Earth had its warmest year on record in 2014, said NOAA and NASA at a joint press conference today. According to NOAA's National Climatic Data Center, global surface temperatures in 2014 were 1.24°F (0.69°C) above the 20th century average, highest among all years in the 1880-2014 record, easily breaking the previous records of 2005 and 2010 by 0.07°F (0.04°C).
New record set without an El Niño event
The new temperature record in 2014 was not a “cheap” record—it was set without an official El Niño event. The previous three hottest years on record—2010, 2005, and 1998—were all characterized by an El Niño event at the beginning of the year, according to NOAA’s Climate Prediction Center. During an El Niño event, warm water in the equatorial Pacific can warm the global surface temperature by 0.1°C or more, making global temperature records more likely. Admittedly, El Niño-like conditions began developing in June 2014, and the threshold for a weak El Niño event was reached in October and maintained through December. However, since there is lag of about 2 - 4 months between the emergence of El Nino conditions and the impact of this warm water on global surface temperatures (Foster and Rahmstorf, 2011), the emergence of El Niño-like conditions late in 2014 did not have a big impact on global surface temperatures. Moreover, January - March of 2014 featured weak La Niña-like conditions in the Eastern Pacific, with cooler-than-average ocean waters that helped depress global temperatures well into the summer.
Figure 3. The global departure of temperature from average from 1965 - 2014, binned by whether or not the year was classified as an El Niño, La Niña, or neutral. 2014 was by far the hottest "neutral" year on record, and the first year since 1990 to set a record without influence from El Niño. Image credit: skepticalscience.com.
UK Met Office forecasts another global temperature record in 2015
What about the new year? The UK Met Office predicts that 2015 is likely to top 2014. Assuming that the Met Office's final numbers for 2014 agree with NASA and NOAA on a global record, this forecast would make 2015 the second record-setting year in a row. The last time we saw consecutive global highs was in 1997 and 1998, when the strongest El Niño event on record gave a major boost to both years (see NOAA’s ENSO dataset). The previous pair of back-to-back record-setters was 1987 and 1988, again bolstered by El Niño conditions. A useful analog for our current situation may be 1980 and 1981. In those two years, new global highs were set without the benefit of any El Niño event. What’s more, the early 1980s marked the beginning of a dramatic rise in global atmospheric temperature that spanned nearly two decades. The rate of global warming since 2000 has been slower than in the 1980s and 1990s, but could back-to-back warmest years on record in 2014 and potentially in 2015 signal the end of this slow-down? Next week, Bob Henson will discuss new research presented at last week's American Meteorological Society meeting pertaining to this subject.
Jeff Masters and Bob Henson
wunderground.com |
