low temperatures on record. All 16 Maryland stations reported average temperatures and average nighttime low temperatures among their five hottest on record in summer 2010.
- In Florida, 9 out of 22 stations reported their hottest average temperatures on record in summer 2010 and 8 reported their hottest average nighttime low temperatures on record. In Fort Lauderdale the average nighttime low temperature for the full summer was 77.7 degrees. Nearly all—21 of 22—Florida stations reported average nighttime low temperatures among their five hottest on record in summer 2010.
- The Midwest also experienced very warm nighttime temperatures. In Illinois and Indiana, 92% and 86% of the stations, respectively, reported average nighttime low temperatures among their five hottest on record.
- Considering all 513 weather stations east of the Mississippi, 40 percent reported their hottest average nighttime low temperatures in 2010 and over 80 percent reported average nighttime low temperatures among their five hottest on record.
- Hundreds of daily maximum temperature records were tied or broken in August at individual stations, while over 6,000 daily records were tied or broken for warmest daily minimum temperature during August 2010.
- Ten states experienced record-warm summers: Rhode Island, New Jersey, Delaware, Maryland, Virginia, North Carolina, Tennessee, South Carolina, Georgia, and Alabama.
- Maine, New Hampshire, Vermont, Rhode Island, Connecticut, and New Jersey each had their warmest year-to-date (January-August) period.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand for Summer 2010 was the highest of the 116-year record, and eighth-highest for August itself. The unusual warmth in the highly populated mid-Atlantic and Southeast contributed to the highest Summer REDTI value on record.
This last point is worth emphasizing. Not only was it hot, but it was particularly hot where most of the U.S. population lives. And it was not just hot during the day, but it didn’t cool off at night. The net effect was that more people had to run air conditioners for more hours than ever before to stay healthy, while people without access to air conditioning faced the most serious health risks.
The record heat this summer was not isolated to the United States. Global temperature data compiled by NASA show that the first eight months of 2010 comprise the hottest such period on record and a preliminary report from NOAA released yesterday indicates that January through August was tied for the hottest on record. This comes on top of the warmest decade on record (2000-2009), which surpassed the previous record set by the 1990s, which itself supplanted the 1980s as the warmest decade on record at that time.
Record-high temperatures are not the only weather extremes we have seen in 2010. Because the atmosphere can hold more moisture as it warms, there is more rapid evaporation when it is dry and more intense rainfall when it is wet. The result is an increase in severe droughts and floods. As we have seen in Russia, Pakistan, China, and the United States, the results have been tragic. Russia has seen hundreds of wildfires and thousands of deaths in Moscow during its worst heat wave on record. In Pakistan more than a thousand people have been killed, and a million more displaced by floods. Flooding this year has also killed more than a thousand people in China, and more than 50 in Iowa and Tennessee.
But pictures really are worth a thousand words, which is why we produced this video:
While one hot summer does not prove that global warming is happening, the long-term global trend does, according to the U.S. National Academy of Sciences, among others. Similarly, we can’t attribute any specific extreme event to global warming with confidence, but we know that we are loading the dice. More record heat and more extreme droughts and floods can be expected in the future as heat-trapping pollution continues to build up in our atmosphere.
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