The Weekly Carboholic: independent statisticians reject recent global cooling claims in blind analysis

Posted on November 12, 2009




Climate disruption deniers have been claiming for years now that the global temperature has been cooling down, even though the temperature data clearly shows that it isn’t. Scientists and statisticians have pointed out that, mathematically speaking, the recent reduced warming trend is well within the noise, or put another way, it’s weather, not climate.

A new report by the Associated Press reveals what many of us knew already – the denier’s claims don’t hold water, statistically speaking. The report is intriguing because the AP provided their data to four independent statisticians without telling them what it was, and all four found that the slower warming of the past decade was statistically insignificant with respect to the actual data.

In a blind test, the AP gave temperature data to four independent statisticians and asked them to look for trends, without telling them what the numbers represented. The experts found no true temperature declines over time.

“If you look at the data and sort of cherry-pick a micro-trend within a bigger trend, that technique is particularly suspect,” said John Grego, a professor of statistics at the University of South Carolina.

Furthermore, the data that the AP sent to the statistician came from two different sources – the National Climate Data Center (NCDC), run by NOAA, and the satellite data preferred by climate disruption deniers that is generated by scientists John Christy and Roy Spencer from the University of Alabama in Huntsville. In both cases, the statisticians found no statistically significant trends over the last ten years.

Statisticians who analyzed the data found a distinct decades-long upward trend in the numbers, but could not find a significant drop in the past 10 years in either data set. The ups and downs during the last decade repeat random variability in data as far back as 1880.

Saying there’s a downward trend since 1998 is not scientifically legitimate, said David Peterson, a retired Duke University statistics professor and one of those analyzing the numbers.

Identifying a downward trend is a case of “people coming at the data with preconceived notions,” said Peterson, author of the book “Why Did They Do That? An Introduction to Forensic Decision Analysis.” (emphasis mine)

The AP interviewed Don Easterbrook, who claimed that “We started the cooling trend after 1998. You’re going to get a different line depending on which year you choose.” According to one of the statisticians, the fact that you have to choose 1998 as your starting point in order to observe a (statistically insignificant) cooling trend is part of the problem.

Grego produced three charts to show how choosing a starting date can alter perceptions. Using the skeptics’ satellite data beginning in 1998, there is a “mild downward trend,” he said. But doing that is “deceptive.”

The trend disappears if the analysis starts in 1997. And it trends upward if you begin in 1999, he said.

This is what’s referred to in statistics as “endpoint sensitivity,” and it’s the main reason that climate disruption deniers like Easterbrook can appear and sound so reasonable when they’re actually misusing or misunderstanding the data.


DDTfig2Melting glaciers releasing pollutants from decades ago

A study published in the journal Environmental Science & Technology has revealed a new and troubling aspect to climate disruption – as glaciers melt, they are releasing persistent organic pollutants like DDT, PCBs, other pesticides, and synthetic musks (chemicals that mask body odor).

The scientists studied the annual sediment layers in a high alpine lake in Switzerland and found that there the annual flux of pollutants varied consistently across all the studied pollutants – the fluxes started low in the 1950s, peaked in the 1960s and 70s, dropped off again in the 1980s, and then rose to a new peak in the late 1990s. But in the case of all the pollutants except for musks, the production of the pollutants ceased by 1986 at the latest, and the musks have been in constant production globally since the late 1980s. The image at right illustrates these peaks for the various pollutants the scientists studied.

According to the study, the first peak corresponds closely to when the production of the various pollutants peaked, either in Switzerland or in continental Europe. That peak likely is a result of airborne delivery of the pollutant, either by way of dust or precipitation depositing the pollution in the lake and surrounding land directly. But since there has been no production (or constant production) of the pollutants in decades, it’s extremely unlikely that dust or rain/snow is responsible for the second peak.

In addition, the authors compare the results from the high alpine, glacial melt-fed lake to several other lower altitude lakes. The comparison shows that the low altitude lakes do not show the same spike in pollutants in the late 1990s that the alpine lake does, but they do show similar dust/precipitation driven spikes in the 1950s, 60s, and 70s.

As a result, the authors’ hypothesized that glacial ice had been accumulating pollutants since the 1960s and 70s and then started releasing those pollutants into the lake as the pollution-laden ice melted. And given the strength of their data, they’re almost certainly correct.

The ramifications of this are significant. Other studies have found recent increases in pollutants around the world even though the production of those pollutants stopped decades ago. Pesticides have been discovered in alpine lakes in the Italian Alps and the Canadian Rockies, and Antarctic penguins have been found to have old DDT in their bodies. If this result holds for other glacially-fed lakes around the world (and there’s no reason to believe that the results won’t hold), then the dangerous pollutants that environmentalists thought had largely been phased out will return and could cause similar ecological damage as they caused decades ago (DDT-thinned eggshells, fishing limitations due to PCBs, etc.). And all as a result of glacier melt that has been caused or enhanced by climate disruption-driven warming. And the results of the study point out that the pollutants present in the studied lake are not likely to be everything that the glacier holds:

The burden of pollutants in Lake Oberaar sediment due to glacier melting is already in the same range as the earlier accumulation from direct atmospheric input. The undiminished increase of the fluxes of many organohalogens into the sediment of Lake Oberaar does not yet prefigure an exhaust of the glacial inventory of these contaminants.

