A quite one-sided and scurrilous piece from the Daily Mail, which attempts to rubbish the latest paper from Christy and McNider. (Learn more about the column’s author here.)
John Christy’s paper, “Satellite Bulk Tropospheric Temperatures as a Metric for Climate Sensitivity”, is hardly controversial in itself. It claims that, based on satellite measurements, the rate of atmospheric warming has not accelerated since 1994. (Note – they are not saying that temperatures have stopped rising.)
To reach their conclusions, they have taken out the effect of the two major volcanic eruptions of El Chichon in 1982, and Pinatubo in 1991. They have also adjusted for ENSO changes.
Neither of these adjustments is in any way controversial or illegitimate, and other scientists have also attempted to calculate their effect previously. Of course, the exact calculations can be properly debated.
Nevertheless, it is inarguable that both volcanic eruptions had a significant cooling effect on the Earth’s climate. Given that they both occurred in the early part of the satellite record, they have, as a result, artificially increased the overall warming trend.
Below is the Christy chart:
As I mentioned, others have carried out similar analysis, for instance, Santer at al in 2014, who came to similar conclusions:
Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously.
And published this graph, which bears an uncanny resemblance to the Christy one:
So why all the fuss?
Quite simply, Christy shows that with the effect of volcanoes taken out, the global temperature trend from 1979 to 2017 falls from 0.155C/decade to 0.096C/decade.
In turn, this means that climate models used in IPCC AR5 show more than double the real underlying warming.
So cue the orchestrated attempts to rubbish the Christy paper. These are direct quotes from the Mail article:
1) In the past, however, scientists have slammed Christy’s research for containing numerous flaws and biases; the researcher has even previously claimed that the atmosphere is cooling.
In an article in The Guardian earlier this year, thermal sciences and climate expert Dr. John Abraham pointed out that the researcher has had to make numerous changes to his studies after other experts noted major errors.
Critics of Roy Spencer and John Christy frequently wheel out these sort of ad hominem attacks, when they can’t argue with the facts.
There were undoubtedly many problems with satellite measurements in the early days, as it was very much a learning exercise then. Many of the problems revolved around the inaccurate data that the satellites themselves were sending back.
In 2006, NOAA commissioned a study into look into the historical discrepancies between surface and satellite datasets, with Tom Wigley as Lead Author. It concluded:
Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human-induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies.
For recent decades, all current atmospheric data sets now show global-average warming that is similar to the surface warming.
2) This time around, Abraham toldthat the team is only accounting for one component of Earth’s climate while neglecting other important factors, including the oceans, ice melt data, and temperatures at the ground level.
There are a number of reasons why this statement is grossly misleading.
a) As recently as last year, the Met Office stated:
Changes in temperature observed in surface data records are corroborated by measurements of temperatures below the surface of the ocean, by records of temperatures in the troposphere recorded by satellites and weather balloons, in independent records of air temperatures measured over the oceans and by records of sea-surface temperatures measured by satellites.
Satellite measurements cannot simply be dismissed out of hand.
b) In 2007, the IPCC was also very clear on the matter:
For global observations since the late 1950s, the most recent versions of all available data sets show that the troposphere has warmed at a slightly greater rate than the surface, while the stratosphere has cooled markedly since 1979. This is in accord with physical expectations and most model results, which demonstrate the role of increasing greenhouse gases in tropospheric warming
In short, both actual observations and theory expect atmospheric temperatures to closely follow surface ones.
3) And, Abraham says they’ve manipulated the raw measurements to decrease warming by about 38 percent.
‘He has published a paper in a third-rate journal, possibly because he couldn’t get his results into a more rigorously reviewed journal. His work reportedly shows that by manipulating actual temperature measurements, the rate of warming has been decreased.
As already stated, Christy’s analysis is perfectly legitimate, and simply follows similar work by Ben Santer amongst others.
Abraham’s accusation of “manipulation” is pejorative, with connotations of cheating.
As for dismissing it as a third-rate journal, I am sure the publishers would disagree.
And by “rigorously reviewed”, I take it he means the sort of pal-review which has passed through many climate papers down the years, which have subsequently been quickly debunked by independent experts.
4) Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network, explained that satellite observations, while good at measuring large temperature differences in the context of weather forecasts, are ‘not reliable for small decadal trends’ (i.e 0.1 degrees C per decade)
‘Bottom line,’ Tans wrote in an email to, ‘do not trust satellite records for long-term temperature trends.’
It is hard to know where to start with this fatuous statement.
As already mentioned, both the IPCC and Met Office have confirmed the relevance and accuracy of satellite data.
As for measuring small decadal trends, surely Tans must know that NOAA’s own surface dataset has annual margins of error of 0.15C, and therefore cannot offer the precision he is looking for either.
And NOAA is so confident of the satellite data, including their own NESDIS database, that they include it every year in their annual joint conference with NASA, which presents the latest climate data. Note how closely NESDIS tracks the UAH data.
Furthermore, NOAA’s own radiosonde data also tracks UAH closely.
5) Responding to the new study, Tans said that both atmospheric and ocean observations have shown greenhouse gases have risen since the 1850s, and this is ‘entirely due to human activities.’
Greenhouse gases are known to trap heat in the atmosphere and the oceans. And, Tans says these effects will linger for thousands of years.
‘The relatively large spread of modeling predictions has zero impact on the conclusion, based on solid observations and established understanding of physics and chemistry that climate change is caused by human actions and that we are just seeing the beginnings of it,’
John Christy certainly does not deny the effect of GHGs, and neither do most sceptical climate scientists.
The purpose of Christy’s paper is to quantify and discuss just how much of an effect they might have, something that is highly relevant when public policy is based on the outcome.
To his shame, Tans’ comments do nothing to contribute to this important debate.
It is hard not to conclude that this whole predictable attack has been highly orchestrated.
It is after all hard to believe that the Daily Mail would even know Abrahams or Tans to ask for comments in the first place.
I sense the hand of someone like Bob Ward or Richard Black here.
See Homewood’s investigation into the Who Writes The Mail’s Green Crap?.
Read more at Not a lot of People Know That
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