Bishop Hill More Climate Change Committee
Oct 3, 2011 Climate: Parliament Climate: WG2 Climate: WG3 Remember this? These were some of the impacts expected for various degrees of global warming as described in the Climate Change Committee's report.
;)
Click for full sizeThe source for this table is IPCC WG2 - it's a direct lift from one report to the other. The IPCC report then provides citations for each impact described.
The one near the top - semi-arid/arid areas increase by 5-8% - struck me as interesting. After all, we have heard about the greening of the Sahel, so I was expecting exactly the opposite impact in Africa.
The table in the IPCC report is sourced from this page, which says:
Furthermore, for the same projections, for the same time horizon the area of arid and semi-arid land in Africa could increase by 5-8% (60-90 million hectares). The study shows that wheat production is likely to disappear from Africa by the 2080s.
The citation is not entirely clear, but appears to be Fischer et al 2005, a paper in Phil Trans B, where a similar claim is made:
Under the climate change scenarios considered, and by 2080s, AEZ estimates of arid and dry semi-arid areas in Africa increase by about 5–8%, or 60–90 million hectares.
This in turn cites a paper by the same authors - but unfortunately for the Climate Change Committee it's a non-peer-reviewed article. The title is "Climate Change and Agricultural Vulnerability" and it was written by the International Institute for Applied Systems Analysis. This is a familiar name, but I can't quite recall where I've come across them before.
Here the claim is as follows:
Climate changes, as projected by GCMs for the SRES B2 and A2 emission scenarios in the 2080s, would result in another 580,000 km2 (scenario B2, with a range of 360,000–760,000 km2) and 920,000 km2 (scenario A2, with a range of 850,000–1,025,000km2) of arid and dry semi-arid lands, an increase of 5.4% and 8.5% over current conditions respectively.
Unfortunately that is as far as the trail runs - there is no citation given for the claim. What we can tell, however, is that the claim is based on climate models, and we know already that no climate models have been shown to have any skill at a regional level. I put this to Lord Turner at the RSE and he fully agreed, but said that the uncertainty made action more important not less so.
Wouldn't you love to be the betting shop owner when he walked through the door?
What seems clear to me is that this bit of science is decidedly iffy - certainly it is not fit to inform UK policymaking. I wonder if any of the other impacts in the IPCC table are any more rigorous?
Reader Comments (58)
Would the insulin metaphor be used if the cost of using the insulin was such that many other people had to suffer as a result though their own medication no longer being affordable or other medical research being cancelled as a result? Is the true cost of the precautionary approach not what could otherwise be accomplished with the significant sums of money involved?
Regarding CO2 supplementation in greenhouses, 1000-1300ppm is a common high benchmark. Light intensity and temperature are major limiting factors. CO2 & ventilation is usually computer controlled to adjust in accordance with light intensity and temp. Different crops require different levels, at different growth stages, e.g. tomatoes, cucumbers, peppers and lettuce would be supplemented at the seedling stage at 800-1000ppm.
CO2 supplementation is required in intensive greenhouses as crops will otherwise decrease the ambient CO2 to around 200ppm at canopy level, this has far more -ive effect than the +ive effect gained by increasing CO2 above ambient.
CO2 supplementation will shave 5-10% off total growing cycle when compared to non supplemented crops, there will be increased crop quality and yield, as well as increased leaf size and thickness. The increase in Tomato yield (and other fruits) is a result of increased numbers of flowers, and faster flowering per plant.
Supplemented crops can also tolerate higher maximum temps, indeed may prefer higher temps IMO.
HTH.
@ Richard Betts - I don't judge how much insulin I take from a model (and if i did I'd be dead in a week).
Do you think my control would be better if I model everything I will eat over the next 50 years and then declare I need this much insulin or I'll die?
What about if I'm playing sport after lunch how does that fit your analogue?
Oct 4, 2011 at 8:59 AM | Shevva
Of course you shouldn't model everything you eat over the next 50 years, that would be ridiculous!
However if you do carbohydrate counting, or Dose Adjustment For Normal Eating, or other schemes, then you probably have some sort of empirical model in your head, based on experience which is continually updated, in which you have rules for how much carbs translates into the insulin dose, and these rules may even change thoughout the diurnal cycle to account for issues such as higher insulin resistance in the morning for example.
Then you have your other rules for the correction if your blood sugar is high, eg: Bm of 15 equals a correction of 1.5 units of insulin, or whatever.
Issues like excercise also need to be taken into account in the rules (ie: an extra factor in your mental model) - you probably give a bit less insulin before or after excercise, or a bit more if you are ill.
If you use an insulin pump this can all become quite sophisticated.
What about Osborne's speech yesterday? He said he wanted to adjust the rate that we spend on renewable energy to match the rest of europe. If the European avergae includes countries like Poland, this would be definitely a slam on the brakes.
No take-up on this point by the MSM. Does anyone know what the impact will be??
@Richard Betts on diabetes
it is known that diabetes is the result of a lack of insulin. It is only a theory that messing about with CO2 will have any significant effect on changing the climate.
Richard, you say
The climate models we have today, claim to be deterministic, as opposed to being heuristic. Therefore, the situation with the CO2-driven climate model is exactly analogous to modeling everything one eats for the next 100 years. The IPCC process is a mole-to-mole accounting model, not a heuristic model, which any diabetic follows with his/her insulin.
I have come to this discussion rather late, but my attention was caught by:
"I put this to Lord Turner at the RSE and he fully agreed, but said that the uncertainty made action more important not less so."
this is a bizarre position to take, but it relates back to the fallacy of the precautionary principle. We are looking at the output of a model. The model may be a good prediction or it may be completely wrong, or somewhere between. Without knowing the confidence we can assign the model output and a probability that the model is right or wrong then you are unable to decide whether action is justified.
As an example, how many people here have decided to insure their property (house, car etc) against meteorite impact damage?
http://open.salon.com/blog/mister_thorne/2008/12/05/get_affordable_meteorite_insurance
If Lord Turner worked in a risk-based decision making sector, such as oil exploration, he would be bankrupt by now.