Tuesday, April 03, 2007

Crops better off with global warming

As the world climate report suggests, crops around the world will be better off with global warming, not worse, as many doomdayers and media outlets report.

They did an internet search of “Global Warming and Agriculture” and found more than 5,000,000 websites, and as they began sampling the sites, we encountered an overwhelming amount of bad news. They continue to say:

literally thousands of experiments have been conducted showing that agricultural plants benefit enormously in environments of higher concentrations of atmospheric carbon dioxide – they increase their rate of photosynthesis, increase water use efficiency, and increase yields. Furthermore, hundreds of experiments have shown that many agricultural plants benefit from higher temperatures, particularly higher temperatures at night. Believe it or not, most agricultural plants benefit from less frost! With all the gloom and doom about increased drought in the future, we note that all climate models predict increased precipitation on a global scale with little ability to predict changes in precipitation at local or even regional scales. Finally, can you name any important agricultural crop that has seen a reduction in yield per unit area over the past century? You cannot, because years of agricultural research have improved both the plants and the farming practices. Our guess is that the research in the future will produce even greater increases in yields, despite any changes that occur to the climate.

and of course have scientific evidence to back them up, quoting a recent article in the journal Climatic Change, entitled “Historical effects of temperature and precipitation on California crop yields.”

• “Wine grape yields were favored by years with warm nighttime temperatures in April and higher rainfall in June. Warm April temperatures reflect decreased risk of frost damage during the vulnerable post-budbreak spring growing period, when frosts can severely depress yields by damaging rapidly developing vegetative and cluster tissues”

• “Lettuce yields appear aided by warm days in April (up to about 23°C), as well as the October prior to harvest year.”

• “Table grape yields were increased with October rains in the year preceding harvest, and with warm nighttime July temperatures.”

• “Orange yields were most correlated with ppt [precipitation] in May and tmin [minimum temperatures] in December prior to and March of the harvest year.”

• “The strongest climatic response variable for cotton was a positive effect on yield for warmer May tmax [maximum temperatures]”

• “Tomato yields increased with warm April tmax, and with June tmax up to 32°C”

• “No significant relationships with climate were identified for pistachios yields”

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