2014 one of Earth's warmest years, if not the warmest

The hot streak continues: Earth just had its warmest October on record

Mashable,

15 November, 2014

Fueled by record warm ocean temperatures, October was Earth's warmest such month on record, according to new data from three independent sources.
Coming after the warmest September on record and the warmest June through August period, the year is virtually certain to set a milestone for the warmest year.

SEE ALSO: World's Oceans Set All-Time Heat Record for Third Time This Year

This could mark an end in a temporary slowdown in the rate of warming, which scientists think has been caused by a mix of manmade and natural factors, which has lasted for about the past 15 years. One of those factors was cooling ocean waters in parts of the Pacific, which appears to be reversing in a big way.

Global temperature anomalies for the month of October 2014, relative to the average from 1951-1980.

IMAGE: NASA-GISS

Based on preliminary NASA data, the planet's average temperature tied with 2005 for the warmest October since records began in 1880. Surface data from
Japan's Meteorological Agency shows it was the warmest October, hands down, while the University of Alabama at Huntsville's satellite dataset pegged the monthly average temperature as the warmest in its records, which date back to 1979, in a tie with October 2012.

The satellite data offers somewhat of an independent check on the surface information, since satellites measure the global average temperature differently than surface weather stations.

The actual rankings from the different centers, especially for an individual month, are not as important as the longterm trend in global average temperatures, which also shows a warming planet, due largely to the buildup in manmade greenhouse gases.

October temperature departures from average from the Japan Meteorological Agency.

IMAGE: JM

Much of the record warmth this year has been driven by unusually mild ocean temperatures, with a massive pool of warm water in the northern Pacific Ocean. This has been influencing weather patterns for much of the past year, reinforcing a ridge of high pressure across the West, which has played a key role in perpetuating the California drought and heat. This ridge has been nicknamed the "ridiculously resilient ridge" by many meteorologists.

September had the highest global average ocean temperatures on record, for any month, since 1880, according to the National Oceanic and Atmospheric Administration (NOAA), with a global average temperature of 61.1 degrees Fahrenheit. This was warm enough to set another milestone that had already been set two previous times this year; 


The average global sea surface temperature was so warm in September that it broke the all-time record

the average global sea surface temperature was so warm in September that it broke the all-time record for the highest departure from average for any month since 1880, at 1.19 degrees Fahrenheit above average.


This broke the previous record of 1.17 degrees Fahrenheit warmer than average set just one month before that, in August, and the previous record before that: 1.15 degrees Fahrenheit above average, set in June.

Although instrument records only date back to 1880, there are many ways for scientists to discern temperatures for centuries before that. A study published last year found that global temperatures are warmer now than anytime in at least 4,000 years, and it's no coincidence that carbon dioxide levels are the highest they've been in at least 800,000 years. Carbon dioxide is the main long-lived greenhouse gas.

It is virtually certain that 2014 will go down in history as one of Earth's warmest years, if not the warmest.

Last month NOAA published data showing that if each month from October through December were to match its 21st century average temperature, then the year will at least tie 1998 and 2010 for the warmest year on record. If these months' average temperatures ranks any warmer than that, then the year will be the warmest in the NOAA dataset.

End of year temperature ranking scenarios from NOAA, as of Sept. 2013.

IMAGE: NOAA

While NOAA does not report its global data until next week, it is certain that October will rank among its top warmest years. This means that November and December would have to be extremely cold, compared to average, in order to avoid having the warmest year.

Or, as the Capital Weather Gang put it, "Considering the October results in so far, a record warm year almost seems inevitable unless temperatures radically tank in November and December."