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Global warming: Tropical ecosystems breathing harder, exhaling more carbon dioxide as planet heats up

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Global temperatures were well above average in 2013.

New study helps assess climate sensitivity of tropical ecosystems

Staff Report

FRISCO — Tropical forest ecosystems are the lungs of the Earth, and they are breathing harder, releasing more carbon into the atmosphere, as global temperatures increase.

According to new research, the tropical carbon cycle has become twice as sensitive to temperature variations over the past 50 years. For every degree that temperatures in the tropics rise, two billion tons of additional carbon are released from tropical ecosystems. according to the study, published last week in Nature. Continue reading

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Pliocene data suggest climate models may be be underestimating some impacts to the oceans and tropics

‘The climate system is capable of remarkable transformations’

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Global temperatures were well above average during this past winter.

By Summit Voice

SUMMIT COUNTY — Climate scientists have long eyed the Pliocene era (between 3 and 5 million years ago) as a standard against which to measure the potential impacts of increasing greenhouse gases. It was the last time the world was in a steady climate warmer than today, with a higher atmospheric carbon dioxide level than that of the pre-industrial age.

Research led by University College London scientists shows that a huge pool of warm water stretching from Indonesia over to Africa and South America dominated the world’s oceans during that era — but none of today’s climate models project similar conditions in the future, suggesting that they may be too conservative in forecasting tropical changes.

“An important question is how much the evidence of climate evolution over the last five million years shapes our assessment of future change,” said UCL geographer Dr. Chris Brierley. “From these observations, it is clear that the climate system is capable of remarkable transformations even with small changes in external parameters such as carbon dioxide,” Brierley said. 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

Global warming drives extreme rainfall in the tropics

Researchers estimate 10 percent increase in rainfall during extreme events for every 1-degree Celsius of warming

Rainfall amounts during extreme weather events in the tropics are expected to increase by 10 percent for every 1-degree Celsius rise in temperatures. Photo by Bob Berwyn.

By Summit Voice

SUMMIT COUNTY — Researchers at MIT say extreme rainfall in the Earth’s tropical regions appear to be more sensitive to global warming than other parts of the world. While they don’t fully understand the mechanism for that higher sensitivity, they estimate that rainfall amounts during extreme weather events — monsoons, thunderstorms and tropical cyclones — are likely to increase by 10 percent for every 1-degree Celsius increase in temperatures.

“The study includes some populous countries that are vulnerable to climate change … and impacts of changes in rainfall could be important there,” said Paul O’Gorman, assistant professor of Atmospheric Science at MIT.

In general, most climate models agree that a warming atmosphere hold more water vapor. When storm systems develop, the increased humidity prompts heavier rain events that become more extreme as the climate warms. Continue reading

Climate: Tipping point for ocean currents?

Fossil record gives clues about climate connecting between tropics and high latitude Atlantic conditions

Blue paths represent deep-water currents, while red paths represent surface currents.

By Summit Voice

SUMMIT COUNTY — Using clues in tiny ocean fossils collected near Venezuela, Texas A&M researchers have been able to trace how the climate-regulating global ocean conveyor-belt circulation changes as the Earth goes through warm and cool cycles.

The 22,000-year climate record includes changes in ocean temperature and salinity in the upper 1,500 feet of water in the western tropical Atlantic. The study  included global climate model simulations under past climate conditions to interpret this new observational record in the context of changes in the strength of the global ocean conveyor-belt circulation.

The data may help explain why the Earth’s climate is so sensitive to ocean circulation patterns, according to geological oceanographer Matthew Schmidt. The study shows an important climate connection between the tropics and the high latitude North Atlantic.  Continue reading

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