Geriatric wheat caused by climate change

She's only 21. Damn you AGW.

Naturally, all the solar schmolar stuff discussed here earlier today is completely ignored by Your ABC, which instead picks on an alarmist research paper about premature ageing in wheat:

Extreme heat can cause wheat crops to age faster and reduce yields, a US-led study shows, underscoring the challenge of feeding a rapidly growing population as the world warms.

Scientists and farmers have long known that high heat can hurt some crops. Now a study led by Stanford University reveals how the damage is done by tracking rates of wheat ageing, or senescence.

Depending on the sowing date, the grain losses from rapid senescence could reach up to 20 per cent, the scientists found in the study, published in the journal Nature Climate Change [abstract here].

Lead author David Lobell and his colleagues studied nine years of satellite measurements of wheat growth from northern India, tracking the impact of exposure to temperatures greater than 34°C to measure rates of senescence.

They detected a significant acceleration of ageing that reduced the grain-filling period. The onset of senescence imposes a limit on the time for the plant to fill the grain head.

“What’s new here is better understanding of one particular mechanism that causes heat to hurt yields,” says Lobell. He says that while there had been some experiments showing accelerated ageing above 34°C, relatively few studies considered temperatures this high.

“We decided to see if these senescence effects are actually occurring in farmers’ fields, and if so whether they are big enough to matter. On both counts, the answer is yes.”

Climate scientists say that episodes of extreme heat are becoming more frequent and more prevalent across the globe, presenting huge challenges for growing crops. (source)

Lobell has been reported frequently in the past on the same subject of decline in wheat yields arising from climate change, and not everyone is convinced by the link Lobell claims:

While the paper [an earlier paper covering similar ground in Science in May 2011] is “an interesting contribution to the discussion,” says John Reilly, an agricultural and energy economist at the Massachusetts Institute of Technology in Cambridge, Massachusetts, its conclusions are “not compelling.” Many caveats and uncontrollable factors—including the price of crops, the latitude at which they are planted, and specific advances in technology—could contribute to the changes in trend that the authors see, weakening their link between yields and warming. “It’s a careful set of work, but it’s just a hard area to work in,” Reilly says.

Reilly points out that IPCC predicts an increase, not a decrease, in global crop production, as more CO₂ in the atmosphere is beneficial for plant growth. But Lobell says his analysis suggests that any advantage this CO₂boost confers is already being pushed to its limit, because warming itself harms crops. (source)

More research needed, perhaps?

UPDATE: The ABC does cover a couple of climate stories today, interestingly the Wall Street Journal letter reported here. The ABC firstly smears the WSJ as “Murdoch-owned” just to set the scene, and after interviewing William Kininmonth (a meteorologist) wheels out who else but Tim Flannery (a mammalogist) to complain that the letter is signed by some who aren’t climate scientists. Oh the irony. Flannery flannels on about Republicans and fails to address any of the substantive issues. Read the transcript here.

And just in case that was a little too “sceptic-friendly” Auntie then rolls on, without pausing for breath, into a decent Green-friendly alarmist story here. The transcript fails to mention that the dominant cause of the issue in question is changes in wind patterns arising from loss of ozone, but the ABC and CSIRO pin it firmly on man-made greenhouse gases. How convenient. I have an email in to the authors of this study asking for some clarifications. I wonder if I’ll get an answer…