Local View: A different climate perspective
Local View: A different climate perspective
Dave Kendle, Lincoln Journal Star, 6/26/2015, original
In the debate over man’s impact on climate, those who seek to use climate change as justification for increased taxation and regulation, including our president, often state that “climate change is settled science.” This is done in an attempt to stifle the debate and ridicule those they disagree with. Scientists though, or people who simply understand science, know that there is no such thing as “settled science,” there is only the best understanding we have today, and we know tomorrow’s understanding will be different. In fact, there is actually very little science discussed in this debate, most of it is simply politics, and it is driven by the desire of the political left for increased control over ever more of the economy. This column is intended to inject at least a little science into the discussion.

Do most scientists who study the Earth believe that human activity has an impact on it? Absolutely, to think otherwise would mean ignoring reality; every organism from the smallest bacteria to the largest whale has an impact on the environment. Some have more than others, for example; photosynthesizing plants, as a group, have the most dramatic impact of all. They emit billions of tons of oxygen into the atmosphere. Before them Earth’s natural atmosphere consisted of mainly CO2 and methane. (An interesting side note is the oxygen they emit was a vile poison to the life that existed prior to them, and they likely caused one of the greatest mass extinctions of all times as a result). However, there is no consensus in the scientific community as to the degree of impact human activity has, or whether on balance that impact will be detrimental to human existence, or beneficial to it, and there is certainly no scientific consensus surrounding the politics of the issue. There is no logical progression from recognizing an impact on the environment to adopting a politically left agenda, or for using the government to force that agenda on others.

The U.S. Environmental Protection Agency predicts average temperature increases of 2 degrees to 7 degrees Fahrenheit due to man’s activities. The validity of this prediction is debatable, but I think it’s useful as a tool to help us gain perspective when we compare the history of Earth’s climate, prior to any significant influence from man’s activities, to predicted levels of change. For reference, the current global average temperature is about 57 degrees Fahrenheit.

The last 2 million years have been characterized by the current ice age. Ice ages are actually quite rare on Earth, comprising only about 10 percent of its history. The climate in this time period has consisted of repeated glacial advances (lasting on the order of 100,000 years) and has featured ice over a mile thick covering much of the northern hemisphere. These glacial periods have been interspersed by much shorter (10,000 to 15,000 years) relatively warm interglacial periods like the one we are currently experiencing, which began about 12,000 years ago. During this 2 million year time period, the average global temperature has varied from a low of approximately 42 degrees Fahrenheit, to a high of approximately 67 degrees. At 57 degrees, the current interglacial period is 4 to 10 degrees cooler than the past interglacial periods.

If we examine climate on an even deeper time scale, we find that the Earth has been generally much warmer than it is at present. Looking back over the last 65 million years, which is the time since the extinction of dinosaurs, we see that the average global temperature has been as high as 80 degrees Fahrenheit. We also see that this time period has been characterized by a more or less steadily degrading climate, culminating in the current ice age at its lowest point.

If we look deeper yet, and consider the entire span of time since the evolution of multicellular life on Earth, we find that for about 90 percent of that time, Earth’s average global temperature has been warmer, and usually much warmer (by as much as 27 degrees), than it is now. In fact, while reviewing the last 500 million years, we find that the Earth is nearly as cold now as it has ever been, and the only times it has been colder are when it has been locked in ice.

Few would argue that human life would benefit from a climate where ice covers all of Canada, half of the U.S., and most of Eurasia, yet there is no reason to assume that the recent cycle of long glacial periods interspersed with short interglacial periods has ended. If man’s activities alter this pattern (although there is little reason to believe they will), and the coming glaciation is delayed, some, including me, might argue that would be a good thing.

So, is it possible to debate the scientific data? Yes, and the conclusions I draw from it are obviously open to debate also, but that’s what’s supposed to happen in public discourse.

Dave Kendle of Lincoln has an undergraduate degree in geology and an MBA from the University of Nebraska-Lincoln. He has worked in industrial mineral operations his entire career.