Climate

Which trees face death in drought?
April 19, 2016 07:19 AM - University of Utah

Two hundred-twenty-five million trees dead in the southwest in a 2002 drought. Three hundred million trees in Texas in 2011. Twelve million this past year in California.  Throughout the world, large numbers of trees are dying in extreme heat and drought events. Because mass die-offs can have critical consequences for the future of forests and the future of Earth’s climate, scientists are trying to understand how a warming climate could affect how often tree mortality events occur – and how severe they could become.

Shift in global winds caused record flooding in the Balkans
April 17, 2016 07:40 AM - Potsdam Institute for Climate Impact Research (PIK) via ScienceDaily

Disastrous floods in the Balkans two years ago are likely linked to the temporary slowdown of giant airstreams, scientists found. These wind patterns, circling the globe in the form of huge waves between the Equator and the North Pole, normally move eastwards, but practically stopped for several days then -- at the same time, a weather system got stuck over Bosnia and Herzegovina, Serbia and Croatia that poured out record amounts of rain. The study adds evidence that so-called planetary wave resonance is a key mechanism for causing extreme weather events in summer. Further, the scientists showed that extreme rainfall events are strongly increasing in the Balkans, even more than the globally observed rise.

"We were surprised to see how long the weather system that led to the flooding stayed over the region -- it's like the Vb cyclone 'Yvette' was trapped there," says Lisa Stadtherr from the Potsdam Institute for Climate Impact Research (PIK), lead-author of the study to be published in Science Advances. "Day after day the rain was soaking the soil until it was saturated, which lead to the flooding that reportedly caused several dozen casualties and 3.5 billion Euro of damages."

 

Clear cutting and its influence on carbon storage
April 15, 2016 07:28 PM - Dartmouth College via ScienceDaily.

lear-cutting loosens up carbon stored in forest soils, increasing the chances it will return to the atmosphere as carbon dioxide and contribute to climate change, a Dartmouth College study shows.

The findings appear in the journal Soil Science.

Soil is the world's largest terrestrial carbon pool. In northern hardwood forests in the United States, mineral soil pools store up to 50 percent of total ecosystem carbon. Logging and other land-use changes are a major cause of soil carbon release, but there has been recent interest to further understand soil carbon dynamics in forested ecosystems after logging. This is of particular importance in the northeastern U.S. because of the great potential for the use of biomass as part of a diversified renewable energy portfolio.

The Dartmouth researchers explored whether clear-cutting changes the strength of the chemical bonds of carbon stored in mineral soils in hardwood forests in the northeastern United States. Clear-cutting involves harvesting all timber from a site at once rather than selectively culling mature trees. Carbon is stored in soil by binding only to certain soil structures.

The researchers collected soils from recently clear-cut forests and from older forests, and pulled carbon from the soil in a sequence of gentle to stronger extractions. The results showed that mature forest stands stored significantly more soil organic carbon in strongly mineral-bound and stable carbon pools than did soils from cut stands.

Study shows most US roofs can support a solar system
April 14, 2016 07:40 AM - Sandia National Laboratories.

Most U.S. rooftops in good repair can take the weight of solar photovoltaic (PV) systems. That’s the conclusion of a three-year study by a research team led by Sandia National Laboratories.

“There is a misperception in the building industry that existing residential rooftops lack the strength to carry the weight load of rooftop solar photovoltaic installations,” said Sandia structural engineer Steve Dwyer. “Most existing well-built wooden rooftops can support PV system loads.”

Sandia took on the job of analyzing rooftop structural strength to address concerns raised in the U.S. Department of Energy’s (DOE) Solar America Cities program. The agency named 25 cities to promote adoption of solar technology at a comprehensive, local level through photovoltaics.

 

The Paris climate accord looks promising
April 12, 2016 08:04 PM - Robert N. Stavins, Director, Harvard Environmental Economics Program

The climate talks that concluded last December were a great success, but it will be decades before we can judge whether the Paris Agreement itself is ultimately successful. What can be said is that the accord provides a good foundation for meaningful progress on climate change, and represents a dramatic departure from the past 20 years of climate negotiations.

