'Slowdown' in sea level rise to 2.4mm/yr. 2003-2011 may not be due to 'Pause' in global warming but natural variation in rainfall per Nature peer reviewed study-Reuters

3/23/14, "Shifts in rainfall, not warming pause, slow sea level rise," Reuters, Alister Doyle

"Heavy rains from the Amazon to Australia have curbed sea level rise so far this century by shifting water from the oceans to land, according to a study that rejects theories that the slowdown is tied to a pause in global warming. 

Sea level rise has been one of the clearest signs of climate change - water expands as it warms and parts of Greenland and Antarctica are thawing, along with glaciers from the Himalayas to the Alps.

But in a puzzle to climate scientists, the rate slowed to 2.4 millimeters (0.09 inch) a year from 2003 to 2011 from 3.4 mm from 1994-2002, heartening skeptics who doubt that deep cuts are needed in mankind's rising greenhouse gas emissions.

Writing in the journal Nature Climate Change on Sunday, experts said the rate from 2003-2011 would have been 3.3 mm a year when excluding natural shifts led by an unusually high number of La Nina weather events that cool the surface of the Pacific Ocean and cause more rain over land.
"There is no slowing in the rate of sea level rise" after accounting for the natural variations, lead author Anny Cazenave of the Laboratory for Studies in Geophysics and Spatial Oceanography in Toulouse, France, told Reuters.

In La Nina years, more rain fell away from oceans, including over the Amazon, the Congo basin and Australia, she said. It is unclear if climate change itself affects the frequency of La Ninas.

Rainfall over land only temporarily brakes sea level rise.

"Eventually water that falls as rain on land comes back into the sea," said Anders Levermann, a professor at the Potsdam Institute for Climate Impact Research, who was not involved in the study. 

"Some of it goes into ground water but most of it will drain into rivers, or evaporate."

HIATUS IN WARMING

The apparent slowing of sea level rise coincided with what the U.N. panel of climate experts calls a hiatus in global warming at the Earth's surface, when temperatures have risen less sharply despite record emissions of greenhouse gases.

"The slowdown in sea level rise...is due to natural variability in the climate and is not indicative of a slowdown in the effects of global warming," Nature Climate Change said.
Many scientists suspect that the "missing heat" from a build-up greenhouse gases in the atmosphere is going into the deep oceans as part of natural variations in the climate.

But, because water expands as it warms, that theory had been hard to reconcile with the apparent slowdown in sea level rise.

Sea levels have risen almost 20 cms since 1900. The U.N. panel of climate experts expects an acceleration, with gains of between 26 and 82 cms over 100 years to the late 21st century.

Melting an ice cube with sides 7 kms (4.3 miles) long is roughly the equivalent of adding a millimeter of water to the world's oceans.

Last year, another study said that unusually heavy downpours over Australia in 2010 and 2011 had curbed sea level rise, before a rebound reaching a rate of about 1 centimeter a year globally, partly as water flowed back into the sea.

"It has tailed off in the past 12 months or so" to above 3 mm a year, said John Fasullo of the U.S. National Center for Atmospheric Research who was lead author of the Australia study.

For the Nature Climate Change study: here."


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11/23/14, "The rate of sea-level rise," Nature.com, Nature Climate Change 

Anny Cazenave, Habib-Boubacar Dieng, Benoit Meyssignac, Karina von Schuckmann, Bertrand Decharme & Etienne Berthier


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Comment:

1. No citation for claims that catastrophic man caused melting is taking place in Greenland or Antarctica. 

2. No citation for claim of catastrophic sea level rise or that such would be caused by catastrophic man caused global warming caused by excess CO2 in China.

3. No citation for claim that water temperature was higher at sites claimed to be melting.

4. No citation for claim that catastrophic human CO2-caused melting is happening in Himalayas nor that "soot is...a big concern in the Himalayas, at high altitudes in some regions bigger than temperature rises" due to growing economies of China and India.

5. No citation for claim of catastrophic human CO2-caused melting of other ice including the Alps, nor mention that particulate matter, not CO2, has been linked to past Alps melting.

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"Scientists used to think soot was unlikely to have been carried high enough to start the glaciers melting, but they now appear to have been mistaken."

9/4/13, "Soot ‘melted Alps glaciers, not heat’," ClimateNewsNetwork.net, Alex Kirby, London

"Scientists think they know why some European glaciers started to shrink decades before climate change had begun to raise temperatures.

It wasn’t warming that attacked the glaciers, they say in the Proceedings of the National Academy of Sciences. It was soot from industry, steam locomotives and domestic fires.

Glaciologists have for years been puzzled by the sudden start in the middle of the 19th century of the retreat of the Alpine glaciers, which number around 4,000.

They had survived in good condition from the 13th century throughout the fairly cool 500-year period called the Little Ice Age. They reached their greatest extent in the mid-1800s, about double what they are now.

But even though it remained cool the glaciers suddenly began shrinking, leading scientists to believe that the Little Ice Age had ended around 1850.

Average global temperatures, though, did not rise significantly – until the end of the 19th century. In fact, Alpine climate records – among the most extensive and reliable in the world  – suggest that the glaciers should have continued to grow for another 50 years or more, until about 1910.

The scientists acknowledge that other parts of the world may also have been affected, but point out that the decline was well documented only in the Alps.

However, soot is also a big concern in the Himalayas, at high altitudes in some regions bigger than temperature rises. The burgeoning economies of China and India contribute huge amounts.

“Something gnawed on the glaciers that climate records don’t capture,” said Georg Kaser, a glaciologist at the University of Innsbruck in Austria and a member of the team that identified black carbon, or soot, as the cause.

“A strong decline in winter snowfall was often assumed to be the culprit. But from all that we know, no such decline occurred.”

Because darker surfaces absorb more heat than lighter, more reflective ones, if enough soot is deposited on snow and ice it can accelerate melting.

Records suggest that by the mid-19th century the air in some Alpine valleys was laden with pollution. “Housewives in Innsbruck refrained from drying laundry outdoors,” says Kaser.

Scientists used to think soot was unlikely to have been carried high enough to start the glaciers melting, but they now appear to have been mistaken.

When Kaser’s team looked at ice cores previously drilled at two sites high in the western Alps – the Colle Gnifetti glacier saddle 4,455 m up on Monte Rosa near the Swiss–Italian border, and the Fiescherhorn glacier at 3,900 m in the Bernese Alps – they found that in around 1860 layers of glacial ice started to contain large amounts of soot.

The team measured the effect the soot would have had on glaciers at the time in terms of  equivalent changes in air temperature. They found that the melting effect of black carbon provided a good explanation of the observed glacier retreat.

Andreas Vieli, a glaciologist at the University of Zurich in Switzerland (who was not involved in the study) said: “…[T]his study offers a very elegant and plausible explanation for the glacier conundrum. It appears that in central Europe soot prematurely stopped the Little Ice Age.”

Only after around 1970, when air quality began to improve, did accelerated climate warming become the dominant driver of Alpine glacier retreat, Kaser says.

He says that if glaciers in the region continue to melt at the rate seen during the past 30 years, there is a risk that nearly all of them will vanish before the end of the century."






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