Climate Feedback

The concept of active human efforts to artificially limit or reverse climate change has been around for some years. Collectively called geoengineering, many such plans, some more fanciful than others, have been proposed by the scientific community, and several were discussed during the final days of the AGU Joint Assembly in Toronto.

One plan, described by Alan Robock of Rutgers University, New Jersey, US, would involve continuously placing fine particles of sulphur dioxide (SO2) into the stratosphere, to block sunlight from reaching Earth’s surface. This, proponents say, would be benign, simply mimicking the effect of large volcanic eruptions, and simulations confirm that northern hemisphere or even global cooling would follow.

Although there is currently no way to do it, the problem is not the technology, Robock said in an interview, amplifying on his oral presentation at the meeting. The technology to inject SO2 particles into the stratosphere might not be that difficult; high altitude military planes could be adapted to do it, he suggested, although there are questions about their ability to deliver particles of the appropriate size. Regardless, the ancillary effects of the experiment could be devastating, he said, by reducing the amount of precipitation associated with the summer monsoon in Asia and Africa, thereby threatening the food supply for billions of people.

A secondary proposal that Robock described in his presentation would provide the SO2 seeding only in the Arctic. The problem is, he said, that winds blow the particles southward, with comparable effects on the monsoons, according to simulations, so there would be no advantage to year-round Arctic-only seeding.

Continue reading "AGU 2009 Joint Assembly: Solutions, and sayonara " »

Posted by Olive Heffernan on May 28, 2009
Categories: AGU 2009 Joint Assembly, Harvey Leifert, Politics, Technology | Permalink | Comments (0) | TrackBacks (0)

Today, at the AGU Joint Assembly, I looked into two kinds of risk: of drought leading to civil violence and of the odds that extreme weather events may cause other types of disruption.

It’s always encouraging to see undergraduates engaged in scientific research, the more so when it is interdisciplinary. That’s what surprised me about a poster with the intriguing title, “Climate Change and Civil Violence,” which turned out to be a class project at Princeton University, stretching over three semesters, with three successive classes of students involved in the research.

The students, led by their professor, Gregory van der Vink, focused on a swath of West Africa - 21 countries from Mauritania to the Central African Republic, including most of the semi-arid Sahel region, as well as coastal forests. They looked at the likelihood that climate change, especially increasingly severe drought, will lead to civil violence in each of the countries studied. It is obviously difficult to attribute specific environmental causes to social phenomena, but the students—majoring in politics, various sciences, pre-engineering, and other fields—gave it a good try.

The choice of drought as the key climatic factor was based on the expectation that the Sahel will further dry, shortening the growing season by at least 20% over the next 40 years. Nomadic herdsmen will, for example, have to move further south or adopt a more sedentary life, or both.

Another key factor is the resiliency of the population, its ability to cope with the coming climatic changes. This factor varies considerably from country to country, the researchers found, and is related to population size, political system, natural resources, and other variables. The relative significance of each of these is difficult to assess, of course.

Bottom line: after exhaustive analysis, the students concluded that the five countries in the study that are most vulnerable to drought-induced civil violence are Nigeria, Senegal, Mali, Côte d’Ivoire, and Gambia. Of these, three—Nigeria, Senegal, and Mali—have already experienced conflicts that included an environmental factor, they say. Of the five, only Gambia has not experienced any violent conflict during the past 10 years.

The study, as the students themselves note, was a preliminary effort to correlate environmental and socio-economic risk factors that could lead to civil violence. They are not predicting specific events in particular countries, but there seems little doubt that this topic is one that will assume increasing importance in coming years to policy makers and civilian populations alike, and not just in Africa.

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Posted by Olive Heffernan on May 27, 2009
Categories: AGU 2009 Joint Assembly, Extreme Events, Harvey Leifert, Research, Society | Permalink | Comments (0) | TrackBacks (0)

Cement and pinot noir were among the highlights of the AGU Joint Assembly in Toronto Tuesday.

