Climate

climate

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

Deforestation hangs climate out to dry

Across the tropics, vast swaths of forest have been cleared to make room for crops and livestock. Beyond releasing vast stores of carbon trapped in soil and biomass, tropical deforestation has the potential to alter hydrological cycles in ways that could affect temperature and precipitation patterns around the planet, according to a new report in Nature Climate Change.
 
13 Jul 2015

Shrinking snowpack projected in western U.S. as rain-snow boundary climbs higher

Gauging the impacts of climate change on future precipitation is challenging, especially in the western U.S., a region with highly variable temperatures, precipitation patterns and terrain. But understanding such impacts in the West — and, in particular, how much precipitation will fall as snow versus rain in the future — is important given the region’s dependence on wintertime snowfall as a freshwater resource. Now, a new study forecasts a broad shift from snow to rain for much of the West — a projection that will require attention from land and water resource managers planning for the future.

24 Apr 2015

Wedge approach proposed to lower water stress

Roughly 30 percent of the global population — or about 2.2 billion people — lives in water-stressed parts of the world, where high freshwater withdrawals endanger ecosystems, agriculture and drinking-water supplies. If current population and water usage trends persist, this fraction could rise to about one-half by the century’s end. In a recent study, researchers — taking a page from the climate-change mitigation literature — have proposed a “wedge” approach to address global water stress, laying out how various tactics could ease the growing problem.

22 Apr 2015

Of temperature and tone: Has climate shaped human languages?

Humans today speak more than 6,500 languages, and thousands more dialects once spoken have gone extinct. Understanding how and why so many languages have evolved over human history has long been the work of linguists. Recently, however, the emerging field of geo-phonetics has begun looking into how geography — and perhaps climate — affects language. In a new study, researchers suggest that humidity and temperature, which can impact our ability to craft certain sounds, appear to have influenced the evolution of tonality in languages in different parts of the world.

20 Apr 2015

Twentieth-century warming linked to Pacific trade winds

Earth’s average atmospheric temperature warmed by about 1.3 degrees Celsius over the course of the 20th century. However, the rate of increase during that time was not constant and scientists have been unable to fully explain the timing and pattern of warming. Now, a recent study has identified a correlation between global temperatures and the strength of Pacific trade winds that may help clear up the some of the confusion.

13 Mar 2015

Down to Earth With: Glaciologist Lonnie Thompson

As a child growing up in Gassaway, W.Va., Lonnie Thompson was poor. When his father died while Thompson was a senior in high school, he realized he’d need to earn a reliable paycheck as quickly as possible. As an undergraduate at Marshall University in Huntington, W.Va., he knew he wanted to study science; he started off as a physics major before settling on geology. Later, when he arrived at Ohio State University (OSU) as a graduate student in 1971, Thompson’s intent was to study coal geology, a practical choice that he believed would quickly secure him a job.

17 Jan 2015

Climate impacting a few of our favorite foodstuffs

Researchers have found that the number of foggy winter days in California’s agriculture-heavy Central Valley has dropped 46 percent on average over the past three decades. Fog shields the valley from sunlight and contributes to the amount of “winter chill” — the amount of time spent between zero and 7 degrees Celsius during winter dormancy — that fruit and nut trees there experience. Sufficient winter chill is necessary for buds, flowers and fruit to develop properly, and although winter chill has previously been observed to have decreased since the 1950s, no one had conducted a long-term analysis of fog occurrence trends in the area, according to Dennis Baldocchi and Eric Waller of the University of California at Berkeley.

24 Sep 2014

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