The carbon dioxide content of our atmosphere on April 2 was 408.79 parts per million (ppm). The measurement on that date last year was 404.68 ppm.

The highest-ever daily CO2 average was 409.56 ppm recorded March 27 this year. The highest number in 2016 was 409.44 ppm. High in 2015 was 404.84 ppm.

The world reached 300 ppm in 1912.

A worldwide temperature increase of 3.6°F is what the climate treaty signed in Paris in 2015 is intended to prevent. An increase of that amount would put us in a climate humans have never before experienced.

The magic number that brings us to a gain of 3.6°F is 475 ppm. That is a 14 percent increase from current levels. This is a projection made by climate scientists in 2015. 

Business as usual is projected to eventually produce a worldwide average annual temperature gain of 8.6°F. 

An increase of 8.6°F makes a very warm winter here, and a very hot summer.

CO2 measurements are taken daily at the Mauna Loa Observatory in Hawaii under the supervision of the National Oceanic and Atmospheric Administration and the Scripps Institution of Oceanography. (scripps.ucsd.edu)