GLOBAL temperature records continued to tumble in June, as the strengthening El Nino in the Pacific combined with background warming from climate change.
Land and sea-surface temperatures last month and for the first half of 2015 were the warmest in 136 years of records, the US National Oceanic and Atmospheric Administration (NOAA) said on Monday.
For the first half of 2015 alone, those surface temperatures were 0.85 degrees Celsius above the 20th century average, beating the previous record set in 2010 by 0.09 of a degree.
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The record temperatures come as nations prepare for a global climate summit in Paris in late 2015. Australia is one of the few developed countries to have declared its post-2020 targets to cut greenhouse gas emissions that scientists say is contributing to the record planetary warmth.
As NOAA noted, the previous record came at a point when the El Nino had finished in 2010. This year, however, the El Nino has barely begun and there is an 80 per cent chance that the event will last beyond March 2016, or the start of the northern spring, the agency said.
Last year was the hottest on record and 2015 is well on course to be warmer still. Since the impact of El Ninos on surface temperatures - typically giving them a 0.1-0.2 kick higher - is more pronounced at the end of the event, 2016 is also a fair chance to set the bar higher again.
El Ninos involve large areas of the central and eastern Pacific warming relative to western regions as trade winds stall or reverse. One result is that the world's biggest ocean becomes less of a heat sink than in a neutral year and can even give back warmth.
As the following NOAA chart shows, however, the El Nino boost to temperatures is coming against a warming trend as rising greenhouse gases capture more of the sun's radiation.
For last month alone, combined average temperatures over the world's land and ocean surfaces were the highest for June on record at 0.88 degrees above the 20th century average of 15.5 degrees, surpassing the previous record set just a year ago by 0.12 degrees.
As NOAA highlighted, four of the first six months have set new warmth records, and last month was also the fourth-biggest departure from a monthly average for any month on record. The two highest monthly departures from average occurred earlier this year in February and March, the agency said.
February, March, May and now June are all records for the month, while four of the previous half year were also records for that month. With so many record months, the rolling 12-month period has been the hottest for the past 10 months, NOAA said.
While the warmth in June was widespread over the planet, it was also Australia's fifth-warmest on record by mean temperatures.
For the year to date, the average global sea surface temperature anomaly of 0.65 degrees was the highest for January–June in the 136-year period of records, surpassing the previous record of 2010 by 0.04 degrees.
The average land surface temperature anomaly of 1.4 degrees surpassed the previous record of 2007 by 0.13 degrees, while sea-surface temperatures were 0.65 degrees above average for the first-half of 2015, edging ahead of the previous record of 2010 by 0.04 degrees.
Most of the world's land areas were much warmer than average, including nearly all of Eurasia, South America, Africa, and western North America, NOAA said.
All of Australia was warmer than average, the agency said.