The “CO2 is Good for Plants” Crock. Turns out — not so much.
December 8, 2010
The video above from NASA, describes recent research indicating decline of primary plant productivity around the planet over the last decade. The study indicates that Global warming may be the cause.
Now Science News reports that “signs of food insecurity – droughts, food riots, five to tenfold increases in produce costs – have erupted around the globe.”
The article explains:
“Severe summer droughts in Russia, Ukraine and Kazakhstan ravaged 2010 cereal yields. When Russia, the fourth largest wheat exporter, imposed an export ban in August, international markets responded with price spikes. Having sold around 17 million metric tons on world markets in 2009, Russia’s 2010 wheat exports are expected to fall closer to 4 million metric tons, according to a November Food Outlookreport by the United Nations Food and Agricultural Organization, or FAO. (Russia’s export ban is slated to remain in effect until next July.)”
Climate deniers continue to cling to the rationale that “Co2 is good for plants” – it’s sixth grade logic that appeals to the Fox News crowd, but actual experience is not bearing it out. Climate Change, in the real world, means increasing numbers of extreme weather events, droughts, floods, storms – which make it more and more difficult for the world’s farmers to conduct business as usual.
• Many crops show positive responses to elevated carbon dioxide and low levels of warming, but higher levels of warming often negatively affect growth and yields.
• Extreme events such as heavy downpours and droughts are likely to reduce crop yields because excesses or deficits of water have negative impacts on plant growth.
• Weeds, diseases, and insect pests benefit from warming, and weeds also benefit from a higher carbon dioxide concentration, increasing stress on crop plants and requiring more attention to pest and weed control.
• Forage quality in pastures and rangelands generally declines with increasing carbon dioxide concentration because of the effects on plant nitrogen and protein content, reducing the land’s ability to supply adequate livestock feed.
• Increased heat, disease, and weather extremes are likely to reduce livestock productivity.
Above and beyond effects on agricultural crops, many deniers will be surprised to learn that the most important plants on earth may not be those that grow in a corn field or rice paddy. Our ocean food chains, the foundation of life on earth, rely on the health of the tiny photosynthesizing organisms that float and bloom in the world’s salt water – and this summer a landmark paper announced that plankton numbers may have dropped as much as 40 percent over recent decades, in response to ocean warming.
“These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.”
Farmers and hunters, people who live close to the land and spend much of their lives outdoors, know about these changes. Last week, Minnesota farmer Jack Hedin wrote in the New York Times about the changes seen on the farmland that his family has tilled for generations. He begins, “The news from this Midwestern farm is not good….”
“The 2010 growing season has again been extraordinarily wet. The more than 20 inches of rain that I measured in my rain gauge in June and July disrupted nearly every operation on our farm. We managed to do a bare minimum of field preparation, planting and cultivating through midsummer, thanks only to the well-drained soils beneath our new home.
But in two weeks in July, moisture-fueled disease swept through a three-acre onion field, reducing tens of thousands of pounds of healthy onions to mush. With rain falling several times a week and our tractors sitting idle, weeds took over a seven-acre field of carrots, requiring many times the normal amount of hand labor to control. Crop losses topped $100,000 by mid-August.”
Agricultural production doesn’t increase merely by adding one or another nutrient, as city slickin’ climate deniers seem to think – biological systems are shaped by the limiting factors. Plug in all the co2 you want, you won’t grow crops in a drought. Burn all the coal you like, when soil is washed away in a flood, the harvest is lost.