ClimateProgress has a post about yet another report, this one by Maoshung Zhao, funded by Nasa and using satellite data, that plant growth is on the wane globally - once again ascribed to warming and drought, a version of which I actually read first in the Guardian. Of course, I do think warming and drought will ultimately destroy agriculture, but there is something much more immediately menacing going on.
"Ambient ozone exposures in the region were sufficient to cause visible foliar injury, early leaf senescence and premature leaf loss in all species. Ozone had significant negative effects on net photosynthesis and stomatal conductance in all species...Water-use efficiency decreased and intercellular CO2 concentrations increased in all species in response to ozone...mean ring width in the AA and NF P. nigra seedlings was reduced by 52 and 46%, respectively..."
And by the way, Steve H, your comment is fascinating. The very first avenue of inquiry I pursued was higher levels of CO2, since that is the major change, but I was told very firmly by the Real Climate scientists and others that there was no way on earth CO2 could adversely impact plants. Hm. If you have any links please post them here or on my blog!
"'The effects of extreme weather on crops are only beginning to be understood. Many scientists had projected that climate change's rising global temperatures would help countries in the North produce more food.
For decades scientists studied the effect of global warming on crops by simply raising temperatures and carbon dioxide levels in greenhouses. They did not take into account the effects of floods and droughts, or reduced yields that result from higher temperatures.
"There's been a severe failing of the scientific community. on that," said Gulledge. "Climate science proceeded amazingly over that period, but this topic was handled poorly.'"
"Based on the observed biochemical, physiological and structural changes in chloroplasts of clone B in response to low concentrations of ozone, we conclude that the increasing concentration of tropospheric ozone represents a risk to natural birch populations."
I don't know WHY scientists insist on saying "represents a risk" rather than "will kill" - or "in decline" instead of "dying".
"Dear Gail ZawackiOldwickI saw your webpage, and it is very interesting. Because we also used satellite radiometirc information in our calculation, which provides us information on how much green leaves in a one square kilometer pixel of each vegetated land on earth, the amount of leaves will be less if ground vegetation experinced damages, regardless of the causes of damages, such as deforestation, insect outbreak, pollutions, etc. But in most cases, we don't know if the reduced leaf amount observed by satellite either caused by climatic stress or human activities at a given pixel without further analysis. Therefore, reduced leaf amount will cause decreased calculated NPP, and ozone effects have been accounted for. But over large scale, a reduction or increase of plant growth generally is caused by climate fluctuations. In our paper, we have mentioned this in the second paragraph (attached)."
Hi, it was very kind of you to reply, thank you so much especially for attaching the whole paper! But I confess I am still confused. The second paragraph you refer to I read as being:"Between 2000 and 2008, CO2 emissions from IPCC in the Fourth Assessment (1). Carbon-budget meth- ods show that the land is becoming a stronger carbon sink, whereas large uncertainties exist in the partitioning of ocean and land carbon-sink components (1, 4). Satellite data can generally provide realistic information on vegetation dy- namics, including land cover change (5, 6), dis-turbances, and recovery (7), which may help to reduce uncertainties in carbon-budget estimates. In this study, we investigate terrestrial NPP and climate variability over the past decade (2000 to 2009) by analyzing satellite data from the Mod- erate Resolution Imaging Spectroradiometer(MODIS) on board NASA’s Terra satellite and ." continued to increase at a rate consistent with the average of the highest- emissions family of scenarios, A1FI, used by theIt is not clear to me how that accounts for ozone. Do I have the wrong paragraph? Or do you mean that measuring leaf loss automatically accounts for ozone damage, and if so, how do you separate ozone damage from losses due to higher temps and/or drought? Sorry to be a pest. I really want to understand this! thanks,Gail
"Gail The word "disturbance" covers this. Also in scientific field, using satellite data, currently we have low capability to tell the specific cause of damaged vegetation (except wildfire and large scale deforestation), such as distinguishing ozone damage from insect attacks from space. [empasis added]But these negative effects from these "disturbance" will low leaf amount as observed by satellite, and hence low NPP. On the other hand, after the disturbances, there is also recovery, as showed a increased leaf amount, which also can be captured by satellite.Maosheng"