As many of us would have predicted (had we bothered with such a prediction), with the release of the IPCC AR5 WGII report, deniers have been busy protesting climate science.
I started to put together a summary of protest articles from WUWT:
- Larry Hamlin says the risks are overstated (archived here).
- The GWPF advisers can't make up their mind if the report is alarmist or if it's a comfort. Richard Tol says the report is too alarmist for his taste and when Bob Ward points out where he's made mistakes Richard goes all sooky (as he does) and claims he's being "smeared". Matt Ridley, on the other hand, says the latest report has "toned down the alarmism". I've written about that already - well not the smeary Richard bit. The IPCC itself has addressed that one! And here's the Daily Mail articles that the IPCC was responding to. (For fun, read the caption under the photo of Ed Davey, half way down the page.)
- Anthony Watts says a journalist for the LA Times is wrong and that crop yields are not depressed because Roy Spencer told him so (archived here).
Hang on, that last one is something I'm quite interested in. I didn't know that Roy Spencer was an expert in agriculture. Maybe it's Roy Spencer who's wrong. Here is what Anthony wrongly "claims":
LA Times Tony Barboza gets caught fear mongering the IPCC report, becomes first victim of facts that don’t agree with claims
....Problem is, the agricultural data doesn’t match the LATimes/IPCC claim, see for yourself:
I decided to look first at what the journalist actually wrote. Here it is, in an article by Tony Barboza in the Los Angeles Times:
One of the panel's most striking new conclusions is that rising temperatures are already depressing crop yields, including those of corn and wheat. In the coming decades, farmers may not be able to grow enough food to meet the demands of the world's growing population, it warns.
So next I turned to the WGII report to see what it stated about crop yields. Chapter 7 is the one about food security and food production system - for people (like me) who find this latest report even harder to navigate than WGI.
As an aside, why couldn't the IPCC just release a single file and one with chapter labels as well as numbers! It takes forever to search each chapter separately when looking for a particular quote. I'd have consolidated the separate chapters into a single document myself except that the files are protected in a way that makes it virtually impossible. And since the IPCC in its wisdom didn't provide a single file, why not have the chapter numbers beside the chapter titles on the web page? Tip: put your mouse over the link beside each chapter title to find out the chapter number. Update - here's a better page which has chapter numbers and titles.)
Be grateful for what we've got I suppose. At least the report is out on time. Here is some of what is in the report regarding crop yields:
Studies have documented a large negative sensitivity of crop yields to extreme daytime temperatures around 30°C. [Chapter 5 AR4, 18.104.22.168.1] These sensitivities have been identified for several crops and regions and exist throughout the growing season (high confidence).
This is probably the part that caught Tony Barboza's attention (my bold italics):
Many studies of cropping systems have estimated impacts of observed climate changes on crop yields over the past half century, although they typically do not attempt to compare observed yields to a counterfactual baseline, and thus are not formal detection and attribution studies. These studies employ both mechanistic and statistical approaches (7.3.1), and estimate impacts by running the models with observed historical climate and then computing trends in modelled outcomes. Based on these studies, there is medium confidence that climate trends have negatively affected wheat and maize production for many regions (Figure 7-2) (medium evidence, high agreement). Since many of these regional studies are for major producers, and a global study (Lobell et al. 2011) estimated negative impacts on these crops, there is also medium confidence for negative impacts on global aggregate production of wheat and maize. Effects on rice and soybean yields have been small in major production regions and globally (Figure 7-2) (medium evidence, high agreement). There is also high confidence that warming has benefitted crop production in some high-latitude regions, such as Northeast China or the United Kingdom Jaggard et al., 2007, Supit et al., 2010; Chen et al., 2010; Gregory and Marshall, 2012).
Yield is affected by growing conditions as well as by planting improved varieties. Plant breeders continue to develop new varieties with improved yield in some crops. But plant breeding can only go so far. Determining what yield would have been like without global warming is not straightforward.
Not only that, but yield is only part of the equation. To feed the world requires a growth in total production (total quantity harvested), not just yield (quantity harvested per hectare). If areas of land become unsuitable for growing particular crops because yield drops too much, then either new areas will have to take up the slack or there'll be less of that crop to go around.
Anthony Watts and Roy Spencer pointed me to the USDA website that has quite a bit of information about crops, total production and yield. I drew up some charts - which I must admit don't inspire confidence in our ongoing ability to feed a growing world population. I've picked out a few of the most common field crops - corn (maize), wheat, barley, oats, sorghum and rice.
Yield of selected field crops
First let's look at yield. That's what Anthony wrote about and that's what was mentioned in the LA Times article. I suggest clicking on the chart to enlarge it.
|Data Source: USDA|
What the chart suggests is that corn yield continues to improve linearly. Wheat has had its heyday. Yield continues to improve but not like it did up to around the mid 1990s. Sorghum isn't making any great strides at all. Rice has picked up a bit after a lull in the late 1990s.
The question that the IPCC would like addressed is whether or not the yield is being adversely affected by global warming. You can't tell that from the charts. You'd need to separate out the yield improvements as a result of plant breeding and crop management from any effect of climate. In other words, if global warming wasn't happening, would the yield be greater or less than it is.
