The fragility of spaceship earth twitter: @KevinClimate web: kevinanderson.info Kevin Anderson Professor of Energy & Climate Change

Coming to terms with our new world vision (1960s -)

The science behind Climate Change What we can do about it

The Great Global Experiment ‘Climate Change and its Consequences’

Some underlying drivers of the world’s climate & weather Gravity Earth’s rotation Topography Volcanoes Life Solar radiation 5

Radiation Shortwave (solar) : from the sun; dominates incoming sources Longwave (terrestrial) : from the earth, dominates outgoing sources 6

THE GREENHOUSE EFFECT SUN EARTH ATMOSPHERE Low temperature The Met.Office Hadley Centre Some of the infrared radiation is absorbed and re-emitted by the greenhouse gases. The effect of this is to warm the surface and the lower atmosphere SUN high temperature Some solar radiation is reflected by the earth’s surface and the atmosphere Solar radiation high temp’ source -short wavelength ATMOSPHERE Solar radiation passes through the clear atmosphere Terrestrial radiation low temperature source longer wavelength (Infrared) EARTH Low temperature Most solar radiation absorbed - warming the surface

Early Contributors Fourier (1827) first advanced the idea that the atmosphere acts like the glass of a greenhouse (Mem de l’ Ac. R. de Sci de l’Inst de France Vol 7.) Tyndall (~1860) first to demonstrate & quantify the impact of the greenhouse gases [infrared emitters] Arrhenius (1896) Provided first predictions of changes in global temperature arising from increases in CO2 concentration. (Phil Trans 41, 237-276)

Breakdown of Warming caused by Greenhouse Effect without with mean Greenhouse Greenhouse Increase Surface Temperature -18oC +15oC 33oC Water Vapour responsible for 60-70% greenhouse effect (~1% of atmosphere – a positive feedback of other GHGs)) Other Gases responsible for ~ 30-40% greenhouse effect (~0.04% of atmosphere)

So what is changing? Drivers: Position of the sun in relation to the earth Volcanic eruptions Solar cycle Concentration of greenhouse gases

How do we know things are changing? - Tree rings – 10,000 years – reflect water availability - Ice cores –160,000 years – Oxygen isotopes and air bubbles (with CO2) provide information (e.g. 1ppm difference in oxygen isotope is equivalent to a 1.5ºC temp changes) - Ocean sediment – million years – proportion of heavy oxygen in sea shells goes up when temperatures drop

Trends of main greenhouse gases atmospheric concentrations pre-industrial ~2015/16 % concentration concentration Increase CO2 280ppmv +400ppmv ~43% CH4 700ppbv ~1835ppbv ~162% N20 270ppbv 328ppbv ~22%

Greenhouse Gas Flows Global flow of CO2 ~ 750 Gt p.a Note: 1 Giga tonne (Gt) is 1000 million tonnes Global flow of CO2 ~ 750 Gt p.a Human emissions of CO2 ~ 40 Gt p.a. Human CO2 added to Atmosphere ~ 18 Gt p.a This has led to a: … ~ 43% increase in atmospheric carbon concentration since ~1800

Historical concentrations The current CO2 concentration has not been exceeded during past 800 000yrs and…probably not during the past 5 million years Evidence for being human made - CO2 from fossil fuels contains no 14C unlike the ‘background’ atmospheric CO2 2050-2100? 2016:

The Greenhouse Effect & Climate Change The Greenhouse Effect is uncontested! without it the earth would be ~ 33K cooler. Climate Change is uncontested! the balance of incoming and outgoing radiation has always fluctuated, with, for example, changes in atmospheric constituents, their relative concentrations, solar variations, etc. Anthropogenic Climate Change is uncontested though slightly different views exist on the degree to which the observed warming is due to anthropogenic emissions. Future anthropogenic Climate Change is contested - a little. the level of future warming depends on the ‘climate sensitivity’ – i.e. how much warming is likely for a doubling in CO2 concentration compared with pre-industrial levels. (IPCC likely range is 2 to 4.5°C; most likely estimate is 3°C)

To Conclude the Science Section: Greenhouse effect is understood Atmospheric concentrations of greenhouse gases are rising Empirical data tends to support the science and the models Feedbacks are, to some degree, understood (net effect exacerbates warming)

Where do human emissions come from ?

What can we do ? Learn to live with increased climate change (adaptation) Find ways to reduce carbon emissions (mitigation)

Adapt to What ? More severe weather events Destruction of Ecosystems Flooding Food shortages Fresh Water shortages Human Migration Increased Military tension Changes in Disease

Adaptation: Equity & Morals! High Carbon emitters geographically & financially able to adapt Low Carbon emitters suffer geographically and financially from climate change impacts - also have less political influence ____________ Today’s generation are the Cause Tomorrow’s generation suffer the Impacts

Adaptation: Equity & Morals! http://www.carbonmap.org/#Emissions