Uncertainty risk and dangerous climate change Uncertainty in

Uncertainty in climate model predictions

Uncertainty in climate model predictions The Hadley Centre has developed a new technique to

Uncertainty in climate model predictions Predicted change in surface pressure over Europe from a

Uncertainty in climate model predictions Global average annual warming predicted by a 53 -member

Uncertainty in climate model predictions The ensemble average warming for a doubling of atmospheric

Uncertainty in climate model predictions Relative frequency of predicted changes in June, July and

Uncertainty in climate model predictions Relative frequency of predicted changes in December, January and

Uncertainty in climate change impacts The ensemble average change in plant productivity (NPP) for

Uncertainty in climate model predictions The ensemble average change in water availability for a

Dangerous climate change Observations suggest that the ocean thermohaline circulation has shutdown in the

Dangerous climate change Predicted daily minimum Central England Temperature (CET) following an artificial shutdown

Dangerous climate change If the Greenland ice sheet were to melt it would raise

Dangerous climate change Predicted warming for CO 2 stabilisation levels of 450 ppm, 550

Dangerous climate change Predicted change in the ice sheet volume following a quadrupling of

Dangerous climate change Extremes of temperature and rainfall can lead to serious impacts. This

Dangerous climate change Relative likelihood of return periods for the temperature exceeding that of

Dangerous climate change European warming predicted by the Hadley Centre model For an IPCC

Observed climate change Observed global average temperatures relative to the end of the 19

Observed climate change Observed global average land temperatures relative to the end of the

Observed climate change Rainfall anomalies for 2003, relative to 1961– 90 © Crown copyright

Observed climate change Temperature anomalies for Jan–Aug 2004, relative to the end of the

Observed climate change Observations show that urban areas are often warmer than surrounding countryside

Observed climate change New analysis of observations suggests that urbanisation has not caused a

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Uncertainty in climate model predictions

Uncertainty in climate model predictions The Hadley Centre has developed a new technique to estimate climate model uncertainty A number of slightly different, but plausible, climate models are used to predict future changes in climate © Crown copyright 2004 Page 3

Uncertainty in climate model predictions Predicted change in surface pressure over Europe from a subset of the model versions used to generate likelihood predictions Results are for a doubling of atmospheric CO 2 concentration © Crown copyright 2004 Page 4

Uncertainty in climate model predictions Global average annual warming predicted by a 53 -member model ensemble for a doubling of atmospheric carbon dioxide concentrations © Crown copyright 2004 Page 5

Uncertainty in climate model predictions The ensemble average warming for a doubling of atmospheric CO 2 Uncertainty in warming predictions (estimated as the difference between the 5 th and 95 th percentiles) © Crown copyright 2004 Page 6

Uncertainty in climate model predictions Relative frequency of predicted changes in June, July and August daily maximum temperature for the seasonal average (blue bars), and extreme 99 th percentile (red bars) © Crown copyright 2004 Page 7

Uncertainty in climate model predictions Relative frequency of predicted changes in December, January and February daily rainfall for the seasonal average (blue bars), and extreme 99 th percentile (red bars) © Crown copyright 2004 Page 8

Uncertainty in climate change impacts The ensemble average change in plant productivity (NPP) for a doubling of atmospheric CO 2 Uncertainty in plant productivity changes © Crown copyright 2004 Page 10

Dangerous climate change

Dangerous climate change Observations suggest that the ocean thermohaline circulation has shutdown in the past, leading to a cooling of the northern hemisphere. If this happened again in the future, what would be the consequences? © Crown copyright 2004 Figure adapted from Rahmstorf, nature 2002 Page 13

Dangerous climate change Predicted daily minimum Central England Temperature (CET) following an artificial shutdown of the THC. The black curve shows the climate with no THC shutdown. The red curve shows the result after THC shutdown © Crown copyright 2004 Page 14

Dangerous climate change If the Greenland ice sheet were to melt it would raise sea levels by 7 m • Is this likely? • If melting starts, how quickly would Greenland melt? Present-day elevation of the Greenland ice sheet. The maximum elevation is approximately 3200 m © Crown copyright 2004 Page 16

Dangerous climate change Predicted warming for CO 2 stabilisation levels of 450 ppm, 550 ppm, 650 ppm, 750 ppm and 1000 ppm Previous model studies suggest that a local warming over Greenland of 2. 7ºC would trigger a melt down © Crown copyright 2004 2. 7ºC Page 17

Dangerous climate change Predicted change in the ice sheet volume following a quadrupling of atmospheric CO 2. Red indicates thick ice while blue indicates thin (or no) ice © Crown copyright 2004 Page 18

Dangerous climate change Extremes of temperature and rainfall can lead to serious impacts. This is another aspect of dangerous climate change. We have estimated: • the man-made contribution to the heat wave experienced in Europe in summer 2003 • how frequent these heat waves may become in the future © Crown copyright 2004 Page 20

Dangerous climate change Relative likelihood of return periods for the temperature exceeding that of the second warmest European summer, when man-made climate change is included (red), and when it is not (green) There is a better than nine in ten chance that human influence has more than doubled the risk of heat waves of the magnitude seen in Europe in 2003. © Crown copyright 2004 Page 21

Dangerous climate change European warming predicted by the Hadley Centre model For an IPCC SRES A 2 emissions scenario more than half of all years are expected to have summers warmer than that of 2003 by the 2040 s. © Crown copyright 2004 Page 22

Observed climate change

Observed climate change New analysis of observations suggests that urbanisation has not caused a false warming trend in the measurements © Crown copyright 2004 Trends in the annual average minimum daily temperature at 264 stations separated into calm conditions – when heat islands are most likely (blue) and windy conditions – when heat islands are less likely (red) Page 29