September was second warmest for the globe and U.S.; 2015 likely headed for the record books

By Tom Yulsman | October 12, 2015 4:38 pm
second warmest

Month-by-month variation of global average temperature from the long-term mean. The first two frames of the animation show 1901 – 1950, and 1951 – 2000, respectively. The third frame shows 2001 through September of this year. Each colored box represents a specific month. V denotes major volcanic eruptions. (Graphic: Makiko Sato, Columbia University; Data: NASA/GISS; Animation: Tom Yulsman)

This past September was the second warmest on record for the globe, according to numbers just released by NASA.

Only September of last year was warmer in NASA’s record, which dates back to 1880. And that was an extraordinarily warm month for the planet. (NOAA will soon issue its own independent analysis of global temperatures during September.)

Meanwhile, the contiguous United States is really starting to heat up, with September coming in as the second warmest in a record spanning 121 years, according to the National Centers for Environmental Information. By comparison, August 2015 was much cooler in the lower 48 states, coming in as 31st warmest on record.

second warmest

Source: Makiko Sato, Columbia University

To illustrate what’s happening globally in a novel way, I created the animation above. My starting point was a static graphic from Makiko Sato of Columbia University. I broke it into three frames, which I then used to make the animation. (Click on the thumbnail at right to see the original, static graphic. And click here to access additional imagery from Sato on temperature trends.)

The animation shows the month-by-month and year-by-year evolution of global average temperatures between January of 1901 and this past September. The first two frames show 1901 through 1950, and 1951 through 2000 respectively. The last frame takes us up to September 2015. (The Vs in some of the squares show months with volcanic eruptions, which tend to cause some cooling.)

I think this imagery illustrates in a particularly compelling way both the short-term variation in the climate system and the overall decadal-scale trend — which clearly is toward increasing warmth.

second warmest

Through September, 2015 has been the warmest on record globally. January through September last year tied with 2010 as second warmest for the period, according to NASA’s analysis. (Modified from a graphic by Makiko Sato of Columbia University. Data: NASA.)

As the graphics above show, for the globe, 2015 is well ahead of 2014 so far. With a strong El Niño headed for a peak in coming months, it would be very surprising if the year didn’t make it into the record books as warmest ever — and possibly by a big margin. That’s because El Niño tends to give its own boost to global average temperature.

While most of the globe’s surface was warmer than average through September in both years, the coolness over significant portions of North America is notable. So is the obvious warmth in much of the West.

Warmth (as well as dryness) in the west, and chill in the east (along with shocking winter storminess in New England) has been a very stubborn pattern for at least two years. In part we can thank what has come to be called “The Blob,” a large pool of very warm sea surface temperates, or SSTs in the Pacific Ocean off the West Coast of North America.

ALSO SEE: Record algae bloom laced with toxins is flourishing in ‘The Blob’ — and spreading in the North Pacific

“One of the feedbacks associated with the warm sea surface temperatures has been a ridge of high pressure in the West,” which has helped maintain the heat in the West, says Gregory Carbin, Warning Coordination Meteorologist with the Storm Prediction Center of the National Weather Service. “But there are hints that maybe SSTs are starting to fall in the Pacific.”

Watch for a future ImaGeo post about that. In the meantime, have a look at this animation to see how temperature conditions have evolved in the Lower 48 so far this year:

second warmest

The monthly evolution of average temperatures year to date in the contiguous United States. (Source: National Centers for Environmental Information)

I created it using maps from the National Centers for Environmental Information. By my count, the western portion of the Lower 48 has been unusually warm for six out of the nine full months of 2015 so far. Unusual coolness occurred in the interior West during just two months: May and July.

Meanwhile, the situation has been reversed in the Midwest and East: This region has seen significant areas of unusual chill for six of the nine months.

second warmest

Source: PRISM Climate Group

The map above suggests that unusual warmth may finally be winning out. It shows how temperatures departed from the long-term mean during September. (It basically depicts the same story as the last frame of the animation above.)

As those warm colors in the map show, most of the Lower 48 experienced higher-than-normal temperatures in September, including the Midwest and Northeast.

In coming days here at ImaGeo, I’m hoping to write a story on El Niño — and it will be a bit of a cautionary tale. So please check back for that.

  • John Compton

    Sorry, but my BS alarm just went off.

    • Leon Maurer

      Have you had your alarm serviced recently? It may have a faulty sensor.

      • CB

        “Have you had your alarm serviced recently? It may have a faulty sensor.”

        lol! Climate Deniers do have a fault going on in their minds!

        I would suggest mentally healthy people do not have arguments with thermometers…

        “we estimate a 97% probability that 2015 will become the warmest year on record.”

        • OWilson

          I agree. I would think you could take that to the bank.

          They control the data, the email servers and the fortune telling.

          Anything less would be incompetence! :)

          • CB

            “I agree.”


            Now which year was the warmest on record, Mr. Wilson?

            What do you think?

            “The year 2014 now ranks as the warmest on record since 1880, according to an analysis by NASA scientists.”


