It has been said that global warming has stopped over the last several years. Some say it has not been happening for 17 years, some say for ten years, some say for 12 years. Let’s test these hypotheses

Hypothesis: June, the most recent month with full data, was an average year, not a warm year.

Now that July is nearly over, we can look back at the data for June and see how warm or cool June was.

According to data from NOAA and NASA, summarized here,

June was one of the hottest such months on record globally…The month extended the unbroken string of warmer-than-average months to 340, or a stretch of more than 28 years. That means that no one under the age of 28 has ever experienced a month in which global average temperatures were cooler than average (based on the 20th century average)….Last month featured unusually wet conditions in the eastern U.S., and tragically wet conditions in northwest India, where rainfall that was 200 percent of average inundated parts of the state of Uttarakhand, killing nearly 6,000 and causing widespread destruction. Areas that experienced higher-than-average temperatures during the month include north-central Canada, most of Alaska — which had its third-warmest June on record — and the Western U.S., where about 80 percent of the region was in some stage of drought by the end of the month.

Huh.

Well, OK, so when we look at June we have to reject the hypothesis. But what about the entire year, so far, from January to June? If global warming has stopped, this should be an average year, right?

Hypothesis: Global warming has stopped, therefore this year is not warm.

Again, from NOAA and NASA, there is evidence that this year so far is the seventh warmest year on record so far. So, if this year is average for the last 14 years, than the last 14 years including this one are very, very warm. Sounds like global warming. However, the jury is still out on this one. There is evidence that certain climate effects that were keeping the atmosphere cooler than it otherwise might be are reversing or changing in a way that may make the rest of the year warmer. So, we are reasonably likely to rise from the 7th warmest year on record to a higher rank. But, in the meantime, here’s a nice graphic for you:

pauldouglas_1374335986_7_9

(Hat tip Paul Douglas)

But what about the Arctic? I’ve heard tell the sea ice melting started out average this year. Therefore, global warming is not real.

Arctic ice melt is average this year

There is really good data for a period of some 30 years or so in the Arctic. The first ten years of that period had ice melting at a certain rate, and the last ten years of those data had more ice melting, such that none of the last ten years were as icy as any of the first ten years. That suggests a trend. Last year the ice melted even more than ever observed, continuing the trend. But early this year, the ice seemed to be tracking average for the last 30 years, so everything is fine!!!!

But wait, over the last few weeks, the ice seems to have caught up, and it is now tracking right on the 98th percentile for all of the years, at the low (more melting, less ice) end. It is quite possible that this year’s ice will catch up to last year and we’ll have the most sea ice-free year recorded, but if not, we’ll probably have the second or third ice free year. So, well, that didn’t work out either.

It is true that a very rapid increase of sea surface and atmospheric temperatures that happened a decade ago was much greater than the rate of increase in heat in these areas over the last ten years, but the earth is still warming. More importantly, the deep ocean seems to be heating at a higher rate, and since 97% of the sun’s extra heat goes into the ocean anyway, we expect the atmospheric temperatures to fluctuate more randomly.

Also, if you live in the US, this has been an exceptionally warm period. Interestingly, US based denialists are screaming about how “global warming has stopped” while at the same time atmospheric warming is catching up in the US where in the past it was not as severe in some other areas of the world.

So, in the end, the evidence that global warming has stopped is … lacking.

Comments

  1. #1 Juice
    July 22, 2013

    If global warming has stopped, this should be an average year, right?

    Damn, you’re dense.

  2. #2 L.Long
    July 22, 2013

    Since politicians only care about money, power, and reelection you have not said anything but bad news so what you said is not important…global warming as stopped!

  3. #3 teeth
    Gaia
    July 22, 2013

    I don’t see why you are unable to understand this rather simple science. Perhaps it is because you know on which side of the bread you get the butter. Remember saying that Fluoride was a Communist plot? How about that cigarette smoking wasn’t bad for you followed up with second hand smoke wasn’t bad either. Then there were weapons of mass destruction, the success of the surge in Iraq and Afghanistan and that you believed in the Biblical God who told you to cut Food Stamps and that raising the minimum wage hurt employment. Sorry to tell you but the tooth fairy is only real to people whose brains are filled with Faux Noise.

  4. #4 teeth
    Gaia
    July 22, 2013

    You see, no one cares about all the science in your article. The best that anyone can do is point out the contradictions in their belief system. Even that isn’t likely to work but I carry around the above disavowal and place it where it might be read by denialists. In the past it has at least made them mad whereas they never read beyond the first sentence of science stuff.

  5. #5 Greg Laden
    July 22, 2013

    Wait, we don’t get the butter FROM the bread we put the butter ON the bread! Right?

  6. #6 andy schroeder
    Brandon, Manitoba, Canada
    July 22, 2013

    Sorry but I resent the misleading title to the article. To put it as gently as possible, such a statement does nothing to advance the truth.

  7. #7 Greg Laden
    July 22, 2013

    Andy, you have not thought this through. Your comment in not gentle, and you are utterly incorrect. Contact me privately if you want to discuss this further.

  8. #8 Sean T
    July 23, 2013

    Greg,

    I’m not a denier, and I certainly accept that the scientific evidence favors the hypothesis that the earth is continuing to warm. However, the claim that if global warming has stopped, then current years should have average temperatures is false.

