Apr
5
No better offs for food supply under climate change?
April 5, 2008 | | 1 Comment
by Rachael
Rising temperature does melt glaciers which affects crop irritation and it is known that cultivating environment in high temperature damages crop growth, but on the other way round, increase in carbon dioxide concentration could cast influence to photosynthesis which in turn, might overcome the situation of dropping crop yields, as pointed out in another report on New Scientist.
The report said that “In regions where the average daily temperatures are expected to rise above 30ºC, rice yields will start to fall off, and the impact will get worse as the temperature increases,” even though “the drop in yield caused by rising temperatures can be counteracted by the boost to photosynthesis provided by the increased levels of carbon dioxide driving climate change.”
Ozone levels affect the crop growth too.
“Harvests will also be reduced by rising ground-level ozone concentrations. They are caused by nitrogen oxides (NOX) from power stations that catalyse the formation of ozone in warm and sunny conditions.” It has been recorded on farms in China and the United States that ozone concentration of around 60 parts per billion causes yields to drop by 14%.
So it could actually be a cycle of factors which are affecting one another. Scientists said on the report that it was too difficult to conclude that how exactly climate change is impacting crop yields. “…most studies look at just one of these factors, making it difficult to know what the combined effect will be.” However, I tend to agree with the latest comment to this piece of article:
“Most major food crops are intolerant of high temperatures and we need to ask what role heat stress is playing in the existing global food shortages, especially with the increasing frequency of severe heatwaves in Australia and Africa.”
The commentator further adds that “Photosynthesis shuts down around 37 degrees C. Serious
damage to most crops is especially evident around 45 degrees C (in the shade)”.
Under this, how much could the so-called increasing carbon dioxide could outweigh the growth of crops when the crops could not manage to support their own lives?
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There’s so much uncertainty in some of these studies that it seems to be little better than speculation…