heatwave

Angry Summer - 123 records broken: Image by Australian Climate Commission, 1 March 2013Melbourne is setting another temperature record: the longest number of days of any month where the maximum temperature exceeds 30 degrees Celsius.

Labour capacity reduced due to heat stress as temperature and humidity rises with Climate ChangeClimate change will result in hotter and more humid environment for the tropics and mid latitudes resulting in increasing economic costs of reduced work capacity due to heat stress. The study by NOAA scientists said work capacity has already reduced by 10 percent due to extreme heat in summer months. This is likely to double to 20 per cent by 2050.

One of the physical properties of warmer air is that it can hold more moisture. So in hot weather atmospheric humdity can be more extreme. But there are physiological limits of human health in coping with temperature extremes. In 2010 Scientists outlined health limits of heat stress with Climate Change. The scientific paper by Steven Sherwood from the University of NSW and Professor Matthew Huber from Purdue University - 'An Adaptability Limit to Climate Change Due to Heat Stress' outlined the health adaptation limits of the human body.

Image courtesy Australian Bureau of MeteorologyA heatwave covering 70 per cent of Australia that started on January 3 has sparked catastrophic bushfires. Tasmania has so far been the most devastated by fire with more than 100 houses and businesses razed, the Tasman peninsula cutoff, without power, and thousands evacuated by boat to Hobart. The Temperature soared in Hobart setting new records for highest daily minimum overnight temperature of 23.4C and a new maximum temperature of 41.3C.

Update Jan 8: Climate Change: Records tumble in extreme heatwave as temperature scale adjusted upwards while Prime Minister Julia Gillard links intensity of bushfires with climate change as NSW survives catastrophic fire conditions. Other states are also experiencing bushfires, but have so far brought the fires mostly under control. The heatwave is expected to last over a week with elevated temperatures particularly in inland areas. It is very unusual that a heat wave covers such a large area of the continent at one time, according to Karl Braganza, manager of climate monitoring at the Australian Bureau of Meteorology.

Australia's weather has switched to hot and dry after one of the wettest two year periods in Australia's history influenced by an extremely strong La Nina event.

Related: Youtube animation of forecast heatwave temperatures | Scientists outline human health limits of heat stress with Climate Change (May 2010) | Flooding rains now burning plains - Bushfire risk and climate change (Oct 2011) | Logging of Victorian mountain ash forests increases bushfire risk (Oct 2011) | Intact native Forests mitigate bushfire in a warming climate (Nov 2011) | CSIRO - Climate change impacts on fire weather

Sea Surface Temperature Anomaly for Australia 28 December 2012High sea surface temperatures (SST) of up to five degrees above normal are currently being experienced off the north-western Australian coast in a marine heatwave event. Like the extreme marine heatwave event in 2011 this will change marine ecosystems causing coral bleaching and fish mortality and impact on fisheries management and biodiversity.

A similar event occurred over several weeks during the 2010/2011 summer which impacted seafood stocks and marine ecosystems and was associated with an extremely strong La Niña event and a record strength Leeuwin Current down the Western Australian coast.

Climate scientists using statistical modeling have estimated an 80 percent chance that climate change was responsible for the July 2010 Russian heatwave.

The paper by Stefan Rahmstorf and Dim Coumou from Germany’s Potsdam Institute for Climate Impact Research - Increase of extreme events in a warming world - was published in Proceedings of the National Academy of Sciences on October 25, 2011 notes:

"For July temperature in Moscow, we estimate that the local warming trend has increased the number of records expected in the past decade fivefold, which implies an approximate 80% probability that the 2010 July heat record would not have occurred without climate warming."

Over fourteen hundred maximum temperature records have been broken or tied across the United States so far this July as a heatwave lingers from the mid-western and southern states and expands to encompass the eastern states. High humidity accompanies the high temperatures making the heat further unbearable. Little relief is being found overnight with highest minimum temperatures recorded also breaking new records: with 1,951 new records and 1,421 tied records to 21st July.

Related: Human health limits of heat stress with climate change | The US 'normal climate' just got hotter | Higher Temperatures and Crop yields in the US