State of the climate: 2017 shaping up to be warmest ‘non-El Niño’ year
Much of the year, though the summer Arctic minimum was only the eighth lowest on record.
2017 is also almost certain to be the warmest year without an El Niño event. When the effects of El Niño and La Niña are removed from the temperature record, the first nine months of 2017 are likely the warmest ever recorded.
Near-record warm temperatures
Ten months in, 2017 is very likely going to be either the second warmest or third warmest year on record, depending on the temperature series used. While there was some speculation earlier in the year that it could challenge 2016 for first place, colder temperatures in the period from June through September have largely eliminated any chance of a new record.
Carbon Brief has examined global temperature data from eight different climate centres around the world, both for the Earth’s surface and the lower troposphere (TLT). Temperatures for the full year of 2017 were estimated using the data available to-date for each dataset, along with projection of the El Niño Index for the remainder of 2017 (see methods at the end of the article for technical details).
The results are shown in the figure below. Annual temperatures from 1979 through 2016 are shown in black for each record, while the likely (95% confidence interval) range of the 2017 annual temperature is shown by the red bar.
The last two records shown, RSS and UAH, come from satellite data and are measuring the atmosphere on average around 5 km up from the surface. While these have similarities to surface temperatures, they are not expected to always respond in the same way to El Niño or other factors.
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