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Science Alert: Experts Respond

Climate change ‘taking place before our eyes’ – WMO report

Posted in Science Alert: Experts Respond on November 29th, 2012.

An international report from the United Nation’s World Meterological Organization (WMO) has highlighted growing evidence of a warming climate that shows little sign of stopping.

WMO’s provisional annual statement on the state of the global climate documents the unprecedented melt of the Arctic sea ice and multiple weather and climate extremes which affected many parts of the world. It was released today to inform negotiators at the United Nations Climate Change Conference in Doha, Qatar.

Video of the WMO’s press briefing at the Doha Conference can be viewed here.

The last eleven years (2001-2011) were among the top warmest years on record, and the first ten months of 2012 indicate that this year will continue this trend.

The report also noted that the Arctic reached its lowest annual sea ice extent since the start of satellite records on 16 September at 3.41 million square kilometres.

“Climate change is taking place before our eyes and will continue to do so as a result of the concentrations of greenhouse gases in the atmosphere, which have risen constantly and again reached new records,” said WMO Secretary-General Michel Jarraud.

The Science Media Centre contacted climate experts for comment on the report.

Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476; smc@sciencemediacentre.co.nz).

Prof James Renwick, Associate Professor of Physical Geography, Victoria University of Wellington comments:

“2012 will be remembered as the year that Arctic sea ice extent set an amazing new record low at the end of the northern summer, falling to less than half of the ‘normal’ amount for the time of year. This resulted in a very warm autumn in many parts of the Arctic, with Alaska running several degrees warmer than normal for months at a time.  At the same time, Antarctic sea ice extent rose to a high of about 5% above normal at the end of the southern winter.

“In terms of global mean surface temperature, 2012 is expected to come in somewhere between 6th and 10th warmest on record, slightly warmer than 2011 but not as warm as 2010. Such a result is a reflection of on-going warming from human emissions of  greenhouse gases, plus natural variations such as the El Niño – La Niña cycle.

“North America experienced several record extremes in 2012: a very  widespread and intense summer heat-wave, combined with drought conditions that decimated corn and other crops across the Midwest and caused a spike in global corn prices.  The drought is the most severe for decades, affecting 80% of all agricultural land in the US, and is on track to be the costliest natural disaster in US history. Then, Hurricane Sandy the week before the Presidential election caused mayhem and widespread loss of life and had a discernable effect on the political conversation in Washington. The unusual track of Sandy is partly related to the loss of Arctic sea ice, which warms the Arctic and allows the northern jet streams to meander much more than normal.  Sandy was snagged by just such a meander, invigorated by an influx of polar air and steered westwards across New York and the northeast US.

“The year started in La Niña conditions, but much of the year has seen neutral (normal) conditions in the tropical Pacific. The ozone ‘hole’ is showing signs of recovering, with the 2012 hole being the smallest for a decade and the breakdown and filling-in of the ozone hole coming  about a month earlier than average, in the first week of November.”

Our colleagues at the UK SMC gathered the following expert commentary:

Prof Sir Brian Hoskins, Director of the Grantham Institute for Climate Change at Imperial College London, said:

“There are always weather records somewhere in the world, but this summary reminds us what a dramatic year it has been globally as well as in the UK. For me the drop in Arctic sea ice area and the persistent drought in the US stand out, the former because it gives a striking picture of global warming in action, and the latter because of its impact on world food supply.”

Dr Dave Reay, Senior Lecturer in Carbon Management, University of Edinburgh, said:

“The stand-out indicator of the ‘State of the Climate’ in 2012 has to be the astonishing drop in sea ice cover in the Arctic. Reaching a minimum extent far below that predicted by most models, this global parasol atop our world was left tattered by increased warming – a warming trend that will be accelerated still further as these vast expanses of reflective ice are replaced by tanker-filled open water.”

Dr Ed Hawkins, National Centre for Atmospheric Science based at the University of Reading, said:

“There’s still two months to go, but it looks like 2012 will be among the warmest years on record, in common with other years over the last decade. The January to October period of 2012 was the 9th warmest since records began in 1850. So, temperatures across the world in 2012 continue the trend of a world that is warming in response to increasing greenhouse gases.

“Notable extremes during 2012 include very warm spring and summer conditions over the US and Canada, accompanied in the US by severe drought conditions. Europe also saw record breaking temperatures during a warm and dry spell in March, which followed exceptionally cold temperatures over much of Europe during February.

“For the UK, while it might not seem like it, the year to date has been slightly warmer than the 1961-90 normal, but it was a year of two halves!  The UK saw a warm and dry start, especially in March, but since April, temperatures have been close to or below normal. Rainfall over the UK has generally been above average since June, in fact June to August 2012 was the second wettest on record (behind 1912). This meant the UK had relatively dry conditions when we might have expected rain and wet conditions during the summer when we might have expected some sunshine.  I’ve calculated that rainfall conditions during 2012 were the second “weirdest” on record in this regard. Research at the University of Reading suggests this behaviour, with a dry spring and wet summer, could be linked to a major warming of the North Atlantic Ocean that occurred back in the 1990s. A transition back to a cooler North Atlantic, favouring drier summers in the UK and northern Europe, is likely and could occur rapidly. Exactly when this will happen is difficult to predict.”

Earlier commentary from the AusSMC:

Dr Blair Trewin, Senior Climatologist at the Bureau of Meteorology

“The World Meteorological Organization (WMO)’s preliminary Statement on the Status of the Global Climate is expected to be released on Wednesday 28 November at approximately 1130 GMT (2230 AEDT). WMO assesses global temperatures using a combination of three data sets, maintained respectively by the U.S. National Climatic Data Center (NCDC), NASA, and the UK Meteorological Office Hadley Centre.

“Based on January-October data already released by NCDC, it is expected that the WMO Statement will report that global temperatures for January-October 2012 will be between 0.40 and 0.45°C above the 1961-1990 average, which is warmer than 2011 but cooler than 2010 –  the world’s equal warmest year on record. It is expected that 2012 global temperatures will rank between the 6th and 10th warmest year on record.

“The WMO Statement will also report on notable events in various parts of the world during 2012, and is expected to include:

  • Severe drought and persistent above-normal temperatures in the United States, which is virtually certain to have its warmest year on record.
  • The lowest Arctic sea ice extent since satellite records began.
  • Well above normal rainfall, with associated major flooding, in large parts of west and central Africa.
  • Near-normal global tropical cyclone activity, but a very active tropical cyclone season in the North Atlantic, including Hurricane Sandy, the most damaging landfall in the United States since 2005.
  • The most significant cold spell since the mid-1980s in large parts of Europe during the first half of February.

“Australian temperatures and rainfall for 2012 to date have both been very close to normal, with generally warm and dry conditions in the later part of the year offsetting a wet and cool January-March quarter. In general northern and eastern Australia have had above-normal rainfall and below-normal temperatures in 2012, whilst the west and much of the south have been warmer and drier than normal. The southwest of Western Australia has been particularly dry, although 2010 was even drier in that region.”

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