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« ECS with Otto | Main | New energy-budget-derived estimates of climate sensitivity and transient response in Nature Geoscience »

Reactions to Otto et al

Press reactions to the Otto et al paper vary from the sublime to the ridiculous.

Matt Ridley in the Times (£) points to the policy implications and notes that mitigation now looks like a pretty daft approach to take:

It is true that the “transient climate response” is not the end of the story and that the gradual warming of the oceans means that there would be more warming in the pipeline even if we stopped increasing carbon dioxide levels after doubling them. But given the advance of nuclear and solar technology, there is now a good chance we will have decarbonised the economy before any net harm has been done.

Fiona Harvey in the Guardian, meanwhile, is trying to push TCR of 1.8°C as "human disaster looming". This is so absurd as to almost defy belief. At the rate of warming implied by the paper, the impacts of global warming are more likely to be positive than negative for the foreseeable future.

Staying with the ridiculous, New Scientist argues that the prospect of little warming for decades to come should add impetus to efforts to secure a global climate deal.

And the paper's lead author is also keen to spin the results, the FT reporting his remarks as follows: the long term, temperatures are still likely to rise to potentially dangerous levels of more than 2°C above those of pre-industrial times, unless greenhouse gas emissions are curbed. that means there is no reason to believe sceptics’ claims that the earth has stopped warming or that climate policies are a waste of money, said the report’s lead author, Alexander Otto of Oxford university’s Environmental Change Institute.

I'm not sure whether Dr Otto has quite grasped the concept of discounting. I think he might have been better sticking to the science than getting involved with the economics.

The BBC also reckons the results do not mean much:

...when it comes to the longer term picture, the authors say their work is consistent with previous estimates. The IPCC said that climate sensitivity was in the range of 2.0-4.5C. 

This latest research, including the decade of stalled temperature rises, produces a range of 0.9-5.0C.

"It is a bigger range of uncertainty," said Dr Otto.

"But it still includes the old range. We would all like climate sensitivity to be lower but it isn't."

Perceptive readers will note that the range quoted of 0.9-5deg;C is different to that quoted by Nic Lewis in his article here last night. The difference is that the BBC is using the whole data range (which includes the poor quality data from the 1970s) whereas Nic is quoting the figure derived only from the most recent and therefore better quality, data. I think reasonable people can differ here, but it is important to note that the mode of the estimate produced by the full range is lower than that of the single-decade estimate.

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Reader Comments (15)

I think the BBC reaction is very important. Although they cage it in "it's still bad" - the headline (which is all people really remember) is not something we've seen before at the beeb - an admission that it's NOT as bad as they thought.

May 20, 2013 at 9:43 AM | Unregistered CommenterTheBigYinJames

The Beeb reports "Since 1998, there has been an unexplained standstill", so how can it credibly report a future projection having certainty?

May 20, 2013 at 9:48 AM | Unregistered CommenterJoe Public

Perhaps OT and apologies in advance for the length but a reminder of what Professor Anderson asked me on this post (

Hi Don,

I don't think there is much/any disagreement with the concept of CO2 fertilisation - certainly I was aware of it being considered and commonly factored in to analysis many years back. However, as with most things it's a matter of scale (level and rate of change). What is your reading of the ppmv level of a high CO2 world? - and also what's your understanding of the impacts on ocean ecosystems where presumably acidification may offset benefits to a degree (or even land ecosystems away from impacts on specific species). This is not my area so given you've read the relevant papers any summaries reflecting the breadth of views for different ppmv ranges and rates of change would be appreciated.



In response I provided Professor Anderson with several papers/links to both CO2 fertilisation/ocean "acidification" (see below).
Unfortunately he has not acknowledged/replied.

is probably as good a place to start and reviews a number of studies using up to 600ppm CO2
Ainsworth, E.A. and Long, S.P. (2005).
What have we learned from 15 years of free-air CO2 enrichment (FACE)? A meta-analytic review of the responses of photosynthesis, canopy properties and plant production to rising CO2. New Phytologist 165: 351-372.

This (
takes us up to about 1800ppm
Schubert, B.A. and Jahren, A.H. 2011. Fertilization trajectory of the root crop Raphanus sativus across atmospheric pCO2 estimates of the next 300 years. Agriculture, Ecosystems and Environment 140: 174-181.

