Tibets glaciers warmest in 2000 years

The Tibetan plateau, whose glaciers supply water to hundreds of millions of people in Asia, were warmer over the past 50 years than at any stage in the past two millennia, a Chinese newspaper said, citing an academic report.

Temperatures and humidity are likely to continue to rise throughout this century, causing glaciers to retreat and desertification to spread, according to the report published by the Chinese Academy of Sciences' Institute of Tibetan Plateau Research.

"Over the past 50 years, the rate of temperature rise has been double the average global level," it said, according to the report on the website of Science and Technology Daily, a state-run newspaper.

Glacier retreat could disrupt water supply to several of Asia's main rivers that originate from the plateau, including China's Yellow and Yangtze, India's Brahmaputra, and the Mekong and Salween in Southeast Asia.

In May, Chinese scientists said Tibetan glaciers had shrunk 15 percent - around 8,000 square km (3,100 square miles) - over the past 30 years.

The new report said a combination of climate change and human activity on the plateau was likely to cause an increase in floods and landslides there. However, rising temperatures had also improved the local ecosystem, it said.

The scientists urged the government to work to reduce human impact on the region's fragile environment.

But Beijing is building a series of large hydropower projects there, with construction of several mega-dams expected to start by 2020. China has built thousands of dams in the past few decades in a bid to reduce its reliance on imported fossil fuels.

India, too, is planning a number of hydro plants along the Brahmaputra river - more than 100 proposals are under consideration - as the country strives to boost electricity generation.

Global warming results drought faster and harder

A new study tries to separate natural and human influences on drought

Yemenis walk through a drought-affected dam on the outskirts of Sana'a, Yemen. Sana a city is running out of water and many relief agencies feel that it could become the first capital city in the world to run out of a viable water supply. Photograph: Yahya Arhab/EPA

We all know that some climate change is natural, in fact, even without humans, the Earth’s climate changes. But, as we have added heat-trapping gases to the atmosphere, we have seen human influence “emerge” from natural variability.

Droughts, one of the most intensely studied climate events, are a perfect example of an effect with both human and natural influences. Separating the relative strengths of the influences is a challenge for scientists. But, when we deal with drought, with its large social and economic costs, it is a challenge we must undertake.

A very recent study tries to do just this. Published in the Journal of Climate, authors Richard Seager and Martin Hoerling cleverly used climate models forced by sea surface temperatures to separate how much of the past century’s North American droughts have been caused by ocean temperatures, natural variability, and humans. What they found was expected (all three of these influence drought), but it's the details that are exciting. Furthermore, the methodology can be applied to other climate phenomena at other locations around the globe.

The very beginning of their paper sets a great framework for the study,

    “In a nation that has been reeling from one weather or climate disaster to another, with record tornado outbreaks, landfalling tropical storms and superstorms, record winter snowfalls, and severe droughts, persistent droughts appear almost prosaic. Droughts do not cause the mass loss of life and property destruction by floods and storms. They are instead slow-moving disasters whose beginnings and ends are even often hard to identify. However, while the social and financial costs of hurricane, tornado, and flood disasters are, of course, tremendous, droughts are one of the costliest of natural disasters in the United States.”

Droughts can be caused by a variety of isolated or interacting phenomena. At its root, drought results from lowered precipitation and sometimes higher temperatures (which increase evaporation rates). The onset of drought can often be linked to variations in ocean temperatures. For instance, La Niña events in the Pacific Ocean as well as elevated Atlantic Ocean temperatures have coincided with United States droughts.

In fact the authors state that the three mid-to-late 19th century droughts, the Dust Bowl, and the drought in the 1950s all depended on persistent La Niña conditions. Of course, other factors played roles as well and ocean temperatures simply don’t explain everything. Perhaps the best example of multiple drought factors is the Dust Bowl of the 1930s. Then, cool Pacific temperatures were not by themselves sufficient. It is likely that land use changes associated with farmland erosion and natural atmospheric variability also played roles.

The authors, therefore, wanted to move beyond a simplistic association of La Niña episodes and warm Atlantic Ocean waters with the occurrence of drought. They asked what other causes might there be and how will things change in the coming years and decades?

Using precipitation data from the University of East Anglia and ocean temperatures from the Hadley Centre combined with climate models, the researchers were able to add or omit the oceanic temperatures and compare the two sets of results. They found that ocean temperature variations cause up to 40% of the changes to precipitation, depending on location. They also found that the oceans can “nudge” the atmosphere to create conditions that are amenable to drought, and that temperature increases associated with human-driven global warming also play a role. In fact,

    “The warming leads to a simulated long-term reduction in soil moisture which, although of weak magnitude compared to soil moisture deficits induced by naturally occurring droughts in the southwest United States, would imply that drought conditions may be entered more quickly and alleviated more slowly owing to long-term warming … Radiative forcing of the climate system is another source of predictability, although not really a welcome one, and rising greenhouse gases will lead to a steady drying of southwest North America. However this is a change that is only now beginning to emerge and currently is exerting less influence on precipitation variability than ocean variability or internal variability.”

