TUC 21 st October 2013 Climate change the

TUC, 21 st 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 400 ppmv for the first time

Why 400 ppmv is a big deal Ice Core Records of Past Climate Change 400 280 © Crown copyright Met Office

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

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

Extremely likely (95100%) 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 Water – where we live Health Climate Variability and Change • Changing Vulnerability Urbanisation Population growth – how we live • Changing Climate Economic Political Food Energy

Increasing confidence that human emissions are increasing the risk of some types of extreme events • 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 Australian rainfall, summer 2012 Iberian drought, winter 2011/12 New Zealand rainfall, winter 2011 Arctic sea ice minimum, autumn 2012 Inundation from Hurricane Sandy, autumn 2012

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)

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

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 1951. • 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.