Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pollutant haze heats the Arctic

11.05.2006


University of Utah study reveals another contributor to polar warming



Arctic climate already is known to be particularly prone to global warming caused by industrial and automotive emissions of carbon dioxide and other greenhouse gases. Now, a University of Utah study finds a surprising new way society’s pollutants warm the far north: the Arctic’s well-known haze – made of particulate pollution from mid-latitude cities – mixes with thin clouds, making them better able to trap heat.

The effect makes the Arctic 2 degrees to 3 degrees Fahrenheit warmer during polluted, cloudy episodes than it would be if the air was clean, concludes the study by Tim Garrett, an assistant professor of meteorology, and Chuanfeng Zhao, a doctoral student in meteorology.


"The Arctic is warming very quickly, especially compared with the rest of the world, due to the greenhouse effect caused by carbon dioxide from factories and cars," Garrett says.

"Now we are finding there is another way pollution can warm up the Arctic. Particulate pollution from factories and cars can be transported long distances to the Arctic, where it changes clouds so that they become more effective blankets, trapping more heat and further aggravating climate warming."

Arctic haze has been seen in the Arctic since the Industrial Revolution began about 1750. "Whalers and explorers noticed what looked like pollution and couldn’t figure out where it was coming from," Garrett says. The Inuit (Eskimos) called it "poo-jok."

Scientists already knew particulate pollutants make clouds more effective at reflecting sunlight, which reduces surface temperatures. So the newly discovered effect is a surprise.

"What we found is an opposing effect where particulate pollution changes clouds so they warm the surface," Garrett says. "This effect is most pronounced in Arctic winter when it is dark and there is no sunlight. The Arctic winter is when it is most polluted because there is almost no precipitation to wash out the pollutants, and there also is a strong inversion."

He notes that the thickness of Arctic sea ice "is affected by such things as how much the atmosphere blankets the surface. Sea ice is changing very rapidly in the Arctic because of surface warming. This may be one contributing factor."

"The Arctic represents the front line of climate change and is projected to warm at a rate at least double that of the Earth as a whole," says University of Utah meteorology Chair Jim Steenburgh, who wasn’t involved in the study. "Although the importance of greenhouse gas emissions is well-documented, particulate pollution also may play an important role in the Arctic climate system. Tim’s work suggests that where pollution and thin clouds are coincident, they act to warm the surface by about 2 degrees to 3 degrees Fahrenheit."

"This represents another important effect of humans on the weather and climate of the Arctic, although additional research is needed to fully understand its contributions to the Arctic climate system," Steenburgh says.

Measuring Heat and Pollution in Alaskan Skies

The new study was published in the April 6 issue of the journal Nature. Garrett and Zhao conducted the study using data collected at two research sites near Barrow, Alaska, the northernmost town in the United States:

U.S. Department of Energy instruments that look upward and measure "multispectral infrared radiation" – essentially different wavelengths or "colors" of heat – emitted by clouds. "We used this data, and some other data, to infer how effective low-lying clouds were at absorbing heat emitted by the Earth’s surface – how good a blanket they were," Garrett says. (The more heat clouds absorb from the ground, the more heat they emit.)
"Using sophisticated theory, we also used these data to estimate how much water the clouds had, and also the sizes of droplets in the clouds."

A National Ocean and Atmospheric Administration research station measured concentrations of particulates, mostly sulfates from coal-burning power plants and smelters and from fossil fuels burned by automobiles and other sources in cities.

The Arctic haze, noted by explorers more than 200 years ago, resembles that seen during winter inversions in the Salt Lake City area. Both areas are desert-like, and pollution is trapped when warmer air aloft holds down cold air at the ground surface.

"The pollution is similar to the haze we get in the Salt Lake Valley," says Garrett. "These [Arctic pollution] concentrations can get very high in winter and spring for exactly the same reasons Salt Lake has high pollution. The Arctic gets the ’inversion’ for months at a stretch during the long, dark winter. The difference is that here [in Salt Lake] the pollution source is local, whereas in the Arctic, the pollution source is from industry far away – mostly from northern Europe and Eurasia."

Garrett and Zhao used four years of measurements from the two sites to measure cloud "emissivity" – how much clouds act like a blanket – and water droplet size in the clouds when the clouds were polluted and not polluted.

"We found that when clouds were present and the air was polluted, the clouds were more effective at stopping the surface from releasing its heat to outer space," Garrett says. "The reason this was true is that the pollution particles made the cloud droplets more numerous, but consequently smaller. Even if the amount of water is the same in the cloud, a larger number of small droplets corresponds to a more effective blanket."

People living in Salt Lake City or other mid-latitude desert climates experience the same effect during winter. "When clouds are present, it doesn’t get as cold at night as when they are absent," says Garrett.

Smaller cloud droplets making the cloud a better blanket is the same physical behavior that explains why a potato cooks faster in a microwave oven if it is cut into smaller pieces. "Same amount of potato, but more efficient cooking, because more of the interior of the potato is exposed to the penetrating microwave radiation," Garrett says.

Tim Garrett | EurekAlert!
Further information:
http://www.met.utah.edu
http://www.unews.utah.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>