USA/Greenland — FRISCO Southwestern dust that darkens Colorados snowpack has clearly been implicated as a key factor in speeding up snow melt, and similar issues may be affecting other snow-covered parts of the planet, including Greenland.
Ohio State researcher Jason Box, a Colorado native, says his analysis of satellite data offers the first direct evidence that smoke from wildfires in the Arctic region is drifting over Greenland, where it may tarnish the ice sheet and make it even more vulnerable to melting.
Box presented his findings at this weeks American Geophysical Union conference in San Franciso, showing images from NASAs Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, which captured smoke from Arctic fires billowing out over Greenland during the summer of 2012.
Soot is an extremely powerful light absorber, said Box, an associate professor of Geography at Ohio Srate. It settles over the ice and captures the suns heat. Thats why increasing tundra wildfires have the potential to accelerate the melting in Greenland.
Researchers have long been concerned with how the Greenland landscape is losing its sparkly reflective quality as temperatures rise. The surface is darkening as ice melts away, and, since dark surfaces are less reflective than light ones, the surface captures more heat, which leads to stronger and more prolonged melting.
Earlier studies have recorded a 6 percent drop in reflectivity in Greenland over the last decade. Box said that will cause enough warming to bring the entire surface of the ice sheet to melting each summer, as it did in 2012.
Box was inspired to investigate tundra fires after his home state of Colorado suffered devastating wildfires this past year. According to officials, those fires were driven in part by high temperatures.
In the Arctic, rising temperatures may be causing tundra wildfires to become more common. To find evidence of soot deposition from these fires, Box and his team first used thermal images from NASAs Moderate Resolution Imaging Spectroradiometer (MODIS) to identify large fires in the region. Then they used computer models to project possible smoke particle trajectories, which suggested that the smoke from various fires could indeed reach Greenland.
Finally, they used that information to examine the CALIPSO data, and pinpoint sooty aerosolssmoke cloudsover Greenland.
Because the only way to truly measure the extent to which soot particles enhance melting is to take ice sheet surface samples, Box is organizing a Greenland ice sheet expedition for 2013. The Dark Snow Project expedition is to be the first of its kind, made possible by crowd-source funding.
The analysis of the MODIS and CALIPSO data was supported by the Ohio State Universitys Climate, Water and Carbon initiative. Collaborators on the fire study include Thomas Painter of NASAs Jet Propulsion Laboratory and graduate student McKenzie Skiles of the University of California, Los Angeles. Extent of surface melt over Greenlands ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as probable melt (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as melt (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth ObservatoryThe failure was in the forest areas.Advertisement
Following a 10-year strategy, ACT fire managers have created a mosaic across the landscape of different fuel levels, burning at every opportunity.
But forests have been too wet to burn this spring and the past two summers.
A network of 500 fire trails and strategic burns along the north-west urban edge, heavy grazing and extra grass slashing will create a fortress for the territory which forecasters say faces a higher than average risk this summer.
After a fire-fuelled tornado in January 2003 killed four Canberrans and frightened thousands more, CSIRO fire expert Phil Cheney told the subsequent inquiry the fire’s penetration into urban areas under extreme conditions did not reflect a failure of fuel management on the urban interface.