Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Shrinking snow and ice cover intensify global warming

The decreases in Earth's snow and ice cover over the past 30 years have exacerbated global warming more than models predict they should have, on average, new research from the University of Michigan shows.

To conduct this study, Mark Flanner, assistant professor in the Department of Atmospheric, Oceanic and Space Sciences, analyzed satellite data showing snow and ice during the past three decades in the Northern Hemisphere, which holds the majority of the planet's frozen surface area. The research is newly published online in Nature Geoscience.

Snow and ice reflect the sun's light and heat back to space, causing an atmospheric cooling effect. But as the planet warms, more ice melts and in some cases, less snow falls, exposing additional ground and water that absorb more heat, amplifying the effects of warmer temperatures. This change in reflectance contributes to what's called "albedo feedback," one of the main positive feedback mechanisms adding fuel to the planet's warming trend. The strongest positive feedback is from atmospheric water vapor, and cloud changes may also enhance warming.

"If the Earth were just a static rock, we could calculate precisely what the level of warming would be, given a perturbation to the system. But because of these feedback mechanisms we don't know exactly how the climate will respond to increases in atmospheric carbon dioxide," Flanner said.

"Our analysis of snow and sea ice changes over the last 30 years indicates that this cryospheric feedback is almost twice as strong as what models have simulated. The implication is that Earth's climate may be more sensitive to increases in atmospheric carbon dioxide and other perturbations than models predict."

The cryosphere is the planet's layer of snow, sea ice and permanent ice sheets.

In the Northern Hemisphere since 1979, the average temperature rose by about 0.7 degrees Celsius, whereas the global average temperature rose by about 0.45 degrees, Flanner said.

For every 1 degree Celsius rise in the Northern Hemisphere, Flanner and his colleagues calculated an average of 0.6 fewer watts of solar radiation reflected to space per square meter because of reduced snow and sea ice cover. In the 18 models taken into consideration by the International Panel on Climate Change, the average was 0.25 watts per square meter per degree Celsius over the same time period.

Flanner points out that the models typically calculate this feedback over 100 years---significantly longer than this study, which could account for some of the discrepancy. Satellite data only goes back 30 years.

To further put the results in context, each square meter of Earth absorbs an average of 240 watts of solar radiation. These new calculations show that the Northern Hemisphere cryosphere is reflecting .45 watts less per square meter now than it did in 1979, due mostly to reduced spring snow cover and summer sea ice.

"The cryospheric albedo feedback is a relatively small player globally, but it's been a surprisingly strong feedback mechanism over the past 30 years," Flanner said. "A feedback of this magnitude would translate into roughly 15 percent more warming, given current understanding of other feedback mechanisms."

To avoid the worst effects of climate change, the scientific consensus is that the global average temperature should stay within 2 degrees Celsius, or 3.6 degrees Fahrenheit, of pre-industrial levels. Scientists are still trying to quantify the extent to which the planet will warm as greenhouse gases accumulate in the atmosphere.

"People sometimes criticize models for being too sensitive to climate perturbations" Flanner said. "With respect to cryospheric changes, however, observations suggest the models are a bit sluggish."

The paper is called "Radiative forcing and albedo feedback from the Northern Hemisphere cryosphere between 1979 and 2008." This research is funded by the National Science Foundation.

For more information:

Mark Flanner:
Michigan Engineering: The University of Michigan College of Engineering is ranked among the top engineering schools in the country. At $180 million annually, its engineering research budget is one of largest of any public university. Michigan Engineering is home to 11 academic departments, numerous research centers and expansive entrepreneurial programs. The College plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world-class Lurie Nanofabrication Facility. Michigan Engineering's premier scholarship, international scale and multidisciplinary scope combine to create The Michigan Difference. Find out more at

Nicole Casal Moore | EurekAlert!
Further information:

More articles from Earth Sciences:

nachricht Wandering greenhouse gas
16.03.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Unique Insights into the Antarctic Ice Shelf System
14.03.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

A new kind of quantum bits in two dimensions

19.03.2018 | Physics and Astronomy

Scientists have a new way to gauge the growth of nanowires

19.03.2018 | Materials Sciences

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Science & Research
Overview of more VideoLinks >>>