With sustained winds of more than 310 km/h, or 195 mph, as it approached the Philippines, Super Typhoon Haiyan has hit land in the past few hours with terrifying force. This makes it the strongest tropical cyclone to make landfall in history.
Haiyan was earlier reported to be the most intense tropical storm in this area since Super Typhoon Tip (1979), and may even have exceeded the force of Tip. It had already been recognised to be one of the four most intense storms on modern record.
Preliminary satellite estimates of the central pressure at the eye of the storm have been reported at around 860 mbar, which if confirmed would make Haiyan the strongest storm ever recorded. Its intensity is recorded as Category 5 (maximum) on the scale for tropical storms and 8.0 (maximum) on the Dvorak scale of intensity.
The US National Oceanic and Atmospheric Administration reports:
The intensification of Super Typhoon Haiyan is being fuelled by “ideal” environmental conditions – namely low wind shear and warm ocean temperatures. Maximum sustained winds are currently at 195 mph, well above the Category 5 classification used for Atlantic and East Pacific hurricanes.
Tropical storms such as Haiyan are known as typhoons in the Pacific, but are the same as the storms labelled hurricanes or cyclones elsewhere. Haiyan is the strongest tropical storm since Hurricane Allen (1980) which hit the Caribbean. It appears to have surpassed Hurricane Camille (1969) in making landfall with wind speeds at Category 5 level.
Already, the reasons for such extreme weather are being scrutinised. The surface water, as well as deeper water, temperatures of the Western Pacific have provided huge amounts of energy for the storm to absorb, fuelling Haiyan’s intensification.
Along with devastating storms, the typhoon will bring a deluge of rain and storm surge, threatening coastal areas of the Philippines with flood and destruction. As the storm progresses across the islands it is expected to weaken and dissipate, tracking towards Vietnam.
The recent IPCC report on climate change highlighted the risks associated with changes in the patterns and frequency of extreme weather events. While individual storms such as Haiyan cannot be directly attributed to such changes, the statistics of such storms will help build a picture of how climate change is affecting the planet. Climatologists are keen to develop models that provide accurate risk factors for tropical cyclones.
As the planet and particularly the oceans heat, simple physics indicates that the energy stored is likely to increase the intensity and frequency of devastating storms like Haiyan, at great cost to coastal communities.