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Climate: Greenhouse gas buildup ‘loads the dice’ for Southwest megadroughts

Odds of 30-year dry spells increase dramatically as global temps rise

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Green bars indicate wet periods, the larger the bar the more unusually wet. In a similar way, yellow indicates dry and droughty periods. The graph stretches from January 1895 on the left to last month on the right, showing how the cycle of droughts alternating with wet years has changed, with dry years becoming more prevalent.

By Summit Voice

FRISCO — Tree ring records clearly show that the southwestern U.S. experienced megadroughts long before the anthropogenic global warming era. One such decades-long dry spell may have been a factor in the collapse of the Anasazi civilization at Mesa Verde.

But the steady buildup of heat-trapping gases in the atmosphere is loading the dice in favor of another megadrought sooner, rather later, according to scientists with Cornell University, the University of Arizona and U.S. Geological Survey. The chances of a decade-long drought is now at least 50 percent, and there’s a 20 percent to 50 percent chance of a 30-year megadrought.

“For the southwestern U.S., I’m not optimistic about avoiding real megadroughts,” said Toby Ault, Cornell assistant professor of earth and atmospheric sciences and lead author of the paper. “As we add greenhouse gases into the atmosphere – and we haven’t put the brakes on stopping this – we are weighting the dice for megadrought conditions.” Continue reading

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Climate: Heat-trapping greenhouse gases the biggest driver of global glacier meltdown

‘In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss’

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Shrinking glaciers on the Dachstein Mountains in Austria will affect water supplies far downstream in local areas and in distant rivers. bberwyn photo.

Staff Report

FRISCO — Some of the world’s glaciers were shrinking before the onset of unchecked heat-trapping pollution, but the human factor in the glacial equation has grown exponentially in the past few decades.

A new modeling study led by scientists at the University of Innsbruck (Austria) shows that only about 25 percent of the global glacier mass loss during the period of 1851 to 2010 is attributable to anthropogenic causes. However, between 1991 and 2010 the fraction increased to about two-thirds.

“In the 19th and first half of 20th century we observed that glacier mass loss attributable to human activity is hardly noticeable but since then has steadily increased,” said researcher Ben Marzeion, explaining that scaled-down regional models can detect an anthropogenic influence in America and the Alps, where glacier changes are particularly well documented. Continue reading

Climate: Scientists call for cuts in methane emissions

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Cutting methane could slow global temperature surge.

Action could help avert climate tipping points

Staff Report

FRISCO — Leading scientists say the U.S. must do more to cut methane emissions from fossil fuel exploitation and other sectors to try and avoid reaching climate tipping points that could have disastrous implications.

Methane is a much more potent heat-trapping gas than carbon dioxide, but it only stays in the atmosphere for about 12 years, which means that big cuts could have a tangible short-term benefit in the race to cap global warming. Continue reading

Study: There’s huge potential for increased food production on existing land

The recent wheat crisis in Russia is a warning sign for potential large-scale global warming impacts. PHOTO COURTESY THE WIKIMEIDA COMMONS.

The recent wheat crisis in Russia is a warning sign for potential large-scale global warming impacts. PHOTO COURTESY THE WIKIMEIDA COMMONS.

Tweaking farm practices could also reduce greenhouse gas emissions associated with agriculture

FRISCO — A systematic University of Minnesota study of global agricultural resources suggest that improving food systems in a few specific regions could make it possible to both meet the basic needs of 3 billion more people and decrease agriculture’s environmental footprint.

The report, published in Science, focuses on 17 key crops that produce 86 percent of the world’s crop calories and account for most irrigation and fertilizer consumption on a global scale. It proposes a set of key actions in three broad areas that that have the greatest potential for reducing the adverse environmental impacts of agriculture and boosting our ability meet global food needs. Continue reading

Climate: Greenhouse gases drive Australia drying trend

Since the 1970s, southern Australia has been experiencing declining rainfall in the fall and winter, creating scenes like this one in a 2007 photograph at Lake Hume. (Creative Commons/ Suburbanbloke)

Since the 1970s, southern Australia has been experiencing declining rainfall in the fall and winter, creating scenes like this one in a 2007 photograph at Lake Hume. (Creative Commons/ Suburbanbloke).

New model can resolve some climate impacts on a regional scale

STAFF REPORT

FRISCO — Increasing concentrations of greenhouse gases and ozone depletion over Antarctica are the main drivers of the long-term decline in rainfall over southwestern Australia, federal scientists said in a weekend press release.

The findings, published in Nature Geoscience, are derived from a new  high-resolution climate model that may help researchers identify more links between heat-trapping gases and regional climate trends, including here in the U.S. Continue reading

Environment: Study shows space-based sensors can accurately measure greenhouse gases and other air pollution

The Four Corners Power Plant in a 1972 photo via Wikipedia.

The Four Corners Power Plant in a 1972 photo via Wikipedia.

Satellite data verified by in-stack measurements

By Summit Voice

FRISCO — Keeping tabs colorless, odorless carbon dioxide emissions is not always easy, yet it will be crucial someday for being able to measure whether countries are meeting targets for emissions reductions.

Scientists with Los Alamos National Laboratory now say they’ve been able to measure air pollution and greenhouse gases from the two coal-fired power plants in the Four Corners — the largest single point source of pollution in the U.S. Continue reading

Will ozone pollution spike with global warming?

A computer-generated split-screen image a split-image simulates the average 20 percent best (left) and 20 percent worst 20 percent (right) visibility at the Long’s Peak vista based on an average of monitored data for years 2000-2004.

A computer-generated split-screen image a split-image simulates the average 20 percent best (left) and 20 percent worst 20 percent (right) visibility at the Long’s Peak vista based on an average of monitored data for years 2000-2004.

Very likely without cuts in pollutants, study says

Staff Report

FRISCO — By 2050, many Americans will see their chances of experiencing unhealthy summertime ozone levels increase by 70 percent, according to scientists with the National Center for Atmospheric Research. Warmer temperatures will make the toxic brew of air pollutants even more volatile unless emissions of specific pollutants that are associated with the formation of ozone are sharply cut, the researchers said in a new study published this week.

Almost all of the continental United States will experience at least a few days with unhealthy air during the summers, the research shows. Heavily polluted locations in parts of the East, Midwest, and West Coast where ozone already frequently exceeds recommended levels could face unhealthy air during most of the summer. Continue reading

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