Thursday, September 04, 2014

The climate-denial charge about a 1970s global cooling consensus

The title on this Guardian article is a little misleading, Brian Cox: scientists giving false sense of debate on climate change by Karl Mathiesen 09/03/2014. Because it's mainly about physicist Brian Cox talking about how bad climate denial is:

He [Cox] said the strategy of challenging the science of climate change was dangerous because it promoted the idea that science was political and up for debate. This weakens the position of science as a reliable basis for deciding how to respond to the world, he said.

"I always regret it when knowledge becomes controversial. It’s clearly a bad thing, for knowledge to be controversial. We can trace back through history the times when knowledge was considered to be controversial. And that’s what we are actually saying when we talk about climate change. We’re saying that there’s something inherently problematic with knowledge.

"Don’t undermine the science just because you don’t like the economics. That’s a dangerous slope, because the problem of course is you’re not undermining just that, you’re undermining the basis of rational decision-making in society."
He does have some advice for scientists talking about this, trying to work around the limitations of average science literacy among popular audiences.

On of the climate deniers' zombie talking points that keeps lurching around is that idea that them smarty-pants scientists a few years ago were saying that the world was getting colder, not warmer.

Thomas C. Peterson, William M. Connolley and John Fleck address this piece of propaganda in "The Myth of the 1970s Global Cooling Scientific Consensus" Bulletin of the American Meterological Society Sept 2008.

As they report, in the 1970s when the climate science as we know it today was in its formative stage, there was an broad assumption that a a longterm cooling trend was underway (end note references omitted):

Efforts to accumulate and organize global temperature records began in the 1870s. The first analysis to show long-term warming trends was published in 1938. However, such analyses were not updated very often. Indeed, the Earth appeared to have been cooling for more than 2 decades when scientists first took note of the change in trend in the 1960s. The seminal work was done by J. Murray Mitchell, who, in 1963, presented the first up-to-date temperature reconstruction showing that a global cooling trend had begun in the 1940s. Mitchell used data from nearly 200 weather stations, collected by the World Weather Records project under the auspices of the World Meteorological Organization, to calculate latitudinal average temperature. His analysis showed that global temperatures had increased fairly steadily from the 1880s, the start of his record, until about 1940, before the start of a steady multidecade cooling.

By the early 1970s, when Mitchell updated his work, the notion of a global cooling trend was widely accepted, albeit poorly understood. The first satellite records showed increasing snow and ice cover across the Northern Hemisphere from the late 1960s to the early 1970s. This trend was capped by unusually severe winters in Asia and parts of North America in 1972 and 1973 which pushed the issue into the public consciousness. The new data about global temperatures came amid growing concerns about world food supplies, triggering fears that a planetary cooling trend might threaten humanity's ability to feed itself. It was not long, however, before scientists teasing apart the details of Mitchell’s trend found that it was not necessarily a global phenomenon. Yes, globally averaged temperatures were cooling, but this was largely due to changes in the Northern Hemisphere. A closer examination of Southern Hemisphere data revealed thermometers heading in the opposite direction. [my emphasis]
Here's where some minimal scientific literacy is needed to make any kind of reasonable judgment on this.

At that time, there were indications of significant and previously unrecongized shifts in global temperatures. Those shifts could have major implications for human life and civilization, e.g., how they affect food supplies. So scientists and policy makers recognized they needed more study.

As Peterson et al also report (end note references omitted):

In 1965, when U.S. President Lyndon Johnson asked the members of his President’s Science Advisory Committee (PSAC) to report on the potential problems of environmental pollution, climate change was not on the national agenda. The polluting effects of detergents and municipal sewage, the chronic problems associated with urban air pollution, and the risks associated with pesticides dominated public discourse about humanity’s impact on the environment. However, in a 23-page appendix, which today appears prescient, the committee’s Environmental Pollution Panel laid out the following stark scenario: emissions of carbon dioxide from the burning of fossil fuels could rapidly reshape Earth's climate. [my emphasis]
It was a new problem in 1965, in the sense that the available instruments and actual studies were showing it to be a matter of concern.

And they explain that work was also being done at that time on historical studies of longterm climate variations in the past. An engineer and geophysicist named Milutin Milankovitch had speculated as early as 1930 "that that highly regular changes in the tilt of Earth's axis and the eccentricity of its orbit around the sun would change the distribution of sunlight hitting the Earth' surface, leading to the waxing and waning of ice ages." (Peterson et al's summary)
Further research over the following decades had shown the validity of the notion "by the late 1970s."

Because Milankovitch's astronomical metronome was predictable over thousands of years, climate scientists could now begin talking about predicting the onset of the next ice age. And they did. Members of the Climate: Long-range Investigation, Mapping and Prediction (CLIMAP) project lived up to their project’s name with a "prediction" of sorts; in the absence of possible anthropogenic warming, "the long-term trend over the next several thousand years is toward extensive Northern Hemisphere glaciation." (Peterson et al, end note references omitted) [my emphasis]

Research also showed that some kinds of particulates generated by human activity had a cooling effect at the same time that fossil fuel burning tended to raise temperatures.

These studies made great strides in the 1970s. As Peterson et al report (end note references omitted):

In July 1979 in Woods Hole, Massachusetts, Jule Charney, one of the pioneers of climate modeling, brought together a panel of experts under the U.S. National Research Council to sort out the state of the science. The panel's work has become iconic as a foundation for the enterprise of climate change study that followed. Such reports are a traditional approach within the United States for eliciting expert views on scientific questions of political and public policy importance. In this case, the panel concluded that the potential damage from greenhouse gases was real and should not be ignored. The potential for cooling, the threat of aerosols, or the possibility of an ice age shows up nowhere in the report. Warming from doubled CO2 of 1.5°–4.5°C was possible, the panel reported. While there were huge uncertainties, Verner Suomi, chairman of the National Research Council’s Climate Research Board, wrote in the report's foreword that he believed there was enough evidence to support action: "A wait-and-see policy may mean waiting until it is too late". Clearly, if a national report in the 1970s advocates urgent action to address global warming, then the scientific consensus of the 1970s was not global cooling.
In the sound-bite, fact-free culture of FOX News and Republican hate radio, though, this history gets boiled down to, "Aw, them scientists don't know what they're talkin' about. They used to say the earth was coolin' off, now they say it's gittin' hotter."

That way, you don't have to learn to pronounce words like "Milankovitch."

Of course, the people who grind out climate denial papers for the Koch Brothers or other fossil fuel industry sugar-daddies can come up with highfalutin language to nitpick the findings of actual climate scientists. The science denial is science denial.

To quote Brian Cox again, "Don't undermine the science just because you don't like the economics. That’s a dangerous slope, because the problem of course is you’re not undermining just that, you’re undermining the basis of rational decision-making in society."

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