school of mathematics, meteorology & physics, university...

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Our high carbon presentOur high carbon present

Revd Professor Ian JamesSchool of Mathematics, Meteorology &

Physics, University of Reading

I.N.James@reading.ac.uk

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Atmospheric carbon dioxideAtmospheric carbon dioxide

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Radiation budgetRadiation budget

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Two views of EarthTwo views of Earth

Visible light Infra-red view

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

The “greenhouse” effectThe “greenhouse” effect

• Carbon dioxide blankets Earth’s surface.

• Sunlight gets in.• Infra-red absorbed and re-

emitted.• Other greenhouse agents –

water vapour, clouds.

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

The carbon cycleThe carbon cycle

• Fossil fuels (coal, oil, natural gas) are made of carbon and hydrogen.

• When burnt, they produce energy, water and carbon dioxide.

Human Natural

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Effects of COEffects of CO22 increasesincreases

• Warmer climate – local variations• Changed patterns of rainfall – drought/flood• More extreme weather events – rain/wind• Melting of ice caps and glaciers• Rising sea levels

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Key impactsKey impactsWater Increased water in moist tropics & high latitudes

Decreased water in mid-latitudes and semi-arid tropicsHundreds of millions suffer water stress

Eco-systems

30% plus species at risk of extinctionCoral mortalityCarbon loss from biosphereSpecies ranges shift; wildfire risks

Food Complex negative impacts on subsistence farmers, fishers and small holdersCereal productivity drops in tropicsCereal productivity rises, then falls in mid-latitudes

Coasts Increasing damage from floods & stormsSome 30% coastal wetlands lostMillions experience coastal flooding each year

Health Malnutrition, diarrhoea, cardio-respiratory & infectious disease increaseIncreased morbidity from heat waves, floods, & droughtsIncreased range of some disease vectors

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Is climate change real?Is climate change real?

Some examples

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Variations of the Earth’s surface temperature for the past 1,000 years

SPM 1b

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Latest global mean temperaturesLatest global mean temperatures 18501850--20072007

Global average temperature

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1840 1860 1880 1900 1920 1940 1960 1980 2000 2020

Tem

pera

ture

ano

mal

y fro

m 1

961-

1990

ave

rage

(o C

)

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Ice core recordIce core record

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Arctic sea iceArctic sea ice

September 1979 September 2005

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Glaciers in retreatGlaciers in retreat

Pasterze glacier, Austria, 1875 Same view, 2004

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

The future: what limits?The future: what limits?

Maximum tolerable temperature rise?- around 2°C

What levels of carbon dioxide will produce this?

- between 450 – 540 ppmWhen do we get there?

- 23 to 44 years if BAU

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

UncertaintiesUncertainties

• Wide uncertainty of magnitude of global and especially regional climate change

• Clouds, ocean circulation, biology all complicate issue

• Separation of CO2 signal from intrinsic variability of climate system

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

CertaintyCertainty

• Dramatic and continuing rises of CO2

• Absorption of i-r by CO2

• Some warming already has occurred and will continue.

• Question: how much?

Ian James University of Reading, Department of MeteorologyE-mail: I.N.James@reading.ac.uk

Today’s world viewToday’s world view