On Sandy and climate change

As seawater floods into lower Manhattan, seeping into subway stops and tunnels, many are talking up the link between climate change and severe storms.

But this is a tricky link to make. As Brad Plumer notes over at WonkBlog, "trying to attribute specific hurricanes to changes in global temperature remains quite difficult." He adds: "In its big report on natural disasters last year, the Intergovernmental Panel on Climate Change (IPCC) said it had “low confidence” that humans were currently affecting tropical cyclone patterns. Hurricanes are far more complicated to study than, say, heat waves and the historical record is patchier."

I emailed MIT's Kerry Emanuel, one of the foremost experts on hurricanes, what he makes of this:

I am not sure we scientists understand the link all that well. North Atlantic hurricane power has been tracking tropical Atlantic sea surface temperature for over a century of record, and we think the recent increase in Atlantic SST (and hurricane power) is related both to increasing greenhouse gases and decreasing sulfate aerosol pollution, both man-made trends.

Sandy is an example of a hybrid storm, drawing energy both from the evaporation of seawater, the source of energy for tropical hurricanes, and from horizontal temperature contrasts, the source of energy for winter storms. But we have not done a comprehensive climatology of hybrid storms, so we do not know whether there are trends in their incidence, nor have we studied how they change in climate model simulations. Thus we really have no basis for saying anything useful about their relationship to climate.

Increased incidence of drought and floods are well predicted consequences of greenhouse gas-induced warming. But we know little about the relationship between climate and  severe thunderstorms and their attendant tornadoes and hailstorms. We have a long way to go, alas.

But even if storms are only marginally more intense or frequent, they can still do a lot more damage as our cities gets denser. As John Seo, a hedge fund manager who specializes in catastrophe bonds -- financial instruments used to hedge against the risk of low-probability events -- warns, "a decade and a half from now, a single hurricane or earthquake will come with a potential price tag of $1 trillion or more."

What's more, even if the link between such storms and climate change were more solid, anything we could have done in recent years to reduce greenhouse emissions wouldn't have mattered as far as Sandy is concerned -- at this point, we're talking about trying to limit ill effects decades from now. As Grist's Dave Roberts puts it, "The oceans will continue to rise for at least 50 years no matter what we do. We can only affect the latter half of century."

Have a nice evening.


Iraq's youngest casualties of war

The U.S. military departed Iraq 10 months ago, but a recent study suggest that its old war may be causing new casualties among Iraqi children.

The Bulletin of Environmental Contamination and Toxicology published a study in September titled "Metal Contamination and the Epidemic of Congenital Birth Defects in Iraqi Cities." The study, which was funded by the University of Michigan's Department of Obstetrics and Gynecology, examines the prevalence of birth defects in the Iraqi cities of Basra and Fallujah, both of which experienced heavy fighting during the worst days of the Iraq war. As originally noted by U.S. analyst David Isenberg, the study found an "astonishing" increase in the number of birth defects in a Basra maternal hospital when compared to before the war.

From October 1994 to October 1995, there were 1.37 birth defects at Al Basrah Maternity Hospital per 1,000 live births. By 2003, at the beginning of the war, the number of birth defects skyrocketed to 23 per 1,000 live births -- a 17-fold increase. Then the number of birth defects doubled again: By 2009, the maternity hospital witnessed a staggering 48 birth defects per 1,000 live births. In 2011, the last year for which data is available, there were 37 birth defects per 1,000 live births.

These figures are wildly out of proportion to the prevalence of birth defects elsewhere in the world. Hydrocephalus, a build up of fluid in the brain, is reported in 0.6 infants per 1,000 live births in California. In Basra, reported cases of hydrocephalus occurred six times more frequently. Neural tube defects (NTDs), brain and spinal cord conditions, are reported in one infant per 1,000 live births in the United States. In Basra, it is 12 per 1,000 live births, "the highest ever reported."

What is the reason for this drastic increase in birth defects? The study proposes that exposure to metal contamination -- notably mercury and lead -- is to blame. To test their hypothesis, the scientists involved in the study conducted a case study of 56 families in the central Iraqi city of Fallujah, which witnessed some of the fiercest fighting of the war. Among the families, more than half of infants were born with a birth defect from 2007 to 2010. Most importantly, the study found that hair samples of babies born with birth defects contained five times more lead and six times more mercury than healthy children. This high level of metal contamination was also found in the parents of children with birth defects in Basra.

This is not the first study to suggest a connection between Iraq's devastating war and high levels of birth defects. A 2010 paper published by the International Journal of Environmental Research and Public Health reported on a questionnaire presented to almost 5,000 residents of Fallujah about incidents of cancer, birth defects and infant mortality within their family. In addition to "alarming rates" of cancer, the study found infants between zero and 1 year old were dying at a rate of 80 per 1,000 births - compared, for instance, to 19.8 children per 1,000 in Egypt.

What is less clear, however, is the connection between the coalition forces' activities and the increase in birth defects. The University of Michigan study notes that lead and mercury are "toxic metals readily used in the manufacture of present-day bullets and other ammunition" - but does not prove a direct link between their use in Basra and Falluja and the rise in birth defects there. Instead, it concludes that the bombardment of those cities "may have exacerbated public exposure to metals, possibly culminating in the current epidemic."

The studies are clear, however, that a health crisis is costing Iraqi infants their lives, and more research is needed to determine the cause and the cure. Until that is done, some uncomfortable questions about the lingering effects of the U.S.-led war will remain.