March was the warmest such month on record for the globe as a whole, according to the Japan Meteorological Agency (JMA), which is one of the centers that keeps tabs on global climate data. The JMA found that global average surface temperatures were 0.56 degrees Fahrenheit (0.31 degrees Celsius) above the 1981 to 2010 average during the month, which beat 2010 to take the top spot.
Sea surface temperature anomalies (degrees C) on April 15, 2015.
But NASA, which is another climate-tracking institution, ranks March a bit lower in its dataset, though the differences in actual numbers are minor. The space agency, for example, found that March was the third-warmest such month on record since 1880, coming in just behind 2002 and 2010.
However, NASA also found that the year-to-date is the warmest January through March period in its record, edging out 2002 and 2010.
The National Oceanic and Atmospheric Administration (NOAA) is expected to release its global temperature data in the next few days. Regardless of whether March ranks as the warmest month or not, it’s almost guaranteed to be in the top-five list, with the year-to-date also running in the top-five warmest such periods on record.
Multiple studies have come out recently showing that a temporary slowdown in the rate of global warming, which lasted nearly two decades and fueled arguments for global warming contrarians, was likely related in large part to a natural cycle of climate variability in the Pacific Ocean.
That cycle, known as the Pacific Decadal Oscillation (PDO), directed excess heat into the depths of the sea, but tempered the increase in global air temperatures somewhat.
The PDO appears to have kicked into a different phase now, one that favors the rapid release of that stored heat, much like a person going to an ATM to take out a large amount cash from a savings account.
The latest study, published this week in Nature Climate Change, found that a larger cycle related to the PDO could “lead to accelerated global warming in the coming decades.”
Pacific Ocean temperatures now bear the hallmarks of a positive phase of the PDO, including milder-than-average water temperatures along the West Coast of North America and parts of the South Pacific, as well as cooler ocean conditions in the central North Pacific. In addition, an El Niño event in the tropical Pacific also favors enhanced global warming for at least the next one to two years.
These natural cycles act to modulate the rate of global warming, turning the warming dial up or down temporarily, but they do not do much to stop the longterm global warming trend when viewed over many decades.
With a positive PDO and an El Niño event, it’s a safe bet that 2015 could very well beat 2014 for the title of warmest year on record. In other words, expect more record warm months to come.