Conversations Over Coffee


The Science of Climate Change


1 For 800,000 years the level of carbon dioxide in our atmosphere was between 200 and 300 parts per million. Never below 200 and never above 300.

2 Since 1850, we have burnt huge amounts of fossil fuel. This produces large quantities of carbon dioxide. Today the level is 418. This is a huge excess of greenhouse gas. The result is a huge excess of heat energy trapped in the atmosphere.

3 This energy causes wildfires and heatwaves in some places, and stronger storms, storm surges and floods in others.

4 This results in a reduced food supply and some places become uninhabitable, creating climate refugees.

5 In the UK we produce less than 60% of our own food – we rely on the excess from other countries. Sir David Attenborough predicted that by 2050 there would be 500 million refugees.


The Carbon Cycle


Carbon cycles between the atmosphere and the land. In the atmosphere it is in the form of carbon dioxide. This is taken in by leaves and fixed by photosynthesis in leaves to form sugars and other solids. This is stored in plants and the land. It is returned to the atmosphere when living things die.

Carbon dioxide provides a warm blanket, otherwise our planet would be frozen.

When there is too much carbon dioxide, trees and other plants flourish and use up the excess. When there is too little, trees and other plants do not do so well and so the carbon level is topped up (by dying vegetation).

At the moment there is a vast excess of carbon dioxide. Trees would naturally reproduce more quickly, but we are cutting more and more down. Scientists find that trees today are 30% larger than in the past. They are trying!