Climate Change what we know What we surmise What we Guess What do we do about it?

1. Richard Wilson Harvard University Climate Changewhat we knowWhat we surmiseWhat we GuessWhat do we do about it?

2. THE EARTH IS A GREENHOUSE(Jaques Fourier 1829 Comptes Rendues)We know the solar flux in energy per unit areaIt is visible and UV lightEnergy from the sun is absorbed and reemitted ininfrared radiation by Stafan’s Law.If the earth were not a greenhouse the temperature would be about 250 degrees KelvinInfrared radiation is absorbed by the upper atmosphere reemits both back to the surface and outwards. increasing temperature by the 4th root of 2

4. This mechanism is fundamentally different from that of an actual greenhouse, which works by isolating warm air inside the structure so that heat is not lost by convection. The greenhouse effect was postulated by Jaques Fourier in 1824, [Comptes Rendues] first infra red absorption experiments on CO2 by John Tyndall in Bristol in 1858, and first applied quantitatively by Svante Arrhenius in 1896. [in Philosophical Magazine]

5. Greenhouse gases * water vapor, 36–70% * carbon dioxide, 9–26% * methane, 4–9% * ozone, 3–7% Water vapor is non – uniform Others are uniform

6. Absorption is in several frequenciesIt is complete at the peak of the spectrum but as T rises, the lines broaden allowing the edges to absorb also.This leads to an rise roughly as the squareroot of the concentration increaseSince CO2 is uniform The Temperature rise from CO2 can be calculated IF ALL ELSE IS CONSTANT

7. CO2 concentrations have been measured for50 years at Muona Lua in HawaiiThey have nearly doubled in that timeabout half the CO2 stays in the atmosphere(shallow oceans..vegetation)DEEP oceans would be a huge sinkBUT ~700 year time constant(Lindzen suggests 70 yrs)Summer lower than winter as northern hemisphere plants absorb

8. As T rises water vapor changes. It probably increases leading to a changeDELTA T = DELTA T (no H2) / (1-F)If H20 were uniform F could be calculated easily. It could be ½ or even unityIf Unity Disaster!(TIPPING POINT)

9. “Warming of the climate system is unequivocal”But why is it warming?

10. The temperatures before 1950 are much less reliable and need modelling.The E Anglia scientists had many discussions on how to describe this, and the recent interception of E mails showed this.Public polls in US show that support for action dropped from 70% to 35%. But I know of no scientist who changed hismind!

11. Models driven with natural factors alone simulate a modest cooling over the past 50 years Colours: Simulations with natural influences alone

12. Models driven with anthropogenic and natural factors are consistent with observed changes Colours: Simulations with human and natural influences

13. And a third: that global temperatures follow the solar cycle length (SCL) Friis-Christensen and Lassen, 1990

14. In 1985 several scientists doubted thatthe temperature rise was realSeitz, Lindzen, Michaels, The model predictions dropped a factor of 2 in 1990s But now there is agreement this far

15. C.f. another prediction made at the time Lindzen (1992,1994): Climate sensitivity = 0.3±0.2oC

16. High level of consensus on the reponse to a given emissions scenario Michaels (2000, 2004) Climate response to the IS92a scenario as predicted by 2001 IPCC models and by Patrick Michaels, University of Virginia

21. What is the economic effect?Here there are uncertaintiesEU Nicholas Stern, now Lord SternAnother view byProfessor William Nordhaus of Yale Universitywith his own model

24. Stern and Nordhaus disagree on how much tospend NOW for damage in 2100(economists discount rate)Stern sets it low or zeroNordhaus more usual (5% to 10%)Freeman Dyson tends to follow NordhausIf discount rate is greater than 0.1% we are already spending far too much on nuclear waste

25. Carbon use by any one of us affects everyone in the world a little bitWe must get a world wide approachWho decides?Wall St?Tyson’s Corner?I do not trust themCroesus’ inventionMONEYOne incentive: millions of small decisions

26. Options reduce populationreduce carbon demandadaptionactive intervention in solar flux(geo engineering)carbon sequestation

27. Anthropogenic contribution to the risk of the 2003 heat-wave Threshold for civil liability Range of uncertainty

28. WHO decides?UN?USA Congress?Environmental Activists?Their Lawyers?Starry Eyed Academics?It is a great playground for “pork barrel” There are several proposed actions which are bad

29. Using ethanol from cornIt uses as much energy to grow cornand upsets agriculture“Cap and trade” with a historical capencourages big increases before legislation startsselling carbon offsetsis analagous to 1600 popes selling indulgenciesWe need an action which allows lots of individual decisionsKing Croesus’ invention: MONEY

30. Corn Ethanol is a scam

31. Crucial items in the carbon cycleEach individual in the world adds a bit to the CO2 concentration for everyone elseWithin a year any carbon coming out of the ground becomes CO2The time scale of global warming is decadesSo control early as caron comes out of the groundALL palcaes are recorded. COAL MINES, OIL WELLS, GAS FIELDS, PORTS OF ENTRYDecide on a cap. Decrease slowly to allow adjustment (3% per year)trade permitseveryone will choose actions to minimize CO2Probably 3 times as efficient as command and control(example USSR vs USA energy)