Research SummaryImagine a world in which glaciers are advancing down Alpine valleys, and storms destroy crops year after year. The Thames in London freezes over. This is the world I study, the Little Ice Age, a period from about 1450 to 1850 when Northern Hemisphere temperatures were 1-2˚C cooler than today. I approach the Little Ice Age as a natural laboratory with which to better understand what processes may cause and amplify global climate change.
One key relationship in the climate system is how sensitive temperature is to specific changes in earth’s energy budget, known as “climate forcings.” The Little Ice Age is believed to have been triggered by several of these climate forcings. For one, a series of volcanic eruptions released aerosols into the air, reflecting the sun’s radiation and cooling the earth’s surface. Additionally, solar radiation itself dimmed several times during this period. Natural archives of temperature contained in tree rings and ice cores have helped scientists quantify the amount of cooling at high latitudes, but less is understood about how much the tropics cooled.
My research in the Cohen lab at WHOI (link to http://www.whoi.edu/cohenlab/) focuses on reconstructing Western Tropical Atlantic sea surface temperatures (SSTs) in the Little Ice Age using the geochemistry of coral skeletons. My results have reconciled previously inconsistent estimates of tropical cooling during this period, and are consistent with a shift in ocean circulation that could have amplified an initially small climate forcing. My coral record also reveals that the Little Ice Age was not uniformly cold, in fact at several times SSTs were as warm as today and displayed variability similar to what we see in the 20th century. In my PhD studies I have also worked to refine geochemical proxies of SST by better understanding how they are affected by the coral’s biologically mediated calcification process. My research helps to reduce the uncertainty in SSTs reconstructed using coral skeletons and unlock the information contained in these uniquely high-resolution archives of information about climate in the past. I hope that my work will link up with other paleoclimate records to better understand the ocean’s response to climate forcings.
Upon graduation from the MIT-WHOI Joint Program, I will begin a AAAS Science and Technology Policy Fellowship (link to http://www.aaas.org/page/stpf/overview) at the US Department of State, where I will serve as a science advisor. I look forward to applying my expertise in oceanography and climate science to inform policy decisions (link to www.alpertalice.com).