In other words, the environmental toll of these pollutants isn’t over yet by a long shot.


gasburnersIEA: climate treaty necessary to keep energy prices low

There are many reasons to address climate disruption, ranging from saving species to reducing U.S. dependence on foreign oil to reducing the chance of catastrophic drought. The economy is usually not considered to be one of the reasons, especially by those who have a vested interest in maintaining their own profits at the expense of the environment and global climate. However, there are those who say that addressing climate change is critical to maintaining a healthy future economy. According to a new Reuters article, we can now add to that small but growing list the International Energy Administration (IEA).

Reuters interviewed Fatih Birol, author of the International Energy Agency’s World Energy Outlook, and he said that the world needed to work towards a carbon dioxide (CO2) concentration of no higher than 450 ppm in order to keep energy costs from skyrocketing by 2030. According to Birol’s estimates, Europe alone would see energy prices increase by 300% over the average of what Europe paid over the last 30 years, from $160 billion per year to $500 billion.

Birol’s also estimates that oil prices will reach $100 per barrel by 2015 and $190 per barrel by 2030. Given that there is evidence that the high oil prices of 2008 were part of what caused the global recession, this should make the U.S. and other oil dependent countries nervous. And the global oversupply of natural gas that is keeping prices low in the U.S. this year won’t last – Birol estimates that the demand for natural gas by 2030 will far outstrip supply.

The Guardian is reporting that an anonymous IEA whistleblower is claiming that US pressure has been applied to redefine the point at which peak oil occurs. If this is true and can be verified, then peak oil is probably much closer than previously expected and Birol’s estimates are very likely optimistic. Similarly, Reuters doesn’t discuss whether Birol has any coal estimates or not, but the USGS has pointed out that the U.S. could be approaching “peak coal” as well, after which the price of energy would skyrocket.

Diversifying energy out of carbon-based fossil fuels makes sense from an environmental perspsective, from a climate disruption perspective, from a green jobs perspective, and from an economic perspective. All that remains is for the world’s governments to accept that it makes sense from a political perspective as well.


floatcityFloating cities as a response to sea level rise

Some ideas are just too cool and deserve mention just because they’re cool. According to the NYTimes blog Green Inc., the Dutch are designing floating cities to replace or augment land-based cities as the global sea level rises over the next few centuries. The floating cities would be connected to each other and to the mainland via floating highways and rail lines. According to the article, the designers plan to use the ocean to help moderate the cities’ temperatures in much the same way as ground source heat pump does – pump cold water up from the depths beneath the city in order to cool it efficiently.

In case you’re not convinced that concrete can be made to float, there are floating bridges across Lake Washington in Seattle – the glacially-carved lake is far too deep to drive pilings into the lake bed to support the bridge, so it floats instead.

The first floating proof-of-concept residences in a Rotterdam residential neighborhood are expected to be available in 2010.


American Physical Society rejects changes to climate change statement

Earlier this year, a small group of American Physical Society (APS) members requested that the APS change it’s official statement on climate change. This statement reads:

Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth’s climate. Greenhouse gases include carbon dioxide as well as methane, nitrous oxide and other gases. They are emitted from fossil fuel combustion and a range of industrial and agricultural processes.

The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.

Because the complexity of the climate makes accurate prediction difficult, the APS urges an enhanced effort to understand the effects of human activity on the Earth’s climate, and to provide the technological options for meeting the climate challenge in the near and longer terms. The APS also urges governments, universities, national laboratories and its membership to support policies and actions that will reduce the emission of greenhouse gases.

A committee was appointed by the Council earlier this year to determine if the latest science justified any changes to the statement. According to the official APS press release, the committee recommended that no changes be made, and on November 8, the Council of the American Physical Society “overwhelmingly” rejected the proposed changes to the 2007 statement on climate change.

Appointed by APS President Cherry Murray and chaired by MIT Physicist Daniel Kleppner, the committee examined the statement during the past four months. Dr. Kleppner’s committee reached its conclusion based upon a serious review of existing compilations of scientific research. APS members were also given an opportunity to advise the Council on the matter. On Nov. 8, the Council voted, accepting the committee’s recommendation to reject the proposed statement and refer the original statement to POPA for review.

The APS has over 47,000 members, of which only 206 appear to have signed the petition to the APS Council. That’s about 0.4% of the APS membership. According to the 2009 “Six Americas” study by the Yale Project on Climate Change and the George Mason University Center for Climate Change Communications, fully 18% of Americans are either doubtful or dismissive of climate disruption. If those numbers applied to the 47,000 members of the APS, we could expect almost 8500 signatories to the APS petition.

There are three possible interpretations of this difference:

  1. Physicists may be less willing to sign online petitions for whatever reason(s).
  2. Physicists may actually be more knowledgeable of the science and mathematics than the average American (or less easily swayed by denial industry-manufactured FUD) and thus they accept the overwhelming scientific data to date.
  3. Both 1 & 2

My best guess is that it’s probably option #3. But even so, I doubt that reticence to sign petitions accounts for a 45x difference from physicists to the general population.

Image credits:
Geophysical Research Letters
Environmental Science & Technology
Delft University, via Green Inc

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