Cyclone Pam Is Just The BeginningPosted: March 14, 2015
Here is an extract from my forthcoming book Solving the Grim Equation, soon to be published by Cambria Books. A hotter world is also a violently stormy world. Every barrel of fossil oil which we extract, every ton of coal we mine and burn, make it less likely that Earth will be a habitable planet within a very few generations. Cyclone Pam has roared through Vanuatu in the Pacific, flattening people, buildings, vegetation. Do we care enough to start changing our lifestyles, immediately?
“Surface seawater at 27 degrees C (80 degrees F) puts enough heat energy in the atmosphere to trigger a hurricane.[i] The hotter the water is, the greater the potential energy. Hurricanes start in tropical latitudes, where the ocean water is warm. The top 300 metres of the world’s oceans warmed about 0.5 degree C between 1965 and 2005, during which time the destructive power of North Atlantic hurricanes doubled. The Mexican tourist resort of Cancún suffered from this power in 2005 when hurricane Wilma blew its beach – its main attraction for tourists – completely away. Wind and water both erode topsoil, which is being destroyed at least ten times faster than the natural replacement rate.[ii]
The top 300 metres of so of the oceans are only a small part of the story, though. Scientists have discovered that, since the millennium, deep ocean water is heating much faster than near the surface. That heat can escape only in a few instances where deep water mixes with surface water, and so everywhere else the heat builds up and up.
Methane leaking from melting permafrost is another powerful greenhouse gas, over a 20-year time span some 86 times more potent than carbon dioxide.[iii] Quite apart from the effects on global climates, methane is a light gas which can cause ships to sink and aircraft to crash. Ship disappearances in the ‘Bermuda Triangle’ have been blamed on the anti-buoyancy effect of methane.[iv]
“The dramatic loss of Arctic sea ice in recent years has created a fundamental new change in the atmospheric circulation in the Northern Hemisphere that has sped up sea ice loss and is affecting fall and winter weather across most of the Northern Hemisphere, according to several recent studies. Arctic sea ice loss peaks in September and October, exposing a large area of open water that heats the air above it. This extra heat has helped drive September-November air temperatures in the Arctic to 1 degree C or more above average over about half of the depth of the lower atmosphere. This deep layer of warm air has grown less dense and expanded, pushing the top of the troposphere (the lower atmosphere) higher. The result has been a decrease in the pressure gradient (the difference in pressure) between the North Pole and mid latitudes. With not as much difference in pressure to try and equalize, the jet stream has slowed down in the Arctic, creating a major change in the atmospheric circulation for the Northern Hemisphere.”
The previous atmospheric pattern, the North Atlantic Oscillation, was present at times but shared the Arctic region with a new pattern, the Arctic Dipole. The Dipole has high pressure over the North American Arctic and low pressure over the Eurasian Arctic, resulting in winds blowing from south to north, bringing more heat into the Arctic, a positive feedback further speeding the disappearance of ice.
The pallor of ice reflects solar radiation back out of the atmosphere, in so far as the rapidly thickening blanket of carbon dioxide and other greenhouse gases permits. Dark ocean, in contrast, absorbs radiation, thus quickening the warming process, and accelerating the rise in sea level. During the 20th century, sea levels rose between 4.4 and 8.8 inches,[vi] and the rise was concentrated in the latter years of the century. Paradoxically, warmer oceans might make the British Isles colder. The rush of cold fresh water from melting glaciers leads to changes in the pattern of ocean currents. In the North Atlantic, that means a dilution of the Gulf Stream that warms the UK and Ireland.
The strength of North Atlantic currents decreased by around 30% between 1992 and 2004, according to research published in the journal Nature[vii] in 2005. Measuring Atlantic water flows at 25 degrees North had been done for only 50 years, and so there was not a longer-term historical context in which to assess the findings, but they did appear to herald a certain chill. Perhaps the British climate would become more like that of Newfoundland and Labrador in Canada, at roughly the same latitudes, between 50 and 60 degrees North. January in Labrador has day temperatures around –10 to –15 degrees C (14 to 5 degrees F). The summer is short, and in July the temperature at the coast may reach 10 degrees C (50 degrees F), up to 15 degrees (59 degrees F) inland. Over most of Labrador, half of the 800 millimetres (31 to 32 inches) of precipitation falls as snow. The whole province of Newfoundland and Labrador covers 156,483 square miles but only 513,000 people live there, just nine per square mile. The harsh climate deters settlement.
Reporting in 2013, the Intergovernmental Panel on Climate Change indicated that the Atlantic Meridional Overturning Circulation, of which the Gulf Stream is part, is likely to weaken by 20% to 44% by 2100, disrupting the weather patterns we have come to accept as ‘normal’ and cooling British temperatures by about 1 degree C (1.8 degrees F).
We do not know the extent to which a cooling Gulf Stream would be offset by higher air temperatures resulting from greenhouse gases, or exactly how these changes would affect our environments and activities, but the prospects of sudden shifts mean that we must be prepared to make rapid and drastic adjustments in our economies and lifestyles.”
[i] A hurricane is called a typhoon in the western Pacific north of the equator and a cyclone in the Indian Ocean.
[ii] The USA National Academy of Sciences, in ‘The lowdown on topsoil: it’s disappearing’ by Tom Paulson, Seattle Post-Intelligencer, http://www.seattlepi.com/national/article/The-lowdown-on-topsoil-It-s-disappearing-1262214.php, January 21st 2008.
[iii] ‘The tipping point in action: twice as much methane released due to seabed permafrost melting’ by Christine Lepisto, November 26th 2013, http://www.treehugger.com/climate-change/tipping-point-action-twice-much-methane-released-due-seabed-permafrost-melting.html.
[vi] US Environmental Protection Agency, data updated August 19th2010.
[vii] ‘Slowing of the Atlantic Meridional Overturning Circulation at 25degN’ by H Bryden, H Longworth and S Cunningham, Nature 2005 Vol.438 pps.655-657.