Climate change and air pollution will combine to curb food supplies

Many studies have shown the potential for global climate change to cut food supplies. But these studies have, for the most part, ignored the interactions between increasing temperature and air pollution — specifically ozone pollution, which is known to damage crops.A new study involving researchers at MIT shows that these interactions can be quite significant, suggesting that policymakers need to take both warming and air pollution into account in addressing food security.The study looked in detail at global production of four leading food crops — rice, wheat, corn, and soy — that account for more than half the calories humans consume worldwide. It predicts that effects will vary considerably from region to region, and that some of the crops are much more strongly affected by one or the other of the factors: For example, wheat is very sensitive to ozone exposure, while corn is much more adversely affected by heat.The research was carried out by Colette Heald, an associate professor of civil and environmental engineering (CEE) at MIT, former CEE postdoc Amos Tai, and Maria van Martin at Colorado State University. Their work is described this week in the journal Nature Climate Change.Heald explains that while it’s known that both higher temperatures and ozone pollution can damage plants and reduce crop yields, “nobody has looked at these together.” And while rising temperatures are widely discussed, the impact of air quality on crops is less recognized.The effects are likely to vary widely by region, the study predicts. In the United States, tougher air-quality regulations are expected to lead to a sharp decline in ozone pollution, mitigating its impact on crops. But in other regions, the outcome “will depend on domestic air-pollution policies,” Heald says. “An air-quality cleanup would improve crop yields.”Overall, with all other factors being equal, warming may reduce crop yields globally by about 10 percent by 2050, the study found. But the effects of ozone pollution are more complex — some crops are more strongly affected by it than others — which suggests that pollution-control measures could play a major role in determining outcomes.Ozone pollution can also be tricky to identify, Heald says, because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.Potential reductions in crop yields are worrisome: The world is expected to need about 50 percent more food by 2050, the authors say, due to population growth and changing dietary trends in the developing world. So any yield reductions come against a backdrop of an overall need to increase production significantly through improved crop selections and farming methods, as well as expansion of farmland.While heat and ozone can each damage plants independently, the factors also interact. For example, warmer temperatures significantly increase production of ozone from the reactions, in sunlight, of volatile organic compounds and nitrogen oxides. …

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Perfect pitch may not be absolute after all

June 11, 2013 — People who think they have perfect pitch may not be as in tune as they think, according to a new University of Chicago study in which people failed to notice a gradual change in pitch while listening to music.When tested afterward, people with perfect, or absolute pitch, thought notes made out of tune at the end of a song were in tune, while notes that were in tune at the beginning sounded out of tune.About one out of 10,000 people has absolute pitch, which means they can accurately identify a note by hearing it. They are frequently able, for instance, to replicate a song on a piano by simply hearing it. Absolute pitch has been “idealized in popular culture as a rare and desirable musical endowment, partly because several well-known composers, such as Mozart, Beethoven, Chopin and Handel, have been assumed to posses absolute pitch,” the researchers write in “Absolute Pitch May Not Be So Absolute,” in the current issue of Psychological Science.The study showed that exposure to music influences how people identify notes from their sound, rather than having a rare, absolute ability at an early age. The research also demonstrates the malleability of the brain — that abilities thought to be stable late in life can change with even a small amount of experience and learning.One of the researchers, Stephen Hedger, a graduate student in psychology at UChicago, has absolute pitch, as determined by objective tests. Joining him in the study were postdoctoral scholar Shannon Heald and Howard Nusbaum, professor in psychology at UChicago.Hedger and Heald decided to pursue the study after a session in which Heald tricked Hedger by covertly adjusting pitch on an electronic keyboard.”Steve and I have talked about absolute pitch, and I thought it might be more malleable than people have thought,” Heald said. While in the lab, Hedger began to play a tune, and Heald secretly changed the pitch with a wheel at the side of the keyboard.Heald changed the tuning to make the music a third of a note flatter than it was at the beginning of the song. Hedger never noticed the change, which was gradual, and was later surprised to discover the music he was playing was actually out of tune at the end.”I was astounded that I didn’t notice the change,” Hedger said. Working with Nusbaum, an expert on brain plasticity, they devised experiments to see if other people with absolute pitch would make the same mistake as Hedger.The researchers recruited 27 people who were identified as having absolute pitch by standard tests and assigned them to two groups for two experiments. The subjects were tested on identifying notes at the beginning of the experiments, and each was able to correctly identify an in-tune note.One group then listened to Johann Brahms’ Symphony No. 1 in C Minor. …

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