Tuesday, May 27, 2014

Flash floods from glacial lakes worry experts

File photo: Ghizar river burst its banks due to flash flood
ISLAMABAD: Meteorologists have been rushed to investigate two glacial lakes that burst out in Gilgit-Baltistan region recently, causing flash floods and disrupting traffic on Karakoram Highway (KKH).
Deputy Commissioner Hunza Usman Ali told Dawn that a lake formed atop the roughly 20 kilometre-long Hussaini glacier in Gojal Valley burst its banks at three or four points on May 7 and the rushing waters damaged some agricultural land but spared the settlements down below.
“Such floodwaters bring down a lot of debris and boulders with them,” he added to explain the closure of the under-construction KKH between Gulmit and Passu for several hours.
Another glacial lake burst its banks in Bargot Valley the next week. Water gushed out for hours from the burst but the people of six villages down below, and their properties, remained safe, according to Pakistan Meteorological Department (PMD) in Islamabad.

Rising temperature and changing climate is accelerating the phenomenon

Deputy Commissioner Usman Ali sounded worried about the seven or eight more lakes that have been formed on the Hussaini glacier that could be hazardous to settlements at lower grounds. Officials of the federal government’s Climate Change Division said that the flooding caused by the two bursting lakes had left residents in the Hussaini village without drinking water for at least two days.
“Glacial lake outburst floods (GLOF) have become a concern,” said PMD Chief Meteorologist Dr Ghulam Rasul explaining “the fairly unique phenomenon” to Dawn where huge lakes are formed on the surface, or water is dammed inside the walls of the glaciers.
“They are particularly dangerous because the walls holding the massive water bodies can break, among a dozen other reasons, due to intense heat of the sun, torrential rains, glacial movement or seismic activity, with flash floods devastating villages lying directly in their paths,” he said.
GLOF events have become a regular feature in the valleys of northern Pakistan in the last few years.
“Two GLOF events at the start of summer are indicative of what is to come when the weather gets warmer,” said Chief Meteorologist Dr Ghulam Rasul. Ground survey teams were heading to the two locations to study how the lakes burst and the damage the bursts caused, he said. The teams are likely to report their findings after a week or 10 days.
PMD’s last survey, conducted in 2013, had identified 36 dangerous glacial risks and declared them hazardous for settlements downhill if they ruptured.
“What makes these lakes particularly dangerous is that the glaciers in Pakistan exist at relatively low heights, between 2,200 metres and 2,300 metres and roughly less a kilometre from the nearest settlements,” observed PMD Meteorologist Atif Wazir. In some cases, potential bursts allow only 30 or 40 minutes to sound an alarm for the threatened population to evacuate to safety, he noted.
“In Nepal glaciers lie at 4,500 metres or more. In case of a glacial lake outburst people have enough lead time to escape to safer or higher grounds in time,” he said.
One of the largest and dangerous glacial lakes is the Gharko Lake in Gilgit-Baltistan. It is about 100 metres long, 77 metres wide and 27 metres deep. The Hinarchi Lake is equally unstable and capable of causing flash floods downhill.
Temperatures in the Northern Areas of Pakistan have risen by 1.5 degrees centigrade between 1990 and 2010, according to the Pakistan Meteorological Department, which has recorded five GLOF events in the last three years.
“Two years ago, the Buni glacier outburst caused extensive damage to houses in its path. Gulkin glacier, close to the Karakoram Highway, bursts out frequently and now regularly feeds the Attabad Lake in Hunza,” said Dr Ghulam Rasul, recalling the formation of the lake in 2008.
Surprisingly, the number of hazardous lakes dotting Swat, Chitral, Gilgit, Hunza, Astore, Shigar, Shyok and the Indus region have decreased from 52 in 2001 to 36 today.
“We are studying how some of these lakes disappeared. However, four more lakes have formed in Chitral and Hunza. Once the ground survey is complete we will know how climate change is impacting glacial melting rate,” said meteorologist Atif Wazir.
Although a $4.1 million GLOF study, funded by the United Nations Development Programme (UNDP), is going on, experts say some of its components need much improvement.

