Glaciers defied hotter temperatures 9000 years ago

Ice, when heated, is supposed to melt.

That’s why a collection of glaciers in the Southeast Himalayas stymies those who know what they did 9,000 years ago. While most other Central Asian glaciers retreated under hotter summer temperatures, this group of glaciers advanced from one to six kilometers.

A new study by BYU geologist Summer Rupper pieces together the chain of events surrounding the unexpected glacial growth.

“Stronger monsoons were thought to be responsible,” said Rupper, who reports her findings in the September issue of the journal Quaternary Research. “Our research indicates the extra snowfall from monsoonal effects can only take credit for up to 30 percent of the glacial advance.”

As Central Asia’s summer climate warmed as much as 6 degrees Celsius, shifting weather patterns brought more clouds to the Southeast Himalayas. The additional shade created a pocket of cooler temperatures.

Temperatures also dropped when higher winds spurred more evaporation in this typically humid area, the same process behind household swamp coolers.

The story of these seemingly anomalous glaciers underscores the important distinction between the terms “climate change” and “global warming.”

“Even when average temperatures are clearly rising regionally or globally, what happens in any given location depends on the exact dynamics of that place,” Rupper said.

The findings come from a framework Rupper developed as an alternative to the notion that glaciers form and melt in direct proportion to temperature. Her method is based on the balance of energy between a glacier and a wide range of climate factors, including wind, humidity, precipitation, evaporation and cloudiness.

Gerard Roe and Alan Gillespie of the University of Washington are co-authors of the new study.

Knowing how glaciers responded in past periods of climate change will help Rupper forecast the region’s water supply in the coming decades. She and collaborators are in the process of determining how much of the Indus River comes from the vast network of glaciers far upstream from the agricultural valleys of India and Pakistan.

“Their study can be used to help assess future glaciological and hydrological changes in the most populated part of our planet, which is a region that is now beginning to experience the profound effects of human-induced climate change,” said Lewis Owen, a geologist at the University of Cincinnati who was not affiliated with this study.

BYU professor Summer Rupper doing field work with Switzerland's Gornergrat glacier. Her newest study details how a group of Himalayan glaciers grew despite a significant rise in
temperatures.

Glaciers that are Actually Growing

There are actually 230 glaciers in the western Himalayas, which includes Mount Everest and K2, that are defying global warming and are actually growing.

A view of the Mt. Everest region from the International Space Station.

"These are the biggest mid-latitude glaciers in the world," John Shroder of the University of Nebraska-Omaha said. "And all of them are either holding still, or advancing."

Shroder and a team of researchers looked at satellite imagery of the region's glaciers going back to 1960. According to the Discovery News report, a total of 87 glaciers in that region surged forward during that period of time.

It's a different story throughout much of the Tibetan Plateau, high-altitude glaciers are dwindling. The situation is potentially dire for the hundreds of millions of people living in China, India and throughout southeast Asia who depend on the glaciers for their water supply, according to the story.

Shroder suspects that the strong winds aloft (close to the jet stream) are carrying more moisture from the warmer Atlantic (not the case recently) and Mediterranean Sea on eastward into the western Himalayas.

New Zealand glacier findings upset climate theory

Fox Glacier is one of the world's climate change indicators.

Research by three New Zealand scientists may have solved the mystery of why glaciers behave differently in the Northern and Southern Hemispheres.

Geologist David Barrell of GNS Science, Victoria University geomorphologist Andrew Mackintosh and glaciologist Trevor Chinn of the Alpine and Polar Processes Consultancy have helped provide definitive dating for changes in glacier behaviour.

They were part of a team of nine scientists, led by Joerg Schaefer of the Lamont-Doherty Earth Observatory at Columbia University in New York, who used an isotope-dating technique to get very precise ages for glacial deposits near Mt Cook.

They measured the build-up of beryllium-10 isotopes in surface rocks bombarded by cosmic rays to pinpoint dates when glaciers in the Southern Alps started to recede. The technology is expected to be widely applied to precisely date other glaciers around the world.

