© crown copyright met office evidence in science and policy scientific evidence vicky pope
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© Crown copyright Met Office
Evidence in Science and PolicyScientific evidence
Vicky Pope
© Crown copyright Met Office
• Growing evidence of man-made climate change
• Importance of natural variability
• Practical information for decision making
• Dealing with complexity and uncertainty
Scientific evidence
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Growing evidence of man-made change
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Scientific evidence• The average temperature of the Earth is 15 ºC. Without the
blanket of greenhouse gases it would be –18 ºC.
• CO2 has risen by 107ppm (38%) from pre-industrial levels of 280ppm.
• Two thirds of the increase is in the last 50 years.
• CO2 is 30% higher than at any time over at least the last 800,000 years.
• Global temperatures have increased decade on decade since the mid 20th century, consistent with the basic physics.
• The water vapour feedback enhances the warming due to man-made greenhouse gases
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Evidence of temperature rise:Independent datasets
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Practical information for decision making
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Central estimate from UKCP models
Upper limit of "high++“ model
Probability forecasts of coastal flood risk allow for a balanced approach to decision making
Change in extreme sea level of 50 year storm
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─ Observations█ Model Individual projections from 2009─ ─ ─
Global average temperature forecast for the next decadeLikely that half the years from 2010 will be warmer than 1998
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The impact of a global temperature rise of 4 ºC
Change in temperature from pre-industrial climate
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Current City population • 3-10 million • 10-20 million
Meltingice
OceanAcidification
Rainforestloss
Reduced crops
Forestfire
Increased drought
Stronger tropical storms
Methane release
More heatwaves