Climate change and the food supply

ResearchBlogging.orgOne of the most-cited effects of global warming is that of rising temperatures on crops – hotter average conditions should lead to warmer, drier conditions, reducing yields in the best growing areas and maybe eliminating them where conditions today are marginal. In this week’s Science, a new study puts some numbers behind that speculation [$-a], and the news is not good.

Photo by Josh Sommmers.

Assembling the results of 23 climate models, authors Battisti and Naylor compare projected temperature ranges for the coming century with the ranges observed in the previous one. By the final decade of the twenty-first century, they say, summertime high temperatures in most of the continental U.S. have a 70% probability of exceeding the hottest summer temperatures ever recorded; in Saharan Africa, much of the Middle East and central Asia, the probability is 90-100%.

To put these numbers into perspective, Battisti and Naylor go to the history books, citing an array of cases in which local high temperatures have disrupted food production, creating regional shortages that eventually impacted worldwide food markets:

By comparison, extremely high summer-averaged temperature in the former Soviet Union (USSR) in 1972 contributed to disruptions in world cereal markets and food security that remain a legacy in the minds of food policy analysts to this day. … Nominal prices for wheat — the crop most affected by the USSR weather shock — rose from $60 to $208 per metric ton in international markets between the first quarters of 1972 and 1974.

Battisti and Naylor end by calling for substantial investment in adaptation measures to prevent “a perpetual food crisis.” Increasingly, this looks like the only practical course of action – although reducing and eliminating man-made greenhouse gas emissions is critical, turning global climate around is going to be like steering an aircraft carrier, and it’s going to get pretty warm before we turn the corner.


D.S. Battisti, R.L. Naylor (2009). Historical warnings of future food insecurity with unprecedented seasonal heat Science, 323 (5911), 240-4 DOI: 10.1126/science.1164363


(Facebook) friendship worth 24 cents, says Burger King

Burger King has released a Facebook application that lets users trade in 10 virtual friendships for a Whopper (street value $2.40). Kottke does the math, and concludes that the total value of relationships recorded by the social network is $1.8 billion. You might think that this means digital media and consumer capitalism devalue human connection. And you’d probably be right.



In a rant set off by a billing dispute with his monolithic and uncaring local electric company, Slacktivist muses on the essential self-destructiveness of opposition to government qua government in a democracy:

Reflexive or visceral anti-government sentiment, in a democracy, is strangely popular given that it is both a form of self-loathing and a self-fulfilling prophecy. Right now, for instance, there’s a pseudo-libertarian reading this very paragraph and shouting, “How naive! The government isn’t of, by or for the people — the government is against the people!” He’s wrong, of course, but if everyone believed that, then his nightmare could become reality. If all the citizens of a democracy abandon any belief in government as the servant of the people for the common good, and if they oppose every attempt to make it so, then they’re not going to remain the citizens of a democracy for very long.

In a democracy, government is, by definition, what the People do together – if government isn’t doing what it ought, whose fault can that be, exactly?


Prayer for the children of Gaza

Jeffrey Goldberg points to Bradley Burston’s prayer for the children of Gaza, published in today’s Haaretz. It’s in the Jewish spiritual idiom, poetic and clearly heartfelt, a direct response to the war prayers famously decried by Mark Twain. But it’s also just a little odd:

Almighty who makes exceptions, which we call miracles, make an exception of the children of Gaza. Shield them from us and from their own. Spare them. Heal them. Let them stand in safety. Deliver them from hunger and horror and fury and grief. Deliver them from us, and from their own.

I can guess the Almighty’s response: “Let Me get this straight – you want Me to shield them from you? Could there be a more direct way to go about this, do you think?” And yet this is the conundrum of any citizen opposed to a war prosecuted by his or her democratically-elected government (as, for example, the last eight years of U.S. foreign policy). “We,” the nation, are responsible for horrors, even as we, the conscience-stricken individuals, look on in horror.


The math-challenged scientist’s best friend

The NY Times has a neat piece about R, an open-source statistical programming language used by scientists worldwide. I’ve used it quite a bit myself, though I’ve hardly scratched the surface of its capabilities. The graphics package alone kicks Microsoft’s arse. Thanks to its price (free), its ease of use (spectacular), and a thriving developer community, R is apparently gaining ground on the commercial competition, the clunky, overpriced SAS.