I have long viewed the dichotomous distinction between Annex I and non–Annex I countries in the Kyoto Protocol as the major stumbling block to progress. The protocol included mandatory emissions-reduction obligations for developed countries, but none for developing countries. That made progress impossible, because significant growth in emissions since the protocol came into force in 2005 has been entirely in the large developing countries — China, India, Brazil, South Korea, South Africa, Mexico, and Indonesia.

 

Reducing food waste could help mitigate climate change
April 11, 2016 07:33 AM - Potsdam Institute for Climate Impact Research

About a tenth of overall global greenhouse-gas emissions from agriculture could be traced back to food waste by mid-century, a new study shows. A team from the Potsdam Institute for Climate Impact Research for the first time provides comprehensive food loss projections for countries around the world while also calculating the associated emissions. Currently, one third of global food production never finds its way onto our plates. This share will increase drastically, if emerging countries like China and India adopt Western nutrition lifestyles, the analyses shows. Reducing food waste would offer the chance to ensure food security, which is well known. Yet at the same time it could help mitigate dangerous climate change.

Rising oceans may pose a bigger threat than previously assumed
April 9, 2016 09:34 AM - Pete Dolack, The Ecologist

Of all the impacts of climate change, one stands out for its inexorable menace, writes Pete Dolack: rising oceans. And it's not just for distant future generations to deal with: new scientific studies show that people alive today may face 6-9 metres of sea level rise flooding well over a million sq.km including many of the world's biggest cities. So where's the emergency response?

There is a possibility, a real danger, that we will hand young people and future generations a climate system that is practically out of their control. We have a global emergency.

When it comes to global warming, what else don't we know?

 

The North Pole had ice-free summers millions of years ago
April 8, 2016 07:22 AM - Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research via ScienceDaily.

An international team of scientists led by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) have managed to open a new window into the climate history of the Arctic Ocean. Using unique sediment samples from the Lomonosov Ridge, the researchers found that six to ten million years ago the central Arctic was completely ice-free during summer and sea-surface temperature reached values of 4 to 9 degrees Celsius. In spring, autumn and winter, however, the ocean was covered by sea ice of variable extent, the scientists explain in the current issue of the journal Nature Communications. These new findings from the Arctic region provide new benchmarks for groundtruthing global climate reconstructions and modelling.

The researchers had recovered these unique sediment samples during an expedition with Germany's research icebreaker RV Polarstern in summer of 2014. "The Arctic sea ice is a very critical and sensitive component in the global climate system. It is therefore important to better understand the processes controlling present and past changes in sea ice. In this context, one of our expedition's aims was to recover long sediment cores from the central Arctic, that can be used to reconstruct the history of the ocean's sea ice cover throughout the past 50 million years. Until recently, only a very few cores representing such old sediments were available, and, thus, our knowledge of the Arctic climate and sea ice cover several millions of year ago is still very limited," Prof. Dr. Ruediger Stein, AWI geologist, expedition leader and lead author of the study, explains.

 

Earth's soils could play key role in locking away greenhouse gases
April 7, 2016 06:51 AM - University of Edinburgh via EurekAlert!

The world's soils could store an extra 8 billion tonnes of greenhouse gases, helping to limit the impacts of climate change, research suggests.

Adopting the latest technologies and sustainable land use practices on a global scale could allow more emissions to be stored in farmland and natural wild spaces, the study shows. 

NASA examines El Nino's impact on ocean's food source
April 4, 2016 07:46 PM - NASA/Goddard Space Flight Center

El Niño years can have a big impact on the littlest plants in the ocean, and NASA scientists are studying the relationship between the two. In El Niño years, huge masses of warm water – equivalent to about half of the volume of the Mediterranean Sea – slosh east across the Pacific Ocean towards South America. While this warm water changes storm systems in the atmosphere, it also has an impact below the ocean’s surface. These impacts, which researchers can visualize with satellite data, can ripple up the food chain to fisheries and the livelihoods of fishermen.

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