Guest Post by Bob Tisdale
Monthly sea surface temperature data from NOAA (ERSST.v3b) are available online well before the global land air+sea surface temperature suppliers (NASA GISS and NOAA NCDC) publish their monthly updates. In addition to annual (January to December) data, GISS also presents what is known as the Meteorological Annual Mean data, using the months of December to November. So, in advance of the release of the GISS and NCDC combined products, let’s see how the global sea surface temperatures in 2014 compare to the previous record high back in 1998, on a Meteorological Annual Mean basis, using the dataset employed by both suppliers (NOAA’s ERSST.v3b). We’ll start the data presentations in 1997 to make the comparison easier, and I’ve also provided color-coded horizontal lines to show the 1998 (blue) and 2014 (red) values. Last, I’ve presented the data in absolute terms, not as anomalies, but that makes no difference.
QUICK NOTE FOR THOSE WHO ARE FIRST DISCOVERING THAT GLOBAL SEA SURFACE TEMPERATURES ARE AT RECORD-HIGH LEVELS: The record high global surface temperatures in 2014 are primarily a response to a prolonged weather event in the North Pacific. See the post here. Putting that in more familiar terms: You often hear meteorologists talking about a blocking high during a heat wave. So it might be easier to think of the record high sea surface temperatures globally being caused by a prolonged blocking high in the extratropical North Pacific, south of Alaska. [End note.]
As shown in Figure 1, global sea surface temperatures (based on NOAA’s ERSST.v3b dataset) from pole to pole were 0.02 deg C higher in (Dec to Nov) 2014 than they were in (Dec to Nov) 1998. That’s read two one-hundredths of a deg C. Two. All of the hubbub this year boils down to two one-hundredths of a deg C.
But GISS masks (excludes) sea surface temperature data in the polar oceans, anywhere sea ice has existed. And NCDC, as far as I know, excludes polar sea surface temperature data seasonally when there is sea ice in a grid. So let’s take a look at global ocean data excluding the polar oceans, Figure 2. That is, we’re looking at the data for the latitudes of 60S-60N. And as you can see, on a Meteorological Annual Mean basis, 2014 surpassed 1998 by only 0.02 deg C for those latitudes as well with the NOAA ERSST.v3b data.
WHAT ABOUT NOAA’S SATELLITE-ENHANCED SEA SURFACE TEMPERATURE DATASET, REYNOLDS OI.V2?
In 2008, NOAA introduced its ERSST.v3 data, which included satellite-data starting around 1982. NOAA quickly discovered the satellite-enhancements rearranged the record high years for their combined land+ocean data, making 1998 once again higher than one of the years in the early-to-mid 2000s. If memory serves, the differences were measured in a few hundredths of a deg C. But NOAA didn’t like that, so they removed the satellite-enhanced data from their long-term sea surface temperature reconstruction, making it a poorer-quality dataset, and renamed the dataset ERSST.v3b.
In 2013, GISS switched to NOAA’s ERSST.v3b sea surface temperature dataset from a combination of the UKMO HADISST data before the satellite era and Reynolds OI.v2 satellite-enhanced data starting in 1982. That of course increased the trend of the GISS data a small amount since 1900 and rearranged the highest temperature rankings in the 2000s a tiny amount in their GISS Land-Ocean Temperature Index (LOTI) data.
NOAA still supplies a satellite-enhanced sea surface temperature dataset. It runs from November 1981 to present. It’s known as Reynolds OI.v2, and it’s the dataset I use in my monthly sea surface temperature anomaly updates. (See the November 2014 update here.) It’s the basis for many of the daily sea surface temperature anomaly maps you see online.
[sarc on] Good thing both data suppliers went to all the trouble to change sea surface temperature datasets. On a “Meteorological Annual Mean” basis, the satellite-enhanced sea surface temperature data in 2014 was 0.01 deg C higher in 2014 than in 1998. They gained one one-hundredth of a deg C by excluding the better-quality satellite-enhanced data. Whew!! [sarc off]
See Figures 3 and 4 for the global “Meteorological Annual Mean” sea surface temperatures from 1997 to 2014, with and without the polar oceans, based on the Reynolds OI.v2 data.
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In a few days, GISS and NCDC will publish their November 2014 values. It will be interesting to see where they fall…and also see how alarmists try to make it appear as though the end of the world is near.