May global temperatures fall 0.16C

The global averaged surface temperature for May 2019 was 0.66C using my spherical triangulation method merging GHCNV3 with HadSST3. This is a significant drop of 0.16C from April 2018. The baseline used is always 1961-1990. I also applied the same calculation to the new V4 data (17400 total stations as compared to 7280 in V3) using both the corrected (V4C) and the uncorrected (V4U) station data.

Global average monthly temperatures. The differences between V4C and V3C appear small, but there is a systematic difference in trend.

Shown below are the annual global average temperatures where the 2019 value is just the average over the first 5 months.

V3 and V4 annual temperatures ( V4 is shown for both the corrected and raw data). Hadcrut3 data shown in green are similar to those used in AR4 showing a hiatus and are based on a 5 degree (lat,lon) weighted average.

I find it  striking how the new V4 data has yet again increased recent warming trends apparently  just by adding more stations. The famous Hiatus which was evident in HadCRUT3 post 1998 has entirely disappeared. You can see this by comparing with the old  2012 HadCRUT3 results as used by AR4. What I find rather strange though is how all the datasets (V3,V4,H3,H4) pivot around exactly the same value for the 1998 El Nino peak. All the datasets, independent of sampling or analysis methods  agree on the same 1998 annual temperature. Why?

One possibility is that adding hundreds of new stations with short time coverage (mostly post 1960) may introduce a post 1990 warming bias simply because they add no new information about pre 1960 temperatures. However, I still can’t understand why 1998 temperatures should remain exactly the same across all datasets, including Cowtan & Way.

1998 was the start of the infamous Hiatus in global warming, so avoiding any increased temperature for 1998 certainly helps in debunking it.

About Clive Best

PhD High Energy Physics Worked at CERN, Rutherford Lab, JET, JRC, OSVision
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6 Responses to May global temperatures fall 0.16C

  1. Fernando L says:

    Do you gave the satellite data available? It would be interesting to use only the 60 north to 60 south data for all data sets to see if there are discrepancies or lapse rate anomalies.

    • Clive Best says:

      No I don’t have the spatial satellite data. However I think my 3D method covers both poles even if coverage is sparse. One effect that is not well known is that pairwise homogenisation is also continuously changing past temperatures as well as latest temperatures. So latest temperatures increase and older values decrease this accentuating trends.

  2. Geoff Cruickshank says:

    Thanks, I’ve been waiting for an update on this series of posts. Re 1998, as all these series will have errors I suppose there must be some chance of it being a coincidence. I have a niggling feeling that for such a coincidence to also happen at the peak of 1998 El Niño has about the same chance of occurring as that of monitoring the time via 4 cheap manually wound watches which happened to agree to the second when JFK was shot.

  3. I wonder what hadcrut3 would be by now…

  4. Snape says:

    “1998 was the start of the infamous Hiatus in global warming, so avoiding any increased temperature for 1998 certainly helps in debunking it.”

    Me: “I own a stock whose value has been increasing by a small but steady amount each year.”
    Skeptic: “Not possible – the market has been flat since 1998!”

    Do I need to prove the broader market wasn’t flat in order to prove my individual stock did well?Ridiculous.

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