Glaciers are sensitive indicators of climate changes, usually advancing when it cools and retreating when it warms.

The first direct confirmation of differences in glacier behaviour between the Northern and Southern Hemispheres, the new work topples theories based on climate in the Northern Hemisphere changing in tandem with the climate in the Southern Hemisphere.

The research argues that at times the climate in both hemispheres evolved in sync and at other times it evolved differently in different parts of the world.

Dr Barrell said their research presented “new data of novel high precision”, though the team has so far chosen not to roll out wider interpretations too quickly.

He said much of it reinforced work done 30 years ago by Canterbury University researcher Professor Colin Burrows, who used NZ glacier data to highlight some of the similarities and differences between northern and southern records over the past 12,000 years.

The paper published in Science magazine yesterday showed the Mt Cook glaciers advanced to their maximum length 6500 years ago, and have been smaller ever since.

But glaciers in the Swiss Alps advanced to their maximum only in the past 700 years - during the Northern Hemisphere’s “Little Ice Age”, which ended about 1860.

During some warm periods in Europe, glaciers were advancing in New Zealand. At other times, glaciers were well advanced in both areas.

In a commentary which accompanied the research, Greg Balco, from the Berkeley Geochronology Centre in California, said the conclusion that glacier advances in the Northern and Southern Hemispheres were not synchronised was “unexpected”.

Dr Barrell said the paper presented only the first instalment of the dating work, and more would be revealed at an international workshop on past climates to be held at Te Papa on May 15.

“The New Zealand findings point to the importance of regional shifts in wind directions and sea surface temperatures,” he said.

Regional weather patterns such as the El Nino Southern Oscillation were superimposed on the global climate trends reflected in the behaviour of glaciers.

wattsupwiththat

”Climate flicker” at the end of the last glacial period

From ETH in Zurich, this interesting essay on the last glacial period has some interesting points to ponder. h/t to Sid Stafford - Anthony

The last glacial period was characterised by strong climatic fluctuations. Scientists have now been able to prove very frequent and rapid climate change, particularly at the end of the Younger Dryas period, around 12,000 years ago. These fluctuations were accompanied by rapid changes in circulation in the oceans and the atmosphere.

Researchers are able to determine when glaciers were stable and when they melted by studying titanium content in glacial lake sediments. (Picture: siyublog/flickr)

Sediment deposits in lakes are the climate archives of the past. An international team of researchers from Norway, Switzerland and Germany have now examined sediments originating from the Younger Dryas period from the Kråkenes Lake in northwest Norway. In the sediments, they found clues that point to a “climate flicker” at the end of the last glacial period, oscillating between colder and warmer phases until the transition to the stable climate of the Holocene, our current interglacial period. The short-term, strong fluctuations of the Younger Dryas would have dwarfed the “extreme weather phenomena” seen today, according to Gerald Haug, professor at the Department for Earth Sciences at ETH Zürich and co-author of the study, which was published online yesterday in “Nature Geoscience”.

Seasonal sediment deposits

Seasonal sediment accumulation, for example, gave scientists clues to these strong climate fluctuations. They can be read in lakes in a similar way to reading rings on trees. In warmer phases and melting glaciers, the accumulation of sediments increases. More clues on the changes in glacier growth were given by the element titanium, which is present in the sediments. Glaciers erode their bedrock, and in doing so concentrate the titanium contained in the sediments they are carrying. The sediments containing titanium are washed into the glacier’s draining lakes in the meltwater. The amount of sediment and the titanium content can therefore allow us to deduce when the glaciers were stable and when they melted. The researchers interpreted the maxims, recurring every 10 years, as phases of strong glacier activity caused by temperature fluctuations and thus as warmer times.

