Navigation Links
Global 'sunscreen' has likely thinned, report NASA scientists

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.

"When more sunlight can get through the atmosphere and warm Earth's surface, you're going to have an effect on climate and temperature," said lead author Michael Mishchenko of NASA's Goddard Institute for Space Studies (GISS), New York. "Knowing what aerosols are doing globally gives us an important missing piece of the big picture of the forces at work on climate."

The study uses the longest uninterrupted satellite record of aerosols in the lower atmosphere, a unique set of global estimates funded by NASA. Scientists at GISS created the Global Aerosol Climatology Project by extracting a clear aerosol signal from satellite measurements originally designed to observe clouds and weather systems that date back to 1978. The resulting data show large, short-lived spikes in global aerosols caused by major volcanic eruptions in 1982 and 1991, but a gradual decline since about 1990. By 2005, global aerosols had dropped as much as 20 percent from the relatively stable level between 1986 and 1991.

The NASA study also sheds light on the puzzling observations by other scientists that the amount of sunlight reaching Earth's surface, which had been steadily declining in recent decades, suddenly started to rebound around 1990. This switch from a "global dimming" trend to a "brightening" trend happened just a s global aerosol levels started to decline, Mishchenko said.

While the Science paper does not prove that aerosols are behind the recent dimming and brightening trends ?changes in cloud cover have not been ruled out ?another new research result supports that conclusion In a paper published March 8 in the American Geophysical Union's Geophysical Research Letters, a research team led by Anastasia Romanou of Columbia University's Department of Applied Physics and Mathematics, New York, also showed that the apparently opposing forces of global warming and global dimming can occur at the same time.

The GISS research team conducted the most comprehensive experiment to date using computer simulations of Earth's 20th-century climate to investigate the dimming trend. The combined results from nine state-of-the-art climate models, including three from GISS, showed that due to increasing greenhouse gases and aerosols, the planet warmed at the same time that direct solar radiation reaching the surface decreased. The dimming in the simulations closely matched actual measurements of sunlight declines recorded from the 1960s to 1990.

Further simulations using one of the Goddard climate models revealed that aerosols blocking sunlight or trapping some of the sun's heat high in the atmosphere were the major driver in 20th-century global dimming. "Much of the dimming trend over the Northern Hemisphere stems from these direct aerosol effects," Romanou said. "Aerosols have other effects that contribute to dimming, such as making clouds more reflective and longer-lasting. These effects were found to be almost as important as the direct effects."

The combined effect of global dimming and warming may account for why one of the major impacts of a warmer climate ?the spinning up of the water cycle of evaporation, more cloud formation and more rainfall ?has not yet been observed. "Less sunlight reaching the surface counteracts the effect of warmer air t emperatures, so evaporation does not change very much," said Gavin Schmidt of GISS, a co-author of the paper. "Increased aerosols probably slowed the expected change in the hydrological cycle."

Whether the recent decline in global aerosols will continue is an open question. A major complicating factor is that aerosols are not uniformly distributed across the world and come from many different sources, some natural and some produced by humans. While global estimates of total aerosols are improving and being extended with new observations by NASA's latest generation of Earth-observing satellites, finding out whether the recent rise and fall of aerosols is due to human activity or natural changes will have to await the planned launch of NASA's Glory Mission in 2008.

"One of Glory's two instruments, the Aerosol Polarimetry Sensor, will have the unique ability to measure globally the properties of natural and human-made aerosols to unprecedented levels of accuracy," said Mishchenko, who is project scientist on the mission.
'"/>

Source:NASA/Goddard Space Flight Center


Related biology news :

1. Global analysis of membrane proteins
2. Global warming increases oyster sensitivity to pollution
3. Grand Challenges in Global Health initiative funds Yale project
4. Global study shows all tobacco bad for the heart
5. Global warming may warrant new approaches to ecosystem restoration
6. Global warming may have damaged coral reefs forever
7. Global malaria map key weapon in fight against malaria, scientists say
8. Global changes alter the timing of plant growth, scientists say
9. Global map shows new patterns of extinction risk
10. Global survey of lizards reveals greater abundance of animals on islands than on mainland ecosystems
11. Low oxygen likely made Great Dying worse, greatly delayed recovery

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:12/22/2016)... 22, 2016 SuperCom (NASDAQ:   ... for the e-Government, Public Safety, HealthCare, and Finance sectors announced today ... been selected to implement and deploy a community-based supportive services program ... California , further expanding its presence in the state. ... This new program, which ...
(Date:12/16/2016)... , Dec 16, 2016 Research and Markets ... Market - Global Forecast to 2021" report to their offering. ... The biometric ... grow at a CAGR of 14.06% from 2016 to 2021. The ... is projected to reach 854.8 Million by 2021. The growth of ...
(Date:12/15/2016)... , Dec. 15, 2016 ... driving experience, health wellness and wellbeing (HWW), ... one in three new passenger vehicles begin ... recognition, gesture recognition, heart beat monitoring, brain ... monitoring, facial monitoring, and pulse detection. These ...
Breaking Biology News(10 mins):
(Date:1/18/2017)... --  Parent Project Muscular Dystrophy (PPMD) , a nonprofit ... dystrophy (Duchenne) , today announced a $600,000 grant to ... (NJIT) and Talem Technologies (Talem) as part of the ... assist people living with Duchenne. PPMD is funding a ... computer, software, a force sensor and a motor – ...
(Date:1/18/2017)... ... January 18, 2017 , ... Announced in December 2016, RoosterBio ... U.S. Secretary of Commerce Penny Pritzker has announced the award of a new ... has announced the award of a new Advanced Regenerative Manufacturing Institute (ARMI). These ...
(Date:1/18/2017)... ... 18, 2017 , ... BidMed, LLC, announced it will hold a ... lab equipment from two different leading institutes. This highly specialized laboratory equipment is coming ... States. This 1-day online auction will take place on BidMed’s website http://www.bidmed.com ...
(Date:1/18/2017)... SAN DIEGO , Jan. 18, 2017  HUYA ... development of China,s pharmaceutical innovations, ... Academy of Sciences Innovation and Investment Company (referred to ... and commercializing biomedical innovations discovered by leading scientists at ... the world. HUYA is the first company ...
Breaking Biology Technology: