Introduction to golbal warming

• Global warming is the term used for the rapid increase in global temperature over the last century.
• It's a type of climate change - a significant change in the weather of a region over a period of at least several decades.
• Global warming also causes other types of climate changes.

Evidence for global warming.

Temperature records

1. Since the 1850s temperature has been measured around the world using thermometers.
2. This gives a reliable but short-term record of global temperature change.

Dendrochronology

1. Dendrochronology is a method for figuring out how old a tree is using tree rings. Most trees produce one ring within their trunks every year.
2. The thickness of the ring depends on the climate at the time, when it's warmer the rings are…