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On Saturday, NASA dropped a bombshell of a climate report. February 2016 has soared past all rivals as the warmest seasonally adjusted month in more than a century of global recordkeeping. NASA’s analysis showed that February ran 1.35°C (2.43°F) above the 1951-1980 global average for the month, as can be seen in the list of monthly anomalies going back to 1880.
The previous record was set just last month, as January 2016 came in 1.14°C above the 1951-1980 average for the month. In other words, February has dispensed with this one-month-old record by a full 0.21°C (0.38°F)—an extraordinary margin to beat a monthly world temperature record by. Perhaps even more remarkable is that February 2015 crushed the previous February record—set in 1998 during the peak atmospheric influence of the 1997-98 “super” El Niño that’s comparable in strength to the current one—by a massive 0.47°C (0.85°F).
An ominous milestone in our march toward an ever-warmer planet
Because there is so much land in the Northern Hemisphere, and since land temperatures rise and fall more sharply with the seasons than ocean temperatures, global readings tend to average about 4°C cooler in January and February than they do in July or August. Thus, February is not atop the pack in terms of absolute warmest global temperature: that record was set in July 2015.
The real significance of the February record is in its departure from the seasonal norms that people, plants, animals and the Earth system are accustomed to dealing with at a given time of year. Drawing from NASA’s graph of long-term temperature trends, if we add 0.2°C as a conservative estimate of the amount of human-produced warming that occurred between the late 1800s and 1951-1980, then the February result winds up at 1.55°C above average. If we use 0.4°C as a higher-end estimate, then February sits at 1.75°C above average.
Either way, this result is a true shocker, and yet another reminder of the incessant long-term rise in global temperature resulting from human-produced greenhouse gases. Averaged on a yearly basis, global temperatures are now around 1.0°C beyond where they stood in the late 19th century, when industrialization was ramping up.
Michael Mann (Pennsylvania State University) notes that the human-induced warming is even greater if you reach back to the very start of the Industrial Revolution. Making matters worse, even if we could somehow manage to slash emissions enough to stabilize concentrations of carbon dioxide at their current level, we are still committed to at least 0.5°C of additional atmospheric warming as heat stored in the ocean makes its way into the air, as recently emphasized by Jerry Meehl (National Center for Atmospheric Research). In short, we are now hurtling at a frightening pace toward the globally agreed maximum of 2.0°C warming over pre-industrial levels.
El Niño and La Niña are responsible for many of the one-year up-and-down spikes we see in global temperature. By spreading warm surface water across a large swath of the tropical Pacific, El Niño allows the global oceans to transfer heat more readily into the atmosphere. El Niño effects on global temperature typically peak several months after the highest temperatures occur in the Niño3.4 region of the eastern tropical Pacific. The weekly Niño3.4 anomalies peaked in mid-November 2015 at a record +3.1°C , so it’s possible that February 2016 will stand as the apex of the influence of the 2015-16 El Niño on global temperature, although the first half of March appears to be giving February a run for its money. We can expect the next several months to remain well above the long-term average, and it remains very possible (though not yet certain) that 2016 will top 2015 as the warmest year in global record-keeping.
Lower atmosphere also sets a record in February
Satellite-based estimates of temperature in the lowest few miles of the atmosphere also set an impressive global record in February. Calculations from the University of Alabama in Huntsville show that February’s reading in the lower atmosphere marked the largest monthly anomaly since the UAH dataset began in late 1978. UAH’s Dr. Roy Spencer, who considers himself a climate change skeptic, told Capital Weather Gang earlier this month, “There has been warming. The question is how much warming there’s been and how does that compare to what’s expected and what’s predicted.” The satellite readings apply to temperatures miles above Earth’s surface, rather than what is experienced at the ground, and a variety of adjustments and bias corrections in recent years (including an important one just this month) have brought satellite-based readings closer to the surface-observed trends.
Arctic leads the way
Figure 2 shows a big factor in the February result: a superheated Arctic. As shown by the darkest-red splotches in the figure, large parts of Alaska, Canada, eastern Europe, and Russia, as well as much of the Arctic Ocean, ran more than 4.0°C (7.2°F) above average for the month. This unusual warmth helped drive Arctic sea ice to its lowest February extent on record in February 2016. The tremendous Arctic warmth was probably related to interactions among warm air streaming into the Arctic, warm water extending poleward from the far northeast Atlantic, and the record-low extent of Arctic sea ice.
Ground Zero for this pattern was the Barents and Kara Seas, north of Scandinavia and western Russia, where sea ice extent was far below average in February. Typically, the Norwegian archipelago of Svalbard—which includes the northernmost civilian settlements on Earth—is largely surrounded by ice from early winter into spring. This winter, the edge of the persistent ice has stayed mostly to the north of Svalbard, which has helped an absurd level of mildness to persist over the islands for months.
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