Initiated in 2011, it was Pakistan’s first Climate Change Adaptation Project focusing on mitigating risks of glacial lake bursts caused by rising temperatures and other reasons. Dawn.com
Is the cause of global warming underground? Carbon in ancient soil is changing the climate, study says

A team of researchers led by UW-Madison Assistant Professor of
geography Dr Erika Marin-Spiotta has found that buried fossil soils
 (pictured) contain significant amounts of carbon and could contribute
 to climate change as the carbon is released through human activities
 such as mining, agriculture and deforestation

Soil buried deep underground that formed on Earth's surface thousounds of years ago has been found to be rich in carbon.
The subsurface features of vanished landscapes add a new dimension to our planet's carbon cycle.
And continued activities by humans could unleash more of this carbon into the atmosphere, a study claims.

The finding, reported in the journal Nature Geoscience, is significant as it suggests that deep soils can contain long-buried stocks of organic carbon.

This could, through erosion, agriculture, deforestation, mining and other human activities, contribute to global climate change.

'There is a lot of carbon at depths where nobody is measuring,' says Dr Erika Marin-Spiotta, a University of Wisconsin-Madison (UW-Madison) assistant professor of geography and the lead author of the new study.

'It was assumed that there was little carbon in deeper soils. Most studies are done in only the top 30 centimeters [11.8 inches].

'Our study is showing that we are potentially grossly underestimating carbon in soils.'

The soil studied by Dr Marin-Spiotta and her colleagues, known as the Brady soil, formed between 15,000 and 13,500 years ago in what is now Nebraska, Kansas and other parts of the Great Plains across the central U.S. 

It lies up to 21.3 feet (6.5 metres) below the present-day surface and was buried by a vast accumulation of windborne dust known as loess begi nning about 10,000 years ago, when the glaciers that covered much of North America began to retreat.

The region where the Brady soil formed was not glaciated, but underwent radical change as the Northern Hemisphere's retreating glaciers sparked an abrupt shift in climate.

This included changes in vegetation and a regime of wildfire that contributed to carbon sequestration as the soil was rapidly buried by accumulating loess.

'Most of the carbon (in the Brady soil) was fire derived or black carbon,' notes Dr Marin-Spiotta, whose team employed an array of new analytical methods, including spectroscopic and isotopic analyses, to study the soil and its chemistry.

'It looks like there was an incredible amount of fire.'

The team led by Dr Marin-Spiotta also found organic matter from ancient plants that, thanks to the thick blanket of loess, had not fully decomposed. 

Rapid burial helped isolate the soil from biological processes that would ordinarily break down carbon in the soil.
Such buried soils, according to UW-Madison geography Professor and study co-author Dr Joseph Mason, are not unique to the Great Plains and occur worldwide.

The work suggests that fossil organic carbon in buried soils is widespread and, as humans increasingly disturb landscapes through a variety of activities, a potential contributor to climate change as carbon that had been locked away for thousands of years in arid and semiarid environments is reintroduced to the environment.

The element carbon comes in many forms and cycles through the environment - land, sea and atmosphere - just as water in various forms cycles through the ground, oceans and the air.

Scientists have long known about the carbon storage capacity of soils, the potential for carbon sequestration, and that carbon in soil can be released to the atmosphere through microbial decomposition.

The deeply buried soil studied by Dr Marin-Spiotta, Dr Mason and their colleagues, a 3.3 feet (one metre) thick ribbon of dark soil far below the modern surface, is a time capsule of a past environment, the researchers explain. 
It provides a snapshot of an environment undergoing significant change due to a shifting climate.

The retreat of the glaciers signaled a warming world, and likely contributed to a changing environment by setting the stage for an increased regime of wildfire.

'The world was getting warmer during the time the Brady soil formed,' says Dr Mason. 
'Warm-season prairie grasses were increasing and their expansion on the landscape was almost certainly related to rising temperatures.'

The retreat of the glaciers also set in motion an era when loess began to cover large swaths of the ancient landscape. Dailymail.co.uk

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