The Progressive


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For Immediate Release
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"Dark Side of Climate Change" Seen in Record Setting Night-Time Temperatures in 37 U.S. States in Summer Of 2010

Special risk seen to elderly, low-income population from reduced overnight cooling; Night-time temperatures more sensitive to greenhouse gas emissions.


While many Americans focused on this summer's day-time record-setting
temperatures, there is growing concern about the largely ignored
pattern of record-setting night-time temperatures, which pose special
dangers to elderly and low-income Americans who are more dependent on
overnight cooling during the hottest months.

A new analysis from the Natural Resources Defense Council (NRDC) shows that:

  • At nearly one of four weather stations in the contiguous
    United States -- 278 out of 1,218 -- the average night-time low
    temperatures for June, July and August 2010 were hotter than at any time
    since 1895.
  • Considering all 513 weather stations east of the
    Mississippi, 40 percent reported their hottest average night-time low
    temperatures on record and more than 80 percent reported average
    nighttime low temperatures among their five hottest on record in summer
  • More than half of all U.S. weathers stations recorded average night-time low temperatures among their five hottest on record.
  • Record night-time temperatures were set at stations in 37
    states: Alabama, Arizona, Arkansas, Connecticut, Delaware, Florida,
    Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine,
    Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New
    Hampshire, New Jersey, New Mexico, New York, North Carolina, North
    Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina,
    South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wisconsin.

Dan Lashof, director, Climate Center, Natural Resources
Defense Council, said: "Welcome to what might be termed 'the dark side
of climate change.' Summer 2010 was the hottest on record in
many locations in the United States. Not only was it hot during the day,
but it didn't cool off at night. 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. The
long, hot summer of 2010 follows the hottest decade on record and more
record high temperatures can be expected in the future as heat-trapping
pollution continues to build up in our atmosphere."

Night-time 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

Kim Knowlton, senior scientist, Health and Environment
Program, Natural Resources Defense Council, said: "Hot, stagnant nights
can prove even more harmful than daytime highs as vulnerable
populations --particularly the elderly and low-income individuals
without air conditioning -- are unable to cool down and get relief from
the stress of day-time heat that persists into the evening."

The NRDC analysis highlights the following states:

  • In Maryland, 12 of the 16 stations in the Historical
    Climatology Network reported their hottest average nighttime low
    temperatures on record in summer 2010. All 16 Maryland stations reported
    average nighttime low temperatures among their five hottest on record
    in summer 2010.
  • In Florida, nearly all -- 21 of 22 -- weather
    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 percent and 86 percent of the
    stations, respectively, reported average nighttime low temperatures
    among their five hottest on record in summer 2010.
  • The Western United States was not as hot as the Eastern
    half of the country. Nonetheless, seven stations in Arizona reported
    average temperatures for this summer among their five hottest on record,
    and 11 stations in New Mexico reported average nighttime low
    temperatures among their five hottest.

The analysis also points out that: "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."

To read the full analysis, please go to

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