This is a Power Point Presentation I built as part of a online Uni course I am doing with Coursera.
The course is called “Turn Down the Heat: Why a 4°C Warmer World Must be Avoided”
This is a Presentation, I could give to a local Transition Towns meeting, and I have given to a “Permaculture Design Course” Class.
There has been some discussion in the blogasphere about humanity running out of time to take action to reduce our greenhouse gas emissions to keep the planet under the safe temperature of 2 degrees centigrade. In 2013 the world continued on the business as usual path, and greenhouse gas emissions continue to increase.
Ask for answers from the audience. Now I’ll give you a brief history.
I would also mention that the existence of the greenhouse effect was reasoned from experimental observations by John Tyndall in 1859, and more fully quantified by Svante Arrhenius in 1896.
Keeling started his observations in 1958 at the Mauna Loa Observatory in Hawaii, and they are still ongoing today. (but no longer being done by Keeling).
There are a number of potential tipping points, none of which is fully understood.
We will only know we have crossed a tipping point with hindsight.
(Note: this graph is in parts per billion (ppb) not part per million (ppm). If you want to compare this graph to a graph of CO2 be careful to get the units right.)
We need to take action on climate change now. We have know about it for a long time, the changing weather tells us it is real, and we are in danger of going past a tipping point unknowingly which we will be unable to return from.