NASA: September Was Warmest on Record

By Tom Yulsman | October 13, 2014 10:43 am
A map showing how temperatures departed from the long-term average during September of 2014. (Source:  NASA/GISS)

A map showing how temperatures departed from the long-term average during September of 2014. (Source: NASA/GISS)

This just in: The global average temperature in September was the warmest in a record dating back to 1880, according to an update from NASA’s Goddard Institute for Space Studies. That makes it two months in a row: August was also the hottest on record by NASA’s reckoning.

Later this week, the National Oceanic and Atmospheric Administration will release its own, independent calculation of how September 2014 stacked up. Sometimes NOAA’s calculation differs. (But this month, I wouldn’t bet on it.)

Unless something really weird happens, 2014 is on track to be the warmest in the instrumental record.

The map above shows how temperatures around the globe varied from the long-term average in September. Two things catch my eye:

  • The warmth bedeviling roughly the western third of the United States and all the way up into Alaska. This is the result of a high-pressure ridge that has remained stubbornly and remarkably persistent for many months (with some short-term ebbing and flowing, to be sure). The ridge has also prevented storms from reaching California, bringing record drought. The flip side is a trough of low pressure across the U.S. mid-section, which has brought cool temperatures this year, although in September, the map indicates temperatures close to normal across that region. (For more detail on this pattern, check out this post from the California Weather Blog.)
  • The tongue of warm ocean water extending west from the coast of South America out into the central Pacific also catches my attention. Warm sea surface temperatures persisting in the eastern and central Pacific comprise the signature of an El Niño trying to be born. Labor pains have been ongoing for quite some time now, and the odds are good that a weak El Niño will emerge in the next couple of months.


You can see these two patterns — the high pressure ridge/low pressure trough over the U.S., and the tongue of warm sea surface water off South America — in the temperature anomaly map for summer of 2014 at right. Click it to enlarge.

Over the long term — meaning decades, not month by month or year by year — global average temperatures have been increasing. Over the past 30 years, each decade has been warmer than the one before it, a clear sign that the climate system is accumulating heat as humankind’s emissions of greenhouse gases have continued unabated.



You can see that fact in the graph above, which charts the global average temperature, as calculated by NASA, since 1880. But you can also see a leveling off in the year-by-year increase in temperature over the past ten years. Skeptics of human-caused climate change have used that to declare global warming dead.

It’s not, as NASA’s calculation above shows pretty clearly. NOAA’s independent assessment of the global temperature trend shows pretty much the same thing.

But what’s up with that year-by-year leveling in global average temperature? I’ve got a story coming out in Discover’s upcoming Year-in-Science issue examining this question in some detail. Without giving so much away that I’ll get scolded by my editor, here is one way to think of it:

If you’ve ever had the flu you know that even while you are wracked by body aches, sneezing, coughing and other symptoms, your temperature can fluctuate. While on average it is high when you have the flu, you might experience periods when it subsides a bit.

Well, the same thing is true of the climate system. Symptoms of climate change abound, as detailed in the latest round of reports by the Intergovernmental Panel on Climate Change — from melting ice sheets, to rising sea levels, to some extreme weather events.

But given the recent plateauing in global average temperature, where is the heat going? When the Year-in-Science issue comes out in late December (or early January), I’ll post some additional detail here at ImaGeo on what scientists are learning about that question. So please stay tuned for that.

In the meantime, keep in mind that 2014 is still on track to be the warmest on record. So that leveling in global average temperature over the past 10 years may be about to end.

  • BO_stinks

    I love the climate, the weather not always so much.

    • Tom Yulsman

      Mr. BO_stinks: Your avatar and username do not speak well of you.

    • ReDQLulz

      Interesting, I love the Earth, but right wing white people too politically recalcitrant to admit the truth when it is front of their bland faces….not so much.

      • Adam

        What does skin color have to do with anything? Bigot.

    • Emkay

      We can all take a lesson from the weather, it does not respond to criticism….

  • David McCaig

    Thank you for your reporting. Greatly appreciated. What I find most significant is that all these records are being set without the warming effects of El Nino which has influenced all previous record setting years – but this one. The Arctic is in horrific shape as many feedback loops have been triggered. I know I’m speculating but since the 2nd half of the year could we be seeing the effects of runaway global warming? The chicken must come home to roost some time.

    • Tom Yulsman

      Hi David: I very seriously doubt that we are seeing runaway global warming. Please keep in mind that you need much, much more than one month’s data, and even one year’s data, to reach conclusions about climate trends. Climate trends are measured in decades, not months or years. And over that timescale, each decade of the last 30 years has been warmer than the one previous to it. There is a clear trend. But if you look carefully at the long-term trend graph, I think you’ll find it difficult to conclude that runaway global warming has begun.

      • Jack Wolf

        Regardless, the news is bad and the prognosis is poor.

  • Hew

    This is a strong evidence global warming is not an average issue, it is not largely due to greenhouse gas carbon dioxide as many scientists claimed, it was stronger cosmic ray radiation from the sun.

  • Ken L.

    For perspective of the “record” September temperature – if global temperatures have peaked and then leveled off, they will, in general, remain higher than any in the past and any increase in the anomaly for a given month will indeed be a record. At any rate, satellite data does not rank September as the warmest on record and I’m curious why the article does not mention that fact?

    It might be noted that there is no significant difference in the increase in temperature between the first half of the twentieth century( if you start at the minimum anomaly in 1910, especially) and the second half, with Anthropogenic Global Warming only considered by most climate scientists to have begun after 1950- 1960. The slope of the graph is clearly similar, save the leveling off between 1940 – 1960. Models using CO2 as the principle driver of climate did not predict the lack of increase in temperatures for the last 17 or so years and, most significantly, overestimated predicted warming – despite higher CO2 levels. Most reputable skeptics to do not claim that global warming is “dead”, per se, based on that fact, but rather that the catastrophic predictions/projections based on the models, which indeed missed on the “pause”, are not to be trusted.

    • OWilson

      Least to be trusted are “instrumental records that go back to 1890”
      Why NASA and NOAA rely on such historically flawed data and ignore (in their breathless pronouncements anyway) the satellite data, which is the only consistent empirical record available can lead to only one conclusion.
      The satellite record for the past 35 years shows no statistically significant (0.39 degrees) warming. Consistent with our interglacial epoch.
      At this rate (even if linear, with no pause) it would take 200 years to add 2 degrees.

  • Brett Price

    Perhaps the last decade 5 year mean is evidence Green renewable energy sources are beginning to have an impact. NASA solar observatory did confirm 2013 to be the end of an 11 year solar high further helping to cool things down a few degrees Celsius. What has been left out of this graph is the Co2 trend during this 5 year mean. More average rain fall and stronger geographic atmospheric climate shifts are driven by higher levels of methane & Co2 which the oceans can not completely absorb. So while the average mean 5 year temperature has now seemingly stabilized methane & Co2 levels are still on the rise. That seems to infer Sun solar output level also plays a key part in how Co2 & methane gas react within the earth atmosphere at times rapidly rising average temperatures.

  • Han Solo

    >hottest on record by NASA’s reckoning.

    Aka, lick your finger, hold it in the wind, and reckon.

  • Buddy199

    IPCC stated “…there is no clear evidence that sustained or worldwide changes in extreme events have occurred in the past few decades.” Why would steadily increasing CO2 and running mean temp over that period have not lead to increased climate destabilization and extreme weather? Seems counter-intuitive.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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