Tag Archives: solar radiation

Great Lakes evaporation study dispels misconceptions, points to need for expanded monitoring program

ANN ARBOR — The recent Arctic blast that gripped much of the nation will likely contribute to a healthy rise in Great Lakes water levels in 2014, new research shows. But the processes responsible for that welcome outcome are not as simple and straightforward as you might think.

Yes, extreme winter cold increases ice cover on the Great Lakes, which in turn reduces evaporation by preventing water vapor from escaping into the air. But this simplistic view of winter ice as a mere “cap” on Great Lakes evaporation is giving way to a more nuanced conception, one that considers the complex interplay among evaporation, ice cover and water temperature at different times of year. (more…)

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Study Links Past Changes in Monsoon to Major Shifts in Indian Civilizations

A fundamental shift in the Indian monsoon has occurred over the last few millennia, from a steady humid monsoon that favored lush vegetation to extended periods of drought, reports a new study led by researchers at the Woods Hole Oceanographic Institution (WHOI). The study has implications for our understanding of the monsoon’s response to climate change.

The Indian peninsula sustains over a billion people, yet it lies at the same latitude as the Sahara Desert. Without a monsoon, most of India would be dry and uninhabitable. The ability to predict the timing and amount of the next year’s monsoon is vital, yet even our knowledge of the monsoon’s past variability remains incomplete. (more…)

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New CU-led Study May Answer Long-Standing Questions About Enigmatic Little Ice Age

A new University of Colorado Boulder-led study appears to answer contentious questions about the onset and cause of Earth’s Little Ice Age, a period of cooling temperatures that began after the Middle Ages and lasted into the late 19th century.

According to the new study, the Little Ice Age began abruptly between A.D. 1275 and 1300, triggered by repeated, explosive volcanism and sustained by a self- perpetuating sea ice-ocean feedback system in the North Atlantic Ocean, according to CU-Boulder Professor Gifford Miller, who led the study. The primary evidence comes from radiocarbon dates from dead vegetation emerging from rapidly melting icecaps on Baffin Island in the Canadian Arctic, combined with ice and sediment core data from the poles and Iceland and from sea ice climate model simulations, said Miller. (more…)

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Deforestation Causes Cooling in northern U.S., Canada

Deforestation, considered by scientists to contribute significantly to global warming, has been shown by a Yale-led team to actually cool the local climate in northern latitudes, according to a paper published Nov. 17 in Nature.

“If you cut trees in the boreal region, north of 45 degrees latitude, you have a net cooling effect,” says Xuhui Lee, the study’s principal investigator and professor of meteorology at the Yale School of Forestry & Environmental Studies. “You release carbon into the atmosphere by cutting down trees, but you increase the albedo effect — the reflection of sunlight.” (more…)

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Rising Air Pollution Worsens Drought, Flooding UMD-Led Study Shows

COLLEGE PARK, Md. – Increases in air pollution and other particulate matter in the atmosphere can strongly affect cloud development in ways that reduce precipitation in dry regions or seasons, while increasing rain, snowfall and the intensity of severe storms in wet regions or seasons, says a new study by a University of Maryland-led team of researchers. (more…)

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Volcanic Eruptions Affect Rainfall over Asian Monsoon Region

Scientists have long known that large volcanic explosions can affect the weather by spewing particles that block solar energy and cool the air.

Some suspect that extended “volcanic winters” from gigantic eruptions helped kill off dinosaurs and Neanderthals.

In the summer following Indonesia’s 1815 Tambora eruption, frost wrecked crops as far away as New England, and the 1991 blowout of the Philippines’ Mount Pinatubo lowered average global temperatures by 0.7 degrees F — enough to mask the effects of greenhouse gases for a year or so. (more…)

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Optimizing Climate Change Reduction

Palo Alto, CA — Scientists at the Carnegie Institution’s Department of Global Ecology have taken a new approach on examining a proposal to fix the warming planet. So-called geoengineering ideas—large-scale projects to change the Earth’s climate—have included erecting giant mirrors in space to reflect solar radiation, injecting aerosols of sulfate into the stratosphere making a global sunshade, and much more. Past modeling of the sulfate idea looked at how the stratospheric aerosols might affect Earth’s climate and chemistry.

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Shrinking Atmospheric Layer Linked to Low Levels of Solar Radiation

WASHINGTON — Large changes in the Sun’s energy output may cause Earth’s outer atmosphere to contract, new research indicates. A study published today by the American Geophysical Union links a recent, temporary shrinking of a high atmospheric layer with a sharp drop in the Sun’s ultraviolet radiation levels. (more…)

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