Climate alarmists are pushing a storyline this month that atmospheric carbon dioxide levels are higher now than at any time in the past 3 million years. The last time carbon dioxide levels were this high, “sea levels were as much as 65 feet higher than they are now, Greenland was mostly green and Antarctica had trees,” USA Today ominously warns (https://www.usatoday.com/story/news/nation/2019/04/04/global-warming-earths-carbon-dioxide-levels-highest-3-million-years/3367027002/). CNN (https://www.cnn.com/2019/04/04/health/co2-levels-global-warming-climate-intl/index.html), The Weather Channel (https://weather.com/news/news/2019-04-04-current-co2-levels-highest-in-three-million-years), and many other media sources are making the same claims. In reality, the claims support the mountains of existing evidence that the Earth’s climate is not very sensitive to atmospheric Carbon Dioxide.
If CO2 is the primary driver of the earth’s climate, then the Earth’s climate should be just as warm now as it was the last time carbon dioxide levels were this high. Sea levels should be 65 feet higher than they are, Greenland should be mostly devoid of ice, and forests should be populating Antarctica. Yet none of these are the case. In fact, none of these are even close to being the case. Nor would they be close to occurring even if our recent warming continues for several more centuries. If CO2 drives climate change, why aren’t temperatures even close to as warm as they were when Carbon Dioxide levels were this high in the past?
Curiously, the current media stories about unprecedented carbon dioxide levels are based on a paper published this month in Science Advances (https://advances.sciencemag.org/content/5/4/eaav7337). The paper’s abstract points out that natural factors induced the ice age epoch that has resulted in glaciers covering much of the northern hemisphere for most of the past 3 million years. The authors of the paper programmed a computer model they claim replicates warming and cooling periods within that 3 million years. Yet the paper observes that during that time span, temperatures have been as much as 2 degrees Celsius warmer than today – long before humans began emitting carbon dioxide into the atmosphere. So once again, if carbon dioxide drives the Earth’s climate, why have temperatures been substantially warmer than today when carbon dioxide levels were lower?
Carbon Dioxide levels may be higher than any time during the past 3 million years. If that is so, however, it merely shows that the Earth’s climate is not nearly as sensitive to carbon dioxide as alarmists claim. Mark this another nail in the coffin of debunked climate alarmism.