The image is from an article on how to use Excel to create an extrapolation model that will provide an accurate picture of the future extent of global warming. Click on the image to read the article. The article was written by a math teacher, and provides a kind of "lesson plan" for teaching math that is based on real life.
I find that I am rather preoccupied by the concept of extrapolation as a way to figure out what the future will be. I have written about extrapolation in this Two Worlds blog on at least five different occasions. I generally end up questioning its usefulness as a predictor of "what will happen," at least if the subject matter of the inquiry involves human beings.
Using the principles of extrapolation to illuminate the future should perhaps be called an "unscientific" method, if it attempts to state what the future "will be" based on an extension of the past.
Human beings can always change what they do, in the world that we create. That's why extrapolation doesn't work as a reliable predictor of the future within that world. In the world of nature, the world of "science," the case may be different. We need to be sure not to get them confused.
Sunday, February 5, 2012
#36 / An Unscientific Method
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This graph does not "provide an accurate picture of the future extent of global warming." It provides a picture of atmospheric CO2 concentrations in the northern hemisphere over the past 53 years.ReplyDelete
The attempt to extrapolate on these data is flawed, as are most all climate models, by unsupported assumptions.
"The observations on the top of Hawaii’s Mauna Loa volcano have shown a disturbing rise in CO2 over the last 50 years." It's not disturbing, it's just a trend of only 53 years.
"here is 100 years of abuse of the world’s air, from 1935 to 2035. We will have managed to increase CO2 levels by around 50% in that 100-year period, assuming the model is close. This is not a good thing." It's not abuse. We really don't know if this is a significant change or not, so we cannot know if it is good or bad. It's good for the growth of plants, that thrives in a higher CO2 concentration.
"According to this model, the CO2 concentration in 2035 will be about 470 parts per million." This assumes that CO2 concentrations will continue to increase linearly as they have over the past 53 years. There is no reason to expect this to be true.
"Throughout the past 1 million years, the CO2 concentrations have ranged between 160 ppm (during ice ages) and were sitting around 280 ppm before the Industrial Revolution." This is an inaccurate and misleading interpretation. In fact, atmospheric CO2 concentrations varied considerably over the past million years and they were not "sitting" at a static level before the industrial revolution.
"The inevitable results of this increased carbon? More warming, more violent weather, more severe flooding and droughts, higher food prices, environmental refugees, etc." Nothing is inevitable. Furthermore, and far more importantly, this assumes that there is a linear causal relationship between atmospheric CO2 concentration and global average surface temperature, and even further, this assumes that global average surface temperature is a significant indicator of global climate change.
This is not to say that global average surface temperature is not increasing. It is clearly documented that temperatures across the globe have increased over the past 500 years since the Little Ice Age. This is a normal rebound from the unusually low temperatures following the Medieval Warming Period, when global temperatures were higher than now, and Inuit peoples followed whales migrating across the Canadian Arctic sea from Siberia to Greenland.
In fact, ice core data consistently demonstrate that the concentration of atmospheric CO2 lagged global average surface temperature increase by up to 800 years. In other words, CO2 levels follow temperature fluctuation, not cause it.
Is there global climate variation? Certainly. Do humans affect global climate patterns? Most likley. Can humans "stop" global warming or change the course of natural climate variation. Most certainly not.