How do human beings change the climate? By changing the data.

For nearly two decades, temperatures have refused to follow the projections of global warming alarmist models. The problem was such that they even changed the name of the theory from global warming to “climate change.” Yesterday, the National Oceanographic and Atmospheric Administration (NOAA) had an unusual answer to the questions surrounding the “hiatus” – namely, it was the data’s fault (Bob Tisdale and Anthony Watts, with commentary from Judith Curry, Watts Up With That):

Here, (lead author Tom) Karl and colleagues focused on aspects of the hiatus influenced by biases from temperature observation networks, which are always changing. Using updated and corrected temperature observations taken at thousands of weather observing stations over land and as many commercial ships and buoys at sea, the researchers show that temperatures in the 21st century did not plateau, as thought. Instead, the rate of warming during the first fifteen years of the 21st century is at least as great as that in the last half of the 20th century, suggesting warming is continuing apace.

It was nice for Karl et al to acknowledge the problems rampant in data temperature. Also, contrary to many of my fellow global warming skeptics, I don’t look askance on data adjustment per se. Correcting biases is a key part of any analysis. In climate science, the process is called homogenization; my field (cost estimation) calls in normalization. My problem has always been the lack of transparency on the data adjustments, which are especially a problem with temperature data because recent adjustments have “cooled” the distant past (pre-World War II) and “heated” the recent past (after World War II). This looks a lot like a thumb on the scales to the untrained eye, and the absence of any way for the trained eye to follow the adjustments doesn’t make it any better.

In this case, the data “corrections” are described (somewhat) by Karl…and they have their own problems.

As Ross McKitrick (also in WUWT) noted, the major shift in temperature data is in the oceans, due to three factors: (1) an increase in the weight given to buoys, (2) an adjustment of +0.12 degrees Celsius to all buoy temperature data, and (3) a cooling in ship-collected data from 1998-2000.

The discrepancy between ship data and buoy data is not news, although whether it’s statistically significant is another issue altogether. Most agree, however, that the buoy data is more accurate, not less. This raises the question: why adjust the buoy data upward at all? Why then add more weight to a dataset that you imply has a serious bias problem? Finally, why is ship data adjusted downward for such a small (and anti-hiatus convenient) period? In the case of that last question, Karl et al claim fealty to dataset that…was shared by few, if any, in the field (McKitrick link again).

K15 say that this accounts for about half the new warming in their data set. They defended it by saying that it brought the ship records in line with the NMAT data. However, this particular step has been considered before by Kennedy et al. and Hirahara et al., who opted for alternative methods in part because, as Kennedy et al. and others have pointed out, the NMAT data have their own “pervasive systematic errors”…

So how important are questions like this? Well, as Tisdale and Watts notes, the British have done their own adjustments to the ocean temperature data, and came up with a very different result (Tisdale and Watts link, see Figures 6 and 7). The difference between the NOAA and the British adjustments account for two-thirds of the new warming Karl “found.” The rest could be explained by what climatologist Judith Curry noticed (Tisdale and Watts):

I am also unconvinced by NOAA’s gap filling in the Arctic, and in my opinion this introduces substantial error into their analysis. I addressed the issue of gap filling in the Arctic in this recent publication: Curry JA, 2014: Climate science: Uncertain temperature trends. Nature Geoscience, 7, 83-84.

Relevant text: “Gap filling in the Arctic is complicated by the presence of land, open water and temporally varying sea ice extent, because each surface type has a distinctly different amplitude and phasing of the annual cycle of surface temperature. Notably, the surface temperature of sea ice remains flat during the sea ice melt period roughly between June and September, whereas land surface warming peaks around July 1. Hence using land temperatures to infer ocean or sea ice temperatures can incur significant biases.”

At this point, dear reader, you may be asking yourself why we’re going so deep into the weeds on data here. The reason is this: the aforementioned data – as adjusted by Karl – is supposed to change the debate on global warming dramatically, if not end it entirely. While temperature data issues have been obvious for a while now, and the underlying argument about the theory itself less well known, the “hiatus” has become the greatest political argument against global warming alarmism in recent years. Those who are determined to use ecological disaster as their excuse for dramatic economic change will cling to the Karl paper like lifeline, because that’s exactly what it is.

However, if (as I suspect) these people are wrong, than resources that could have been used to solve the numerous other problems this world has will get misallocated to counter a threat that may be much smaller than the alarmists claim, if it even exists at all. We are only two centuries removed from the Little Ice Age (next year is the bicentennial of America’s “Year Without a Summer”), and contrary to the alarmists’ insistence, it remains a very open question how much of the 19th and 20th century warming was due to LIA recovery, solar activity, or us.

In Hampton Roads this is particularly acute because recent water-level rises are assumed to have a partial cause in global warming. However, most scientists also acknowledge that the land in Tidewater is sinking. How much has dealing with the latter been shunted in favor of clamoring about the former?

Or, as Curry put it in her own blog last year (on another data issue)…

This incident is another one that challenges traditional notions of expertise. From a recent speech by President Obama: “I mean, I’m not a scientist either, but I’ve got this guy, John Holdren, he’s a scientist,” Obama added to laughter. “I’ve got a bunch of scientists at NASA and I’ve got a bunch of scientists at EPA.”

Who all rely on the data prepared by his bunch of scientists at NOAA.

@deejaymcguire | facebook.com/people/Dj-McGuire | DJ’s posts