Log in

Register




DAVOS, April 5, 2018 (AFP) — Europe’s mountain summits are flush with new plant species, a greening that has increased in lock-step with the acceleration of global warming since the mid-20th century, researchers said on Wednesday.

Looking at more than 300 summits scattered across the continent, they found that five times as many plant types migrated to higher ground over the last decade than did 50 years ago, from 1957 to 1966.

High mountain areas have warmed nearly twice as much as the planet as a whole, which has seen an increase of one degree Celsius  since the mid-19th century.

“Across all summits, the increase in plant species richness has accelerated,” a team of 53 scientists led by Sonja Wipf from the Institute for Snow and Avalanche Research in Davos, Switzerland reported in the journal Nature.

“This acceleration has been particularly pronounced during the past 20-30 years.”

But the flourishing of high-altitude flora may be ephemeral, the researchers cautioned.

“Even if biodiversity is increasing, it’s not something that will necessarily persist,” said co-author Jonathan Lenoir, an expert in biostatistics at France’s National Centre for Scientific Research.

“We may be seeing the accumulation of an extinction debt if these new arrivals crowd out the emblematic, and more fragile, high-altitude species,” he told AFP.

In ecology, “extinction debt” refers to the delayed negative impact on a species of changes in the environment, such as habitat loss or decreased rainfall.

The crescendo of new plants at high altitudes is consistent with a much broader, planet-wide transition known to scientists as the “great acceleration”.

On one side is evidence that humanity shifted into high gear around 1950, with exponential jumps in population, urbanisation, the construction of large dams, fertiliser and water use, energy consumption, and plastic production, to name but a few indicators pointing sharply upward from around that time.

On the other side, starting at the same time, are similarly dramatic spikes in Earth’s vital signs: atmospheric concentration of greenhouse gases (CO2, methane, nitrous oxide), ozone depletion, ocean acidification, tropical forest loss, the collapse of global fish stocks, and, of course, the increase in average air temperature.

That list also includes the greening of high-mountain regions, according to the new study.

“The observed acceleration of biodiversity change in mountain ecosystems highlights the rapid and widespread consequences of human activities on the biosphere,” the authors concluded.

Evidence for long-term changes on flora and fauna has been hard to come by.

Hundreds of recent studies have shown how climate change has affected plant and animal migration, food supply and behaviour, but only over relatively short time periods.

 

By By Paul Voosen, Science Magazine

THE WOODLANDS, TEXAS, March 21, 2018 - ​A last-ditch remedy for a climate disaster might be waiting in your kitchen. If efforts to control greenhouse gases fail, finely powdered salt spread through the upper troposphere could hold off the sun's rays and cool the planet, researchers reported here today at the Lunar and Planetary Science Conference. The approach could be more benign than other schemes for putting a temporary hold on climate change.

For several decades, scientists have suggested ways to “geoengineer” the climate. Several proposals call for injecting microscopic particles, called aerosols, into the stratosphere, the quiet region of the atmosphere above the troposphere about 18 kilometers up from the equator. There they reflect sunlight back into space, mimicking the influence of large volcanic eruptions that have temporarily cooled the planet in the past.

Such proposals often involve sulfates, particles that form in the stratosphere from sulfur dioxide ejected by volcanoes, or other molecules with high reflectivity, such as diamond dust or alumina (aluminum oxide). But all these approaches have drawbacks, says Robert Nelson, a senior scientist at the Planetary Science Institute who is based in Pasadena, California. Sulfur dioxide, for example, could eat away at the ozone layer or cause acid rain.

Alumina could be even worse, Nelson says. Although it is extremely reflective, it could embed in the lungs if inhaled and cause chronic disease similar to silicosis. “I was raised in Pittsburgh, [Pennsylvania,] and I remember as a child seeing black lung victims struggling to get down the street.” Still, given the limited amount of alumina that could be required, it’s far from certain such a health risk would be a genuine concern.

