Transcript Climate Change Science

Climate Change
Science
David Stevenson
Institute of Atmospheric and
Environmental Sciences
University of Edinburgh
Joint Statement from the world’s
science academies for the 2005 G8
1. Climate change is real – the evidence is
overwhelming
2. We can reduce the causes of climate
change – no single solution, but needs
major changes in human behaviour
3. Future climate change (in the next few
decades) is inevitable – we need to
start preparing now
Global surface temperature 1855-2005
World has warmed 0.7°C in last century
Recent warming is unprecedented
The warming is happening almost everywhere
Nearly all the worlds glaciers
are in retreat…
1875
2004
Sea levels are rising – 10-15 cm in last 100 years…
Sea-level from satellites: 4 cm rise in last 10 years
Thames Barrier Usage 1982-2003
Spring is getting earlier!
What is driving climate change?
• Increases in greenhouse
gases, in particular CO2
• Main sources are burning
fossil fuels; also
deforestation and
agriculture
• Minor influences on
climate from natural
processes (solar
variations, volcanoes)
Including natural and
anthropogenic forcings
makes the model produce
the best simulation of
20th century climate
Q: Why worry about climate change ?
Q: Why worry about climate change ?
What are our future options?
‘Danger’ level
CO2 emissions scenarios
Global temperature projections
• Warming of ~2°C is almost inevitable –
even with very optimistic emissions;
• 2°C is considered to be the
‘dangerous’ level of climate change…
Q: Why worry about climate change ?
Q: Why worry about climate change ?
Joint Statement from the world’s
science academies for the 2005 G8
1. Climate change is real – the evidence is
overwhelming
2. We can reduce the causes of climate
change – no single solution, but needs
major changes in human behaviour
3. Future climate change (in the next few
decades) is inevitable – we need to
start preparing now