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Just war theory and the Gaza crisis

I haven’t posted so far about the latest Israeli-Palestinian shitstorm because it started while I was home for Christmas, and because I didn’t really have anything to post about, besides that it looks like, as I say, a shitstorm. Now, Andrew Sullivan takes a look at the ongoing mess through the lens of just war theory. It’s a good piece, taking a more serious approach to the justice of Israel’s response to Hamas than I’ve seen or heard in my usual Liberal Media mix. (Although NPR did run a very good interview with an Israeli government spokesman Saturday.) Sullivan’s conclusion isn’t a surprise, but it’s good to see in print:

I need to repeat: There is no “just war” excuse for Hamas’ murderous terrorism or for its refusal to acknowledge or peacefully co-exist with Israel. But there’s no reading of traditional just war theory that can defend what Israel is now doing and has done either. Maybe I am missing an element here. Or maybe just war theory cannot account for modern terrorism.

Bingo. Why does just war theory have difficulty with terrorism? Maybe because terrorism isn’t war – it’s crime. Reading this, I immediately thought of something Bruce Schneier wrote back in October, about a study of terrorists’ effectiveness at achieving stated political goals. Which, it turns out, is generally nil. This is because terrorists are more like street gangs than governments:

Individual terrorists often have no prior involvement with a group’s political agenda, and often join multiple terrorist groups with incompatible platforms. Individuals who join terrorist groups are frequently not oppressed in any way, and often can’t describe the political goals of their organizations. People who join terrorist groups most often have friends or relatives who are members of the group, and the great majority of terrorist are socially isolated: unmarried young men or widowed women who weren’t working prior to joining. These things are true for members of terrorist groups as diverse as the IRA and al-Qaida.

This means Israel’s approach to Hamas (and much U.S. anti-terrorism policy) is a little like the government of California dealing with its drug problem by bombing inner-city Los Angeles. No just war theory exists that can support it.

Nearly immediate follow-up: Informed Comment’s recent post (regrettably under-referenced, but recommended by a friend who knows the region) suggests that the present situation is more like the government of California provoking a drive-by shooting as an excuse to bomb downtown L.A.


Evolution applied: Biological warfare against mosquito-borne disease

ResearchBlogging.orgThis week’s issue of Science starts the new year with an exciting application of evolutionary dynamics: a sort of biological warfare agent to control disease-bearing mosquitoes.

Even in the twenty-first century, mosquito-borne diseases like malaria and Dengue fever remain major public health challenges, particularly in the developing world. When vaccines are not available, the only way to prevent these diseases is to control the mosquitoes that spread them. Yet mosquito populations have evolved resistance to commonly-used pesticides, and others, like DDT, have dangerous environmental side effects.

Aedes aegypti, a disease-bearing
mosquito species

Photo by dincordero.

It’s no wonder, then, that biologists are interested in ways to harness evolutionary population dynamics to reduce mosquito populations. McMeniman et al. take a big step toward this goal using the parasitic bacterium Wolbachia [$-a]. Wolbachia, which infects many other insect species, behaves like a “selfish gene” within its hosts. The bacterium is transmitted from females to their offspring, but not from males; so it induces infected females to lay more female eggs, and it kills the offspring of matings between infected males and uninfected females. This lets Wolbachia spread rapidly through populations, even if being infected is bad for the host.

Using Wolbachia against mosquitoes is not new; previously, people have discussed using genetically engineered forms of the bacterium to deliver agents that fight the diseases inside their carriers. But as McMeniman et al. describe, infection of the Dengue-bearing mosquito Aedes aegyptes actually already cuts the lifespan of the host in half. The Dengue pathogen needs time to incubate inside the mosquito host before it can be passed on to a human – longer, it turns out, than Wolbachia-infected mosquitoes typically live.

With this discovery, controlling Dengue or malaria could be as simple as introducing Wolbachia-infected female mosquitoes into at-risk areas, and monitoring the infection’s spread. Together with common-sense public health measures like distributing mosquito nets and reducing standing water sources, Wolbachia has the potential to save and improve millions of lives.


C.J. McMeniman, R.V. Lane, B.N. Cass, A.W.C. Fong, M. Sidhu, Y.-F. Wang, S.L. O’Neill (2009). Stable introduction of a life-shortening Wolbachia infection into the mosquito Aedes aegypti. Science, 323 (5910), 141-4 DOI: 10.1126/science.1165326

A.F. Read, M.B. Thomas (2009). MICROBIOLOGY: Mosquitoes cut short Science, 323 (5910), 51-2 DOI: 10.1126/science.1168659