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 Dune ecosystem modelling
23.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>