December 18, 2013
Plant Genetic Engineering Needed To Adjust For Climate Change?

David Rotman argues that genetic engineering of plants will be needed to feed the world because climate change will speed the spread of plant diseases. This could lead off into a discussion on whether the globe is warming. Well, the signal from the ocean is much clearer on that score (warming) than the signal from atmospheric temperatures. Since the oceans have way more mass than the atmosphere I'm thinking the oceans are telling us what we need to know.

But we don't need global warming in order to see the necessity of crop genetic engineering. Cheaper faster transportation and global trade are already spreading many plant diseases around the world. The spread of plant diseases is nothing new though. The American chestnut tree was almost entirely wiped out from 1900 to 1940 without climate change as the culprit. The problem is more basic: Lots of plants evolved in local areas where some fungus or other organism did not exist and so the plants in that area have no evolved resistance. Move lots of stuff around the world and the result is lots of funguses (I refuse to use the Latin plural form), bacteria, and insects show up and wipe out local organisms.

Agriculture has this problem worse than wild organisms because lots of crops are heavily inbred with little genetic diversity. So, for example, it is not surprising that the biggest banana variety, Cavendish, is threatened with elimination by a fungus. Other banana varieties, less developed for agriculture, could be used as substitutes. But it would be more economically advantageous to just put a resistance gene in Cavendish.

C. liberibacter asiaticus is threatening to wipe out oranges. Only genetic engineering can save orange trees.

I think population growth is going to lead to a massive trashing of the environment even if we do very extensive crop genetic engineering to increase yields per acre. Global warming, if it comes, will make the destruction of habitats go even faster as more land gets pushed into agricultural production to compensate for the loss of other crop lands due to drought and heat.

Share |      Randall Parker, 2013 December 18 09:21 PM 

David Friedman said at December 19, 2013 12:42 AM:

I don't see why you expect that, due to global warming, "more land gets pushed into agricultural production to compensate for the loss of other crop lands due to drought and heat." Climate is complicated, but if I had to guess, the effect of global warming will be to increase agricultural production, not decrease it.

To see why, consider the following points:

1. Warmer weather means longer growing seasons, which tends to mean greater output.

2. CO2 is an input to photosynthesis so, ceteris paribus, more CO2 ought to mean more productive agriculture.

3. Human land use at present is limited by cold, not by heat--the equator is inhabited and productive, the poles are not. Global warming will push the habitable zone of the northern hemisphere north, increasing the amount of usable land by two or three orders of magnitude more than sea level rise decreases it.

4. Global warming will be greater in colder places and times, because water vapor is a greenhouse gas, and the more of it in the air, the less the additional effect of adding CO2. That means warmer winters relative so summers, warmer cold regions relative to warm regions.

So far as I know, "warming leads to drought" is pure conjecture, unsupported so far by observed trends--like the "warming leads to hurricanes" claim.

destructure said at December 19, 2013 4:42 AM:

European greenies are terrified of global warming and gene modified foods. So how do they convince them to accept GM foods? Tell them it's for global warming. LOL

Neil Craig said at December 20, 2013 6:54 AM:

No the signal from the atmosphere (zero warming for the last 18 years despite the alarmists originally promising a 2-6 C rise by 2050) than from the sea. This is because there are no long term records for below the first few feet of sea so by definition, no honest comparison can be made.

JP Straley said at December 20, 2013 9:15 AM:


"I think population growth is going to lead to a massive trashing of the environment.."

Really? You've only just figured this out?

Next you'll be asking if perhaps we are at the point of severely diminishing returns (even negative returns) with respect to population growth.

Question: What is the single most environmentally destructive technology? Answer: Agriculture. It takes 100% of the primary productivity of the land and turns it to human use. Animals and adaptive plants (these are considered pests or weeds) are destroyed.

JP Straley

Wolf-Dog said at December 21, 2013 5:42 AM:

Genetically engineered trees have pros and cons.

Pros: such trees grow very fast and provide more wood and sugar density. 1,000 gallons of liquid fuel per year can be obtained from an acre of genetically modified eucalyptus trees. And the remainder can be used as pellets to burn for power generation.

Cons: genetically modified trees are said to be invasive and they can destroy rival plants.

Randall Parker said at December 21, 2013 3:18 PM:

JP Straley,

No, I have not just figured out that population growth is going to cause further trashing of the environment. I've written about this years ago and believed it before I started blogging.

David Friedman,

During the Medieval Warm Period the Western United States was in a drought. Are those two events causally related? Dunno. I found a good piece by Andrew Revkin about whether we know what causes mega-droughts. Brad Plumer summarizes opinion of climate scientists on warming and drought and that has a pretty interesting global graphic on warming and drought. Note that warming causes more evaporation from soils. So more precipitation is needed the hotter it gets.

The return of extreme drought to the western United States would be disastrous.

Randall Parker said at December 21, 2013 3:23 PM:

Also, see this piece by Revkin for a sense of how uncertain climate researchers are over warming's impact on drought frequency. Martin Hoerling and Kerry Emanuel responded to an Op-Ed by James Hansen. Also see this follow-up piece with more commentary from Martin Hoerling and Dan Miller.

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