Category: global warming

Antarctic sea ice meltdown likely in a warming world

New study offers climate clues from most recent interglacial warm period

Antarctic sea ice
Antarctic sea ice is likely to decline dramatically in coming decades, which could lead to amplification of global warming in the southern hemisphere. @bberwyn photo.

By Bob Berwyn

The last time the Earth was as warm as today was about 128,000 years ago — and Antarctic sea ice extent was 65 percent smaller than it is now, according to British scientists who tracked past climate change in the region by studying ice core samples from that era.

That means Antarctic sea ice is on course to shrink dramatically in the decades and centuries ahead, said British Antarctic Survey scientist Max Holloway, who with a team of researchers analyzed oxygen isotopes in ice and air bubbles trapped for 128,000 years in the East Antarctic Ice Sheet. Continue reading “Antarctic sea ice meltdown likely in a warming world”

Ocean acidification seen as huge threat to Atlantic cod

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Climate change to put a big hit on cod stocks.

Fish larvae seen as highly sensitive to CO2

Staff Report

New lab experiments suggest that increasing ocean acidification could take a big bite out of the economically important cod fishery in the North Atlantic. The research suggests that the buildup of CO2 in the ocean could double the mortality of newly-hatched cod larvae.

Members of the German research network BIOACID quantified the impacts, showing that recruitment could decrease to levels of one quarter to one twelfth of the recruitment of the last decades. Cod have already been under intense fishing pressure for decades, and the new study, published in the online journal PLOS ONE, identifies climate change as an emerging new threat. Continue reading “Ocean acidification seen as huge threat to Atlantic cod”

Colorado Gov. Hickenlooper eyes executive order on climate change

Is Colorado a hotspot for global warming?
Is Colorado a hotspot for global warming?

Draft document highlights global warming threats to state

Staff Report

Colorado Governor John Hickenlooper says a “shifting climate” threatens many of the state’s vital industries, including skiing and agriculture, and he wants the state’s power plants to cut greenhouse gas emissions by 35 percent in the next 15 years from 2012 levels. The goals are outlined in a draft version of an executive order on mitigating and adapting to climate change, which spells out some specific threats of global warming that are already well-known, including:

  • Greater air pollution will lead to a more hospital admissions and increased cases of respiratory illness;
  • Changes in precipitation can adversely impact the amount and quality of Colorado’s water resources;
  • Changes in runoff patterns, intense precipitation, and rising temperatures can negatively affect food production and result in greater risk of food contamination and waterborne illness.

Continue reading “Colorado Gov. Hickenlooper eyes executive order on climate change”

Global warming started earlier than you think

New study suggests climate is very sensitive to greenhouse gases

Despite ups and downs from year to year, global average surface temperature is rising. By the beginning of the 21st century, Earth’s temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies.
Despite ups and downs from year to year, global average surface temperature is rising. By the beginning of the 21st century, Earth’s temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies).

Staff Report

Although the rate of global warming has increased dramatically in the last few decades, a new study suggests that human activities have been driving climate change for the past 180 years. The findings suggest that global warming is not just a  20th century phenomenon, and that the climate system is, indeed, quite sensitive to the buildup of heat-trapping pollution.

The study was led by Nerilie Abram, of  The Australian National University, who  warming began during the early stages of the Industrial Revolution and started leaving a fingerprint in  the Arctic and tropical oceans around the 1830s, much earlier than scientists had expected. Continue reading “Global warming started earlier than you think”

Will global warming boost groundwater supplies in the Upper Colorado River Basin?

Some climate models project more rainfall in the West

A bend in the Yampa River near Dinosaur National Monument in northwest Colorado.
Will global warming boost flows in Colorado River tributaries? @bberwyn photo.

Staff Report

While most recent research suggests that the Colorado River will be depleted well beyond current demands as global temperatures increase, there may be one small bright spot on the horizon. Even if runoff from snow declines, groundwater replenishment in the basin may hold stead under projected increases in  precipitation, the U.S. Geological Survey and U.S. Bureau of Reclamation found in a new study.

“You can’t manage what you don’t measure,” said Fred Tillman, lead author and USGS scientist. “These results are the first step in understanding the quantity of groundwater we can expect in the Upper Colorado River Basin; however, further studies are needed to help more accurately forecast future groundwater availability.”

The Colorado River is a critically important source of water for more than 35 million people in the United States and 3 million people in Mexico. As much as half the water flowing in the rivers and streams in the Upper Colorado River Basin originates as groundwater. Understanding how much groundwater is available and how it’s replenished is important to sustainably manage both groundwater and surface water supplies in the Colorado River basin now and in the future.

In the new study, USGS and Reclamation scientists estimated projected changes in groundwater recharge for the Upper Colorado River Basin from recent historical (1950–2015) through future (2016–2099) time periods using climate projections and a groundwater-recharge model.

Simulated future groundwater recharge through 2099 is generally expected to be somewhat greater than the historical average in most decades due to an anticipated wetter future climate in the basin under the most advanced climate modeling projections. Groundwater resources are replenished through increases in precipitation, which may offset reductions from increased temperatures. The full report is available online in the journal Geophysical Research Letters.

But researchers urged caution interpreting the results because a few of the models suggested  decreased future recharge relative to the historical climate period.

Continue reading “Will global warming boost groundwater supplies in the Upper Colorado River Basin?”

What’s the tipping point for Antarctica’s ice sheets?

New study suggests rapid meltdown during post-ice age warming

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How long will it take for Antarctica’s ice sheets to melt? @bberwyn photo.

Staff Report

After taking a close look at rocks from West Antarctica’s dramatic Ellsworth Mountains, climate researchers say there’s a chance that ice sheets in the region could melt quickly as the planet warms, potentially causing sea level to rise by  six to eight feet.

The new study, published in Nature Communications, took a close look at Antarctic climate change about 21,000 years ago during a period of warming after the coldest point of the most recent Ice Age. They found that  the West Antarctic Ice Sheet reached a tipping point, after which it thinned relatively quickly, losing 400m of thickness in 3,000 years. Continue reading “What’s the tipping point for Antarctica’s ice sheets?”

Climate: July breaks global temperature mark — again

Mideast heatwave set records

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All northern hemisphere land areas recorded above average temperatures in July 2016.

Staff Report

There was no letup to the global heatwave in July, according to the National Oceanic and Atmospheric Administration, which reported this week that the month ended up as the warmest ever recorded on planet Earth.

Federal climate trackers said it was the 15th month in a row with above average temps, making it the longest such streak in NOAA’s 137 years of record keeping. The global temperature for July has been above average for 40 years in a row, since 1976. July was also the 379th consecutive month with temperatures above the 20th century average. The last month with temperatures below the 20th century average was December 1984, at 0.09 degrees Celsius below average.

The combined average temperature over global land and ocean surfaces was 0.87 degrees Celsius above the 20th century average, besting the previous July record set in 2015 by 0.06 degrees Celsius. Across the world’s land areas, the average temperature was 1.10 degrees Celsius above the 20th century average. Continue reading “Climate: July breaks global temperature mark — again”