Look, this comes from Lester Brown so there\’s obviously going to be something wrong with it. However, this is what they say:
The study, published in the journal Science, examined how rising temperatures affected the annual crop yields of all major producer nations between 1980 and 2008. Computer models were used to show how much grain would have been harvested in the absence of warming. Overall, yields have been rising over the last decades and the models took this into account. The scientists found that global wheat production was 33m tonnes (5.5%) lower than it would have been without warming and maize production was 23m tonnes (3.8%) lower.
So its a rather if my aunt had balls sort of analysis. We assume that increased temperatures will have a certain effect and here\’s the result of making that assumption.
Yes, there is more, this is from Lester, remember?
although the rise could be as low as 6.4% if the increased carbon dioxide in the atmosphere strongly boosts plant growth and yields – a factor that is not well understood by scientists.
So their more remarkable results seem to include only the cost, not the benefits. Hmm.
Much more interesting though is, well, let\’s assume that they\’re correct and in good faith (Oh, c\’mon, this is Lester), well, how important is this?
Oh. Despite these terrible effects of global warming, we\’ve been increasing production of wheat all the while. Indeed, eyeballing that, production has gone up by more than the calculated loss.
So not very important at all then.
Contrary to what he claims
“if the increased carbon dioxide in the atmosphere strongly boosts plant growth and yields – a factor that is not well understood by scientists.” the increase in yield with increasing CO2 is extremely well understood by scientists. In fact it’s about the only thing about atmospheric CO2 we do understand. This is because you can do controlled experiments with different artificially created atmospheres on a small scale and actually measure the differences.
“… a factor that is not well understood by scientists.”
Perhaps they should ask the commercial greenhouse guys. It’s well understood by them, which is why they raise the CO2 levels to 1000ppm or so.
Exactly. I covered CO2 and plant growth in school, circa 1978. It’s O-Level stuff.
And long before then my father was artificially increasing CO2 in his greenhouses- sometimes with dry ice, usually by burning propane.
The graph here shows that 20% of crop production is due to the increase in atmospheric CO2. Even if real world results are slightly less than the experiment al ones it suggests that the nature of the catastrophe in “catastrophic global warming” is not easily found. http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm
it’s a tough case to make, earlier harvests, more Winter wheat…ergo lower harvests in total,,,it seems to be a win-