The key “barometer” of climate change is the measurement of the concentration of Carbon Dioxide in the atmosphere. As we already know, Green House Gases (GHGs) act rather like a “sleeping bag” around the earth trapping heat inside the atmosphere. The more GHGs in the atmosphere, the hotter the earth will get.
The chart details the increase in Carbon Dioxide we have experienced over the last 100 years and demonstrates the clear correlations between CO2 concentration and climate change.
As the chart shows, this will not be the first time the earth has experienced temperature changes. Ironically, prehistoric man in a small population may have been better prepared than us to deal with climate change, especially with the demands we make on our planet and our relatively fragile infrastructure. This is, however, the first time that man is creating the catalyst for climate change, namely Green House Gases.
In terms of a safe upper limit for CO2 (the main greenhouse gas), scientists are now recommending 350 parts per million. Currently CO2 concentrations stand at 387ppm. Unless we are able to rapidly return to 350ppm this century, we risk irreversible events such as the melting of the Greenland ice sheet, major methane releases from increased permafrost melt and the destruction of carbon sinks through changes in our ecology or fire.
However, before we can begin to reduce CO2 in the atmosphere we need to stop it rising. Currently, CO2 is increasing at 2 parts per million per annum with the rate of increase also increasing.
Specifically, there are four numbers that we should be cognizant of with regard to global warming: these are 275, 387, and 350 and 450.
Chart from Mauna Loa Observatory in Hawaii: CO2 Concentrations
