Global warming may bring tsunami and quakes-scientists

fonte:reuters
By Richard Meares

LONDON, Sept 16 (Reuters) - Quakes, volcanic eruptions, giant landslides and tsunamis may become more frequent as global warming changes the earth's crust, scientists said on Wednesday.

Climate-linked geological changes may also trigger "methane burps", the release of a potent greenhouse gas, currently stored in solid form under melting permafrost and the seabed, in quantities greater than all the carbon dioxide (CO2) in our air today.

"Climate change doesn't just affect the atmosphere and the oceans but the earth's crust as well. The whole earth is an interactive system," Professor Bill McGuire of University College London told Reuters, at the first major conference of scientists researching the changing climate's effects on geological hazards.

"In the political community people are almost completely unaware of any geological aspects to climate change."

The vulcanologists, seismologists, glaciologists, climatologists and landslide experts at the meeting have looked to the past to try to predict future changes, particularly to climate upheaval at the end of the last ice age, some 12,000 years ago.

"When the ice is lost, the earth's crust bounces back up again and that triggers earthquakes, which trigger submarine landslides, which cause tsunamis," said McGuire, who organized the three-day conference.

David Pyle of Oxford University said small changes in the mass of the earth's surface seems to affect volcanic activity in general, not just in places where ice receded after a cold spell. Weather patterns also seem to affect volcanic activity - not just the other way round, he told the conference.

LONDON'S ASIAN SUNSET

Behind him was a slide of a dazzlingly bright orange painting, "London sunset after Krakatau, 1883" - referring to a huge Asian volcanic eruption whose effects were seen and felt around the world.

Volcanoes can spew vast amounts of ash, sulphur, carbon dioxide and water into the upper atmosphere, reflecting sunlight and sometimes cooling the earth for a couple of years. But too many eruptions, too close together, may have the opposite effect and quicken global warming, said U.S. vulcanologist Peter Ward.

"Prior to man, the most abrupt climate change was initiated by volcanoes, but now man has taken over. Understanding why and how volcanoes did it will help man figure out what to do," he said.

Speakers were careful to point out that many findings still amounted only to hypotheses, but said evidence appeared to be mounting that the world could be in for shocks on a vast scale.

Tony Song of NASA's Jet Propulsion Laboratory in California warned of the vast power of recently discovered "glacial earthquakes" -- in which glacial ice mass crashes downwards like an enormous landslide.

In the West Antarctic, ice piled more than one mile (1.5 km) above sea level is being undermined in places by water seeping in underneath.

"Our experiments show that glacial earthquakes can generate far more powerful tsunamis than undersea earthquakes with similar magnitude," said Song.

"Several high-latitude regions, such as Chile, New Zealand and Canadian Newfoundland are particularly at risk."

He said ice sheets appeared to be disintegrating much more rapidly than thought and said glacial earthquake tsunamis were "low-probability but high-risk".

McGuire said the possible geological hazards were alarming enough, but just one small part of a scary picture if man-made CO2 emissions were not stabilized within around the next five years.

"Added to all the rest of the mayhem and chaos, these things would just be the icing on the cake," he said. "Things would be so bad that the odd tsunami or eruption won't make much difference."

(Editing by Robin Pomeroy)