Tuesday, June 19, 2018

2018 has the fourth hottest May on record

Sou | 1:45 AM Go to the first of 11 comments. Add a comment
Summary: May 2018 was the fourth hottest May on record. The 12 month period to May 2018 was the third hottest June to May period on record.

According to GISS NASA, the average global surface temperature anomaly for May was 0.82 °C, which is 0.09 °C less than the hottest - May 2016.

Below is a chart of the average of 12 months to May each year. The 12 months to May 2018 averaged 0.82 °C above the 1951-1980 mean, which was 0.19 °C cooler than the 12 months to May 2016.

This makes it the third hottest June to May 12 month period on record after 2016 and 2015.

Figure 1 | Global mean surface temperature anomaly for the 12 months to May each year. The base period is 1951-1980. Data source: GISS NASA

Next is a chart of the month of May only. This May was also 0.82 °C above the 1951-1980 average and was the fourth hottest May on record. It was 0.09 °C cooler than May 2016, which was 0.91 °C above the 51-80 mean. Hover over the chart to see the anomaly in any May:
Figure 2 | Global mean surface temperature anomaly for the the month of May only. The base period is 1951-1980. Data source: GISS NASA

Where was it hot?

In April, although of course much hotter overall than it was just a few years ago, it was very much hotter than normal in parts and very much cooler in other parts. In May something similar happened up in the northern hemisphere, though without the same extent of extremes. Move the arrow at the left to the right to compare May with April.

May 18
April 18

Figure 3 | Maps showing mean surface temperature, anomalies for May and April, from the 1951-1980 mean. Data source: GISS NASA

Year to date chart

For the record, here is the year to date progressive chart. You need to understand what it is to make sense of it. The chart below shows the average temperature for the year at each point on each separate line on the chart. The topmost line is 2016. The fat black line with dots, which goes to May, is 2018.

For each year at January, the point is just the anomaly for January. At February, the point is the average anomaly for January and February. At May, it's the average of January to May inclusive - all the way to December, which is the average for the whole year.

So the 2018 year shows that the average for the period January to May is 0.83 °C. This is 0.33 °C lower than the average year to date for May 2016, toward the end of the massive El Nino. It is 0.17 °C lower than the average year to date was in May 2017. It's a tad ahead (by 0.01 °C) of the average year to date to May in the next hottest year, 2015. The average over the entire 2016 year is 0.99 °C (the point marked for December on the 2016 line) and this year is not expected to be another hottest year.

Figure 4 | Progressive year to date global mean surface temperature anomaly. The base period is 1951-1980. Data source: GISS NASA

If there is another El Nino this year, which could be on the cards, then it's not out of the question that 2018 would end up the third warmest year on record, ahead of 2015. (The temperature anomaly for the rest of the year would have to average more than 0.89 C before 2018 could claim third spot.)


  1. And the Australian BOM has issued an El Nino watch. Something tells me the "cooler" global temperature is not going to last.

  2. Any odds on this becoming the 2nd hottest year?

  3. If the El Nino come in late in the year, the year to date graph for 2018 is likely to be flat like 2005.

    IMHO 2018 is most likely to average around its present level of 0.82C and be 4th warmest.

  4. OT. Just added this thought to Willis's latest:

    "So every scientific association on the planet is wrong because: someone turned the heat up in a meeting 30 years ago, and some bloggers.

    Only, it probably never happened. Oh dear.

    No wonder nobody takes you seriously now (if anyone ever did)."

    The coward won't publish it naturally, but just want to remind them how fringe and deluded they are over there... ;-)

    1. The Washington Post debunked that "opened the windows and shut off the air conditioning" story a few years ago.

      I went further and examined high resolution interior and exterior photos of the meeting room in the Dirksen Building that Hansen's testimony was presented in... it had (and has) high floor to ceiling bronze-framed neoclassical windows that did not open.

      Another myth favored by deniers bites the dust.

    2. Thanks Magma.

      Here's a link to the Washington Post fact check:


      So, here’s the reality. The room may have been a bit stuffy, but that was because of television cameras, not because of any manipulation of the windows or the air conditioning. And the hearing date was not set because it the hottest period of the year; instead, that was how the timetable for the bill was determined.

      It is rather remarkable that events that happened just 27 years ago could so easily get twisted and misreported, based on one overenthusiastic interview. It is a quintessential example of Washington self-puffery.

    3. I stand corrected, for once Watts allowed my post through. Reproducing it here probably helped. Naturally my response to the responses was censored, making me look foolish, can't have too much free speech in the same thread.

      Elsewhere poster Alan Tomalty has published a disgusting ad hominem attack on James Hansen complete with a long list of untruths and half-truths, starting with the lie that Hansen predicted that the West Side Highway would be underwater by 2008 - speaking off the cuff in an interview for a magazine his actual timescale was to 2028, and assumed a doubling of CO2 - and going downhill from there. This dishonest and defmatory outburst received 40 upvotes from the fake sceptics who infest that swamp.

      Deluded and mendacious - and that's just the commenters.

    4. Worth noting: in 2012, part of that highway (running along the west side of Manhattan by the Hudson River) *was* underwater during Hurricane Sandy.

  5. In a month where a few of my naïve acquaintances have waxed lyrical about the possibilities, John Bushell makes a straightforward, clear, and logical case against carbon sequestration and storage:


    Bottom line: it's an excuse to squeeze out a little bit more self-serving profit before handing to the future a ruined climate and little or no money or other capacity to ameliorate or otherwise repair and maintain what's left.

    1. Meanwhile, here in the UK, we have just voted to construct a 3rd runway at Heathrow. Passenger surveys show that the majority of flights are for leisure purposes: so getting away on a foreign holiday is far more important than our children having any kind of future.

    2. While almost simultaneously nixing a Tidal Barrage that would have provided 150,000 homes with renewable energy for 100 years....

      Chances of us meeting our climate change targets now nil, and I can't even blame Trump....


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