Remaking Boston: An Environmental History of the City and Its Surroundings

13. Biological Responses to Climate Change in Boston

 Biological Responses to Climate Change in Boston Abraham J. Miller-Rushing and Richard B. Primack THE behaviors of plants and animals are changing in response to warming temperatures. In recent years biologists have observed birds wintering farther north, tropical frog populations declining, and insects relocating to higher altitudes on mountain slopes because of changes in climate.₁ Yet the most convincing evidence that living organisms are responding to global warming comes from the timing of spring events. Analyses of these records show conclusively that wild and cultivated plants are flowering earlier, birds are migrating earlier, and ponds are ice-free earlier than in the past because of warmer spring temperatures.² Historical records from the Boston area provide some of the best evidence for these changes in the United States. Observations of changes in the timing of spring events are particularly compelling when examined over very long time frames—the longer the better .Variability in temperatures can be quite large, even during the course of a decade, so research into temperature-related events such as spring flowering or migrations is stronger when supported by several decades’ worth of ob13 servations. Much of the data currently available, however, has come from the notebooks of professional biologists who have made observations for the purpose of documenting basic ecology. Despite the value of these data for understanding how certain species in certain places have already responded to global climate change, too few long-term data sets exist to make them useful in predicting future impacts on many species in many locations.³ To build a more taxonomically and geographically complete picture, scientists need more information. The additional information that scientists need can often be found in sources unusual for biological studies but typical in historical research. For example, dated historical photographs, collections of botanical specimens (also known as herbarium specimens), and journals and records of amateur naturalists can document when birds migrate or when plants flower. This chapter presents three case studies from our work in the Boston area. The first describes our use of herbarium specimens to track changes in flowering times.⁴ The second shows the value of personal journals—in this case the journals of the naturalist Kathleen Anderson of Middleborough, Massachusetts .₅The third describes changes as shown in photographs from Concord, Massachusetts, and the Arnold Arboretum in Jamaica Plain.₆ These case studies highlight the utility of herbarium and archival collections in climate change research and set the stage to find even more. Boston’s Naturalist History Even without taking into account its storied past as a center of U.S. history , Boston is an especially good place to look for naturalist observations and records. From the perspective of climate change studies, the strength of this tradition lies in the length and continuity of naturalist activities in the Boston area. For example, the botanist Edward Jarvis documented the composition of the flora of Concord, Massachusetts, in , a feat that has been repeated four times since. The famous philosopher and naturalist Henry DavidThoreau observed flowering times and ice-out atWalden Pond. Later botanists, Alfred Hosmer, Richard Eaton, and ourselves have since followed in Jarvis’s and Thoreau’s footsteps.⁷ The Boston area also has outstanding weather records to match the naturalist tradition.The Blue Hill Meteorological Observatory is the longest continuously running meteorological station in North America.⁸ It maintains weather records that date back to  and ice-out records for Abraham J. Miller-Rushing and Richard B. Primack  Houghton’s and Ponkapoag ponds that date back to .⁹ Today the Observatory maintains a written record of the temperature, precipitation, cloud, wind, barometric pressure, and humidity observations that have been made, often on an hourly basis, since the station’s founding. In addition to Blue Hill, fifty-nine other weather stations are located within forty kilometers of Boston. Many of these sites have records dating back to  or earlier and are still in operation, including stations in Boston (at Logan International Airport), Bedford (at Hanscom Field), Norwood, and South Weymouth. Other archives contain weather records dating back to .₁⁰Yet even with its widely known history of climatologic and naturalist data collection, we have discovered that the wealth of naturalist records in Boston includes several sources of data that have not previously been used to document species’ responses to climate change.These sources of data include herbarium specimens , personal journals, and photographs. Herbarium Specimens For examining the utility of herbarium specimens, we turned to one of...