The climate alarmist crowd never tires of insisting that anthropogenic additions to atmospheric carbon dioxide—up by 45 percent, from 280 to about 407 parts per million, since before the Industrial Revolution—are driving historically unprecedented and likely-to-become catastrophic global warming, and that they’re exacerbated by increases in atmospheric methane (CH4) driven by the rising temperature, making methane a positive feedback. The claim rests on the notion that carbon dioxide level drives temperature rather than vice versa.
Long-term geological data show a pretty consistent correlation between CO2 and temperature, giving the claim its initial attractiveness.
But there’s a problem. Detailed analysis of the data shows that the time sequence is opposite what the claim requires.
That’s been shown by a variety of studies in the past, including Cornwall Alliance Senior Fellow David Legates’s review article “Carbon Dioxide and Air Temperature: Who Leads and Who Follows?” Two-and-a-half years ago geologist Euan Mearns contributed “The Vostok Ice Core: Temperature, CO2, and CH4.”
Now Mearns has followed up with “The Vostok Ice Core and the 14,000 Year CO2 Time Lag,” which makes the case more strongly than ever. Here’s his lead:
A detailed analysis of temperature, CO2 and methane variations from the Vostok ice core is presented for the time interval 137,383 to 102,052 years ago. This captures the termination of the glaciation that preceded the Eemian interglacial and the inception of the last great glaciation that succeeded the Eemian. At the termination, CO2 follows dT exactly, but at the inception CO2 does not follow temperature down for 14,218 years. Full glacial conditions came into being without falling CO2 providing any of the climate forcing. This falsifies the traditional narrative that dCO2 amplified weak orbital forcing effects. It is quite clear from the data that CO2 follows temperature with highly variable time lags depending upon whether the climate is warming or cooling.
Methane on the other hand lags temperature by about 2,000 years at the termination but follows temperature down exactly at the inception. It therefore follows that methane and CO2 are not coupled. Each responds in their own time to changing climate. The absence of coupling may be explained by the different bio-geochemical pathways these gasses have in the biosphere – ocean – atmosphere system.
Ken Haapala, President of the Science and Environmental Policy Project, writing in SEPP’s latest newsletter, summarizes the lessons from Mearns’s lengthy piece:
CO2 and Ice Ages: Geologist Euan Mearns takes a close look at the data on temperatures, carbon dioxide (CO2), and methane (CH4) found in the Vostok Ice Core of Antarctica. Many in the climate establishment will not like what he sees. He focuses on the Eemian warm period between 130,000 and 115,000 years ago. This warm period was the last warm period before the current warm period, the Holocene. In her 2008 graphs showing the relationship between CO2 and temperatures from the Vostok Ice Core covering the entire record, Jo Nova stated the average lag was about 800 years, with temperatures rising (falling) about 800 years before CO2 rising (falling). This lag indicates that CO2 could not be the cause of rise or fall of temperatures. In the data, the largest lag was in the Eemian, particularly with falling temperatures.
Mears examines, in detail, the period of cooling from 128,300 years ago to 114,082 years ago, a period of over 14,000 years. During this period, CO2 concentrations varied around 270 ppm (parts per million), between 260 and 280 ppm. Yet, temperatures steadily dropped over 7 degrees K while CO2 concentrations remained roughly constant.
This analysis clearly showed that the earth cools independently of CO2 concentrations. The argument advanced by members of NASA-GISS, and others, that CO2 is the control knob of the earth’s temperatures is directly contradicted by the evidence. There is a loose relationship between rising temperatures and rising CO2, but not between falling temperatures and falling CO2. Ice Ages occur despite relatively high concentrations of CO2. (Note: laboratory experiments show the relationship between CO2 and temperatures are highly logarithmic, and increasing concentrations of CO2 from about 270 ppm to levels found today of about 400 ppm have a minor effect on increasing temperatures.)
Mearns performs a similar analysis on the relationship between temperature and methane (CH4). He found that as the temperatures rose into the Eemian interglacial, methane concentrations lagged behind, by a few thousand years. But, when temperatures fell, going into the next ice age, methane concentrations closely followed.
His findings for the Eemian can be summarized as follows: When temperatures rise, CO2 closely follows; when temperatures fall, CO2 separates. When temperatures rise, CH4 lags behind; when temperatures fall, CH4 closely follows.
Mearns speculates on the varying lags. When temperatures rise, oceans rapidly release CO2. When temperatures fall, plant growth produced by higher temperatures and CO2 release the CO2 slowly. The oceans slowly absorb this release of CO2. For CH4, when temperatures rise, bacteria producing the methane react slowly; but when temperatures fall, they freeze rapidly.
Then, what causes the fall (and increase) in temperatures if the Milankovitch cycles are too weak to explain them alone as the climate establishment claims? Mearns suggests it may be variation in the thermohaline circulation of the oceans. This has been suggested by others such as the late Bill Gray. Some scientists suggest it was the closing of Caribbean seaway about 5 million years ago that set up the thermohaline circulation resulting in current period of ice ages starting about 3.5 million years ago.
Another nail in the coffin of climate alarmism—and all the more reason for the demise of the United Nations Framework Convention on Climate Change and its offspring, the Paris climate accord. The Trump Administration should be listening.