Total production of selected field crops
Next have a look at the total production of the same field crops. Here is the result:
|Data Source: USDA|
Once again, corn is the clear leader, with a huge hike in total production in the past few years. Wheat is tapering off. Rice has moved back toward the trend line. Oats and barley are in decline and sorghum is fairly steady.
Lastly, consider the area harvested for the same crops.
|Data Source: USDA|
Looking at the chart, the area planted to corn has gone up in the last few years in particular. Putting this chart together with the other two, corn has a double advantage - more area planted plus considerable improvement in yield. Wheat on the other hand has to rely on yield improvements because the area planted has shrunk compared to the late 1970s. Rice growing continues to expand. Oats and barley are quite out of favour, while sorghum is only slowly declining.
What does this mean? Keeping pace with a growing population.
These field crops are only interchangeable to a limited extent from a cropping perspective. Corn and rice needs lots of water. Wheat, oats and barley can be grown as dryland crops but they need moisture to germinate. They don't want too much rain when the grain is ripening or they'll get all sorts of fungal infestations and other problems. Sorghum can grow where other crops can't, but there are a lot of different types suiting different conditions. In other words, when climate changes - autumn or spring rains are no longer reliable, or the summer is wet instead of dry, or there are extended periods of drought and the irrigation water is no longer available - then production drops in that region, or even ceases entirely.
The reason I'm not encouraged is that looking at wheat for example, it suggests that any growth in total production will come down to continued improvements in plant yield, not in area planted. There is only so much improvement before yield improvements start to taper off. But the human population is still increasing.
Different areas are suited to different types of agriculture. There isn't a lot of land about that can be converted to cropping. Some horticultural land will probably shift to field crops as climate changes. I'm thinking particularly of my home state, where horticultural production needs irrigation. Our region is going to keep getting hotter and drier. Water will become more scarce and more costly. That will mean a shift in production. So we may get wheat instead of cherries. (Well, more likely wheat instead of citrus or wine.)
On the other hand, in the marginal cropping land in some regions, farmers are giving up. Wheat has been grown on marginal land in south western australia - and that's getting drier.
I'm not going any further with this for now. There is more on the topic in WGII (Chapter 7). Just thought it worth an article because we need to eat. And if production doesn't keep pace with the growing world population then food prices will rise and food will become scarce. This will have lots of flow on effects such as famine, civil unrest and mass migration. Plus large areas of land may be left unmanaged, with consequent damage to the environment.
From the WUWT comments
There were lots of people who moaned that newspapers and journalists don't check facts. Ironic, eh? The journalist wrote what was in the IPCC report. It was the WUWT crowd who didn't check the facts - they just lapped up what Anthony Watts and Roy Spencer fed them, without question. Without checking it for meaning or accuracy.
Billy Ruff'n says:
April 1, 2014 at 11:35 am
You’re letting facts get in the way of feelings….
Peter Miller probably knows "where to look" but was too lazy. He says:
April 1, 2014 at 11:36 am
The facts are boring and don’t sell newspapers, but scary unfounded stories sell newspapers.
It is probably no more than this. Also, the hack was too lazy to check the facts, or so uninformed and pig ignorant that he did not know where to look.
Brian R probably means every word he writes and speaks on behalf of all WUWT-ers when he says:
April 1, 2014 at 11:40 am
Facts? We don’t need no stinking FACTS!
JimS wouldn't make a good reporter because he says:
April 1, 2014 at 11:45 am
The difference between a good reporter and a poor one is this: a good reporter checks the facts; a poor one doesn’t. It seems as though the AGW movement, if we can call it that, survives and thrives because the quality of good media reporting has dropped considerably.
James Ard might have made a fool of himself after he says:
April 1, 2014 at 11:48 am
Will the refutation of their just plain wrong claims be allowed in their letters to the editor?
April 1, 2014 at 11:39 am
Tony Barboza is a name I expect to see on the back of a boxer’s robe. Sounds like his aspirations significantlly exceed his mental abilities. “Hey, with haf a brain, I coulda’ been somebody.”
RM3 Frisker FTN opts for "CO2 is plant food", ignoring the fact that excessive heat kills plants and crops need water, and says:
April 1, 2014 at 11:47 am
Maybe we could convince Lord Mockton to write a post that again uses the graph showing both CO2 vs Time and Temperature Anomaly vs Time with the thirteen plus year pause while CO2 continues to climb. Further in the post would be a second graph showing Agriculture Yields vs Time and CO2 vs Time, illustrating the correlation between CO2 concentration growth and Agriculture Yields. In other words CO2 equals Plant Food. QED via the Correlation yields Causation logic of the Alarmists.
Mac the Knife goes for a conspiracy ideation and says:
April 1, 2014 at 12:01 pm
“Maybe he’s just too lazy to check facts like this? Or, is it belief mixed with incompetence?”
The third possibility is a willingness to ‘shade the truth’ sufficiently to create a perception of alarm…. and sell more subscriptions to secure his paycheck.
April 1, 2014 at 12:09 pm
Tony did his job. He spread fear so the Progressive boot can be pressed against our necks.
rw is an "ice age comether" and says:
April 1, 2014 at 12:27 pm
If it keeps getting colder, we will see crop reductions. So Tony may have his predictions right even if he’s a bit off regarding causation.
I read through every single comment and only one person, mark 543, had checked the facts or looked at the IPCC WGII report itself. One or two others picked it up later in the discussion but in the main, the WUWT commenters are a bunch of mindless m....