February 19th, 2020

The physics is clear: it will get hotter

By Letter to the Editor on September 7, 2019.

In an Aug. 27 letter to The Herald, Shawn Smith suggested that our understanding of the greenhouse effect here on Earth is an extrapolation from observations of Venus. He goes on to describe concern over the greenhouse effect as “a leap of logic.” In doing so, he is being extremely unfair to the physical sciences community.

The field of molecular spectroscopy, the study of the absorption of radiation by molecules, is well over 100 years old. Similarly, the study of energy transfer between molecules has its roots in early 20th-century science, and has been pursued vigorously since at least the 1960s. Gas dynamics, through which we understand larger-scale transfers of heat and matter in the atmosphere, has been studied seriously since the mid-19th century. I could go on.

We understand the underlying physics of the greenhouse effect very, very well, and our understanding of the relevant processes, at both small and large scales, continues to advance. Expected warming trends are calculated from basic physics, and not extrapolated from a single data point as Mr. Smith suggests.

Mr. Smith’s argument regarding the relative concentrations of carbon dioxide in the Venusian and Earth atmospheres is a seductive one. How could such a small quantity of carbon dioxide have the dramatic effects claimed? The difficulty lies in thinking about balances between heat gained by the atmosphere, in particular by infrared radiation from the Earth’s surface, and heat lost to space. Greenhouse gases act like a blanket, slowing the escape of infrared radiation, one of the planet’s most important means of dissipating heat. If you make the blanket thicker (adding more carbon dioxide), heat escapes more slowly, raising the temperature of the atmosphere.

Our understanding of global warming is based on a great deal of well-understood physics. By adding CO2 to the atmosphere faster than it can be removed, we are thickening the blanket that keeps our planet warm. Whether we like it or not, the physics is inescapable: it’s going to get hotter.

Marc R. Roussel

Professor, Department of Chemistry and Biochemistry

University of Lethbridge

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14 Responses to “The physics is clear: it will get hotter”

  1. Good to see a letter on heat transfer from earth to space that avoids hysterical claims of imminent disaster. Time to get back to basics?

  2. IMO says:

    Mr. Pendergast’s response goes beyond callousness. Pendergast’s assertion that Professor Roussel’s letter avoids any “hysterical claims of imminent disaster” completely ignores the devastation wrought by hurricane Dorian in the Bahamas and the forecast for storm surges and flooding as Canadians living in coastal areas in the maritimes evacuate their homes and prepare for Dorian’s landfall later tonight.

    • Huh? Hurricane Dorian? Is that somehow significantly connected to Professor Roussel’s letter, IMO?

      • IMO says:

        “The strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth’s climate is warmed by increasing levels of greenhouse gases in the atmosphere. Although we cannot say at present whether more or fewer hurricanes will occur in the future with global warming, the hurricanes that do occur near the end of the 21st century are expected to be stronger and have significantly more intense rainfall than under present day climate conditions. This expectation (Figure 11) is based on an anticipated enhancement of energy available to the storms due to higher tropical sea surface temperatures.”


  3. biff says:

    with regard to the smith letter, let us consider the folly of comparing overkill/saturation to the smallest level of what it takes to kill something. to provide such an extreme standard, as smith does, roughly equates with suggesting that because someone drank a gallon of arsenic to kill oneself, or was riddled by 100 bullets and died (venus and its c02), that one could not possibly perish simply by drinking a mere ounce of arsenic or being hit by only one bullet (earth and its c02). smith’s basis is utter nonsense, while we get a far more acceptable basis from mr roussel.

    • grinandbearit says:

      I am trying to decide if confirmation bias or cherry-picking better describes GM’s interaction with information on the web. Definitely confirmation bias… or maybe cherry-picking.. tough call. So many fallacies and just one guy.

  4. zulu1 says:

    Another way to look at this situation is that if co2 levels are the major cause of global warming ,as supported by governments around the world then new sources of taxation (ie carbon taxes) can be implemented. Secondly , research funding will only be provided if your research confirms this point of view. No bias here !

  5. phlushie says:

    Right on Zulu. Colllaboration to divert personal finances.

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