From these articles you can probably see why I am relaxed about bioproductivity in a high [CO2] world.

Much has been said about the dangers of ocean acidification (actually a slight drift towards a more neutral, but still alkaline pH), without an understanding that many organisms, particularly calcifying ones, have lived through periods when atmospheric [CO2] was considerably higher than today or, indeed, future projections. Again the worriers appear to have overlooked the facts. Thus scleractinian (hard) corals evolved during the Triassic some 250 to 200 million years ago, when atmospheric [CO2] was some 5 x higher than todays.

McCulloch, M., Falter, J., Trotter, J. and Montagna, P. 2012. Coral resilience to ocean acidification and global warming through pH up-regulation. Nature Climate Change 2: 623-627.

Growth of Western Australian Corals in the Anthropocene, Science 3 February 2012: Vol. 335 no. 6068 pp. 593-596. DOI: 10.1126/science.1214570

Natural variation, and the capacity to adapt to ocean acidification in the keystone sea urchin Strongylocentrotus purpuratus

Morgan W. Kelly†,*, Jacqueline L. Padilla-Gamiño†, Gretchen E. Hofmann
DOI: 10.1111/gcb.12251

A rapidly growing body of literature documents the potential negative effects of CO2-driven ocean acidification (OA) on marine organisms. However, nearly all of this work has focused on the effects of future conditions on modern populations, neglecting the role of adaptation.

Finally following Dr Richard Bett’s intervention regarding CO2 becoming saturating;

“You're right that CO2 fertilization is included in climate models - I worked on that area of the Met Office Hadley Centre model in the 1990s. I see Don cites a paper with Graham Farquhar as a co-author - we use Farquhar's formulation in our model. While photosynthesis does indeed increase as CO2 concentrations rise, this saturates at higher concentrations. i.e.: the benefit does not go on indefinitely. You know the implications of this, but for the benefit of other readers, this means that the resulting carbon sink (which has been partly offsetting anthropogenic emissions in the past) probably won't continue at its current rate. The airborne fraction of CO2 emissions, which is currently about 50%, is therefore expected to become larger. This should be taken into account in translating emissions scenarios to concentration scenarios.”

@Richard, I too have used Farquhar's model when putting together software to measure photosynthesis and calculate A/Ci curves.
Whilst you are correct that photosynthesis saturates at higher concentrations, this is true of any enzyme-mediated biological reaction.
The point is that photosynthesis is not going to saturate any time soon :-)

This paper may help you
Plant biomass is known to increase in response to elevated atmospheric CO2 concentration (pCO2); however, no experiments have quantified the trajectory of crop fertilization across the full range of pCO2 levels estimated for the next 300 years. Here we quantify the above- and below-ground biomass response of Raphanus sativus (common radish) across eight pCO2 levels ranging from 348 to 1791 ppmv. We observed a large net biomass increase of 58% above ground and 279% below ground. A large part of the net increase (38% of the above-ground and 53% of the below-ground) represented biomass fertilization at the high levels of pCO2 (700–1791 ppmv) predicted if fossil fuel emissions continue unabated. The trajectory of below-ground fertilization in R. sativus greatly exceeded a trajectory based on extrapolation of previous experiments for plants grown at pCO2 < 800 ppmv. Based on the experimental parameters used to grow these plants, we hypothesize that these experiments represent the maximum CO2 fertilization that can be achieved for this plant growing under low light levels.

Note photosynthesis saturates at higher light intensities the higher the [CO2]. If anything this paper underestimates the upper limits for CO2 saturation.

And even when CO2 does saturate, plants will still gain benefit from lowered transpiration- thus allowing then to grow with less water/live in more arid places from which they are currently excluded.


May 20, 2013 at 9:48 AM | Unregistered CommenterDon Keiller

@Joe Public.

But I thought the "science was settled"?
How can the post 1998 standstill be "unexplained"?

May 20, 2013 at 9:50 AM | Unregistered CommenterDon Keiller

This will further undermine the whole IPCC/Science/Policy enterprise. You cannot pay for 23 years of research and end up with a bigger range of uncertainty.

It's as if Boeing threw money to perfect a new plane only to discover it just as reliable years after becoming operational as it was when still a prototype

(...wait a moment!!...)

