1. Points for discussion
Have human activities changed the composition of Earth’s atmosphere?
Has Earth’s temperature changed in the past 150 years? In the past 1000 years?
What does the IPCC report mean when they refer to ‘forcings?’
What’s the difference between the greenhouse effect & global warming?
What is the difference between detection & attribution?

8. Detection: 0.6°C± 0.2° warming in the 20th century (at the 95% confidence level)
Attribution: “most of the observed warming over the last 50 years is likely (i.e. 66% to 90% chance) to have been due to the increase in greenhouse gas concentration” level)