The climate science behind

the numbers in the news

Clare Bryden

15 June 2013

400 ppm

Source: http://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html

350 ppm

Carbon dioxide concentrations

400 ppm in 2013

Business as usual700 ppm in 2100?

Source: http://www.carbonvisuals.com/blog/400-ppm

CO2 emissions since 1850 (red)Exponential growth (blue)

Source: http://www.guardian.co.uk/environment/2013/apr/17/why-cant-we-give-up-fossil-fuels

Carbon dioxide emissions from fossil fuel combustion

19711972

19731974

19751976

19771978

19791980

19811982

19831984

19851986

19871988

19891990

19911992

19931994

19951996

19971998

19992000

20012002

20032004

20052006

20072008

20092010

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

International aviation bunkers

International marine bunkers

Middle East

Non-OECD Americas

China

Asia

Africa

Non-OECD Europe and Eurasia

OECD Europe

OECD Asia Oceania

OECD Americas

m illion tonnes carbon d ioxide

Source: International Energy Agency 2012

2ºC

Climate science

Emissions

Concentrations

Temperatures & other climate impacts

Human and other impacts

Feedback loops

Taking observations

Understanding earth processes

Future projections

Attribution of events to climate change

Impact of mitigation

Need for adaptation

1961-90 average

Climate models have improved

over time

Natural influences are not enough to explain changes in temperature

Earth’s orbital changetoo slowSolar heating variationstoo small

Aerosols/ volcanoescool climate

Including both human and natural influence

Greenhouse gasesdominant influence

“Unequivocal” that climate change is happening

“Very likely”that it is caused by human activity

i.e. more than 90% probabilityor at least 9 to 1 on

IPCC Fourth Assessment Report, 2007

Arctic Sea Ice

Source: Met Office presentation to COP18, Dohahttp://www.metoffice.gov.uk/media/pdf/0/8/part_1_Our_Changing_Climate.pdf

Age of Arctic sea ice at the end of the melt season

European summer temperatures

Source: Met Office

Every year climate change leaves over 300,000 people dead, 325 million people seriously affected, and economic losses of US$125 billion.

2.8 billion people are vulnerable to the physical effects, and 4 billion people if socio-economic effects are included. 500 million people are at extreme risk.

Source: http://www.ghf-ge.org/human-impact-report.pdf

80% by 2050

For all the uncertainty about the detail, every science academy in the world accepts the mainstream view of man-made global warming.

Virtually every government has agreed the world must limit the global temperature increase to 2°C – a level which isn't by any means "safe" but may be enough to avoid the worst impacts.

Two facts on climate science and politics

12

Source: http://www.skepticalscience.com/97-percent-consensus-cook-et-al-2013.html

One of the most disturbing things about listening to scientists studying climate change, then, is the fear in the voices and words of people not accustomed to be

fearful, and the sense that generally speaking, scientists are far more worried than most of us are.

We can either believe they are worried because they are foolish, easily frightened and scaremongering, or we

can believe they are afraid because they are seeing things they have never seen before with implications

that are terrifying, and do not understand why the rest of us are so unafraid.

Sharon Astyk, 2007

The media largely consists of humanities graduates. They may be able to argue the toss about Rousseau or Goethe, but they

almost glory in ignorance over the most basic principles of scientific research. Also, many of them suspect that “It’s just a

bunch of people in lab coats who never agree anyway.”

What’s the point of scrupulous research? The specialist correspondent is sidelined in favour of a simplistic ‘big story’. It matters not whether the truth may be more complex, there are

papers to be sold.

Ben Goldacre, Bad Science column

UK Climate Change Act 2008

Cut in emissions of 60% by 2050

Stabilisation at 550 ppm

But very likely that 2ºC exceeded

Cut in emissions of 80% by 2050

Stabilisation at 450 ppm

...

Cuts required for a 50% chance of not exceeding 2°C

Each 10-year delay adds 0.5ºC to the most likely temperature rise

Source: Met Office presentation to COP18, Dohahttp://www.metoffice.gov.uk/media/pdf/0/8/part_1_Our_Changing_Climate.pdf