May 20, 2013 at 9:54 AM | Unregistered CommenterMaurizio Morabito

This will further undermine the whole IPCC/Science/Policy enterprise. You cannot pay for 23 years of research and end up with a bigger range of uncertainty.

It's as if Boeing threw money to perfect a new plane only to discover it just as reliable years after becoming operational as it was when still a prototype

(...wait a moment!!...)

May 20, 2013 at 9:54 AM | Registered Commenteromnologos

This paper appears to be dancing on the head of a pin in an attempt to gain acceptance for the concept that the recent 'slowdown' in global warming is encompassed by the previous 'settled science'.

I don't buy it.

May 20, 2013 at 10:10 AM | Unregistered CommenterBilly Liar


The climb down was always going to be gradual. They are downwardly moving the 'average' sensitivity, it seems on a monthly basis. I know it's not the U-turn people want, but that was always unrealistic.

May 20, 2013 at 10:24 AM | Unregistered CommenterTheBigYinJames

May 20, 2013 at 9:54 AM | Maurizio Morabito

This will further undermine the whole IPCC/Science/Policy enterprise. You cannot pay for 23 years of research and end up with a bigger range of uncertainty.

It's as if Boeing threw money to perfect a new plane only to discover it just as reliable years after becoming operational as it was when still a prototype

(...wait a moment!!...)

The Laws of Economics preclude one from paying a little and getting a lot, however, the same Laws of Economics do not prevent one from paying a lot and getting very little ... climate science (tm).

May 20, 2013 at 10:54 AM | Unregistered CommenterStreetcred

I'm in favour of finding honourable exit strategies for people associated with the IPCC débâcle, but not at the cost of appearing to support further bad science as a remedy for previous mistakes.

The phrase "[transient] climate response” I can live with. But the term "Equilibrium climate sensitivity" is a misleading abstraction from models. It is not describing a system at equilibrium, but a system ostensibly at a steady state. Unwarranted assumptions are what got them where they are today.

Conceptually, as I was taught chemical thermodynamics, a system at equilibrium is sitting in a potential-energy well on the reaction coordinate. The potential gradient is precisely zero at the bottom of the well (and positive non-zero at every surrounding point in the well).

May 20, 2013 at 10:58 AM | Unregistered Commentermichael hart

In the meantime, The Sunday Times this week had a major 'discussion' feature (Q & A) about domestic solar panels, entitled: 'Has the sun set on solar power?'...
Stopping slightly short of 'don't touch them with a bargepole', taking account of the reduced (and reducing further) feed-in tariff, and bearing also in mind that these things are not 'fit and forget', the article was pretty damning. Basically, the sums just don't add up to anything like the sort of returns being implied by the salesmen.
Furthermore, don't even think about fitting them if you're planning to sell your house any time soon; they automatically put buyers off.

May 20, 2013 at 1:07 PM | Unregistered Commentersherlock1

"It's worse than we thought!"

(Because if it's not as bad as we thought then all the backtracking and climb-downs will be painful)

May 20, 2013 at 1:57 PM | Registered CommenterSkiphil

Lord Ridley says:

there is now a good chance we will have decarbonised the economy before any net harm has been done

And on the same day, Rossi's ECAT gets independant confirmation here.

May 20, 2013 at 4:49 PM | Registered Commentersteve ta

The Ridley article can be read at less expense here

He seems convinced this is a real game-changer, e.g.

So this study is about as authoritative as you can get. It uses the most robust method, of analysing the Earth’s heat budget over the past hundred years or so, to estimate a “transient climate response” — the amount of warming that, with rising emissions, the world is likely to experience by the time carbon dioxide levels have doubled since pre-industrial times.

The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too. That is to say, up until my teenage children reach retirement age, they will have experienced further warming at about the same rate as I have experienced since I was at school.

In other words, the panic ought to be over. In his words

The strong possibility that climate change will be slow and harmless must be taken seriously before we damage more lives, landscapes and livelihoods in its name.

Amen to that.

May 20, 2013 at 9:32 PM | Registered CommenterJohn Shade

"decarbonised the economy"

Reductio ad absurdum. The removal of humanity.

May 20, 2013 at 9:40 PM | Unregistered CommenterManfred

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