Climate

climate

Humans, megafauna coexisted in Patagonia before extinction

During the last ice age, giant mammals roamed the wide-open steppes of what is now Patagonia. Around the time that humans were making their way down through North America and into South America, the climate began warming and large species of giant sloths and saber-toothed cats soon disappeared. Now, researchers looking at mitochondrial DNA from some of these megafaunal species are shedding light on the timing of the extinction and whether encroaching humans or changing climate — or both — were to blame for their disappearance.

11 Oct 2016

Tiny ocean bacteria could play big role in climate

In the 1990s, researchers identified the most abundant group of organisms in the ocean as Pelagibacterales, a class of free-living bacteria that live in surface waters as a microscopic but major part of the phytoplankton community. Now, a new study suggests that Pelagibacterales could play an important role in the global climate cycle by producing dimethylsulfide (DMS), an organosulfur compound that stimulates cloud formation when it gets into the atmosphere.

05 Sep 2016

Late Antique Little Ice Age underpinned unrest and upheaval in Europe and Asia

Effects of climate change on society aren’t just a contemporary concern. A new study has found that a cold snap in the sixth and seventh centuries may have been the catalyst for a period of societal turmoil, marked by famine, plague and political tumult.

06 Jul 2016

Comment: How long have humans been altering Earth's climate?

The early anthropogenic hypothesis holds that greenhouse gas emissions from agriculture, as early as 7,000 years ago, kept the Holocene climate warmer than it otherwise would have been.

08 Apr 2016

Crippling heat stress projected by midcentury in densely populated regions

Extreme heat is the world’s top weather-related killer. Exposure to extreme heat caused more than 7,800 fatalities in the U.S. from 1999 to 2009, according to a 2013 report by the U.S. Centers for Disease Control and Prevention. And a single heat wave last summer killed at least 2,300 people in India, according to NOAA.

05 Apr 2016

North Sea uplift caused Jurassic cooling event

The climate of the Jurassic, long envisioned as ubiquitously warm from the equator to the poles, was actually more dynamic, sometimes cooling dramatically, according to a new study. The research joined isotopic and sedimentological data to suggest that an abrupt cooling event occurred in the midlatitudes early in the Middle Jurassic as a result of changing ocean currents associated with a feature known as the North Sea Dome.

31 Mar 2016

Atmosphere, more than ocean, might drive Atlantic climate variation

Atmospheric, not oceanic, circulation may be the main driver of climate variations over the North Atlantic Ocean, potentially complicating future hurricane and drought predictions, according to the authors of a new study.
 
01 Feb 2016

Lake sediments suggest mild volcanic winter after massive Toba eruption

Roughly 74,000 years ago, the largest volcanic eruption of at least the last 2.5 million years — and possibly the last 27 million years — spewed as much as 5,000 cubic kilometers of magma and ash, the latter of which spread far and wide from the source. This catastrophic eruption of the Toba supervolcano on the Indonesian island of Sumatra has long been suggested as a trigger for a precipitous period of global cooling known as a “volcanic winter” that in turn might have driven early humans to the brink of extinction. In a new study, researchers dispute these notions, concluding from an analysis of climate-sensitive microfossils preserved in lake sediments in East Africa — the ancestral home of early humans — that the region experienced little or no cooling following the massive eruption. 
 
10 Jan 2016

No laughing matter: Ocean nitrous oxide emissions greater than thought

Nitrous oxide is a potent greenhouse gas and, since the banning of chlorofluorocarbons in 1987, it has become the main driver of ozone loss from the stratosphere. Most atmospheric nitrous oxide is emitted from agricultural land and soils, but roughly a third is thought to come from the ocean. However, marine sources and sinks of the gas are not well understood. 
 
27 Nov 2015

Solar flare calibration reveals past patterns of volcanism and cooling

When Mount Pinatubo erupted in the Philippines in 1991, it sent a cloud of ash and sulfuric acid into the atmosphere that blocked incoming solar radiation and caused global temperatures to drop 0.5 degrees Celsius for three years. Quantifying such effects of prehistoric volcanic eruptions on climate, however, has long proved difficult due to inconsistencies in the proxies used to reconstruct atmospheric and temperature fluctuations. In a new study, scientists have used markers left by an unusual solar flare event to align ice-core and tree-ring records, enabling a more accurate accounting of the effects of volcanic eruptions in recent millennia.
 
25 Nov 2015

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