While parts of Australia have been experiencing a warmer than average autumn, Europe and parts of North America have experienced extreme cold weather caused by a strong Arctic Oscillation, similar to the weather in 2010.
According to Peter Hannam in the Brisbane Times, the temperatures in Sydney has reached 20 degrees C for 26 consecutive days, a new record for this late in May in more than 150 years of record keeping. It is also likely to be one of the driest 30 days in autumn on record for Sydney. Offshore along most of the NSW coast, sea surface temperatures are between 1.5 and 3 degrees above normal.
Globally, March 2013 was tied with 2006 for 9th warmest March on record, since records started in 1880. The northern Hemisphere averaged 0.78 degrees C. above normal, placing it tied for 11th warmest on record. It was also the 10th warmest on record for the southern Hemisphere, averaging 0.52 degrees C. above the 1951-1980 average. The global temperature for March 2013 averaged 0.59 degrees C. above the 1951-1980 average.
In the article below republished from the Conversation under Creative Commons licence, Blair Trewin, Australian Bureau of Meteorology and Karl Braganza, Australian Bureau of Meteorology explain what is happening with cold extremes and why average temperatures over the hemisphere and the global average are still increasing.
An Australian scientist has warned against misinterpreting the cold spells in Europe and North America and the heavy rains and flooding in Australia as climate change not occurring. Barrie Hunt, an Honorary Research Fellow with the CSIRO Marine and Atmospheric Research, said that seasonal cold spells will still be expected under enhanced greenhouse conditions and that the long term trend is that the global climate is warming.
“Despite 2010 being a very warm year globally, the severity of the 2009-2010 northern winter and a wetter and cooler Australia in 2010 relative to the past few years have been misinterpreted by some to imply that climate change is not occurring,” said Mr Hunt.
“Recent wet conditions in eastern Australia mainly reflect short-term climate variability and weather events, not longer-term climate change trends. Conclusions that climate is not changing are based on a misunderstanding of the roles of climatic change caused by increasing greenhouse gases and climatic variability due to natural processes in the climatic system."
While Australia sizzles, much of Europe, North America, China and Asia has been subjected to snowstorms and freezing weather disrupting trade and transport with climate deniers chortling that global cooling is here. But further north - Eastern Siberia, Alaska, Northern Canada and Greenland, average winter temperatures are actually warmer - caused by the climate pattern known as the Arctic Oscillation.
The Arctic Oscilliation is a winter climate pattern in the Northern Hemisphere defined by difference in air pressure between mid latitude air pressure and the air pressure over the Arctic. When low pressure predominates in the Arctic, the winds confine the extremely cold air and the Arctic Oscillation is called positive. When the pressure system weakens, allowing the cold air to slide south and warmer air to gather in the Arctic, the Arctic Oscillation is said to be negative.
According to the National Snow and Ice Data Center "Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia."
Climate sceptic meteorologist Anthony Watts has written about Global cooling headed our way for the next 30 years? based upon the Daily Mail article - The mini ice age starts here - that put forward 'a global trend towards cooler weather that is likely to last for 20 or 30 years'. The article is based upon their mis-interpretation of the research of prominent IPCC researcher Professor Mojib Latif.
Latif's team published research in the Journal Nature in 2008 regarding natural fluctuations in ocean temperature that could have a bigger impact on global temperature than expected. That cooling in the oceans could on occasion offset global warming. The scientists stressed that the research did not challenge the predicted long-term warming trend.
However Mojib Latif, Professor for Climate Physics at the Leibniz Institute of Marine Sciences at Kiel University in Germany, told the Guardian newspaper - Leading climate scientist challenges Mail on Sunday's use of his research - that: "It comes as a surprise to me that people would try to use my statements to try to dispute the nature of global warming. I believe in manmade global warming. I have said that if my name was not Mojib Latif it would be global warming."
"The natural variation occurs side by side with the manmade warming. Sometimes it has a cooling effect and can offset this warming and other times it can accelerate it." Mojib Latif said.
Mojib Latif made a key presentation at the World Climate Conference 3, held in Geneva in September 2009 where he conjectured that it "may well happen that you enter a decade or maybe even two, when the temperature cools relative to the present level" but that "the jury is still out about the relative contribution of this internal variability". You can read Key excerpts from Mojib Latif's WCC presentation on Deep Climate. His remarks were reported and misrepresented by science journalists and particularly climate sceptics that we would actually see a decade or two of global cooling.
In an email published by Deep Climate Mojib Latif clarified "what I said is that the cooling in the Atlantic and Pacific may offsset global warming for a decade so that there may be not much of an additional warming. I showed a prediction that was published last year in the science magazine 'nature'."
"I also pointed out that the British group issued a competing forecast for the next decade. They predict that global warming will continue at the rate of the last decades. Thus, and I made this very clear, there is quite some uncertainty about the short-term evolution. Yet we all agree that in the long run, say by 2050 and thereafter, the earth will considerably warm, if we do not considerably reduce global greenhouse gas emissions."
Latif projects a likely average warming of 0.18C in the next decade, and 0.35C in the following decade as part of the overall warming trend - not a trend for cooling.
Meanwhile, we are likely to see further weather records broken in the deep freeze or the sizzling heat, part of weather variability, changing climate patterns and a long term global warming trend that scientists attribute to human caused CO2 emissions. Regions will continue to be affected to varying degrees by regional varying climate patterns like the Arctic Oscillation.
Takver is a citizen journalist from Melbourne who has been writing on Climate Change issues and protests including Rising Sea Level, Ocean acidification, Environmental and social Impacts since 2004.
