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The subnivium, a secret world beneath the snow, is at risk from global warming

Declining spring snowcover will impact plants and animals use deep snow cover as a refuge from winter cold

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Spring snow cover in the northern hemisphere is in decline. Graphic courtesy Rutgers Global Snow Lab.

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Melting snow reveals the subniveal world.

By Bob Berwyn

FRISCO — Beneath winter’s deep snows there is a secret world of frozen insects and amphibians in quasi-hibernation, where small mammals scoot about eating bugs and fungi. It’s an ecoogical world that’s mostly invisible but functions as a critical part of larger ecosystems. The subnivium, as scientists have dubbed it, is now at risk from global warming.

Since 1970, snow cover in the Northern Hemisphere has declined by as much as 3.2 million square kilometers during the critical spring months of March and April. Maximum snow cover has shifted from February to January and spring melt has accelerated by almost two weeks, according to a team of university researchers who set out to discover some of the ecological impacts of the loss of snow cover. Visit the Rutgers Global Snow Lab for more details on snow cover. Continue reading

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Global warming: More extreme rainfall events nearly certain

Warmer atmosphere, more moisture, more rain

Breckenridge, Colorado recently recorded an all-time 24-hour record rainfall event during a summer thunderstorm. Bob Berwyn photo.

Breckenridge, Colorado recently recorded an all-time 24-hour record rainfall event during a summer thunderstorm. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Large parts of the northern hemisphere could see a 20 to 30 percent increase in extreme precipitation events by the end of the century. Extra moisture due to a warmer atmosphere dominates all other factors, leading to notable increases in the most intense precipitation rates, according to a new NOAA-led study.

The study shows a 20-30 percent expected increase in the maximum precipitation possible over large portions of the Northern Hemisphere by the end of the 21st century if greenhouse gases continue to rise at a high emissions rate.

“We have high confidence that the most extreme rainfalls will become even more intense, as it is virtually certain that the atmosphere will provide more water to fuel these events,” said Kenneth Kunkel, Ph.D., senior research professor at the Cooperative Institute for Climate and Satellites-North Carolina and lead author of the paper. Continue reading

Growing temperature contrast between northern and southern hemispheres likely to have big impacts on rainfall

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Tropical rainbands are likely to shift northward as the northern hemisphere warms more than the southern. Photo courtesy NASA.

‘To expect that rainfall patterns would stay the same is very naïve’

By Summit Voice

SUMMIT COUNTY — A growing temperature disparity between the southern and northern hemispheres could have significant long-term effects on tropical rainfall patterns, potentially shifting monsoons in some areas, or leading to drought in other regions.

Climate scientists aren’t exactly sure how that will play out, but they are starting to measure the temperature differences between the two hemispheres to create an index that might help forecast some of the changes. Continue reading

Winter Solstice 2012: The world definitely is not ending

Winter starts

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The 2011 winter solstice sunset in Frisco, Colorado.

By Bob Berwyn

SUMMIT COUNTY — With all the hoopla of Christmas, it’s easy to forget that the winter solstice was marked by deeply spiritual ceremonies long before the emergence of Christian traditions. But if you take a moment today to contemplate the sun hanging at it’s lowest and most southerly point in the sky, it’s a little easier to understand why ancient people took the trouble to erect massive stone monuments to observe the day.

Try and see the world from the perspective of a Stone Age hunter in a time when the universe was infinitesimally more mysterious than it is today. Now, we understand orbital cycles. Notwithstanding the end-of-the-world hype, we can be fairly certain that the days will soon start getting longer again. We can keep warm in our homes, and fend off the dark with electric lights.

But there must have been a time when the long, dark nights at the start of winter were frightening, with no real assurance that spring would arrive once more. Gradually, through observation, even the ancient ones figured it out, and the fact that the cycle of shortening days was at an end became reason for celebration. Continue reading

June 2012 global temps the 4th-warmest ever

Land-surface temperatures at an all-time high

Above-average temperatures prevailed across most of the world, adding up to the fourth-warmest June on record

By Summit Voice

SUMMIT COUNTY — The global temperature in June, averaged from thousands of weather stations, was the fourth-warmest on record for the planet, at 1.13 degrees above the 20th century average, according to the monthly update from the National Climatic Data Center.

