The further to the left or the right you move, the more your lens on life distorts.

Thursday, October 01, 2009

The Yamal Data Set

One of the core concepts in experimental science is the “data set.” Data are collected from a specific source, are archived, and are the analyzed in a variety of different ways to develop a set of findings. The original data must always be available so that other scientists can validate both the analysis that was conducted and the findings that were derived. It’s standard operating procedure.

In most cases, as the size of the original data set grows, the validity of any analysis also grows. Sure, there can and will be a few bad data points, but these wash out statistically as the number of data points increases. To oversimply, that’s why political pollsters don’t query only six people when conducting a national poll.

It seems odd, therefore, that one of the seminal scientific studies that supports the supposition that global temperatures are rising and will continue to rise at precipitous rates (a study referenced by many climate change papers over the past decade) is based on a data set with only 12 data points. It seems even more unusual that the authors of this seminal study chose not to include well over 200 additional data points, even though they were part of the original data set. Even more intriguing is that the authors of the seminal study refused to release the original data set to other investigators for almost nine years.

The data set in question is housed at the Climatic Research Unit (BRU), University of East Anglia, Norwich, U.K. and was named the Yamal data set. It incorporated measurements of tree rings collected throughout the Yamal Peninsula in Siberia. Paleoclimatologists argue that they can determine reasonably accurate indications of ambient temperature from this tree ring data.

Richard Fernandez of The Belmont Club tells the story of a lone (retired) mathematician who spent years try to get a look at the Yamal data set. It tuns out that Yamal was used to depict what has become popularly called the “hockey stick graph.”

Popularized by Al Gore, the hockey stick graph shows a precipitous rise in global temperatures over the last few decades. Using the hockey stick graph as a base, Gore extrapolated the data to claim that catastrophic temperature change (with all of its deleterious effects) was around the corner. This claim has been adopted with religious zeal by some scientists, almost all international politicians, and the Obama administration. As a consequence, massive worldwide policy initiatives are being developed. The question is—are they being developed to solve a problem that has been improperly characterized and incompletely understood.

Andrew Orlowski provides background:
At issue is the use of tree rings as a temperature proxy, or dendrochronology. Using statistical techniques, researchers take the ring data to create a "reconstruction" of historical temperature anomalies. But trees are a highly controversial indicator of temperature, since the rings principally record Co2, and also record humidity, rainfall, nutrient intake and other local factors.

Picking a temperature signal out of all this noise is problematic, and a dendrochronology can differ significantly from instrumented data. In dendro jargon, this disparity is called "divergence". The process of creating a raw data set also involves a selective use of samples - a choice open to a scientist's biases.

Yet none of this has stopped paleoclimataologists from making bold claims using tree ring data.

In particular, since 2000, a large number of peer-reviewed climate papers have incorporated data from trees at the Yamal Peninsula in Siberia. This dataset gained favour, curiously superseding a newer and larger data set from nearby. The older Yamal trees indicated pronounced and dramatic uptick in temperatures.

How could this be? Scientists have ensured much of the measurement data used in the reconstructions remains a secret - failing to fulfill procedures to archive the raw data. Without the raw data, other scientists could not reproduce the results. The most prestigious peer reviewed journals, including Nature and Science, were reluctant to demand the data from contributors. Until now, that is.

At the insistence of editors of the Royal Society's Philosophical Transactions B the data has leaked into the open - and Yamal's mystery is no more.

From this we know that the Yamal data set uses just 12 trees from a larger set to produce its dramatic recent trend. Yet many more were cored, and a larger data set (of 34) from the vicinity shows no dramatic recent warming, and warmer temperatures in the middle ages.

In all there are 252 cores in the CRU Yamal data set, of which ten were alive 1990. All 12 cores selected show strong growth since the mid-19th century. The implication is clear: the dozen were cherry-picked.

It does seem odd that only the data that “proved” the hockey stick hypothesis was chosen, even though many more data points were available, but let’s set that aside for the moment.

It’s reasonable to assert that arguments can be made on both sides of the climate change question. And that’s the problem—this issue is NOT settled. It also seems that some of the data and many of the claims on both sides of the issue represent shoddy science and a distinct political ideology.

Rather than recognizing that the science is far from settled, Left-leaning politicians state emphatically that consensus has been reached and that those who question the “consensus” are “deniers.”

Following the lead of our President in his deliberations over Afghanistan, it might be a good idea to step back for a moment and re-evaluate the science of climate change.

We can and should move forward quickly on energy independence and work very hard to develop and commercialize alternative energy sources. But establishing arbitrary and ultimately unattainable CO2 gas reductions won’t solve the global warming problem if it does exist, but is guaranteed to impose an indirect tax on those least able to afford it.