Tag: James Hansen

Global warming research eyes ‘runaway’ ice melt

Sea level forecasts may be way off

Will there be runaway ice sheet melting? Bob Berwyn photo.

By Summit Voice

FRISCO — Most climate models are probably underestimating the rate of sea level rise expected during the next few decades, according to some of the latest research that tries to quantify how much ice may melt off the Greenland and Antarctica ice sheets.

A Dec. 26 update by James Hansen and Makiko Sato warns that melting of those ice sheets could increase sea level rise exponentially higher than most existing forecasts, potentially inundating coastal cities around the world with several feet of water by the end of the century.

The short paper discusses the linearity assumptions in most existing climate models and suggests that, if greenhouse gas emissions continue unchecked, “the climate forcing will be so large that non-linear ice sheet disintegration should be expected and multi- meter sea level rise not only possible but likely.” Continue reading “Global warming research eyes ‘runaway’ ice melt”


NASA: Global warming ups odds for ‘extreme’ heat waves

Trend toward extreme heat starts to show through natural background of natural variability

Extreme summer heat across the northern hemisphere is statistically linked with global warming, according to a new NASA study.

By Summit Voice

LINZ, AUSTRIA — A new NASA study suggests recent heat waves are linked with the overall trend of global warming. Earth’s land areas are much more likely to experience extreme summer heat than they were just a few decades ago, according to research published this week in the Proceedings of the National Academy of Sciences.

The study, authored by NASA’s James Hansen, analyzed mean summer temperatures since 1951 and showed that the odds have increased in recent decades for what they define as “hot,” “very hot” and “extremely hot” summers.

“This summer people are seeing extreme heat and agricultural impacts,” Hansen said in a NASA press release. “We’re asserting that this is causally connected to global warming, and in this paper we present the scientific evidence for that.” Continue reading “NASA: Global warming ups odds for ‘extreme’ heat waves”

NASA: Sun doesn’t drive global warming

Solar activity isn't a big factor in global warming. PHOTO COURTESY NASA.

Earth warmed even during lengthy period of low solar activity

By Summit Voice

SUMMIT COUNTY — NASA researchers led by James Hansen say their latest study shows that the sun is not the main factor driving global warming, as the planet continued to warm between 2005 and 2010, an unusually long-lasting period of low solar activity.

The study also suggests that many climate models have underestimated the cooling effect of aerosols, but that more information about the distribution of the tiny particles to perfect calculations of the Earth’s energy balance.

“The fact that we still see a positive imbalance despite the prolonged solar minimum isn’t a surprise given what we’ve learned about the climate system, but it’s worth noting because this provides unequivocal evidence that the sun is not the dominant driver of global warming,” said Hansen, director of NASA’s Goddard Institute for Space Studies. Continue reading “NASA: Sun doesn’t drive global warming”

Global warming: Natural cycles ‘overwhelmed’

NASA scientist Hansen warns that capping temperature increases at 2 degrees Celsius may not be enough to avoid massive impacts

A 2-degree Celsius rise in global temperatures could lead to a major meltdown of ice caps.

By Summit Voice

SUMMIT COUNTY — Even as world leaders struggled to find some mechanism to curb greenhouse gas emissions, new research by NASA scientist James Hansen suggests that the Earth’s climate may be more sensitive than previously believed.

“Limiting human-caused warming to 2 degrees is not sufficient,” Hansen said. “It would be a prescription for disaster … Humans have overwhelmed the natural, slow changes that occur on geologic timescales,” Hansen said.

Hansen, along with co-author Makiko Sato, studied how Earth’s climate responded to past natural changes to try and answer one of the fundamental climate science questions: “What is the dangerous level of global warming?” Continue reading “Global warming: Natural cycles ‘overwhelmed’”

NASA’s Hansen: There is no ‘global cooling’

The most recent science on global temperatures shows the rate of warming is unchanged.

Politics, not science, drives global warming skepticism
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More global warming stories.

By Bob Berwyn

SUMMIT COUNTY —  The politicization of climate science, including direct attacks on the credibility of researchers, has made it more difficult to communicate the results of important research, NASA scientist James Hansen wrote in a recent draft paper on observed global temperature changes.

The repeated attacks on climate scientists in the media have taken a toll, as recent polls show a growing public skepticism about climate science. Hansen, one of lightning-rod figures for global warming deniers, said the best available science shows clearly that there is no global cooling, as has been widely reported by people trying intentionally to confuse the public. Continue reading “NASA’s Hansen: There is no ‘global cooling’”