Study tracks links between sea ice and climate

No smoking gun — yet

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Large areas of open water where there historically was ice is affecting regional air temperatures and atmospheric circulation in the Arctic. Image courtesy NASA.

By Bob Berwyn

FRISCO — There’s no doubt that the continuing decline of Arctic sea ice is going to affect climate and weather across the northern hemisphere, but researchers are still trying to pinpoint exactly what the impacts will be.

In one recent study, scientists with the Cooperative Institute for Research in Environmental Science found that as sea ice disappeared, the areas of relatively warm open water began to strongly influence the atmosphere, increasing surface temperatures in the region, and shifting low- and high-pressure zones around most markedly in the fall and winter.

“The way I see it, it’s one of the wild cards out there,” said Mark Serreze, director of the National Snow and Ice Data Center. “The issue is just what those changes are going to  look like. That’s what we’re really still grappling with, we don’t have a handle on this … Is there a smoking gun? No, not yet,” Serreze said, discussing the findings of the new study. Continue reading

Global warming could fuel European hurricanes

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Tropical storms are more likely to affect Europe as Atlantic sea surface temperatures rise.

Severe winds to increase in the North Sea and the Gulf of Biscay, especially during autumn

By Bob Berwyn

SUMMIT COUNTY — European climate scientists say global warming will drive a northeastward expansion of the tropical Atlantic hurricane breeding ground, with four times as many storms of tropical origins affecting parts of Western Europe in coming decades.

In the Bay of Biscay, the number of storms with tropical-storm-force winds could increase from 2 to 13 by the end of the century, said researcher Reindert Haarsma.

The initial results suggest that the impacts may not be as great in the low-lying Netherlands as in some other areas because the strong winds associated with the events will generally be from the southwest, Haarsma said.

With hurricanes forming farther north and warmer sea surface temperatures in the region, tropical storms are more likely to reach the mid-latitudes, where they will merge with the prevailing westerlies. Even if they lose hurricane status, they are likely to remain stronger, and sometimes re-intensify before landfall, potentially with serious impacts in parts of Europe.

“Our model simulations clearly show that future tropical cyclones are more prone to hit Western Europe and do so earlier in the season,” said the researchers with the Royal Netherlands Meteorological Institute. Continue reading

Global warming: Study suggests temperatures in West Antarctica rising much faster than previously estimated

New data fills gap in Antarctic climatology

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A new evaluation of temperatures records from West Antarctica raises concerns about impacts to sea level rise. Bob Berwyn photo.

By Summit Voice

FRISCO — A new analysis of temperature records from a research station in West Antarctica suggests that temperatures in the remote region have climbed steeply in the last half-century, by as much as 4.3 degrees since 1958.

The findings, published in the most recent issue of Nature Geoscience, heighten concerns about the future contribution of Antarctica to sea level rise, because researchers say the West Antarctic Ice Sheet is especially sensitive to climate change.

Since the base of the ice sheet rests below sea level, it is vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 mm to sea level rise each year—second to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year, according to Ohio State University doctoral student Julien Nicolas. Continue reading

Global warming: Eastern U.S. to see more heatwaves, rain

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University of Tennessee researchers say the eastern U.S. can expect more heatwaves and increased precipitation in a warming world. Image courtesy NASA.

New climate model pinpoints predictions down to the city level

By Summit Voice

SUMMIT COUNTY — As climate models become more sophisticated, researchers have started to fine-tune global warming impacts to the regional level, including more drought and water shortages expected in the Southwest, seasonal ice-free conditions in the Arctic, and hotter, wetter conditions in the Eastern U.S., according to a new University of Tennessee study.

The researchers, Joshua Fu, a civil and environmental engineering professor, and Yang Gao, a graduate research assistant, say heat waves will become more severe in most regions of the eastern United States and, that both the Northeast and Southeast will see a drastic increase in precipitation. Continue reading

Global warming: The longer we wait, the harder it gets

Meeting 2-degree warming target requires immediate action

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Even without El Niño, Nov. 2012 temps were far above average across most of the globe. Graphic courtesy NASA.

By Summit Voice

SUMMIT COUNTY — Delaying meaningful action on climate change is tempting, but will likely prove to be very costly in the long run, an international group of researchers warned this week in an article in Nature Climate Change.

The easiest path is to reaching the targeted 2-degree cap in global temperatire increases would be to significantly cut greenhouse gas emissions. If that doesn’t happen by 2020, the goal is still attainable, but at a much greater cost, with much higher climate risks and and under exceedingly optimistic assumptions about future technologies.

Timely cuts in emissions leaves more doors open in the long run, said the researchers from the International Institute for Applied Systems Analysis in Laxenburg, Austria, ETH Zurich in Switzerland, and the National Center for Atmospheric Research in Boulder.

The researchers say this is what needs to happen sooner, rather than later:

Nuclear power would need to remain on the table as a mitigation option, or people would need to quickly adopt advanced technology strategies, including electric vehicles and highly efficient energy end-use technologies such as appliances, buildings, and transportation. Meanwhile, coal-fired power plants would need to be rapidly shut down and replaced with other energy sources.

