Discussion > Writing and reviewing IPCC AR5
Richard Betts,
Firstly, thanks for the heads-up on the imminent IPCC publication.
Secondly, you commented earlier (10:34) on the rate of CO2 uptake being influenced by temperature. My layman's understanding is that CO2 levels were pretty constant - in recent times - until burning fossil fuels became widespread. Your comment calls that into question as it suggests that the levels should have changed during episodes like the Little Ice Age or the Middle Age Warming.
Are there any records or proxies which show how CO2 levels reacted to such temperature swings? (I realise that modern instrumental measurements did not start until the 50s).
mikeh
mikeh
Yes, a bit, although the effects were relatively small and showed up in North America records but not the Antarctica records, see this paper. This would appear to be consistent with the prevailing idea that the episodes you mention were more localised rather than being coherent global events.
Richard Betts
Richard
The Japanese IBUKI satellite showed that the highest concentrations of CO2 were over areas with low industrial emissions how does that fit with your AGW theories?
Dung
Dung
CO2 stays in the atmosphere a long time and gets mixed around the world. The CO2 concentration in any one place is affected not only by where the emissions are, but also the sinks (eg: growing forests) and the atmospheric circulation.
Richard Betts
Richard, are there no benefits from increasing CO2 in the atmosphere. Wouldn't a warming world be wetter, with more precipitation? And wouldn't that extra heat, precipitation and CO2 increase vegetation? And, of course act as a sink for CO2, or are we just going to be fed the usual efforts to frighten us into submission?
Will there be a list of which "projections" made in previous reports have come to fruition?
I know that there are many climate scientists who genuinely believe they're trying to save the world, and I don't doubt their integrity, but do you know what you're actually doing? You're foot soldiers for the environmentalist movement and I, for one, would rather my grandchildren, and great grandchildren took a chance on the horrors supposed to be awaiting them in the next SPM, than suffer at the hands of environmentalists. They have form, while handwringing for the future of our grandchildren they have driven up energy prices in the industrial world with no regard to the consequences for the poor and have deprived, and continue to try to deprive, real live human beings of cures for real life human diseases.
Maybe I'm being a bit over pessimistic, maybe when the scientists and the politicians wake up to the fact that no one can foretell the future this will just go away (the environmentalists won't).
I've often pondered a test for you modellers, the Grand National isn't as complex as the climate, although pretty complex, do you believe you could build a model that can identify the winner a priori? If you do, you have my email address, I'll try to find the funding. Should be easy.
geronimo
Geronimo
Yes, there are benefits from increasing CO2 in the atmosphere, see this Met Office research news item about a paper by my colleagues and myself which suggests that the effects of CO2 on plants is beneficial in partially offsetting the increasing water stress expected from a rising global population. Climate change effects are included too, and they are a mixed bag, with some positive and some negative impacts on water stress.
The top 3 statements of the news item are:
Higher carbon dioxide (CO2) concentrations in the future will change the way plants use water, and might help relieve the water stress caused by a larger global population and climate change.Population growth is projected to be the main driver of an increase in the number of people experiencing water stress in 21st Century.
Climate change is projected to be less important, and may actually decrease the global number of people in water stress - although regionally there will be winners and losers.
I disagree with much of what the environmental movement do - I disagree with them on GMOs for example - but as an objective scientist I'm not going to hide my results just because someone I disagree with likes them. If you see me on Twitter you'll see me call out bad science whenever I see it, no matter which side it comes from.
The Grand National might be quite a good analogy to climate projections, as there's some things we can predict and others that we can't. We can be confident that the horses will (on average) run forwards, just as we can be certain that the climate will confident that the climate will (on average) continue to warm if the concentrations of greenhouse gases continue to increase. There will be some deviations from these - some horses will fall, some years will be cooler than preceeding years - and we can't predict in detail what these will be. We can't even predict how many horses will finish, and we can't predict exactly what the rate of future warming will be. But we can be confident of the general direction of both the race and global temperature.
So, trying the predict the winner of the Grand National is more like trying to predict exactly which year of the 21st Century will be warmest - too much complexity and randomness to make this possible. Predicting long-term temperature change as a result of increased greenhouse gas concentrations is more like predicting how many horses will finish.