So Nelson continued to look for other reflective compounds that might be less hazardous to human health. In 2015, he was studying evaporated salts on the surface of other solar system bodies such as the dwarf planet Ceres. He soon realized that simple table salt is more reflective than alumina, while also harmless to humans. Just as important, Nelson believes that salt, when ground into small enough particles of the right shape and dispersed randomly, would not block outgoing infrared heat released by Earth, adding to its cooling effect.

Nelson is not the first to consider salt, says Matthew Watson, a volcanologist at the University of Bristol in the United Kingdom. Watson led a geoengineering experiment, called the Stratospheric Particle Injection for Climate Engineering project, that was canceled in 2012. His group briefly considered salt for stratospheric injection, he says, but problems popped up.

First, there's a lot of chlorine in salt, and chlorine can contribute to destroying ozone. That alone could be enough to kill salt as a candidate, Watson says. Few would likely welcome injecting a particle that could reopen the ozone hole. "[This] could be a big problem," agrees David Keith, an energy and climate scientist focused on geoengineering at Harvard University. Salt is also highly attracted to water, and water is scant enough in the stratosphere that injecting even limited amounts of salt could potentially alter, for example, the formation of the realm’s wispy clouds, to unknown effects.

Nelson hopes these concerns could be addressed by injecting salt in the high troposphere, above the clouds but below the stratosphere. He also plans to look more closely at salt's properties; if he can resolve some of these questions, he'd like to see a test of the particles above a region forecasted to experience life-threatening extreme temperatures. This would test the science while potentially benefiting society in the short term, he says. Such a research effort could only come after thorough engagement with the public, Nelson adds.

But like nearly all scientists interested in geoengineering, Nelson stresses that the strategy is no substitute for action to curb carbon emissions. No type of solar radiation management, for example, would prevent rising carbon dioxide from acidifying the oceans. This research should only be done so the world can potentially buy itself some time, Nelson says. “This would be a palliative, not a [long-term] solution.”

 

March 4, 2018 - The estimated cost of measures to limit Earth-warming greenhouse gas emissions can be more than offset by reductions in deaths and disease from air pollution, researchers said on Saturday.
 
It would cost $22.1 trillion (17.9 trillion euros) to $41.6 trillion between 2020 and 2050 for the world to hold average global warming under two degrees Celsius (3.6 degrees Fahrenheit), a team projected in The Lancet Planetary Health journal.
 
For the lower, aspirational limit of 1.5 C, the cost would be between $39.7 trillion and $56.1 trillion, they estimated.
 
But air pollution deaths could be reduced by 21-27 percent to about 100 million between 2020 and 2050 under the 2 C scenario, the team estimated, and by 28-32 percent to about 90 million at 1.5 C.
 
"Depending on the strategy used to mitigate climate change, estimates suggest that the health savings from reduced air pollution could be between 1.4-2.5 times greater than the costs of climate change mitigation, globally," they wrote.
 
Health costs from air pollution include medical treatment, patient care, and lost productivity.
The countries likely to see the biggest health savings were air pollution-ridden India and China, said the researchers, who used computer models to project future emissions, the costs of different scenarios for curbing them, and the tally in pollution-related deaths.
 
"The health savings are exclusively those related to curbing air pollution," study co-author Anil Markandya of the Basque Centre for Climate Change in Spain told AFP.
 
"Other health benefits are not included, which of course makes our figures underestimates of the total benefits."
 
The costs of limiting warming, Markandya explained, included higher taxes on fossil fuels like oil and coal, which in turn raise the costs of production.
 
The world's nations agreed on the 2 C limit in Paris in 2015, and undertook voluntary greenhouse gas emissions reduction targets.
 
These pledges, even if they are met, place the world on a 3 C trajectory, scientists say.
To date, the average global temperature is thought to have increased by 1 C since the Industrial Revolution.
 
"We hope that the large health co-benefits we have estimated... might help policymakers move towards adopting more ambitious climate policies and measures to reduce air pollution," said Markandya.
 
Air pollution from fossil fuel emissions, particularly fine particulate matter and ozone, has been linked to lung and heart disease, strokes, and cancer.