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Dr. Andrew Dessler in ‘Introduction to Modern Climate Change': “Is today’s climate changing? […] The answer is an emphatic yes.” [General Commentary]

January 15, 2014 12:42 am1 comment


Dr. Andrew Dessler in “Introduction to Modern Climate Change” (p. 25):

Putting it all together: Is today’s climate changing?

The answer is an emphatic yes! In fact, the evidence is so strong that the IPCC calls today’s warming unequivocal — meaning it is beyond doubt. It is worth exploring the source of high confidence in this conclusion. First, there is great consistency among the various data sets. The surface thermometer record as well as the satellite record show that temperatures are going up. The loss of ice on the Earth’s surface is consistent with these increasing temperatures, as is in the increase in the heat content of the ocean. Finally, the observation of increasing seal level fits with both the loss of ice and the increasing heat content of the ocean.

Introduction to Modern Climate Change (cover)

Importantly, these various data sets are susceptible to different kinds of errors. For example, issues such as changes in the station environment, which may affect the surface thermometer record, do not affect the satellite record. Issues such as orbit drift affect the satellite record but do not affect the surface thermometer record. And neither of these problems affects the measurements of glacier length or sea level. This means that there is no single problem or error that could push all of the temperature data in the same direction. Because of this, there is essentially no chance that enough of these sources could be wrong by far enough, and all in the same direction, that the overall conclusion that the climate is currently changing could be wrong.

Moreover, the data sources we have reviewed are just a small part of the mountain of evidence that the Earth is warming. Other corroborating evidence includes decreased northern hemisphere snow cover, thawing of Arctic permafrost, strengthening of mid-latitude westerly winds, fewer extreme cold events and more extreme hot events, increased extreme precipitation events, shorter winter ice seasons on lakes, and thousands of observed biological and ecological changes that are consistent with warming (e.g., poleward expansion of species ranges and earlier spring flowering and insect emergence). Not every single data set shows warming, but such contrary data are rare, regionally limited, and vastly outnumbered by evidence of warming.

Because of this, there should be no question in your mind that the Earth’s climate is warming.

Source: Andrew E. Dessler, Introduction to modern climate change, Cambridge University Press, 2011. (Book websiteCambridge’s book websiteReview in BAMSReview in Physics Today).

The above excerpt and textbook cover are republished under fair use. See 17 U.S.C. 107.



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  • John Nielsen-Gammon

    Andy and I are in the same department here at Texas A&M, so I’m going to plead conflict of interest. However, this does go back to how you define warming…see my comments on the NIPCC fact check from last week.