Data for the global temperature of 2015 have been released by Nasa, Noaa and the UK Met Office. As anticipated 2015 is the warmest year on record and consistent with the El Nino boosting global temperatures, along with a contribution from the unprecedented warming caused by the so-called Pacific “blob.”
Noaa says 2015 was 0.16°C+/-0.09°C warmer than the previous record which was 2014. Nasa says that 2015 was 0.13°C+/-0.10°C above 2014. The UK Met Office said that 2015 was 0.18°C +/- 0.10°C above 2014.
Nasa made a key statement; “Only once before, in 1998, has the new record been much greater than the old record by that much.” This clearly because 2015 was like 1998 a strong El Nino year. Because of this it is unwise to use 2015 in any trend analysis. It is essential to view the 2015 along with subsequent years to catch the cooling La Nina effect. Only this way can the El Nino contribution be properly assessed. Using 2015 to increase the trend of recent years is unsafe. Remember when some analysts used 1998 as a start point for global temperature trend analysis they were rightly criticised for it. It now seems that some are using a strong El Nino year – 2015 – as the endpoint for their analysis!
Not showing such caution the director of Nasa Giss, Gavin Schmidt said, “Last year’s temperature had an assist from El Nino but it was the cumulative effect of the long term trend that has resulted in the record warming we are seeing.” This assertion is not supported by the Nasa Giss data. In 2015 no month between January – September set a record for that month.
All things considered it seems that some have forgotten the viewpoint expressed frequently when adjacent years changed little in global temperatures; one can read too much into a single year.
A fuller analysis will be published subsequently.