b'LETTER FROM THE PRESIDENTCARNEGIE INSTITUTIONFOR SCIENCE Working to Understand 1530 P Street, NWand Fight Washington, D.C.20005-1910202.387.6400 Climate ChangePresidentEric D. Isaacs.Director, Department of Embryology On a crisp, clear autumn day, it is Yixian Zheng deeply sobering to read the reports . of yet another month of record-Director, Geophysical LaboratoryMichael Walter setting global temperaturesActing Director, Department ofGlobal Ecology Data from the National Oceanic and Atmospheric Joe Berry Administration show that this past summer was the . warmest on record for the Northern Hemisphere, and Director, The Observatories Septembers average temperature was roughly 1.02F Crawford H. Greenewalt Chair warmer than the average from 1981-2010. Most troubling is John Mulchaey the knowledge that, as greenhouse gas emissions continue, . global temperatures will continue to break records. Acting Director, Department of Plant Biology These grim realities bring home the urgent nature of the climate-focused work Zhiyong Wang we are doing here at Carnegie. Across our departments, researchers are delving . deeply into global warming and the mechanisms of its effects at every scale and are Director, Department of Terrestrial Magnetism seeking innovative strategies to mitigateor even reversethe ongoing damage to Richard Carlson the environment. . Consider this recent research from our Department of Global Ecology, which Chief Operating Officer takes a thoughtful look at a potential climate solution that may sound a bit like the Timothy Doyle plot of a science fiction movie: block solar radiation by filling the atmosphere with . artificial volcanic ash particles. Although the notion may seem far-fetched, some Chief Development Officer researchers have speculated that the well-known cooling effects of large volcanic Ann McElwain eruptions might be mimicked through massive deployment of aerosol particles in . the atmosphere. A paper in Geophysical Research Letters, coauthored by Ken Editor Caldeira, used sophisticated modeling to compare the climate impacts of a single Tina McDowell volcanic eruption with the effects of long-term deployment of aerosol particles. The . models show that both natural and engineered atmospheric particulates cause a Science Writerrapid decrease in the Earths surface temperature. However, the studys results show Natasha Metzler thatjust as in so many dystopian science-fiction moviesour human attempts to synthesize natural phenomena may have unexpected and potentially negative consequences. The models showed that volcanic eruptions and geoengineered aerosol systems would have very different impacts on rainfall patterns. More broadly, the authors warn that scientists should be cautious about extrapolating the results of geoengineering from the effects natural occurrences.As ocean temperatures rise, coral communities around the world are responding to heat stress by bleachingexpelling the single-celled algae that live inside coral polyps, provide them with nutrients, and create their vivid colors. If the bleached www.CarnegieScience.edu coral is not recolonized with new algae, it starves and dies. To help save these crucial'