Carbon dioxide levels are high and rising.
Over the last hundred years, humans have burnt a lot of coal, oil, gas, and wood. This burning has released enormous amounts of carbon dioxide (CO2) into our atmosphere, and the concentration of carbon dioxide in the atmosphere has soared since 1900.
Look at the CO2 levels over the last 400,000 years
Carbon dioxide levels in the atmosphere have a strong influence on temperatures, so these recent increases in the CO2 levels are concerning.
The orange line shows how the level of “carbon dioxide in our atmosphere” has moved over the last 400,000 years.
Graph: US National Aeronautics and Space Administration NASA. See the latest version of this graph.
For the 650,000 years before 1950, CO2 levels moved between low levels near 180 ppm during ice ages, and high levels near 300 ppm.
Since 1950, the CO2 concentration in the atmosphere has soared from about 300 ppm to over 400 ppm. This increase in CO2 over the last 60 years is clearly exceptional.
The CO2 levels are rising faster
In the 1960s, the increase of CO2 concentration was about 1 ppm per year. Now the increase is about 2 ppm per year and getting bigger. It may soon be 3 ppm per year.
Atmospheric CO2 accumulating faster than ever (New Scientist, 2006)
In April 2014, the CO2 concentration hit 400 ppm.
Conservatively, assuming that CO2 keeps on increasing at 2.0 ppm each year, the CO2 level will reach 572 ppm by 2100.
Our species has never experienced such high levels of CO2
The concentration of CO2 in our atmosphere is already far above any level experienced for 800,000 year. Our species, Homo Sapiens, emerged about 250,000 years ago. The species from which we evolved, Homo Erectus and Homo Neanderthalensis, emerged about 400,000 years ago. So, our species, and the web of life around us, evolved with CO2 levels between 180 and 300 ppm. They have never before experienced CO2 concentrations at the current 400 ppm, let alone the forecast levels. We do not know whether the environment that has nurtured our species can survive, if we allow these high levels of CO2 to remain for an extended period, warming the planet more and more.
These high levels of CO2 risk life as we know it
Carbon dioxide levels influence global temperatures. While CO2 levels remain above about 300 ppm, the oven remains turned on – and we are cooking our planet. By maintaining our high levels of CO2 we are risking life as we know it on our planet.
We need to be decreasing the CO2 levels, not increasing it by 2 or 3 ppm each year.
Last Modified: 9 Sep 2018