* Astronomy

Dramatic changes to the lives and livelihoods of Arctic-living communities are being forecast unless urgent action is taken to reduce greenhouse gases, according to the Intergovernmental Panel on Climate Change (IPCC).
Its Working Group II predicts wide-ranging thawing of the Arctic permafrost which is likely to have significant implications for infrastructure including houses, buildings, roads, railways and pipelines. A combination of reduced sea ice, thawing permafrost and storm surges also threatens erosion of Arctic coastlines with impacts on coastal communities, culturally important sites and industrial facilities.
One study suggests that a three degree C increase in average summer air temperatures could increase erosion rates in the eastern Siberia Arctic by three to five metres a year. In some part of the Arctic, toxic and radioactive materials are stored and contained in frozen ground. Thawing may release these substances in the local and wider environment with risks to humans and wildlife alongside significant clean up costs.
Warmer temperatures also represent new economic opportunities but also challenges in the Arctic. Declines in sea ice are likely to open up the Arctic to more shipping, oil and gas exploration and fisheries. A comprehensive sustainable development plan is urgently needed for the region to maximise the opportunities and minimise potentially damaging impacts.
The future health and well being of Arctic peoples is a major question. The report, part of the IPCCs fourth assessment, recognises that Arctic communities and indigenous peoples lives and livelihoods are intimately linked with their environment but that this is already changing.
Inuit hunters are now navigating new travel routes in order to try to avoid areas of decreasing ice stability that is making them less safe. In the future, increased rainfall may trigger additional hazards such as avalanches and rock falls. Inuit hunters are also changing their hunting times to coincide with shifts in the migration times and migration routes of caribou, geese as well as new species moving northwards.
Some impacts of climate change may improve human well-being. Opportunities for agriculture and forestry may increase. There is evidence that Arctic warming could reduce the level of winter mortality as a result of falls in cardiovascular and respiratory deaths.
But this will have to be set against possible increases in drought in some areas, the emergence and survival of new pests and diseases, likely contamination of freshwaters and health and psychological impacts of the loss of traditional social and kinship structures.
However, it is likely that in order for Arctic communities and cultures to survive and conserve their centuries-old ways of life decisive emissions reductions will be needed alongside adaptation to the climate change already underway.

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This satellite image released by NASA Wednesday Sept. 28, 2005 shows the minimum concentration of Arctic sea ice in 2005 occurring on September 21, 2005, when the sea ice extent dropped to 2.05 million sq. miles, the lowest extent yet recorded in the satellite record.

"The melting and retreat trends are accelerating" - Ted Scambos, of the University of Colorado at Boulder's National Snow and Ice Data Centre.


Credit NASA


New satellite observations show that sea ice in the Arctic is melting faster while air temperatures in the region are rising sharply.
Since 2002, satellite data have revealed unusually early springtime melting in areas north of Siberia and Alaska. Now the melting trend has spread throughout the Arctic, according to a national collaboration of scientists study released by the University of Colorado at Boulder's National Snow and Ice Data Centre statement released Wednesday Sept. 28, 2005.

A stalagmite from an Alpine cave may indicate that global warming is not as unusual as many think.
Deposits laid down in the stalagmite have enabled a European team to probe past climates confirming a Medieval Warm Period between AD 800 and 1300.
The warm spell is also indicated in some studies of tree-rings, ice-cores and coral reef growth records.
Writing in Earth and Planetary Science Letters the researchers suggest that global warming is a natural process.

Other scientists, however, say phenomena such as the Medieval Warm Period become less significant when broad sets of so-called "proxy data" are calibrated and synthesised to give a truly global picture - not just regional ones.
When this is done, they argue, the warming witnessed in the past few decades appears to be very unnatural.

The latest research was performed by Augusto Mangini and Peter Verdes, of the Heidelberg Academy of Sciences, Germany, and Christop Spotl, of the Institute for Geology and Palaeontology, at the University of Innsbruck, Austria.
SPA-12 is a 20cm long stalagmite recovered from Spannagel cave in the Central Alps, a remote part of an extensive high-altitude complex of caves extending for at least 10km.
At an altitude of almost 2,500m the conditions inside the cave have remained relatively constant for possibly the past 5,000 years and certainly the past 2,000 years. Any changes there have been, the researchers believe, due to long-term changes in climate.

Several factors enabled the team to use SPA-12 to reconstruct the Alpine climate over the past two millennia.
For one, the relatively high radioactive uranium content of the mineral-rich liquid dripping from the roof to form the stalagmite makes it possible to date the time at which the various layers were laid down.
In addition, the stable environment in which SPA-12 has grown makes it relatively straightforward to relate its isotopic composition to the temperature at which various parts of the stalagmite formed.

SPA-12 also shows evidence of the so-called "Little Ice Age", a temperature dip between roughly 1400 and 1850 when there is complimentary evidence from tree-rings and glacier advances that at least Northern Europe chilled a little.
The long-term changes in temperature as revealed by SPA-12 are at odds with the temperature change profile adopted by the Intergovernmental Panel on Climate Change (IPCC).



The IPCC temperature curve only shows small variations during the last 1,800 years with an abrupt temperature increase after 1860 - the so-called "hockey stick" - which is generally ascribed to the increase of greenhouse gasses in the atmosphere.

But the researchers analysing SPA-12 say that the stalagmite's temperature record is corroborated by ice-core records from Greenland and sediment deposits on the sea floor near Bermuda, both of which show evidence for a Medieval Warm Period.
The implications of SPA-12 will stoke up what is already an acrimonious debate between global warming sceptics and the scientific "consensus".
The latter say the hockey stick profile of recent temperature change is now evident from several studies using different raw data and methodologies.

The former argue the present climate is experiencing a natural rebound and that the IPCC should abandon the hockey stick and return to its 1990 position when the existence of the Little Ice Age and the Medieval Warm Period were recognised as more significant climate events.