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 Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

nachricht Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>