Tag: global warming tipping points

Forests may not benefit from rising CO2 levels

Intense aspen and scrub oak color in this aerial view of Eagle County, Colorado.
Aspen and scrub oak forests in western Colorado. @bberwyn photo.

Study says disastrous tipping points could be reached by 2050

Staff Report

Forests of the future may not be able to remove heat-trapping CO2 from the atmosphere as effectively as previously thought, scientists said in a new study that’s based on an extensive analysis of tree ring data from the past.

“We utilized a network of more than two million tree-ring observations spanning North America. Tree-rings provide a record into how trees that grow in different climates respond to changes in temperature and rainfall,” said Brian Enquist, a professor in the UA’s Department of Ecology and Evolutionary Biology and a fellow of the Aspen Center for Environmental Studies in Aspen, Colorado.

The research challenges assumptions about how forests will respond to warmer average temperatures, increased greenhouse gas emissions, and shifting rainfall patterns. It also suggests that the warming climate already is rapidly pushing many forests towards an ecological tipping point, which may be reached as early as 2050, Exposure to unprecedented temperatures hampers tree growth and makes them susceptible to other stress factors. Continue reading “Forests may not benefit from rising CO2 levels”

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Global warming: Many U.S. coastal areas to see frequent flooding sooner rather than later

High water at the mouth of the Mississippi River, near Venice, Louisiana.
High water at the mouth of the Mississippi River, near Venice, Louisiana. bberwyn photo.

Study eyes flood ‘tipping’ points

Staff Report

FRISCO — Rising sea levels will subject many coastal areas in the U.S. to frequent flooding by the middle of the century, according to a new NOAA study aimed at identifying flood “tipping points.” By 2050, a majority of U.S. coastal areas are likely to be threatened by 30 or more days of flooding each year the study concluded.

The research was led by NOAA scientists William Sweet and Joseph Park and published this week in the American Geophysical Union’s online peer-reviewed journal Earth’s Future. Continue reading “Global warming: Many U.S. coastal areas to see frequent flooding sooner rather than later”

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 “What’s the climate tipping point for permafrost?”