World News: Earth to get hotter despite global warming slowdown (13 March 2014)

Earth to get hotter despite global warming slowdown

WASHINGTON: Earth's climate would continue to warm during this century on track with previous estimates, despite the recent slowdown in the rate of global warming, a new Nasa study has warned.

The research hinges on a new and more detailed calculation of the sensitivity of Earth's climate to the factors that cause it to change, such as greenhouse gas emissions.

Drew Shindell, a climatologist at Nasa's Goddard Institute for Space Studies in New York, found Earth is likely to experience roughly 20 per cent more warming than estimates that were largely based on surface temperature observations during the past 150 years.

Global temperatures have increased at a rate of 0.12 degrees celsius per decade since 1951, researchers said.

But since 1998, the rate of warming has been only 0.05 degrees celsius per decade - even as atmospheric carbon dioxide continues to rise at a rate similar to previous decades, they said.

Recent research suggested Earth may be less sensitive to greenhouse gas increases than previously thought.

The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), issued in 2013, also reduced the lower range of Earth's potential for global warming, said researchers.

To put a number to climate change, researchers calculate what is called Earth's "transient climate response."

This calculation determines how much global temperatures will change as atmospheric carbon dioxide continues to increase — at about one per cent per year — until the total amount of atmospheric carbon dioxide has doubled.

The estimates for transient climate response range from near 1.4 degrees celsius offered by recent research, to the IPCC's estimate of 1.0 degrees celsius.

Shindell's study estimates a transient climate response of 1.7 degrees celsius, and determined it is unlikely values will be below 1.3 degrees celsius.

In order to understand the role played by carbon dioxide emissions in global warming, it is necessary to account for the effects of atmospheric aerosols, researchers said.

While multiple studies have shown the Northern Hemisphere plays a stronger role than the Southern Hemisphere in transient climate change, this had not been included in calculations of the effect of atmospheric aerosols on climate sensitivity.

When corrected, the range of likely warming based on surface temperature observations is in line with earlier estimates, despite the recent slowdown, researchers said.

The research was published in the journal Nature Climate Change.


soure from: http://timesofindia.indiatimes.com/home/environment/global-warming/Earth-to-get-hotter-despite-global-warming-slowdown/articleshow/31940484.cms

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India News: India's sulphur dioxide emissions on the rise: Nasa (3 Jan 2014)

India's sulphur dioxide emissions on the rise: Nasa

Researchers have drafted a map that depicts sulphur dioxide concentrations in 2011-12 and 2005, and the relative size of power plants in India.

WASHINGTON: Emissions of sulphur dioxide - atmospheric pollutant with health and climate impacts - from power plants in India increased by over 60 per cent between 2005 and 2012, new data analysed by a Nasa satellite found.

In 2010, India surpassed the US as the world's second highest emitter of SO2 after China, according to estimates previously published by Zifeng Lu of Argonne National Laboratory, and other scientists.

The same research showed that about half of India's emissions came from the coal-fired power sector, Nasa said.

Researchers have drafted a map that depicts sulphur dioxide concentrations in 2011-12 and 2005, and the relative size of power plants in India.

While some atmospheric SO2 is produced by volcanoes and other natural processes, a substantial amount is produced by human activities such as the combustion of fuels with sulphur- containing impurities and the smelting of metals such as copper and nickel, researchers said.

The gas contributes to the formation of acid rain and, in high concentrations, can cause respiratory problems. It is also a precursor for sulfate aerosols, a type of suspended particle that can affect the properties of clouds - an effect that is difficult to measure and remains a large point of uncertainty in climate models.

India's Central Pollution Control Board noted in a 2012 report that the national mean concentration of sulphur dioxide had declined from 2001 to 2010, an estimate based on data from ground-based monitoring stations, researchers said.

However, most of the stations are located in urban areas, where regulations have indeed reduced pollution locally. Only some of the stations in India collect measurements near the source of power plant emissions, they said.

"We should know the air quality not only in populated cities, but also in industrial areas, where coal-fired power plants truly dominate national sulphur dioxide emissions," said Lu.

The new analysis of sulphur dioxide emissions comes two years after researchers developed a method to observe power plant emissions using measurements captured by an instrument on the Aura satellite.

The Ozone Monitoring Instrument (OMI) measures ozone and other key air quality components - including sulphur dioxide and nitrogen dioxide - and collects data over the same locations at the same time daily.

Using OMI's eight-year record of observations, Lu and colleagues averaged measurements of sulphur from 65 power plants in 23 regions.

Over time, a pattern emerged that allowed scientists to distinguish nearly constant power plant emissions from more variable background concentrations of sulphur dioxide.

The study was published in the journal Environmental Science & Technology.

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http://timesofindia.indiatimes.com/home/environment/global-warming/Indias-sulphur-dioxide-emissions-on-the-rise-Nasa/articleshow/28094720.cms

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