A story making the rounds is creating headlines such as the one in the ever credulous Arizona Daily Star: “Flatulent dinosaurs helped warm Earth, study says.” British researchers posit that the flatulence of herbivorous dinosaurs produced so much methane that it warmed the climate. The paper, published in Current Biology is summarized by the authors as follows:

Mesozoic sauropods, like many modern herbivores, are likely to have hosted microbial methanogenic symbionts for the fermentative digestion of their plant food. Today methane from livestock is a significant component of the global methane budget. Sauropod methane emission would probably also have been considerable. Here, we use a simple quantitative approach to estimate the magnitude of such methane production and show that the production of the greenhouse gas methane by sauropods could have been an important factor in warm Mesozoic climates.

If you read the story (full text here) you will find that the contention depends on many assumptions and rather extravagant extrapolation. The gassiest dinosaurs were the Sauropods which became abundant during the Jurassic Period about 150 million years ago. Global temperatures are estimated to have been 18 F warmer than today, but that warmth began in the preceding Triassic Period about 250 million years ago. There seems to be a timing problem. Also, the researchers estimate that the amount of methane produced by dinosaurs was similar to the amount produced today by livestock farming and industry, so why aren’t we warmer?

At the end of the paper, the researchers note as an attempted justification for their speculation:

 ”Although dinosaurs are unique in the large body sizes they achieved, there may have been other occasions in the past where animal-produced methane contributed substantially to global environmental gas composition: for example, it has been speculated that the extinction of megafauna coincident with human colonization of the Americas may be related to a reduction of atmospheric methane levels.”

That references a 2010 paper in which the researchers estimated the amount of methane produced by mammoths and other large herbivores. They speculate that the arrival of humans in North America and the subsequent disappearance of these animals reduced methane emissions and led to an abrupt cooling period, the Younger Dryas, about 12,800 years ago.

At the end of the Younger Dryas, the global temperatures and atmospheric methane both rose rapidly. So where did the methane come from since those flatulent mammoths were no more? The mammoth fart theory fails to explain previous similar abrupt cooling and warming in the Older Dryas period and the Oldest Dryas period, nor a subsequent similar event about 8,200 years ago.

Both of these papers present interesting stories, but they both fail upon close inspection. Still, science is speculative and the stories make headlines and get the authors published.

See also:

Arizona Geological History Chapter 5: Jurassic Time

Ice Ages and Glacial Epochs

Research Review 3 Climate cycles and a Mammoth Mystery

“Madness is the exception in individuals but the rule in groups.” – Nietzsche.

There is an interesting post at WUWT by Paul MacRae which examines why the climate debate is so polarized: “Why climate science is a textbook example of groupthink.” It examines the question of why even “the best and the brightest” can be so wrong. There are many examples in history such as the Vietnam war, Watergate, the Bay of Pigs, the Edsel, New Coke.

There are three main categories of symptoms in the “Groupthink syndrome:”

1. Overestimate of the group’s power and morality, including “an unquestioned belief in the group’s inherent morality, inclining the members to ignore the ethical or moral consequences of their actions.”

2. Closed-mindedness, including a refusal to consider alternative explanations and stereotyped negative views of those who aren’t part of the group’s consensus. The group takes on a “win-lose fighting stance” toward alternative views.

3. Pressure toward uniformity, including “a shared illusion of unanimity concerning judgments conforming to the majority view”; “direct pressure on any member who expresses strong arguments against any of the group’s stereotypes”; and “the emergence of self-appointed mind-guards … who protect the group from adverse information that might shatter their shared complacency about the effectiveness and morality of their decisions.”

It’s obvious that alarmist climate science—as explicitly and extensively revealed in the Climatic Research Unit’s “Climategate” emails—shares all of these defects of groupthink, including a huge emphasis on maintaining consensus, a sense that because they are saving the world, alarmist climate scientists are beyond the normal moral constraints of scientific honesty (“overestimation of the group’s power and morality”), and vilification of those (“deniers”) who don’t share the consensus.

Read the entire article here.

The comments on that post are interesting also.

From the unintended consequences department: A new study, which confirms several previous studies, presents observational evidence that shows “a significant warming trend of up to 0.72 °C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions.”

The paper and abstract:

Zhou, Liming, Yuhong Tian, Somnath Baidya Roy, Chris Thorncroft, Lance F. Bosart and Yuanlong Hu 2012: Impacts of wind farms on land surface temperature. Nature Climate Change. doi:10.1038/nclimate1505

The abstract reads

The wind industry in the United States has experienced a remarkably rapid expansion of capacity in recent years and this fast growth is expected to continue in the future. While converting wind’s kinetic energy into electricity, wind turbines modify surface–atmosphere exchanges and the transfer of energy, momentum, mass and moisture within the atmosphere. These changes, if spatially large enough, may have noticeable impacts on local to regional weather and climate. Here we present observational evidence for such impacts based on analyses of satellite data for the period of 2003–2011 over a region in west-central Texas, where four of the world’s largest wind farms are located. Our results show a significant warming trend of up to 0.72?°C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions. We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind turbines.

This phenomenon has implications for the surface temperature record in that it tends to bias the readings. Dr. Roger Pielke (University of Colorado) notes that “Because of the redistribution phenomena and the shallow layer affected, observed minimum temperatures are a very poor measure of the accumulation of heat in the atmosphere.” As a consequence, he recommends, “the minimum land surface air temperature should not be used as part of the construction of a global average multi-decadal surface temperature trend.” Pielke maintains that any large-scale land use change such as urbanization and deforestation can have similar results.

I’ve reported a previous study by M.I.T. study that found similar results:

Electricity generated by wind power may raise temperatures and costs