Warming hits 'tipping point' [Siberia melting]

Siberia feels the heat It's a frozen peat bog the size of France and Germany combined, contains billions of tonnes of greenhouse gas and, for the first time since the ice age, it is melting

A vast expanse of western Sibera is undergoing an unprecedented thaw that could dramatically increase the rate of global warming, climate scientists warn today.

Researchers who have recently returned from the region found that an area of permafrost spanning a million square kilometres - the size of France and Germany combined - has started to melt for the first time since it formed 11,000 years ago at the end of the last ice age.

The area, which covers the entire sub-Arctic region of western Siberia, is the world's largest frozen peat bog and scientists fear that as it thaws, it will release billions of tonnes of methane, a greenhouse gas 20 times more potent than carbon dioxide, into the atmosphere.

It is a scenario climate scientists have feared since first identifying "tipping points" - delicate thresholds where a slight rise in the Earth's temperature can cause a dramatic change in the environment that itself triggers a far greater increase in global temperatures.

The discovery was made by Sergei Kirpotin at Tomsk State University in western Siberia and Judith Marquand at Oxford University and is reported in New Scientist today.

The researchers found that what was until recently a barren expanse of frozen peat is turning into a broken landscape of mud and lakes, some more than a kilometre across.

Dr Kirpotin told the magazine the situation was an "ecological landslide that is probably irreversible and is undoubtedly connected to climatic warming". He added that the thaw had probably begun in the past three or four years.

Climate scientists yesterday reacted with alarm to the finding, and warned that predictions of future global temperatures would have to be revised upwards.

"When you start messing around with these natural systems, you can end up in situations where it's unstoppable. There are no brakes you can apply," said David Viner, a senior scientist at the Climatic Research Unit at the University of East Anglia.

"This is a big deal because you can't put the permafrost back once it's gone. The causal effect is human activity and it will ramp up temperatures even more than our emissions are doing."

In its last major report in 2001, the intergovernmental panel on climate change predicted a rise in global temperatures of 1.4C-5.8C between 1990 and 2100, but the estimate only takes account of global warming driven by known greenhouse gas emissions.

"These positive feedbacks with landmasses weren't known about then. They had no idea how much they would add to global warming," said Dr Viner.

Western Siberia is heating up faster than anywhere else in the world, having experienced a rise of some 3C in the past 40 years. Scientists are particularly concerned about the permafrost, because as it thaws, it reveals bare ground which warms up more quickly than ice and snow, and so accelerates the rate at which the permafrost thaws.

Siberia's peat bogs have been producing methane since they formed at the end of the last ice age, but most of the gas had been trapped in the permafrost. According to Larry Smith, a hydrologist at the University of California, Los Angeles, the west Siberian peat bog could hold some 70bn tonnes of methane, a quarter of all of the methane stored in the ground around the world.

The permafrost is likely to take many decades at least to thaw, so the methane locked within it will not be released into the atmosphere in one burst, said Stephen Sitch, a climate scientist at the Met Office's Hadley Centre in Exeter.

But calculations by Dr Sitch and his colleagues show that even if methane seeped from the permafrost over the next 100 years, it would add around 700m tonnes of carbon into the atmosphere each year, roughly the same amount that is released annually from the world's wetlands and agriculture.

It would effectively double atmospheric levels of the gas, leading to a 10% to 25% increase in global warming, he said.

Tony Juniper, director of Friends of the Earth, said the finding was a stark message to politicians to take concerted action on climate change. "We knew at some point we'd get these feedbacks happening that exacerbate global warming, but this could lead to a massive injection of greenhouse gases.

"If we don't take action very soon, we could unleash runaway global warming that will be beyond our control and it will lead to social, economic and environmental devastation worldwide," he said. "There's still time to take action, but not much.

"The assumption has been that we wouldn't see these kinds of changes until the world is a little warmer, but this suggests we're running out of time."

In May this year, another group of researchers reported signs that global warming was damaging the permafrost. Katey Walter of the University of Alaska, Fairbanks, told a meeting of the Arctic Research Consortium of the US that her team had found methane hotspots in eastern Siberia. At the hotspots, methane was bubbling to the surface of the permafrost so quickly that it was preventing the surface from freezing over.