Sequestration of carbon dioxide, that is, pulling it out of the air and storing it where it cannot affect climate as a greenhouse gas, is a quest that engages many scientists and engineers. Proposals have been made to store CO2 deep in the ocean and in depleted mines far underground. Soon, though, you may be able to walk on sequestered CO2, says Sidney Omelon, a chemical and materials engineer with Calera Corporation, a California start-up.

The purpose of a project under study and described in Omelon’s Joint Assembly poster Tuesday is to capture CO2 from concentrated sources, such as emissions from power plants. Step one is to channel the gas into an aqueous environment, in order to precipitate carbonate minerals. The novel part is what happens next. Calera is developing a process to incorporate this precipitate into the built environment, specifically in concrete used for street paving and buildings.

Cement, a key ingredient of concrete, is an ideal substance into which the precipitate can be added, Omelon said in an interview. She does not know of any other comparable projects. Surprisingly, in her view, it hasn’t been tried until now. “Honestly, I can’t believe no one [else] thought of it first,” she said.

Calera is also looking into using captured CO2 in aggregate, another key component of concrete. Even when concrete structures eventually crumble, the material itself would remain stable, Omelon said, and the CO2 would not escape to the atmosphere.

We are looking at CO2 as a resource, not just as a pollutant, Omelon concluded. “I think if we just turn our brains to this, we can do some really useful things with carbonate minerals and also just try and reduce our general energy consumption, so that we don’t emit as much CO2.”

Continue reading "AGU 2009 Joint Assembly: From paving to pinot noir " »

Posted by Olive Heffernan on May 26, 2009
Categories: AGU 2009 Joint Assembly, Harvey Leifert, Mitigation, Regional climate, Technology | Permalink | Comments (2) | TrackBacks (0)

Level 7 of the Metro Toronto Convention Centre is situated above Level 8, and Level 6 is higher still. Once you find your way around, it’s seems the perfect place to study atmospheric inversions and other climatological phenomena. That’s what is happening at the centre this week during the Joint Assembly of the American and Canadian Geophysical Unions, along with a half-dozen other Earth and space science societies.

This annual event, once known as AGU Spring Meeting, has attracted some 2,500 presentations, ranging from Atmospheric Science to Volcanology, and the ones touching on climate change turn up under a variety of headings. Climate change may occur globally, but it impacts locally, and regional impacts were the topic of numerous presentations Monday at Joint Assembly.

The issue facing researchers and policy makers alike is scaling down the results of global climate models to make useful predictions for specific locales, like cities, counties, or watersheds, predicting how climate change may affect local populations, industries, and wildlife.

In the US state of New Hampshire, for example, the multimillion dollar ski industry depends upon a large and consistent snowpack. Cameron Wake of the University of New Hampshire said that to be economically viable, ski operators must count on a season of at least 100 days, ideally including Christmas week. But, a group of regional scientists estimates that by 2100, New Hampshire will warm between 1.9o and 6.9o Celsius, the extremes of several models tested. The greatest warming will be in winter. Also, there will be more rain and less snow in winter, and anticipated droughts will further reduce the number of days with snow on the ground. By the 100-day standard, Wake said, and even with snowmaking equipment, almost all New England ski areas will be vulnerable by 2100.

New York City has always prided itself on its water supply. New Yorkers turn the tap and enjoy mountain spring water piped from protected watersheds far upstate. But will climate change affect the quality of that water—currently four million liters for nine million customers daily—in years to come? The city is actively addressing that question, said Mark Zion of New York’s Environmental Protection Agency.

Continue reading "AGU 2009 Joint Assembly: Global change, local impacts" »

Posted by Olive Heffernan on May 25, 2009
Categories: AGU 2009 Joint Assembly, Climate prediction, Harvey Leifert, Regional climate | Permalink | Comments (0) | TrackBacks (0)