Thursday, September 20, 2007


We don't know yet whether melting icecaps play any role, but scare stories don't help, says Jose Rial, professor of geophysics at the department of geological sciences, University of North Carolina []

Your article (Melting icecap triggering earthquakes, September 8) is misleading and alarmist. As a climatologist/seismologist working on glacial seismic activity in the Jakobshavn glacier basin - precisely the area your reporter mentions - I know that local earthquakes (or glacial quakes) are actually fairly common in the area and have been for a long time. I also know that there is no evidence to suggest that these quakes "are happening far faster than ever anticipated" in the region, as Dr Corell of the global change programme at Washington's Heinz Centre is quoted as saying.

Glacial earthquakes in Greenland have been monitored for decades using the global seismic network, and although their number has increased over the last five to six years - likely due to Arctic warming - in Jakobshavn their number has actually decreased since 1996, according to a recent report by G Ekstr”m and V Tsai from Columbia University. However, because these scientists used sensors quite remote from the area, small quakes may have been missed in Jakobshavn, which is not as glacially quake-active as other studied areas in eastern and north-western Greenland.

To take a closer look, in 2006 and again in 2007 I deployed an array of 10 seismic sensors near Swiss Camp, a permanent glaciological station some 50km north of the Jakobshavn glacier, operated by the University of Colorado. The unique data gathered by the close array have given us a better idea of what dynamic processes are involved in glacial quakes, as well as the realisation that it is still too early to know what it all means in terms of the evolution of the Jakobshavn glacier, or the icecap.

It is unfortunate that your article led with the falling-sky statement: "The Greenland icecap is melting so quickly that is triggering earthquakes as pieces of ice several cubic kilometres in size break off." Actually, just the opposite seems to happen. As ice melting increases, the number and size of glacial quakes eventually decreases, since there is more water around to lubricate ice motions (quakes occur if there is enough friction to temporarily keep ice from sliding smoothly).

We find that the area where glacial quakes are strongest and most frequent is along the margins of the ice stream that feeds the glacier, where ice rubs against the rock in the deep valley along which the ice stream moves; we find no evidence that the ice has been "fused to the rock for hundreds of years" and is just now breaking apart. Actually, it will take years of continued surveying to know whether anything here is "accelerating" towards catastrophe, as the article claims.

I believe that to battle global climate change effectively we need the strong support of a well-informed, actively engaged public. There is great urgency indeed in all these climate matters and I understand the threat of climate change to society; but the evidence needs to be there before we needlessly alarm the public who sustain our research.


Daily pill may save blood clot patients

A pill taken once a day could save the lives of thousands of the people who die in English hospitals every year from blood clots, according to a study published in The Lancet medical journal. Venous thrombo-embolism (VTE) - or blood clot - kills 25,000 people a year in English hospitals, more than the number of people who die from breast cancer, Aids or road traffic accidents.

The current treatment used in hospitals to prevent blood clots after hip replacement surgery is the injection Heparin. Yet a number of elderly patients, often discharged a few days after surgery, could find it difficult to inject themselves or to return to hospital for injections. Data has shown that the pill Dabigatran, taken once a day for an average of 33 days, is as effective as Heparin in preventing blood clots after hip replacement surgery. It will be available early next year and will be the first medicine available as a pill to prevent blood clots in hospital.

Patients undergoing surgery are particularly at risk of getting blood clots - a third of patients who are readmitted are done so because of deep vein thrombosis. Evidence shows that it takes an average of 21 days for a patient who has undergone a total hip replacement to develop a VTE, and that in three quarters of cases this was after they had been discharged from hospital. Guidelines from the Department of Health and the National Institute for Health and Clinical Excellence (Nice), which highlighted the problem, say that at-risk patients should receive treatment for a month following hip replacement surgery. A pill could therefore be more convenient.

Prof Simon Frostick, professor of orthopaedics at the University of Liverpool, who conducted the study, said: "Given the trend for shorter hospital stays following joint replacement surgery, it is becoming increasingly important to have anti-coagulant treatments available which are safe and easy to use. "Once-daily oral Dabigatran may be an attractive alternative to other regimens." This comes after Sir Liam Donaldson, the chief medical officer for England, said there was "room for improvement" in the treatment of patients at risk of blood clots. He said in a foreword to a Department of Health report in March: "The evidence suggested that in England around 25,000 people a year died from VTE in hospitals alone."


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