Last month, some of the world's worst air polluters, including the US and Australia, announced a partnership to cut greenhouse gas emissions through the use of new technologies.

The deal came after Tony Blair struggled at the G8 summit to get the US president, George Bush, to commit to any concerted action on climate change and has been heavily criticised for setting no targets for reductions in greenhouse gas emissions.

Well, maunder means to talk inchoherently or to move aimlessly, something I've been known to do by the time my ice cubes melt in my bourbon. The explanation you're looking for is below however and I didn't use google Wiipedia is better! ;^)

The Maunder Minimum is the name given to the period roughly from 1645 to 1715 A.D., when sunspots became exceedingly rare, as noted by solar observers of the time. It is named after the later solar astronomer E.W. Maunder who discovered the dearth of sunspots during that period by studying records from those years. During one 30-year period within the Maunder Minimum, for example, astronomers observed only about 50 sunspots, as opposed to a more typical 40,000–50,000 spots.

Sunspot observations
The Maunder Minimum occurred between 1645 and 1715 when only about 50 spots appeared as opposed to the typical 40–50,000 spots. The minima counts for 10-year periods from 1610-1681 are as follows:

Decade Sunspots
1610 9
1620 6
1630 9
1640 2
1650 3
1660 1
1670 0
1680 1

During the Maunder Minimum enough sunspots were sighted so that 11-year cycles could be extrapolated from the count. The maxima occurred in 1674, 1684, 1695, 1705 and 1716.

The sunspot activity was then concentrated in the southern hemisphere of the Sun, except for the last cycle when the sunspots appeared in the northern hemisphere too.

According to Spörer's law, at the start of a cycle spots appear at ever lower latitudes, until they average at about lat. 15° at solar maximum. The average then continues to drift lower to about 7° and after that, while spots of the old cycle fade, new cycle spots start appearing again at high latitudes.

The visibility of these spots is also affected by the velocity of the sun's rotation at various latitudes:

Solar
latitude Rotation period
(days)
0° 24.7
35° 26.7
40° 28.0
75° 33.0

Visibility is somewhat affected by observations being done from the ecliptic. The ecliptic is inclined 7° from the plane of the Sun's equator (latitude 0°).

Little Ice Age
The Maunder Minimum coincided with the middle — and coldest part — of the so-called Little Ice Age, during which Europe and North America, and perhaps much of the rest of the world, were subjected to bitterly cold winters.

Whether there is a causal connection between low sunspot activity and cold winters is the subject of ongoing debate. Some scientists believe that solar variation drives climate change more than carbon dioxide does (see global warming).

Other observations
Recently published research suggests that the Sun's rotation slowed in the deep Maunder minimum (1666–1700).[1] (#wp-endnote_Vaquero2002) At our current level of understanding of solar physics, a larger and slower Sun necessarily implies a cooler Sun that provides less heat to Earth. (The mechanism behind the Sun's expansion and contraction is still unclear, although many stars undergo pulsations to some degree or another; see variable star.)

Solar activity events recorded in radiocarbon.The lower solar activity during the Maunder Minimum also affected the amount of cosmic radiation reaching the Earth. The resulting change in the production of carbon-14 during that period caused an inaccuracy in radiocarbon dating until this effect was discovered.

Graph showing proxies of solar activity, including changes in sunspot number and cosmogenic isotope production.Solar activity also affects the production of beryllium-10, and variations in that cosmogenic isotope are studied as a proxy for solar activity.

Other historical sunspot minima have been detected either directly or by the analysis of carbon-14 in ice cores or tree rings; these include the Sporer Minimum (1450–1540), and less markedly the Dalton Minimum (1790–1820). In total there seem to have been 18 periods of sunspot minima in the last 8,000 years, and studies indicate that the sun currently spends up to a quarter of its time in these minima.

References
^ Vaquero J.M., Sánchez-bajo F., Gallego M.C. (2002). "A Measure of the Solar Rotation During the Maunder Minimum". Solar Physics 207 (2): 219. DOI:10.1023/A:1016262813525 (http://dx.doi.org/10.1023/A:1016262813525)

This entry is from Wikipedia,

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