Category Archives: Climate science

2018 surface temperature update, part 1: Recent divergences continue

gmst-diff-1996-2018-nasa-hc-2018-12-1.png2018 was the fourth warmest year in the global surface temperature record, according to year end updates from NASA, NOAA and the UK MetOffice, albeit somewhat cooler than the 2016 peak. This continues a string of record or near-record annual temperatures, with the top four occurring in the past four years.

As in my previous updates (see here and here), I’ll provide some additional context, highlighting the issue of coverage bias and ongoing Arctic warming.  Series that use statistical methods to account for areas with few or no observations, especially in the Arctic, continue to diverge markedly from  those with little or no interpolation. Recent observations also show the emergence of a seasonal pattern in Arctic warming, an important aspect of coverage bias that has been less explored thus far. In addition, the last decade or so has seen the emergence of ship-buoy SST bias, first identified in a key 2015 paper from NOAA and confirmed in our 2016 paper.

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2017 surface temperature update

The recent synchronized update of all four of the most closely followed temperature series (along with the buoy-based SST series from our 2016 paper, Hausfather et al) has inspired a long overdue surface temperature update.  First I’ll look at the four global temperature series over the last 35 years, and then examine 2017 in the context of recently identified biases in GMST records.

GMST oper 1980-2017 2017-09

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Coverage bias and recent trends in global surface temperature, part 1

In retrospect, 2014 was an interesting year for climate watchers, and a turning point of sorts. That year, global mean surface temperature matched record highs for the instrumental period, without any assist from the El Nino weather pattern that usually accompanies such warm years.  That turned out to be a prelude to a record-smashing 2015. And 2016 may well provide an unprecedented third surface temperature record in a row, as the influence of  the current super El Nino will likely peak in the first half of this year.

But 20GMST 1990-201414 was also notable scientifically for the emergence of a previously under-examined scientific issue: namely coverage bias in observed surface temperature series, especially the HadCrut4 record issued by the UK Met Office.

This most widely cited temperature series does not account for missing areas, especially in high latitudes, likely leading to an underestimate of the overall rise in global temperature since the 19th century.

Not only that, but there is increasingly compelling evidence that the recent short-term slowdown in the surface temperature record was much less pronounced than previously estimated, if rapid Arctic warming is fully reflected, along with potential biases from the changing mix of sea surface temperature measurement sources in recent years.  Thus the discrepancy between very short-term and multi-decadal trends in the observations appears to have been exaggerated in prior estimates, including IPCC AR5.

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Open Thread #8

I’m working on two or three projects that are taking a little more time than I would like. But in the mean time, here’s a new thread for open discussion of climate science and related matters not discussed in other recent threads.

A first look at UAH 5.3

Readers here (and elsewhere) have noted the release of a new version of the UAH satellite-derived tropospheric temperature record by John Christy and Roy Spencer. As noted by Spencer on March 5, version 5.3 seeks to remove, or at least mitigate, a spurious annual cycle that was apparently exacerbated in the changeover from the older MSU sensors to the newer AMSUs back in 1998.

The new data set is now available, so I’ll show some graphs that highlight the differences between the two versions. But first I’ll give a brief background on the matter, including my role.

[Update, March 10: It appears that John Christy was first notified of the annual cycle issue in October 2008, although it is unclear whether he understood the implications at that time. ]

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Vaclav Smil on climate change: “No global warming in past ten years”

Smil at Q2CHere’s an astonishing segment from a  recent interview with futurist Vaclav Smil, conducted by New York Times environmental reporter Andrew Revkin. Smil claims that there has been “no global warming in the past ten years” and appears to suggest that we can safely ignore the problem of climate change because it won’t hit with “full force” any time soon, and its full impact is as yet unknown.

The interview came last Saturday at the Quantum to Cosmos Festival (Q2C)l in Waterloo, Ontario, a 10-day presentation of the Perimeter Institute for Theoretical Physics. Smil is a professor at the University of Manitoba in Winnipeg, and the author of 30 books, the most recent being “The Global Catastrophes and Trends: The Next Fifty Years.”

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Let the backpedalling begin

KHantemirovRM Fig 5 zoomThe latest battle over the “hockey stick” has taken quite a turn, one that may finally lay to rest all the  absurd claims of its demise made by contrarians (not to mention apparently libelous accusations of scientific malfeasance). In previous posts, we discussed climate blogger Steve McIntyre’s scurrilous accusations of “cherrypicking” against UK dendrochronolgist Keith Briffa, and summarized a a quick technical critique of McIntyre’s work by a dendrchronologist known as Delayed Oscillator.

Now comes new evidence that McIntyre’s accusations were completely false. And not only that, one of the Russian researchers who actually control the raw tree-ring data that McIntyre was mistakenly hounding Briffa for, has apparently confirmed that utilization of  a newer more complete Yamal data set has no substantial effect  on Briffa’s Yamal temperature reconstruction.

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