Scientists are still unable to determine what is causing the "warming hole" over United States.
Some have suggested natural variations in sea surface temperatures could be responsible, but recent studies indicate the hole has been
created due to air pollution.
Temperatures are increasing on global scale, but in the central and eastern United States warming has not kept pace with other parts of
the world over much of the last century.
As shown in the lower map, which is based on data from NASA's Surface Temperature Analysis (GISTEMP), parts of the United States even
cooled between 1930 and 1990. Areas of the greatest cooling are blue; those that warmed are red.
Climate scientists have taken to calling the large area of cooling a "warming hole" because the areas surrounding it have warmed at a faster rate.
While working at Harvard University, Eric Leibensperger
used global climate models to estimate the cooling effect sulfates have had on the climate of the United States since 1950.
As seen in the top map, they found that between 1970 and 1990-the period when sulfates were at their highest levels-average temperatures were nearly 1°Celsius
(1.8°Fahrenheit) cooler in a core area centered on Arkansas and Missouri and about 0.7°Celsius cooler in a larger tear-drop region throughout
the Midwest and Mid-Atlantic.
The cooling effect extended into the North Atlantic Ocean as well; sulfate pollution lowered sea surface temperatures there by 0.3°Celsius.
Image credit: NASA
Leibensperger's research also shows that the cooling effect from sulfates is diminishing.
The amount of the pollutant in the atmosphere has declined significantly in the last few decades due to the Clean Air Act.
According to Environmental Protection Agency estimates, the amount of sulfur dioxide (a precursor to sulfates) released into the atmosphere fell by 58
percent between 1980 and 2010. Satellites have confirmed the decrease; the Ozone Monitoring Instrument (OMI) on the Aura satellite observed a sharp
decline in sulfates over the eastern United States between 2005 and 2010.
As a response to the declining sulfate levels, Leibensperger's modeling shows temperatures over the central and eastern United States have increased
by 0.3°Celsius between 1980 and 2010. How much more warming can we expect as sulfate concentrations continue to decline? Not much, according to Leibensperger.
Sulfate concentrations have declined so much already that the impact of future decreases won't be nearly as substantial.
MessageToEagle.com based on material provided by NASA.
Latest Spectacular Solar Flare Will Hit STEREO-B Spacecraft, Spitzer And Curiosity
The Sun continues to show its more violent side.
A spectacular solar flare erupted from the Sun's northeastern limb yesterday, sending an beautiful arcing jet of super-heated plasma blasting off into space.
The explosion, captured by Nasa's Solar Dynamics Observatory at about 5.45pm yesterday evening, was one of the most beautiful seen in years.
Europe's Future Climate Will Bring Violent Winter Storms
The climate in Europe can change dramatically very soon.
According to a new study Europeans can expect more violent winter storms in the future.
A weakening of the warm North Atlantic ocean current, the Meridional Overturning Circulation, during the
next century has already been predicted by climate scientists, with suggestions it could lead to colder sea temperatures and reduced warming in Britain.
Dangerous Fast and Furious - Birth Of Africa's New Ocean - with video
The only places where mid-ocean ridges appear above sea level are Ethiopia and Iceland.
Two new studies into the so-called “plumbing systems” that lie under volcanoes could bring scientists closer to predicting large
eruptions and reveal new information about where magma is stored and how it moves through the geological plumbing network.
New Evidence Links Earth's Extreme Weather
To Human-Caused Global Warming
From the many single events a pattern emerges. At least for extreme rainfall and heat waves the link with human-caused
global warming is clear, the scientists show in a new analysis of scientific evidence in the journal Nature Climate Change.
Less clear is the link between warming and storms, despite the observed increase in the intensity of hurricanes.