Typhoon Haiyan Influenced byClimate Change, Scientists Say
Extreme storm events such as super typhoon Haiyan, which wreaked havoc in the Philippines on Friday, are more likely in the future as the build-up of greenhouse gases warms the planet, scientists say.
Winds from typhoon Haiyan were estimated to have been 314km/h or higher when the monster storm made landfall on the Philippine island of Samar. That speed, if confirmed, would make it the strongest storm on record, exceeding hurricane Camille, which hit Mississippi in the US in 1969, according to US meteorologist Jeff Masters' WunderBlog.
Australian scientists say gauging the intensity of the storm – which included a tsunami-like storm surge and heavy rainfall – would be difficult because of limited information emanating from the storm-battered region. The death toll from the city of Tacloban alone may exceed 10,000 people, local authorities say.
Professor Will Steffen, a researcher at the ANU and member of the Climate Council, said scientists understand how a hotter, moister climate is already affecting storms such as Haiyan.
“Once [cyclones] do form, they get most of their energy from the surface waters of the ocean,” Professor Steffen said. “We know sea-surface temperatures are warming pretty much around the planet, so that's a pretty direct influence of climate change on the nature of the storm.”
Data compiled from the US National Oceanic and Atmospheric Administration shows sea temperatures were about 0.5 to 1 degree above normal in the waters to the east of the Philippines as Haiyan began forming. The waters cooled in the storm's wake, an indication of how the storm sucked up energy.
Typhoons – or tropical cyclones as they are known in Australia, and hurricanes in the US – require sea-surface temperatures of at least 26.5 degrees to form, according to the Bureau of Meteorology. The low-pressure systems can persist over lower sea-surface temperatures once they get going.
Kevin Walsh, an associate professor at the University of Melbourne and an expert in tropical meteorology, said warmer sea-surface temperatures are only one factor in determining the ferocity of a cyclonic event. The key is the temperature difference between those seas and the tops of the storms, high in the troposphere.
While data on temperatures at sea levels well known, gathering the information at levels up to about 20 kilometres above the surface has been more difficult until recent times, with weather balloons and other devices now more common.
That temperature differential in cyclones, though, is expected to widen as storm heights push higher in the atmosphere, Dr Walsh said.
“In the future, you’re talking about the difference of the sea-surface temperature and the temperature of the troposphere height – that increases even though the upper troposphere warms in a warming world.” - See more at: http://renewablenow.biz/renewable-science.html#sthash.MTqM27ld.dpuf