2015 nearly sure to be warmest year on record

‘We have the knowledge and the tools to act. We have a choice. Future generations will not’

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Global meltdown? @bberwyn photo.

Staff Report

A new report released just days before the start of the Paris climate talks makes it clear why there is so much interest in reaching an agreement to cap global warming. The World Meteorological Organization said it’s all but certain that 2015 will be the hottest year on record.

The global average temperature for the year will probably cross a symbolic threshold, reaching 1.0 degrees Celsius above the pre-industrial era, capping a five-year span that is also the warmest on record, the WMO said, blaming a strong El Niño and human-induced global warming. Read more of the WMO information here.

The state of the global climate in 2015 will make history as for a number of reasons,” said WMO Secretary-General Michel Jarraud. “Levels of greenhouse gases in the atmosphere reached new highs and in the Northern hemisphere spring 2015 the three-month global average concentration of CO2 crossed the 400 parts per million barrier for the first time. 2015 is likely to be the hottest year on record, with ocean surface temperatures at the highest level since measurements began,” Jarraud said.

“Greenhouse gas emissions, which are causing climate change, can be controlled. We have the knowledge and the tools to act. We have a choice. Future generations will not,” he added. “Added to that, we are witnessing a powerful El Niño event, which is still gaining in strength. This is influencing weather patterns in many parts of the world and fuelled an exceptionally warm October. The overall warming impact of this El Niño is expected to continue into 2016,” he said.

WMO issued its provisional statement on the status of the climate in 2015, and an additional five-year analysis for 2011-2015, to inform negotiations at the U.N. Climate Change Conference in Paris.

A preliminary estimate based on data from January to October shows that the global average surface temperature for 2015 so far was around 0.73 degrees Celsius above the 1961-1990 and about 1 degree Celsius above the pre-industrial 1880-1899 period.

The global average sea-surface temperature, which set a record last year, is likely to equal or surpass that record in 2015. The global average temperatures over land areas only from January to October suggest that 2015 is also set to be one of the warmest years on record over land.

South America is having its hottest year on record, as is Asia (similar to 2007), and Africa and Europe their second hottest.

The full effect of the strong 2015 El Niño on global temperature is likely to continue after El Niño peaks. However, other impacts are already being felt.  In early October, NOAA declared that record global ocean temperatures had led to a global coral bleaching event. This began in the North Pacific in the summer of 2014 and spread to the South Pacific and Indian Ocean in 2015.

Consistent with typical El Niño impacts, large areas of Central America and the Caribbean recorded below average rainfall. Brazil, which started the year in drought in southern and eastern areas, saw the focus of the drought shift north with scant rainfall during the dry season over the Amazon. India’s monsoon rainfall was 86 percent of normal. In Indonesia, the low rainfall has likely contributed to the increased incidence of wildfires. Peru was affected by heavy rain and flooding, as was Argentina.

The oceans have been absorbing more than 90 percent of the energy that has accumulated in the climate system from human emissions of greenhouse gases, resulting in higher temperatures and sea levels. In the first nine months of 2015, global ocean heat content through both the upper 700 meters and 2000 meters of the oceans reached record high levels. The latest estimates of global sea level indicate that the global average sea level in the first half of 2015 was the highest since satellite observations became available in 1993.

Significant warmth was recorded across large areas of the oceans. The Tropical Pacific was much warmer than average, exceeding 1 degree Celsius over much of the central and eastern equatorial Pacific, consistent with the signature of a strong El Niño. The northeast Pacific, much of the Indian Ocean and areas in the north and south Atlantic were significantly warmer than average.  Areas to the south of Greenland and in the far southwest Atlantic were significantly colder than average.

Significant warmer than average temperatures were recorded over the majority of observed land areas, especially western North America, large areas of South America, Africa and southern and eastern Eurasia. China had its warmest January-to-October period on record. For the continent of Africa, 2015 currently ranks as the second warmest year on record. Australia had its warmest October on record and a heatwave early in the month set new records for early season warmth.

Climate Change Attribution

Scientific assessments have found that many extreme events in the 2011-15 period, especially those relating to extreme high temperatures, have had their probabilities over a particular time period substantially increased as a result of human-induced climate change – by a factor of 10 or more in some cases.

Of 79 studies published by Bulletin of the American Meteorological Society between 2011 and 2014, more than half found that anthropogenic climate change contributed to extreme events. The most consistent influence has been on extreme heat, with some studies finding that the probability of the observed event has increased by 10 times or more.

Examples include the record high seasonal and annual temperatures in the United States in 2012 and in Australia in 2013, hot summers in eastern Asia and western Europe in 2013, heatwaves in spring and autumn 2014 in Australia, record annual warmth in Europe in 2014, and the Argentine heatwave of December 2013.

Some longer-term events, which have not yet been the subject of formal attribution studies, are consistent with projections of near- and long-term climate change. These include increased incidence of multi-year drought in the subtropics, as manifested in the 2011-15 period in the southern United States, parts of southern Australia and, towards the end of the period, southern Africa.

There have also been events, such as the unusually prolonged, intense and hot dry seasons in the Amazon basin of Brazil in both 2014 and 2015 which, while they cannot yet be stated with confidence to be part of a long-term trend, are of considerable concern in the context of potential “tipping points” in the climate system as identified by the Intergovernmental Panel on Climate Change.

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