By Stephen Stretton
Christopher Monckton gave a talk at the Cambridge on Monday 8th October. The following sets out some comments on his presentation
- Monckton’s work is not published in any scientific journal. Monckton is not a scientist, he owes his title to inheritance not to eminence in any field.
- Monckton’s greatest error is to ignore the effect of water vapour on climate – as the climate warms, more water evaporates, trapping more heat.
- He doesn’t even mention the possibility of carbon cycle and methane positive feedbacks ‘vicious circles’, with temperature causing co2 emissions as well as co2 causing temperature increase. He ignores the possibility that climate change between the ice ages, might be an example of this.
- Methane feedbacks have been hypothesised (The Clathrate Gun Hypothesis) to be the cause of the greatest extinction event of all time, the end-Permian extinction, where 95% of all life died.
- He ignores the fact that solar irradiance has fallen since 1980, whereas the temperatures have continued to rise.
- He ignores the lags in the system due to the great thermal mass of the oceans.
- He ignores the cooling effect of sulphate aerosols (seen after volcano eruptions) which may have masked global warming.
- The economic costs of climate change are due to extreme events such as hurricanes, heatwaves etc and the additional energy put into the system. Monckton ignores the disruption that these will cause across the world.
- Stern says we need to pay 1% of GDP to avoid 5-20%, or possibly even greater, unquantifiable and abrupt dangers.
- Monckton assumes that anyone who urges action on climate science is part of some vast ‘left-wing conspiracy’. Is Sir Nicholas Stern, former chief economist at the World Bank, part of the same vast left-wing conspiracy?
- Monckton doesn’t consider the recent literature on the optimum course of action when faced with extreme risk. He is not managing global risks prudently.
RealClimate. com Debunking of Monckton’s Arguments
…The piece spends a lot of time discussing climate sensitivity but since they don’t clearly say so upfront, it might not at first be obvious. We have often made the case here that equilibrium climate sensitivity is most likely to be around 0.75 +/- 0.25 C/(W/m2) (corresponding to about a 3°C rise for a doubling of CO2).
Instead it purports to show using ‘common sense’ arguments that climate sensitivity must be small (more like 0.2 W/m2, or less than 1°C for 2xCO2). Our previous posts should be enough to demonstrate that this can’t be correct, but it worth seeing how they arithmetically manage to get these answers. To save you having to wade through it all, I’ll give you the answer now: the clue is in the units of climate sensitivity – °C/(W/m2). Any temperature change (in °C) divided by any energy flux (in W/m2) will have the same unit and thus can be ‘compared’. But unless you understand how radiative forcing is defined (it’s actually quite specific), and why it’s a useful diagnostic, these similar seeming values could be confusing. Which is presumably the point.
Readers need to be aware of at least two basic things. First off, an idealised ‘black body’ (which gives of radiation in a very uniform and predictable way as a function of temperature – encapsulated in the Stefan-Boltzmann equation) has a basic sensitivity (at Earth’s radiating temperature) of about 0.27 °C/(W/m2). That is, a change in radiative forcing of about 4 W/m2 would give around 1°C warming. The second thing to know is that the Earth is not a black body! On the real planet, there are multitudes of feedbacks that affect other greenhouse components (ice albedo, water vapour, clouds etc.) and so the true issue for climate sensitivity is what these feedbacks amount to.
So here’s the first trick. Ignore all the feedbacks – then you will obviously get to a number that is close to the ‘black body’ calculation. Duh! Any calculation that lumps together water vapour and CO2 is effectively doing this (and if anyone is any doubt about whether water vapour is forcing or a feedback, I’d refer them to this older post).
But we are still not done! The next thing to conveniently forget is that climate sensitivity is an equilibrium concept. It tells you the temperature that you get to eventually. In a transient situation (such as we have at present), there is a lag related to the slow warm up of the oceans, which implies that the temperature takes a number of decades to catch up with the forcings. This lag is associated with the planetary energy imbalance and the rise in ocean heat content.
And finally, you can completely contradict all your prior working by implying that all the warming is due to solar forcing. Why is this contradictory? Because all of the above tricks work for solar forcings as well as greenhouse gas forcings. Either there are important feedbacks or there aren’t. You can’t have them for solar and not for greenhouse gases. Our best estimates of solar are that it is about 10 to 15% the magnitude of the greenhouse gas forcing over the 20th Century. Even if that is wrong by a factor of 2 (which is conceivable), it’s still less than half of the GHG changes. And of course, when you look at the last 50 years, there are no trends in solar forcing at all. Maybe it’s best not to mention that.
There you have it. The cuckoo has come in and displaced the whole field of climate science. Impressive, yes? Errrr…. not really.