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Study helps narrow global warming projections

‘We need to manage the risks of warming with the knowledge we have.’

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A NASA map shows global warming temperature trends.

FRISCO — Australian scientists say that, even though they’ve managed to narrow the range of projected global warming, some uncertainties will always remain. The findings underscore the need to cut greenhouse gas emissions, said University of Melbourne professor David Karoly.

“Our results reconfirm the need for urgent and substantial reductions in greenhouse gas emissions if the world is to avoid exceeding the global warming target of 2 degrees needed to minimize dangerous climate change,” Karoly said.

The study found that exceeding 6 degrees Celsius warming by the end of the century is unlikely, while exceeding 2 degrees is very likely under a business-as-usual emissions scenario. Continue reading

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Study tracks greenhouse gas fingerprint in tropical atmosphere

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A change in tropical wind patterns could impact winter weather in the northern hemisphere.

A ‘fingerprint’ of the expected global warming signal?

By Summit Voice

SUMMIT COUNTY — A regular cycle of high-altitude winds in the tropics has weakened substantially in the past few decades, showing a clear fingerprint of greenhouse gas-induced global warming.

The winds in question, about 10 miles up, alternate between easterlies and westerlies about every other year, affecting chemical composition of the global atmosphere and even the climate at Earth’s surface, according to researchers with the International Pacific Research Center, University of Hawaii at Manoa, and the Japan Agency for Marine-Earth Science and Technology.

Specifically, those atmospheric pulses can modify the behavior of monsoon precipitation and influence stratospheric circulation in northern hemisphere winter by inducing sudden stratospheric warmings that, in turn, can lead to outbreaks of Arctic weather across the mid-latitudes of the northern hemisphere. Continue reading

Climate: Atmospheric CO2 reaches 400 ppm

Concentration will wane from seasonal high point, but long-term trend is up

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Mauna Loa. Photo courtesy USGS.

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Carbon dioxide in the atmosphere this week reached a level last recorded 2 to 5 million years ago.

By Summit Voice

FRISCO — Climate scientists have been closely tracking atmospheric carbon dioxide levels for a long time, but this week, the colorless, odorless gas made big headlines.

An atmospheric observatory on Mauna Loa for the first time measured daily concentrations of CO2 at slightly above 400 parts per million, a dubious milestone which, better than any other number, captures the extent to which we are changing the world. Continue reading

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

What’s the climate tipping point for permafrost?

Cave study offers clues on temperature threshold

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Global permafrost is a significant factor in the climate-change equation. Map courtesy United Nations Environmental Program.

By Summit Voice

SUMMIT COUNTY — Climate scientists have long been warning that a meltdown of Arctic permafrost will trigger a spike in greenhouse gas emissions as long-frozen organic soils give up their carbon to the atmosphere. What’s not yet clear is how fast and how much of the permafrost will melt, but a new study helps identify a temperature threshold that could lead to widespread melting.

A team led by Oxford University scientists studied stalactites and stalagmites in caves along Siberia’s permafrost frontier, where the ground begins to be permanently frozen in a layer tens to hundreds of meters thick.

The stalactites and stalagmites only grow when liquid rainwater and snow melt drips into the caves. The formations record 500,000 years of changing permafrost conditions, including warmer climate periods. After studying the paleoclimate clues in the caves, the researchers concluded that another 1.5 degrees of warming would be enough to cause substantial thawing of permafrost far north from its present-day southern limit. Continue reading

Draft report IDs key global warming threats

Activists say deep greenhouse gas cuts needed to avoid climate disaster

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Seasonal temperature anomalies by season in 2012.

By Summit Voice

FRISCO — A recent federal draft report on climate change has spurred renewed calls for deep cuts in greenhouse gas emissions to avert the most serious impacts from rising global temperatures.

The report, which is in a public comment phase, concludes that global warming is already affecting the U.S. Warmer temperatures will endanger food supplies, increase the risk of flooding and powerful hurricanes, and warm the country by as much as 10 degrees by 2100.

The report finds that global warming has already delivered hotter summers, more flooding and periods of extreme heat that “last longer than any living American has ever experienced.” 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

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