That's my view anyway. Analogies are always a bit iffy, but hopefully you get my point :-)
Richard Betts
Richard,
I am setting up a separate discussion thread on the issue of historic CO2 levels. If you can spare a moment, your comments would be much appreciated.
mikeh
"That's my view anyway. Analogies are always a bit iffy, but hopefully you get my point :-)"
And I hope you got mine
.
I'm just a smidge disappointed with the Grand National thing, we could have done good things together. As you know I've just arrived on twitter so will be keeping an eye on your pronouncements -:)
Thanks for the heads up on benefits of CO2, didn't the IAC give the IPCC a rap for not talking about the benefits that would certainly accrue from CO2 enrichment while highlighting projections that might come true?
geronimo
Plant production under climate change is quite complex, with many competing factors and feedbacks. One 2007 study of three major crops found that higher temperatures are already counteracting the CO2-fertilization effect:
"Global scale climate–crop yield relationships and the impacts of recent warming"
David B Lobell and Christopher B Field 2007 Environ. Res. Lett. 2 014002
http://iopscience.iop.org/1748-9326/2/1/014002/
David Appell
Richard
I am sorry to be dense but should you not have written (based on ice core samples):"We can be confident that if the climate continues to warm, the concentration of co2 in the atmosphere on average will continue to increase"? You have it back to front. The empirical ice core evidence is, is it not, that increased concentrations of co2 in the atmosphere lag temperature and not the other way round. You and your models in fact have no idea whether or not the atmospheric temperature is going to go up, down or stay the same whilst you can be fairly certain that, absent some great economic or natural catastrophe, co2 will keep on increasing as the poorer world catches up with the rest of us.
Mike Post
Richard
I can ask you to change one of your models since it is completely wrong :P
There will be no water stress whatever population we have. The invention/discovery of Graphene means that salt will be cheaply and easily "filtered" out of sea water and last time I looked, roughly two thirds of the Earth is covered with the stuff.
Dung
I have not been following this discussion thread at all closely, thanks to my low opinion of the IPCC organisation and leadership. There are no doubt many worthy 'innocents' contributing good work to their studies, but the organisation itself is rotten.
My query/suggestion is to ask any readers here who have or will take a detailed interest in the forthcoming reports, to do some 'compare and contrast' work with the most relevant sections of the NIPCC report 'Climate Change Reconsidered II'. That might help us all get the best from each of them.
John Shade
Plant production under climate change is quite complex, with many competing factors and feedbacks. One 2007 study of three major crops found that higher temperatures are already counteracting the CO2-fertilization effect:"Global scale climate–crop yield relationships and the impacts of recent warming"
David B Lobell and Christopher B Field 2007 Environ. Res. Lett. 2 014002
http://iopscience.iop.org/1748-9326/2/1/014002/Sep 24, 2013 at 5:15 PM | Unregistered CommenterDavid Appell
In figure 1a, yields of all six crops studied rose over the studied period, five them enormously.
Discussing the potential multi-variate causes, the authors sensibly state "..the relative importance of these different mechanisms cannot be determined from the empirical relationships"
I fail to see how they then manage to infer doom from the rather scant data they presented.
michael hart
I suggest reading the paper, especially section 3.2.
David Appell
I suggest you explain to me how:
"Estimates of lost production..."
"Inferred impacts..."
"blah-de-blah-de-blah..."
...substitute for data, which is most noticeable by it's absence in this paper.
michael hart
Why would you write to me, and not the authors?
David Appell
Why, indeed. :)
johanna
The list of people who took part in the IPCC AR5 review process has now been posted up by the IPCC. I have written a blog post about the relatively small number of sceptics who did take part, and the sceptics' dilemma of whether to do so or not.
Paul Matthews
The First and Second Order Drafts of the WG1 report, along with the review comments and author responses, are here.
Richard Betts
As most people here are aware, the Summary for Policymakers (SPM) of the IPCC AR5 Working Group 1 report (The Physical Science Basis) is scheduled to be released on Friday 27th September. The final drafts of the chapters, prior to copy-editting, will be released on Monday 30th September.
All these documents will be available here.