“You would need to shut down a coal power plant each week for ten years if you still wanted to reach the two-degree Celsius target,” said IIASA energy program leader Keywan Riahi, who also worked on the study. Continue reading

Global warming: Study confirms greenhouse gas ‘fingerprint’ in distinct patterns of temperature change

Study links regional atmospheric warming with greenhouse gases. Photo courtesy NASA.

Study will anchor new IPCC climate change assessment

By Summit Voice

FRISCO — Just as thousand of delegates gather in Doha, Qatar for the UN’s annual climate talks, researchers are releasing a wealth of new observational data that verifies the output from existing climate models.

In recent example, a team of climate scientists from the Lawrence Livermore National Laboratory and colleagues from 16 other organizations compared simulations from 20 different computer models to satellite observations, finding that tropospheric and stratospheric temperature changes are clearly related to human activities.

“It’s very unlikely that purely natural causes can explain these distinctive patterns of temperature change,” said Lawrence Livemore National Laboratory atmospheric scientist Benjamin Santer, who is lead author of the paper appearing in the Nov. 29 online edition of the journal, Proceedings of the National Academy of Sciences. “No known mode of natural climate variability can cause sustained, global-scale warming of the troposphere and cooling of the lower stratosphere.” Continue reading

CU study eyes water, climate and land-use tipping points

Reservoirs were left high and dry by this summer’s drought.

National Science Foundation funding enables detailed research on trans-basin water diversions

By Summit Voice

SUMMIT COUNTY — As some West Slope aquatic ecosystems teeter on the brink of collapse due to water diversions, a group of CU researchers will use a $1.4 million grant from the National Science Foundation to try and pinpoint tipping points, beyond which systems may be pushed into an unsustainable state.

The research will examine how changes in land use, forest management and climate may affect trans-basin water diversions in Colorado and other semi-arid regions in the western United States, finding thresholds that could compromise the sustainability of the policies and procedures that dictate the timing and quality of water diverted from Colorado’s West Slope to the Front Range.

The grant, part of the National Science Foundation-U.S. Department of Agriculture Water Sustainability Climate Program, was awarded to assistant professor Noah Molotch of the geography department, who singled out Summit County as one focus area for the study. Continue reading

Global warming: Arctic temps out of synch with natural cycles

Paleo-climate data suggests region should be cooling, but greenhouse gas forcing has overpowered nature pattern

New research shows that the Arctic reversed a long-term cooling trend and began warming rapidly in recent decades. The blue line shows estimates of Arctic temperatures over the last 2,000 years, based on proxy records from lake sediments, ice cores and tree rings. The green line shows the long-term cooling trend. The red line shows the recent warming based on actual observations. Courtesy Science, modified by UCAR.

By Summit Voice

SUMMIT COUNTY — Without ever-increasing concentrations of heat-trapping greenhouse gases in the atmosphere, the Arctic would gradually be cooling instead of experiencing the rapid warming that’s been documented in the past few decades.

The long-term cooling trend, documented back to at least 2,000 years ago, is related to wobbles in the Earth’s orbit that have reduced the intensity of sunlight reaching the Arctic in summertime, when Earth is farther from the Sun, according to a recent study led by scientists from Northern Arizona University and the National Center for Atmospheric Research.

But in the middle of the 20th century, the gradual cooling ended abruptly, replaced by a sharp increase in Arctic temperatures — even though orbital cycles would suggest a continued cooling trend. The research, based on geologic records and computer models, strongly suggests that the heat-trapping effects of greenhouse gases are overpowering natural climate cycles. Continue reading

Weather: Lasers to give more accurate snowpack readings

Boulder-based researchers field testing new technology

Boulder researchers are exploring more accurate ways to measure snowpack.

Ethan Gutmann examines a laser instrument for measuring snow. (©UCAR, Photo by Carlye Calvin.

By Summit Voice

SUMMIT COUNTY — Specialized lasers and the latest GPS technology will help meteorologists make more accurate assessments of snow cover and snowpack — critical measurements for determining avalanche danger, predicting water supplies and anticipating flood hazards.

“We’ve been measuring rain accurately for centuries, but snow is much harder because of the way it’s affected by wind and sun and other factors,” said Ethan Gutmann, a researcher at the Boulder National Center for Atmospheric Research. The new technology will finally give scientists the  ability to say exactly how much snow is on the ground, he added. Continue reading

Global warming: CU-led study pinpoints Earth’s ice loss

Arctic sea ice extent is below average in early February, according to the National Snow and Ice Data Center.

New data to help project sea level rise

By Summit Voice

Earth’s glaciers and ice caps outside of the regions of Greenland and Antarctica are shedding about 150 billion tons of ice annually, according to a new study led by the University of Colorado Boulder.

The total mass ice loss from Greenland, Antarctica and all Earth’s glaciers and ice caps between 2003 to 2010 was 1,000 cubic miles, about eight times the water volume of Lake Erie.

“The total amount of ice lost to Earth’s oceans from 2003 to 2010 would cover the entire United States in about 1 and one-half feet of water,” said CU-Boulder physics Professor John Wahr, who helped lead the study. Continue reading

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