Harvard Medical School, September 23, 2008 – You know the signs of a stroke. Or do you? You’d probably recognize the classic symptoms, such as sudden weakness on one side of the body or blurred vision, but often the signs are much less obvious. A crushing headache may come on without warning. Your face may feel numb. You may have inexplicable trouble speaking or following what people say.

How to tell when someone’s having a stroke

* Crooked smile. Have the person smile or show his or her teeth. If one side doesn’t move as well as the other or seems to droop, that could be sign of a stroke.
* Arm drift. Have the person close his or her eyes and hold his or her arms straight out in front for about 10 seconds. If one arm does not move, or one arm winds up drifting down more than the other, they may be having a stroke.
* Slurred speech. Have the person say, “You can’t teach an old dog new tricks,” or some other simple, familiar saying. If the person slurs the words, gets some words wrong, or is unable to speak, that could be sign of a stroke.

Knowing all the warning signs of a stroke may one day save your life and well-being. That’s because the faster you recognize the symptoms, the sooner you can get medical help. And prompt treatment is the key to shielding your brain from a stroke’s damage and sparing you serious disabilities such as paralysis, speech impairment, and dementia.

Every 45 seconds, someone in the United States has a stroke. Stroke is the third leading cause of death in the United States and other industrial countries, trailing only heart disease and cancer. In the United States, about 700,000 people have a stroke each year. If you have a stroke, the risk of dying from it increases with age: 88% of deaths from stroke are in people 65 and older. About two-thirds of people who have a stroke have some resulting disability and require rehabilitation.

The odds of having a stroke more than double for each decade after age 55. Two-thirds of strokes involve people over 65. Men and women are about equally likely to have a stroke, but women have a greater risk of dying from one. Race is another risk factor. African-Americans, for example, are almost twice as likely to suffer a stroke as are whites.

Although you can’t change your age or race, you can take steps to reduce other risk factors for stroke, especially ischemic stroke. The most common risk factors for both ischemic stroke and TIAs (transient ischemic attacks, or “mini strokes”) are high blood pressure (hypertension), diabetes, unhealthy cholesterol levels, and obesity. All of these factors affect the health of your blood vessels — increasing the risk not only of stroke, but also of heart disease. That’s why medications and other steps you take to reduce the risk of an ischemic stroke will also benefit your heart.

Some types of hemorrhagic strokes are more likely to occur in people with chronic high blood pressure. But other types of hemorrhagic strokes seemingly strike out of the blue. Although abnormal blood vessel conditions such as an aneurysm (a bubble in the blood vessel wall that could rupture) or an arteriovenous malformation (an abnormal tangle of blood vessels) increase the risk, these conditions may only be discovered inadvertently while you are undergoing testing for something else or may not be discovered until a stroke occurs.

Fortunately, medicine has made considerable strides in understanding how to treat and prevent strokes. Medical imaging devices now enable medical teams to begin to diagnose a stroke accurately within minutes. Large studies have clarified which medications and other treatments are best for which patients. For those who need rehabilitation, experimental techniques are showing promise in helping patients make better progress than was possible even just a few years ago.

Preliminary findings suggest that massive deposits of subsea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats

Arctic scientists discover new global warming threat as melting permafrost releases millions of tons of a gas 20 times more damaging than carbon dioxide

By Steve Connor, September 23, 2008, The Independent.co.uk – The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.

The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.

Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. Scientists aboard a research ship that has sailed the entire length of Russia’s northern coast have discovered intense concentrations of methane – sometimes at up to 100 times background levels – over several areas covering thousands of square miles of the Siberian continental shelf.

In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through “methane chimneys” rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a “lid” to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.

They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years.

Methane is about 20 times more powerful as a greenhouse gas than carbon dioxide and many scientists fear that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane.

The amount of methane stored beneath the Arctic is calculated to be greater than the total amount of carbon locked up in global coal reserves so there is intense interest in the stability of these deposits as the region warms at a faster rate than other places on earth.

Orjan Gustafsson of Stockholm University in Sweden, one of the leaders of the expedition, described the scale of the methane emissions in an email exchange sent from the Russian research ship Jacob Smirnitskyi.

“We had a hectic finishing of the sampling programme yesterday and this past night,” said Dr Gustafsson. “An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These ‘methane chimneys’ were documented on echo sounder and with seismic [instruments].”

At some locations, methane concentrations reached 100 times background levels. These anomalies have been seen in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres, amounting to millions of tons of methane, said Dr Gustafsson. “This may be of the same magnitude as presently estimated from the global ocean,” he said. “Nobody knows how many more such areas exist on the extensive East Siberian continental shelves.

“The conventional thought has been that the permafrost ‘lid’ on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane… The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed.”

The preliminary findings of the International Siberian Shelf Study 2008, being prepared for publication by the American Geophysical Union, are being overseen by Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences. Since 1994, he has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane “hotspots”, which have now been confirmed using more sensitive instruments on board the Jacob Smirnitskyi.

Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia’s rivers due to the melting of the permafrost on the land.

The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.

Independent.co.uk, September 23, 2008 – There are two significant facts about methane in terms of global warming. It is about 20 times more potent as a greenhouse gas than carbon dioxide, and there are massive stores of it locked away under the permafrost of the northern hemisphere.

Methane is produced naturally by the decay of water-logged vegetation. Over thousands of years it has accumulated under the ground at northern latitudes and has effectively been taken out of circulation by the permafrost acting as an impermeable lid.

What makes methane so potentially dangerous is that its release from under the now-leaking permafrost could accelerate global warming, which in turn would speed the melting of the permafrost and release even more methane. Scientists believe this has happened in the geological past with devastating consequences for the global climate and life.

Like carbon dioxide, average methane concentrations in the atmosphere have risen significantly since the Industrial Revolution, increasing from about 700 parts per billion (ppb) in 1800 to about 1,790ppb today. Much of this increase is down to human activities, notably oil and gas exploration, and agriculture.

For the past 10 years, average global methane concentrations have levelled out, probably because of improvements in Russian gas exploration. However, for the first time in more than a decade, scientists recorded an increase in global methane in 2007 and are set to measure a further increase this year.

Scientists at the US National Oceanic and Atmospheric Administration (NOAA) have identified the Arctic as a potentially important new source of methane as temperatures in the region increase; it is one of the most rapidly warming places on Earth. “We’re on the look-out for the first sign of a methane release from thawing Arctic permafrost. It’s too soon to tell whether last year’s spike in emissions includes the start of such a trend,” said NOAA’s methane expert Ed Dlugokencky last April.

The good news about methane is that it is quickly degraded in the environment, with an average lifetime of about 12 years, compared to the 100 years of carbon dioxide. The bad news is that we do not understand how the methane stores in the north will behave as the region experiences more extensive thaws. The fear is that the amounts released will make global warming far worse than expected.