TUC, 21st October 2013 Climate change – the scientific evidence and its implications Why climate change matters to us all Julia Slingo, Met Office Chief Scientist TUC Green Growth conference 21 October 2013

Atmospheric Concentrations of Carbon Dioxide: Crossing 400ppmv for the first time

© Crown copyright Met Office Why 400ppmv is a big deal Ice Core Records of Past Climate Change

IPCC 4 th and 5 th Assessment Reports: Warming is unequivocal ‘Pauses’ in warming are expected and understood

Inter-Governmental Panel on Climate Change (2013) Changes across the climate system are consistent with a warming world

Extremely likely ( %) that most of observed increase in global surface temperature since 1951 caused by human influence (IPCC 2013). Assertion that we survived the Medieval Warm Period and Little Ice Age ignores the rapid increases in the world’s population and in the sophistication of our current civilisation.

Global Interdependencies: Circle of Securities Changing Exposure – where we live Changing Vulnerability – how we live Changing Climate Climate Variability and Change Urbanisation Population growth Water Economic Food Energy Political Health

Report by UK and US scientists looking at extreme events in 2012 Half of the extreme events studied displayed some evidence that human induced climate change was a contributing factor. USA heatwave, spring 2012 Iberian drought, winter 2011/12Arctic sea ice minimum, autumn 2012 New Zealand rainfall, winter 2011Australian rainfall, summer 2012Inundation from Hurricane Sandy, autumn 2012 Increasing confidence that human emissions are increasing the risk of some types of extreme events

Projections of future global warming Global warming >2˚C is likely for scenarios with little mitigation of emissions. No mitigation leads to a world more than 4˚C warmer than pre-industrial times Inter-Governmental Panel on Climate Change (2013)

Projections of future sea level rise Long Term Commitment to Climate Change Global average sea level will rise during the 21 st century; it is very likely that it will rise faster than it has during the last 40 years. Inter-Governmental Panel on Climate Change (2013)

National Risk Register A number of key national risks can be expected to increase in likelihood and impact as a result of climate change ‘Moving to the right’

Total CO 2 emissions are strongly linked to total warming If warming is to be limited to 2˚C, total CO 2 emissions need to be limited to ~1000 Gigatonnes of Carbon (‘Trillionth Tonne’).

In conclusion... Climate change is unequivocal. It is extremely likely that human influences have been the dominant cause of the observed warming since There is already evidence that climate change is leading to more extreme weather events that affect a world that is increasingly exposed, vulnerable and interdependent Current trajectories of carbon emissions take us towards a world 4˚C warmer than the present by the end of the century If warming due to human emissions is to be limited to 2˚C, total emissions need to be limited to 1000 Gigatonnes of Carbon. About half of this has already been emitted.