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http://www.cleanmpg.com/photos/data/2/AmericanFlag.jpg Global warming's effects on agriculture would actually be quite complicated—and mostly not for the better. (http://www.newsweek.com/id/216175?from=rss)

http://www.cleanmpg.com/photos/data/500/wheat_farmer.jpgJeneen Interlandi - NEWSWEEK (http://www.newsweek.com) - Sept 27, 2009

Problems with this issue is wishful thinking has replaced honest analysis --Ed.

It's true that some crops will prosper on a warmer planet, but the key word there is "some." According to a 2007 government report, higher CO2 levels and longer growing seasons will increase yields for fruit growers in the Great Lakes region. But many major American crops, such as sorghum, sugar cane and corn already use CO2 so efficiently that more of it probably won't make much difference to them.

What will make a difference are all the other things we'll have more of as temperatures rise—namely droughts, bugs and big storms. More droughts mean lower crop yields—especially for Southern states. Researchers at the University of Oregon found that in New Mexico alone, reduced stream flow could cost farmers $21 million in crop losses. Meanwhile, melting snow in the Western U.S. will increase water availability in spring but decrease it in summer, forcing farmers to change cropping practices.

As pests adapt their migration patterns to our warmer climate, farmers will have to either use more pesticide (anywhere from 2 to 20 percent more, depending on the crop, according to another government study) or plant hardier crops. Floods and hurricanes increasing in frequency and intensity mean farmers will have to brace themselves for still more crop losses, and the federal crop insurance program (FCIP) will have to get used to writing bigger insurance checks. A single record-breaking Midwestern 1993 flood cost them $2 billion in lost crops....http://www.newsweek.com/id/216175?from=rss

This article is more than a bit alarmist.

Regarding crop CO2 usage, most of our crops have C3 metabolism and would benefit from higher CO2 levels. The three crops they mentioned as not being affected all have C4 metabolism, and beside the three they mentioned, I can't think of any other major crops using a C4 metabolism.

As far as pests go, if they can overwinter further north due to a warmer climate, then they'll just show up earlier during the growing season than they do now and may produce extra generation of pests during the growing season. But this is no worse then what they experience a state or two further south. So I might experience the pests that Florida's farmers see and Wisconsin farmers might see the pests that Kentucky now has. But the current pest load doesn't appear to have shut down the farmers in Florida, and I doubt that they would shut down my garden here in SC. Anyhow, the insect pests I see in my garden vary from year to year in timing and numbers as it is, so what's the dif.

Even if you can't grow cranberries in NJ and almonds in central CA, they'll be able to grow them further north than they can now and at higher latitudes providing longer days during the growing season, which likely would make them even more productive then they currently are now when grown further south. And they could replace those almonds in the central valley with macadamia, citrus, or other cold-sensitive crops that they can't currently grow in that location.

The obvious problem I see is more severe weather, as we've seen with worse flooding, more severe droughts, and stronger storms. Weather has gotten more intense with more CO2.

Harry

The only worst flooding I've seen in this region have been in suburban/urban watersheds where, as people keep cutting down more of the forests and paving over more of the land so precipitation runs off immediately and has no where to go but into people's houses, so it shows up on the evening news. From what I've seen here, flood levels in rural, mostly undeveloped watersheds hasn't changed noticeably in the 30 years that I have lived in this area. Flooding is actually reduced in many parts of upstate SC compared to what it was in the early 1900's because many of the severely eroded cotton fields have grown back in pine and hardwood forests and so hold back the water that used to run unchecked, producing the many deep erosion gullies (now recovering) that you can find out in the woods.

The severe drought we've had in the past few years in the SE is no worse than the severe drought they had here back in the 1930's that also produced the dust bowl out west.

So far, I haven't seen more severe weather around here. It just shows up more often on the news because increasing amounts of the earth are covered with dense concentrations of humanity, so more of the severe weather is being witnessed and photographed. A tornado that rambles across a lightly populated countryside, knocking down a few acres of forest and killing a few squirrels and deer doesn't rate a mention on the evening news. If that same tornado rambles across an Atlanta suburb and knocks down a few dozen homes and kills a dozen people, then it is the result of "extreme weather being caused by global warming" and blared all over the evening news.

There is a widespread, prolonged drought in the western US that could very well be connected to global warming/climate change.

Harry

I'm going to throw in another variable - we use more water than ever.

There is a widespread, prolonged drought in the western US that could very well be connected to global warming/climate change.

Harry

What widespread, prolonged drought? Scientists have reconstructed the drought history in the western US back to 800 AD and the current drought is minor compared to some that have occurred over the past 1200 years. That's the problem. People look at the weather fluctuations that have occurred over the past 20-30 years and start freaking, when they need to look back over at least the past 1000 years to get an accurate picture as to what weather fluctuations are normal for the region.

http://www.livescience.com/environment/041027_Drought_Record.html

http://www.worldclimatereport.com/index.php/2006/07/07/the-fire-this-time-more-perspective-needed/

http://www.edwardsaquifer.net/pdf/MalcolmCleavelandDroughtStudy.pdf

http://www.treeringsociety.org/TRBTRR/TRRvol57_1_89-103.pdf


The recent flooding of Manila by typhoon Ondoy is another good example of how the spread of mankind's urban areas has made the weather appear to be getting worse. Some people are pointing the finger to global warming as the cause (shades of Katrina), but if this torrential deluge had occurred in some forested, remote, lightly populated region of the Philippines, the flooding wouldn't have been as severe since the forest would would have been able to absorb much of the rain. More importantly, it wouldn't have made the news headlines because there would have been few people around to notice it and the few trees washed out along the banks of a river in flood stage or the odd landslide of rain-sodden soil along with its forest wouldn't have reached the damage threshold for news reporting.

Climate Change has skeptics, but sustainability is more certain.

Resources such as water are used at a higher rate per capita than before.

We have more people using those resources.

The Colorado River does not always flow to the ocean due to the use.

Sustainability is also a problem in agriculture with tilling and the exposed plowed soils causing soil erosion, loss of organic and biological diversity in soils due to an over reliance on synthetic fertilizers. Also with all of the herbicides used for conventional no-till farming as well as the pesticides and fertilizers getting into the water table. Then there is the increasing reliance on a smaller and smaller gene pool of hybrid crops for the bulk of food production.

http://www.cnn.com/2009/TECH/science/09/28/climate.insurance/index.html

HONG KONG, China (CNN) -- The last fifty years have borne witness to a spate of climate related disasters across the world causing over 800,000 fatalities and $1 trillion in economic loss.

More frequent wildfires have been blamed on rapidly changing weather caused by climate change.

Those stark facts come from the Economics of Climate Adaptation (ECA) Working Group, a group of NGOs and corporations that has produced a report warning that if countries do not take active steps to build resilience to climate change soon, they are likely to suffer even larger economic losses in the coming decades.

According to the ECA report published on September 14, climate catastrophes have risen in direct proportion to global temperatures over the last several years.
Harry