Summary ........................................................................................................................................................ 2
Climate Change Q&A
1 Is the climate warming? ........................................................................................................................... 3
2 How do scientists know that recent climate change is largely caused by human activities? ............. 5
3 CO2
is already in the atmosphere naturally, so why are emissions from
human activity significant? ...................................................................................................................... 6
4 What role has the Sun played in climate change in recent decades? ................................................... 7
5 What do changes in the vertical structure of atmospheric temperature—from the
surface up to the stratosphere—tell us about the causes of recent climate change? ........................ 8
6 Climate is always changing. Why is climate change of concern now? ................................................. 9
7 Is the current level of atmospheric CO2
concentration unprecedented in Earth’s history? ................ 9
8 Is there a point at which adding more CO2
will not cause further warming? .................................... 10
9 Does the rate of warming vary from one decade to another? ............................................................. 11
10 Does the recent slowdown of warming mean that climate change is no longer happening? ........... 12
11 If the world is warming, why are some winters and summers still very cold? .................................... 13
12 Why is Arctic sea ice decreasing while Antarctic sea ice is not? ......................................................... 14
13 How does climate change affect the strength and frequency
of floods, droughts, hurricanes, and tornadoes? ................................................................................. 15
14 How fast is sea level rising? .................................................................................................................. 16
15 What is ocean acidification and why does it matter? ........................................................................... 17
16 How confident are scientists that Earth will warm further over the coming century? ...................... 18
17 Are climate changes of a few degrees a cause for concern? ............................................................... 19
18 What are scientists doing to address key uncertainties
in our understanding of the climate system? ...................................................................................... 19
19 Are disaster scenarios about tipping points like ‘turning off the Gulf Stream’
and release of methane from the Arctic a cause for concern? ............................................................ 21
20 If emissions of greenhouse gases were stopped, would the climate return
to the conditions of 200 years ago? ..................................................................................................... 22
The Basics of Climate Change ............................................................................................. B1–B8
Conclusion ............................................................................................................................................... 23
Acknowledgements ............................................................................................................................ 24
For Further Reading ......................................................................................................................... C3