Royal Society Links Climate Changes to Geological Shocks
'Tiny' climate changes may trigger
quakes
The Independent (U.K.), April 19,
2010
Climate change could spark more "hazardous"
geological events such as volcanoes, earthquakes and landslides,
scientists warned today.
In papers published by the Royal Society,
researchers warned that melting ice, sea level rises and even
increasingly heavy storms and rainfall - predicted consequences of
rising temperatures - could affect the Earth's crust.
Even small changes in the environment could
trigger activity such as earthquakes and tsunamis.
And some evidence suggests the consequences
of climate change were already having an impact on geological activity
in places such as Alaska, researchers writing in the journal the
Philosophical Transactions of the Royal Society A said.
Bill McGuire, of the Aon Benfield UCL Hazard
Research Centre at University College London, and the author of a
review in the journal of research in the area, said warming temperatures
melted ice from ice sheets and glaciers and increased the amount of
water in the oceans.
As the land "rebounds" back up once the
weight of the ice has been removed - which could be by as much as a
kilometre in places such as Greenland and Antarctica - then if, in the
worst case scenario, all the ice were to melt - it could trigger
earthquakes.
The increase in seismic activity could, in
turn, cause underwater landslides that spark tsunamis.
A potential additional risk is from
"ice-quakes" generated when the ice sheets break up, causing tsunamis
which could threaten places such as New Zealand, Newfoundland in Canada
and Chile.
The reduction in the ice could also
stimulate volcanic eruptions, according to the research.
And the greater weight of the water in the
oceans where sea level has risen as ice melts can "bend" the Earth's
crust. This produces magma and causes volcanic and seismic activity in
coastal or island areas - where the majority of 550 volcanoes whose
eruptions have been historically documented are found.
Increased volcanic activity could cause more
landslides, and have impacts well beyond the area where the volcano is
situated - for example by releasing sulphur clouds into the atmosphere
or by affecting air travel.
Prof McGuire said the changes could occur in
the coming decades or over centuries, rather than thousands of years,
depending on factors such as how quickly sea levels rose.
And he warned: "The rise you may need may be
much smaller than we expect. Looking ahead at climate change, we may
not need massive changes.
"One of the worries is that tiny
environmental changes could have these effects."
His review said there was "mounting
evidence" of seismic, volcanic and landslide activity being triggered or
affected by small changes in the environment - even specific weather
events such as typhoons or torrential rain.
Prof McGuire said that in Taiwan the lower
air pressure generated by typhoons was enough to "unload" the crust by a
small amount and trigger earthquakes.
Other impacts of rising temperatures include
glacial lakes bursting out through rock dams and causing flash flooding
in mountain regions such as the Himalayas, as well as rock, ice and
landslides as permafrost melts.
And he said there may be "tipping points" in
the geological systems, where the crust reaches a threshold that causes
a step-change in the frequency of such events - but it was not clear
where those thresholds might lie.
At times in the past climate change has been
seen to have links with enhanced levels of potentially hazardous
geological activity - for example after the end of the last ice age.
But they have not been fully considered as
potential impacts of the rapid changes in the climate expected in the
future and there was a great deal of uncertainty about what might happen
in coming years.
Prof McGuire called for a programme of
research focusing on the potential geological hazards that global
warming could bring, with the leading body on global warming, the
Intergovernmental Panel on Climate Change (IPCC), addressing the issue
directly in its future assessments.
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