A new NASA study has found that an important counter-balance to the warming of our planet by greenhouse gases – sunlight blocked by dust, pollution and other aerosol particles – appears to have lost ground.

The thinning of Earth’s "sunscreen" of aerosols since the early 1990s could have given an extra push to the rise in global surface temperatures. The finding, published today in the journal Science, may lead to an improved understanding of recent climate change. In a related study published last week, scientists found that the opposing forces of global warming and the cooling from aerosol-induced "global dimming" can occur at the same time.

The entire debate about global warming is a mirage. The concept of ‘global temperature’ is thermodynamically as well as mathematically an impossibility, says professor at The Niels Bohr Institute, University of Copenhagen, Bjarne Andresen who has analyzed this hot topic in collaboration with professors Christopher Essex from University of Western Ontario and Ross McKitrick from University of Guelph, both Ontario, Canada.

It is generally assumed that the atmosphere and the oceans have grown warmer during the recent 50 years. The reason for this point of view is an upward trend in the curve of measurements of the so-called ‘global temperature’.

Data collected in 2005 from Hurricane Rita is providing the first documented evidence that rapid intensity changes can be caused by clouds outside the wall of a hurricane's eye coming together to form a new eyewall.

Hurricanes can gain or lose intensity with startling quickness, a phenomenon never more obvious than during the historic 2005 hurricane season that spawned the remarkably destructive Katrina and Rita.

Researchers flew through Rita, Katrina and other 2005 storms trying to unlock the key to intensity changes.

Atmospheric scientists have uncovered fresh evidence to support the hotly debated theory that global warming has contributed to the emergence of stronger hurricanes in the Atlantic Ocean.

The unsettling trend is confined to the Atlantic, however, and does not hold up in any of the world's other oceans, researchers have also found.

Scientists at the University of Wisconsin-Madison and the National Climatic Data Center (NCDC) of the National Oceanic and Atmospheric Administration reported the finding in the journal Geophysical Research Letters. The work should help resolve some of the controversy that has swirled around two prominent studies that drew connections last year between global warming and the onset of increasingly intense hurricanes.

Science doesn’t always happen at a lab bench. For University of Toronto Mississauga physicist Kent Moore, it happens while strapped into a four-point harness, flying head-on into hurricane-force winds off the southern tip of Greenland.

Moore, chair of the Department of Chemical and Physical Sciences, is heading to Greenland from Feb. 18 to March 11 as part of the Greenland Flow Distortion experiment (GFDex), an International Polar Year research project involving Canadian, British, Norwegian and Icelandic scientists. Moore, a professor of atmospheric physics, is leading the Canadian contingent.

Credit: University of Toronto.

As climate change scientists develop ever more sophisticated climate models to project an expected path of temperature change, it is becoming increasingly important to include the effects of aerosols on clouds, according to Joyce E. Penner, a leading atmospheric scientist at the University of Michigan.

That's because aerosols, fine particles such as smoke and dust that form droplets in clouds and change cloud thickness, affect how much sun is able to pass through the cloud to Earth, as well as the amount of moisture that's returned to Earth. Both moisture and sunlight play significant roles in climate change.

Three hundred million years ago, Earth's climate shifted dramatically from icehouse to hothouse, with major environmental consequences. That shift was the result of both rising atmospheric carbon dioxide concentrations and the melting of vast ice sheets, new research by University of Michigan paleoclimatologist Christopher Poulsen shows.

Poulsen will discuss his findings in a symposium titled "Geosystems: Climate Lessons from Earth's Last Great Icehouse" at the annual meeting of the American Association for the Advancement of Science in San Francisco.

The changes occurred during the period of Earth's history when the continents were consolidated into a single supercontinent, Pangaea.

For the first time, NASA scientists have used a shrewd spaceborne detective to track the origin and movement of water vapor throughout Earth's atmosphere. This perspective is vital to improve the understanding of Earth's water cycle and its role in weather and climate.

For the first time, NASA scientists have used a shrewd spaceborne detective to track the origin and movement of water vapor throughout Earth's atmosphere. This perspective is vital to improve the understanding of Earth's water cycle and its role in weather and climate.

This view depicts the distribution of "heavy" and "light" water vapor molecules over Earth's tropics.

When a small pebble drops into a serene pool of water, it causes a ripple in the water in every direction, even disturbing distant still waters. NASA researchers have found a similar process at work in the atmosphere: tiny particles in the air called aerosols can cause a rippling effect on the climate thousands of miles away from their source region.

Dust from Africa's Saharan Desert lingers in high altitudes as it crosses the Atlantic Ocean. This picture was taken from an aircraft northeast of Barbados in 2006. Cumulus clouds can be seen poking through the tops of the dust layer, which is seen as a milky white haze. (Credit: NOAA)