    Consider a hypothetical data set of global average temperatures such as the following:

    year 1: Avg temp 20C
    year 2: 20.2
    year 3: 20.3
    year 4: 20.7
    year 5 20.9
    year 6: 21.4
    year 7 21.7
    year 8 21.8
    year 9 22.0
    year 10 22.0
    year 11 22.0
    years 12-25: 22.0

    Would we not be correct in claiming during year 25 that “global warming has stopped for the past 15 years.”? Is it also not true that year 25 is not an average year, but rather tied for the hottest year on record, at least on record in the hypothetical data set? Therefore, to claim that the fact that this year is one of the hottest on record is evidence that global warming hasn’t stopped is not really a valid claim.

  9. #9 Greg Laden
    July 23, 2013

    That is both correct and incorrect. Global warming refers to the heating of the earth’s atmosphere, surface, and oceans since pre-industrial times over a prior baseline. For global warming to “stop” there would have to be a return to baseline. If all of the last X years were the same as each other, i.e., a perfectly flat line with no increase, that is still global warming.

    Your comment would be correct if it referred to the rate of warming. As it happens, however, there is still an increase in temperatures over the last several years in all of the areas we measure it, and an alarming increase in the deep oceans.

  10. #10 Sean T
    July 24, 2013

    I’m not climate expert, so I’ll certainly defer to you. I’ve always understood the claim that “global warming has stopped” to equate to “the average global temperature has not risen” over whatever period for which the claim has been made. If my understanding of it is what is claimed, then your argument is not a valid one. Certainly, I’ll also defer to you (or if you aren’t a climate scientist, I’ll defer to those who are) about the current increase in temperatures over the last few years.

  11. #11 Greg Laden
    July 24, 2013

    Sean, I interpret it that way. The thing is, the average global temperature has risen over these various periods of time. What has happened is that there was a period of more rapid rise followed by a period of less rapid rise of surface temperatures, and this second period of less rapid rise of surface temperatures is associated with a more rapid rise in deep sea temperatures.

  12. #12 Cat
    Melbourne, Australia
    July 24, 2013

    Just like to say thank you Greg for this and all the previous info given about the state of our planet.

    I’m not a scientist so plenty goes over my head, and it can be hard to tell if someone is being honest or has some other hidden agenda.

    You’re straight forward and back it up with legitmate figures so I get a lot of my global warming news from you.

  13. […] Evidence that global warming has stopped [Greg Laden's Blog] (scienceblogs.com) […]

  14. #14 Steve
    California
    August 16, 2013

    Does a grown man running a science blog really not understand the difference between warm and warming? Warm means above average temperature. Warming means the temperature is increasing. Is that so complicated? If the global average temperature is 70, and the last ten years have been 80, then the last ten years have been warm but there has been no warming. By the logic in this article any temperature above the average is warming. So consecutive years of average temperatures of 80, 79, 78, 77, 76 and 75 is global warming because all of the values are above 70.

  15. #15 Greg Laden
    August 16, 2013

    Last year was WARMER than any year on record. The last ten years are WARMER than any previous ten years on record. The current year promises to be WARMER than all but maybe 5 or 6 of all the years on record.

    Warmer. Warming. And warm. All of them.

  16. #16 Steve
    California
    August 16, 2013

    You run a science blog but you don’t look at data do you. The 3 major global average temperature data bases, GISS, NCDC, and HADCRUT4 all show cooling trends in the 5 and 10 year running averages. That is data, and that is not warming, that is cooling. Here is the link: http://www.skepticalscience.com/global-warming-stopped-in-1998.htm

  17. #17 Steve
    August 16, 2013

    I don’t know if global warming has stopped, my opinion is the current decline from the rising that occured in the 70s 80s and 90s is because of the amount of sulfur being emitted from emerging nations, especially China, along with the CO2 produced in burning coal. Sulfur in the air reduces the amount of sun energy reaching the earth. However CO2 remains in the air much longer than sulfur, so if we can reduce world wide coal burning the warming may resume, maybe faster than ever. There was a 30 year pause in global warming from 1945 to 1975 that may have been due to high sulfur production by the US and others during the industrialization after WW2.

  18. #18 Greg Laden
    August 16, 2013

    Steve I fixed that link for for you. Sorry, blog policy, no links to bs sites in the comments.

    From that source, “To claim global warming stopped in 1998 overlooks one simple physical reality – the land and atmosphere are just a small fraction of the Earth’s climate (albeit the part we inhabit). The entire planet is accumulating heat due to an energy imbalance. The atmosphere is warming. Oceans are accumulating energy. Land absorbs energy and ice absorbs heat to melt. To get the full picture on global warming, you need to view the Earth’s entire heat content….”

  19. #19 Nick
    August 25, 2013

    If Global Warming was real, we would not be constantly attacked with propaganda about it. It would remain hidden, just like any real ecological problem. Those discussing it and trying to warn the people would be ridiculed. The governments and organization would not embrace them, invest in them, fund them, or help them in their efforts.

    When we see such an effort for an ecological problem, it has to be mere marketing for new products and services, transfer of market power, etc. Global Warming is a new industry based on a theory, and nothing more.

  20. #20 GregH
    August 25, 2013

    No sir, if Global Warming was real, everyone, from governments to the military to insurance companies would be sitting around the pool drinking fizzy drinks and saying, “Boy, I sure hope the public never finds out about this. Nah, they’ll never notice that the weather is changing or that Spring shows up two weeks early or that all those glaciers are melting.” Everything would be business as usual, kind of like it has been for the last 30 years.

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