A seemingly self-preserving cycle

The scientists also examined a sediment core from seabed deposits of the same age in the North Atlantic. They reconstructed the original temperature and salt concentration of the water based on microfossils and the oxygen isotope ratio in the sediment. It was shown that the results from the lake sediments corresponded to those from the sea sediments. “The melting of glaciers was caused by the warm Gulf stream advancing into this region,” Gerald Haug explains. This increase in temperature caused the west winds to shift to the north and brought warm air to northern Europe. However, the meltwater draining into the Atlantic lowered the salt concentration and the density of the surface water, changing the convection in the ocean, which in turn allowed new sea ice to form. Subsequently, the Gulf Stream and the west winds were again forced out of the North Atlantic area and the region cooled down once again. These processes were repeated for around 400 years, until the current interglacial period was able to stabilise itself.

The Würm glaciation began around 100,000 years ago and lasted until around 10,000 years ago. In this period, there were strong fluctuations between warm and cold phases, particularly in the North Atlantic area. The Younger Dryas, which ushered in the current interglacial period, is one of the best-known and best-researched abrupt climate changes of that glaciation. It began around 12,900 years ago and at first caused an abrupt temperature drop in the northern hemisphere, as well as a temperature rise of up to 10°C in less than 20 years towards the end, around 11,700 years ago.

Unclear mechanisms

Up until now, there have been several studies which document the glacial conditions during the Younger Dryas period of 1,200 years. However, the mechanisms which caused it, sustained it and finally led to an interglacial period have yet to be fully understood. The researchers believe that further high-resolution studies of this type could give insights into how glacial periods are triggered and how they are brought to an end.

Latest Update on the Glaciers of the World

The World Glacier Monitoring Service (WGMS), which is based out of the University of Zurich in Switzerland has updated their report on a number of the world's glaciers.

According to the WMGS, a clear majority of more than 80 glaciers across the globe are still melting at high rates, according to the ScienceDaily article

For the year 2007, (which is the latest data from the WGMS) the results indicate that there has been an overall additional further loss of average ice thickness of roughly 0.67 meter water equivalent (m w.e.). Some glaciers in the European Alps lost up to 2.5 m w.e.

This is a time lapse look at the Vernagtferner Glacier in Austria and how it has shrunk between 1912 and 2003. Image courtesy of the United Nations Environment Program.

2007 was the 6th year this century in which the average ice loss of the referenced glaciers has exceeded a 1/2 meter in thickness, which more than doubles the melt rates of the 1980's and 1990's.

The average ice loss in 2007 was not as extreme as 2006, but there were big differences between mountain ranges across the globe.

In addition to the large losses in the European Alps, there were significant losses in the referenced glaciers in Columbia and Bolivia.

Some glaciers actually gained mass, and those included the maritime glaciers in Scandinavia, and in western North America, the North Cascades and the Juneau Ice Field.

Here is the link to the latest glacier data from the WGMS.

By the way, coordinated international glacier monitoring began in 1894.

Internationally Glaciers Are Dethawing at a Dreadful Pace

Everywhere glaciers are retreating at a swifter pace than at any point since records began, states The Independent. Scientists from the International Glacier Monitoring Service, which follows 32 glaciers across 11 mountains, calculate that from 1853 to 1967 glaciers retreated at a net average pace of 32 centimeters per annam. Between 1972 to 2001 the amount retreating increased to 65 to 85 centimeters a yr. Since then the norm has comprised greater than one metre a yr. And last season recorded the biggest losses up til now of 1.1 m.

Worldwide glaciers are receding at any rate as fast as those in this small sample with possibly fatal results for local villages. Shortly there will be a lot more deluges, and in the future, water supplies will disappear, meaning sharp mains water deficits.

Chamonix French Alps, with its high number of glaciers, the consequences of global warming and the disappearing of glaciers could be noticeably sensed. This is perhaps why lots of shops and locals seem to be more cognisant of these issues so are therefore trying to undertake measures to limit their energy consumption. With luck it isn’t too little too late to halt the upshots of climate change and ensure an environment for our kids.