This conclusion agrees with other researchers who have shown that, while human-emitted greenhouse gas warming may not cause a particular drought, it can make drought come on earlier, faster, and harder than it otherwise would.

There are two issues that I will be watching closely. The first is that any extra damage caused by drought as a consequence of human emissions will not scale linearly with attribution. For instance, if human impacts are responsible for 10% of a drought’s severity, it does not mean that human impacts are responsible for 10% of the social or economic cost.

A great example of this is with Superstorm Sandy. While admittedly not a drought, the example will make the point. It has been estimated that human-caused increases to water temperatures caused perhaps 10% more rain to fall. This extra 10% rainfall caused more than 10% of the economic damages associated with rainfall. Similarly, the human-induced sea level rise of 1 foot was only about 10% of the storm surge. But, this extra foot caused a disproportionate amount of flood damage. With this in mind, I would really like to know how the social and financial costs will change in the future as droughts set in earlier, faster, and harder because of greenhouse gas warming.

Secondly, there may well be a human influence on these otherwise natural causes. For instance, scientists have argued that greenhouse gas warming may change the ocean temperature fluctuations, particularly in the Pacific. Similarly, there are many new studies linking increasing greenhouse gases with atmospheric circulation changes. Since both of these features affect drought, they appear, at least to me, to be potential indirect human influences.

We will have to wait to learn more, let’s hope the wait isn’t too long.

-post by John Abraham
-theguardian

Carbon dioxide emissions up by 29 percent: Report

London: Carbon dioxide emissions are up by 29 percent since 2000, far beyond the capacity of the global "sinks" to absorb such volumes, says a report.



The use of coal as a fuel has now surpassed oil and developing countries now emit more greenhouse gases than developed countries - with a quarter of their growth in emissions accounted for by increased trade with the West.

An international team of researchers under the umbrella of the Global Carbon Project reports that over the last 50 years, the average fraction of global carbon dioxide emissions that remained in the air each year was around 43 percent.

The rest was absorbed by the carbon sinks on land and in the oceans. During this time, this fraction has likely increased from 40 percent to 45 percent. The team brings evidence that the sinks are responding to climate change and variability.

Corinne Le Quere professor at the University of East Anglia (UEA) and the British Antarctic Survey, who led the study said: "The only way to control climate change is through a drastic reduction in global carbon dioxide emissions."

"The earth's carbon sinks are complex and there are some gaps in our understanding, particularly in our ability to link human-induced carbon dioxide emissions to atmospheric carbon dioxide concentrations on a year-to-year basis," Le Quere said.

"But, if we can reduce the uncertainty about the carbon sinks, our data could be used to verify the effectiveness of climate mitigation policies," he concluded.

These findings were published in Nature Geoscience.

Source: IANS

Women believe in global warming more than men

Washington: Women tend to believe in the scientific consensus on global warming more than men, finds a recent study.



The findings challenge common perceptions that men are more scientifically literate, said sociologist Aaron M. McCright at the Michigan State University in the US.

"Men still claim they have a better understanding of global warming than women, even though women's beliefs align much more closely with the scientific consensus," said McCright.



The study is one of the first to focus in-depth on how the genders think about climate change, reports the journal Population and Environment.

Understanding how the genders think about the environment is important on several fronts, said McCright, who calls climate change "the most expansive environmental problem facing humanity," according to a Michigan State University release.



"Does this mean women are more likely to buy energy-efficient appliances and hybrid vehicles than men," he said. "Do they vote for different political candidates? Do they talk to their children differently about global warming?"

McCright analysed eight years of data from Gallup's annual environment poll that asked fairly basic questions about climate change knowledge and concern.



He said the gender divide on concern about climate change was not explained by the roles that men and women perform such as whether they were homemakers, parents or employed full time.

Instead, he said the gender divide likely is explained by "gender socialisation."

According to this theory, boys in the US learn that masculinity emphasises detachment, control and mastery.




A feminine identity, on the other hand, stresses attachment, empathy and care - traits that may make it easier to feel concern about the potential dire consequences of global warming, McCright said.

"Women and men think about climate change differently. And when scientists or policymakers are communicating about climate change with the general public, they should consider this rather than treating the public as one big monolithic audience," he said.

Source: IANS