          • OWilson

            Don’t suppose you noticed the qualification.

            “according to AN analysis by NASA scientists”.

            (Those guys are smarter than you Chicken Littles, by a mile.) :)

          • CB

            “Don’t suppose you noticed the qualification.”

            LOL! No, I noticed it! According to the people who study the subject, 2014 was the warmest year on record.

            Which year was the warmest on record, Mr. Wilson?

            “The year 2014 was the warmest year across global land and ocean surfaces since records began in 1880.”


          • OWilson

            So, what did you do to prepare for the “Catastrophe”? :0

            Tell us who measured and collected all those instrument readings back in 1880 when most of the globe was listed as “unexplored” :)

          • CB

            “what did you do to prepare for the “Catastrophe”?”

            Your question assumes that which is not in evidence, and the reason it’s not in evidence is because you’re running like a coward from my question.

            Which year was the hottest on record, Mr. Wilson?

            Try leading with a number this time… or even saying “I don’t know”!

            …that would be far more honest than what you’ve been doing…

            “2015 May Just Be Hottest Year on Record”


    • Leslie Graham

      Oh Geezus – give it a rest will you.
      Now that the effects of global warming are simply an obvous everyday reality all over the world the last-of-the-deniers are sounding increasingly shrill, desperate and, frankly, insane.
      But worse than that – you’re booooooring!
      The grown-ups are trying to have an intelligent discourse concerning what is to be done about it and your pathetic ‘La La La I can’t hear you’ garbage is just so infantile.
      If you don’t have the guts to admit that events have long ago proved your absurdist conspiracy fantasies to be total and utter BS then at least have the decency to STFU and get out of the way while the grown-ups try to clean up your mess for you.
      We don’t have the time nor the patience to humor your moronic anti-science junk any longer

      • OWilson

        You’re an adult? :)

        You represent the AGWers quite well.

        • CB

          “you represent the AGWers quite well.”

          AGW stands for “anthropogenic global warming”, the fact that humans warm the planet by producing greenhouse gasses, something that has been known for over a century.

          Leslie does represent that understanding very well!

          I think the word you’re looking for is “scientists”, though, not “AGWers”…

          “The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century”

          • OWilson

            Caso cerrado :)

      • CB

        “The grown-ups are trying to have an intelligent discourse concerning what is to be done about it”

        We should do that!

        I favour a globally-negotiated carbon tax and sequstration credit that slowly increases over time until we are sequstering more carbon than we’re emitting.

        How would you fix the problem?

        “In 2009, humans released about 8.4 billion tons of carbon into the atmosphere by burning fossil fuel.”

        • TyphoidMikey

          I’d fix the problem but forbidding people to release any more CO2 about the Global Warming Hoax.

          • CB

            “I’d fix the problem but forbidding people to release any more CO2 about the Global Warming Hoax.”

            …but forbidding people would do what?

            The fact that CO₂ warms the planet was first proved by scientists living over a century ago.

            Is it likely they were engaging in a hoax that hasn’t been noticed by a single person in all that time?

            What do you think?

            “Overlooked by modern researchers is the work of Eunice Foote, who, three years prior to the start of Tyndall’s laboratory research, conducted similar experiments on absorption of radiant energy by atmospheric gases, such as CO₂ and water vapor. The presentation of her report at a major scientific convention in 1856 was accompanied by speculation that even modest increases in the concentration of CO₂ could result in significant atmospheric warming.”


          • TyphoidMikey


          • CB

            “the Sun also warms the planet. Why not just get rid of it?”


            I can think of a reason, Mikey!!!

            Can you?

            “Even in the event of the Sun entering a new Maunder Minimum… the climate response is very small compared to the projected warming due to anthropogenic influences”


          • TyphoidMikey

            Plants also need CO2 to live, and that paper has nothing to do with this discussion. Fail.

            BTW, we’re not on a first name basis.

      • CB

        “The grown-ups are trying to have an intelligent discourse concerning what is to be done about it”

        We should do that!

        I favour a globally-negotiated carbon tax and sequstration credit that slowly increases over time until we are sequstering more carbon than we’re emitting.

        How would you fix the problem?

        “In 2009, humans released about 8.4 billion tons of carbon into the atmosphere by burning fossil fuel.”

    • Bill

      Does it say anywhere what that average temperature was? I scanned it twice and say references to anomalies and such but no Temperature. I’m curious because the temperature at the height of the last interglacial period was higher than it was over the last few years. I’m trying to understand if this is a deviation from normal interglacial climate change.

  • Mike Richardson

    October doesn’t look to be breaking the trend, either, at least where I live. Louisiana’s now under a complete burn ban due to drought (October’s often dry for us, but this one has been especially dry). Temperature wise, we’ve already had a few afternoons with highs in the nineties. At least this weekend is supposed to be cooler.

  • Theo

    For some good news, NASA has confirmed a persistent net increase in Antarctic ice mass, new ice is being added faster than glacial melt.



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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