Land-surface temperatures measured alone set an all-time record for the month, with the northern hemisphere at 2.34 degrees above average and globally at 1.93 degrees above average. June was the second consecutive month with record global land surface temperatures. The last time June temperatures were below average was in 1976.

In the Northern Hemisphere, it was the third month in a row with record-setting heat over land, with most areas seeing temperatures running well above average. Only northern and western Europe, and the northwestern United States were cooler than average. Continue reading

Global warming: Cornell researchers say melting Arctic ice may be setting the stage for more extreme winter weather

A weakening of the polar vortex and jet stream is likely to lead to more severe winter weather outbreaks.

‘Arctic wildcard stacking the deck in favor of more severe winter outbreaks

By Summit Voice

SUMMIT COUNTY — Evidence continues to mount that melting Arctic ice is having a significant effect in the mid-latitudes, where most people live, and it’s not something that’s going to take decades to develop.

Instead, researchers say, the warming of the high latitudes has decreased a historic pressure gradient at the boundary of the high- and mid latitudes. Basically, the pressure difference has decreased, and that is having a fundamental effect on the way the jet stream moves from west to east in the northern hemisphere. Continue reading

Climate: Soot a factor in declining spring snow cover

Decline of reflective snow cover likely to speed overall warming

Soot is contributing to a steady decline in spring snow cover.

By Summit Voice

SUMMIT COUNTY — Heat-trapping greenhouse gases aren’t the only reason the spring snow cover across the northern hemisphere has been declining steeply the past few decades.

By tweaking a sophisticated set of climate models, researchers found that black carbon and dust — both generated by human activities — are at least part of the reason that spring snow cover in Eurasia is declining faster than across North America.

Declining spring snow cover has a feedback effect of intensifying warming because snow-covered ground reflects incoming radiation. Once the snow is melted, the heat is absorbed. Continue reading

Winter solstice, 2011

To everything, turn, turn …

Solstice at Stonehenge. PHOTOGRAPH COURTESY ANDREW DUNN VIA WIKIPEDIA AND A CREATIVE COMMONS LICENSE.

By Summit Voice

SUMMIT COUNTY — Today is the first day of winter, but if you’re waiting for the solstice, you’re too late. While we commonly refer to an entire day as the solstice, in reality it’s just a short moment in time when the northern hemisphere is at it maximum tilt away from the sun, at 23.5 degrees. That moment occurred last night Dec. 21) at 10:30 p.m. Continue reading

Climate: Global scale of current warming is unpredecented

‘What is happening today is unique from a historical geological perspective’

New research suggests historical climate change occurred mainly on the local or regional level.

By Summit Voice

SUMMIT COUNTY — Simultaneous warming in the southern and northern hemispheres hasn’t occurred in at least 20,000 years, and possibly longer, according to a Swedish researcher who says his findings refute one of the more common arguments against global warming.

“What is happening today is unique from a historical geological perspective,” said Svante Björck, a climate researcher at Lund University.

Björck directly addressed the argument that climate has always changed in cycles by showing that, in the past, when when, for example, the temperature rises in one hemisphere, it falls or remains unchanged in the other.

“My study shows that, apart from the larger-scale developments, such as the general change into warm periods and ice ages, climate change has previously only produced similar effects on local or regional level,” says Svante Björck. Continue reading

South Atlantic current a big player in global climate

Warm, salty water from the south could balance impacts of melting polar ice cap

Agulhas Current system and its "leakage" into the Atlantic Ocean, affecting climate. Credit: Erik van Sebille, RSMAS.

By Summit Voice

SUMMIT COUNTY — Leakage from an ocean current running along the east coast of Africa could ameliorate some anticipated global warming impacts in the northern hemisphere, according to University of Miami researchers, who recently published a study in the journal nature suggesting that the Agulhas Current could be a significant player in global climate variability.

The Agulhas Current transports warm and salty waters from the tropical Indian Ocean to the southern tip of Africa. There most of the water loops around to remain in the Indian Ocean (the Agulhas Retroflection), while some water leaks into the fresher Atlantic Ocean via giant Agulhas rings.

Once in the Atlantic, the salty Agulhas leakage waters eventually flow into the Northern Hemisphere and act to strengthen the Atlantic overturning circulation by enhancing deep-water formation. Recent research points to an increase in Agulhas leakage over the last few decades, caused primarily by human-induced climate change. Continue reading

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