Greenhouse gas warming overrides all other climate signals

Posted on April 23, 2013 by Bob Berwyn

Late 20th century temperature spike reversed long cooling trend

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New study finds that Europe’s 2003 heatwave brought the hottest temperatures in 2000 years.

By Summit Voice

SUMMIT COUNTY — Heat-trapping greenhouse gases have driven global temperatures higher than at any other time during the past 1,400 years, according to a new study covering all seven continents. The big spike between 1971 and 2000 reversed a natural cooling trend that had lasted several hundred years, according to climate data from tree rings, pollen, cave formations, ice cores, lake and ocean sediments, and historical records from around the world.

“This paper tells us what we already knew, except in a better, more comprehensive fashion,” said study co-author Edward Cook, a tree-ring scientist at Lamont-Doherty Earth Observatory who led the Asia reconstruction. (more…)

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Climate: Current warming in Arctic unprecedented

Posted on October 2, 2012 by Bob Berwyn
Is Svalbard ground zero for global warming?

August 2012 global temperatures anomalies.

Svalbard might be ground zero for global warming, with some research suggesting it may warm faster than any other spot on Earth. Photo courtesy, NASA.

By Summit Voice

SUMMIT COUNTY — A group of researchers led by a Columbia University climate scientist William D’Andrea took direct aim at misleading information about historic climate records this week, releasing a study showing that temperatures in some parts of the Arctic are higher than they’ve been at any time during the past 1,800 years.Global warming deniers have used evidence of warmer temperatures during the so-called Medieval Warm Period to undermine the reality that heat-trapping greenhouse gases are inexorably warming the planet.

But the climate reconstruction from Svalbard casts new doubt on the reach of the Medieval Warm Period, and undercuts skeptics who argue that current warming is also natural. Since 1987, summers on Svalbard have been 2 degrees to 2.5 degrees Celsius (3.6 to 4.5 degrees fahrenheit) hotter than they were there during warmest parts of the Medieval Warm Period, according to the new study. (more…)

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Study suggests Southwest fires driven by year-to-year weather cycles rather than long-term climate variations

Posted on May 17, 2012 by Bob Berwyn

A low-intensity ground fire burns through ponderosa pine during a prescribed fire in Grand Canyon National Park. PHOTO COURTESY NATIONAL PARK SERVICE.

New study offers more evidence that historical fire suppression is the main contributing factor in today’s big southwestern fires

By Summit Voice

SUMMIT COUNTY — A detailed analysis of historic fire-scar records and tree-ring data going back centuries offers more evidence that recent mega-fires in the Southwest are unprecedented and likely a result of widespread fire suppression.

While many of today’s southwestern forests haven’t seen a fire in more than 100 years, historical records show that, in the pre-suppression era, they rarely went as long as 40 or 50 years without a low-intensity ground fire.

To reach their conclusions, researchers at Southern Methodist University used a statistical model that encompassed 1,500 years of climate and fire patterns. They wanted to test if today’s dry, hot climate alone is causing the megafires that routinely destroy millions of acres of forest. (more…)

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West: Wildfire regimes out of synch with climate cycles

Posted on February 15, 2012 by Bob Berwyn

‘Policies of fire suppression that do not account for this unusual environmental situation are unsustainable.’

One of the many wildfires that burned during a record fire season in Texas. PHOTO COURTESY TEXAS FOREST SERVICE/INCIWEB.

By Summit Voice

SUMMIT COUNTY —After a careful comparison of historic fire frequency and climate records (based in part on an extensive charcoal database) a team of university researchers concluded that human activity reduced the frequency of wildfires from the 1,000-year maximum to the 1,000-year minimum — in less than 100 years, leading to a fire deficit.

In short, fire regimes are out of whack with climate cycles. A combination of drought, a build-up of combustible fuels and increased tree mortality is the recipe for a “perfect storm” of wildfire conditions, the researchers warned in a Feb. 14 paper published in Proceedings of the National Academy of Sciences.

The long-term perspectives gained through these studies demonstrate how strongly climate and people affect the present-day landscapes and forests of the American West, and how they may change in the future, said  University of Oregon geography professor Patrick Bartlein, one of the paper’s authors. (more…)

Filed under: climate and weather, Colorado, forest fires, forests, global warming | Tagged: , , , , , | 3 Comments »

Study: Deforestation may lead to drought

Posted on February 3, 2012 by Bob Berwyn

Could forest-clearing in beetle-killed stands tilt regional climate toward dry conditions?

New research tracks rainfall patterns in Central America 

By Summit Voice

SUMMIT COUNTY — As if the pine beetle outbreak weren’t bad enough, there’s new evidence to suggest that widespread forest clearing can change precipitation patterns on regional scale, tilting climate toward drought conditions.

The findings by NASA climatologist Ben Cook suggest ancient Meso-American civilizations of the Mayans and Aztecs likely amplified droughts in the Yucatán Peninsula and southern and central Mexico by clearing rainforests to make room for pastures and farmland.

Converting forest to farmland can increase the reflectivity, or albedo, of the land surface in ways that affect precipitation patterns. (more…)

Filed under: climate and weather, Environment, Snow and weather, Summit County news | Tagged: , , , , , , | 1 Comment »

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