The graphic that shows why 2015 global temperatures are off the charts

If there is one chart that might finally put to rest debate of a pause or “hiatus” in global warming, this chart, from the US National Oceanic and Atmospheric Administration, is it.

The chart shows the “year-to-date average global temperature” for each month, for 2015 and the six warmest years on record.

The December end of year point gives the “annual global average temperature”, and these December points show that the hottest year so far was 2014, followed by 2010 and 2013, 2005, 2009 and 1998 in that order.

So far we only have the first 9 months of 2015, but so far 2015 has been far and away the hottest year on record.  The other hot years cluster together with crossovers, but 2015 is clearly above the rest, consistently by about a tenth of a degree.

The current intensifying El Nino has helped drive global temperatures to yet another record monthly high. September 2015 was not only the seventh month so far this year to set a new record for heat, it was also the most anomalously hot month in 135 years of data, the highest departure from average for any month among all 1629 months in the record that began in January 1880.

For years, climate change sceptics relied on a spike in global temperatures that occurred during the monster 1997-98 El Nino to say the world had stopped warming because later years, even though they were hotter, were not clearly hotter, even as greenhouse gas emissions continued to rise.

Never mind that US government scientists found the hiatus was an illusion because the oceans had absorbed most of the extra heat that satellites could tell the Earth was trapping.  Nor that 2005, 2010 and 2014 all set subsequent records for annual heat. Those record years were too incrementally warmer compared with the 1997 mark to satisfy those who wanted to believe climate change was a hoax.

But it is 2015, with an El Nino that is on track to match the record 1997-98, that looks set to blow away previous years of abnormal warmth.  Australia’s Bureau of Meteorology said this month that the El Nino was now on course to challenge the 1997-98 event as the strongest on record, and was not expected to peak until late this year.  This would suggest that, short of a major disruptive event such as a huge volcanic eruption, 2015 will easily eclipse heat records in previous years.

Climate change sceptics will probably not concede in their battle to avoid action to curb emissions.  They’ll probably say that satellite or meteorological data must have been manipulated or … Still, they now have one more inconvenient chart they have to find a reason to ignore.

Sydney Morning Herald: Peter Hannam: 22 Oct 2015

The US National Oceanic and Atmospheric Administration,
Global Analysis: September 2015

Key Words: Climate Change, denial
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