Ice Core Data Debunk CO2 Level Concerns

The NOAA Climate.gov website provides “science & information for a climate-smart nation”.  A February 20, 2020 post “Climate Change: Atmospheric Carbon Dioxide” included the concern :

The global average atmospheric carbon dioxide in 2018 was 407.4 parts per million (ppm for short), with a range of uncertainty of plus or minus 0.1 ppm. Carbon dioxide levels today are higher than at any point in at least the past 800,000 years.

They post summarized the concern with the following highlights:

·  Human activities have increased the natural concentration of carbon dioxide in our atmosphere, amplifying Earth's natural greenhouse effect.

·  The global average amount of carbon dioxide hit a new record high in 2018: 407.4 parts per million.

·  The annual rate of increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases, such as those that occurred at the end of the last ice age 11,000-17,000 years ago.  

The post included a chart showing “ ice CO2 during ice ages and warm periods for the past 800,000 years” supporting their concerns.  What they didn’t show was corresponding global temperatures.  That the prior interglacial periods in the 450,000 years included in the Vostek ice cores had peak temperatures similar to current levels despite the lower CO2 levels. The Eemian period some 130,000 years ago were 4 deg C higher than current levels with 290 ppm CO2 levels.

Clearly CO2 levels were not determinative of global temperatures during the four previous interglacial periods. While temperatures during the four periods quickly started downward.  However the current Holocene warming has lasted several thousand years.  The increased fossil emissions have done little to change concentration. 

The current 5 gigatons carbon (GtC) emissions annually raise CO2 by 2ppm.  If doubled to 10 GtC over the next 50 years, CO2 levels would increase from 420 to 620 ppm.  CO2 warms Venus because its 65.5% of the atmosphere.  There’s little evidence increasing CO2 from 0.042 to 0.062 will have any effect.  That Al Gore’s “inconvenient truth” was a lie.