P2C2: Positive Feedback between Dust, Radiation, Precipitation and Temperature as a Driver for Abrupt Climate Change

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Aerosol feedbacks represent one of the highest uncertainties in the dynamics of the Earth system (IPCC, 2007). Paleoclimate records show significant fluctuations in dust associated with changes in climate. However, the role of dust as a feedback to climate change in the past and into the future remains highly uncertain. The proposed working hypothesis is that a positive feedback between dust, radiation, precipitation and temperature is an important driver for abrupt climate change. Researchers from the University of Miami will focus on two periods of abrupt climate change in the Atlantic: Heinrich Event 1 and the termination of the African Humid Period. These are two periods of abrupt climate change for which the source of the abruptness is still a matter of debate. PIs will run transient paleoclimate simulations using the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) coupled to an interactive dust model, synthesize paleo-dust and drought records, and test the sensitivity of their results to changes in dust optical properties. Intellectual MeritThe proposed research will advance our understanding and knowledge of forcing and feedbacks associated with desert dust in past periods of abrupt climate change, and determine if climate change is more abrupt when dust is an interactive component. Through model-data synthesis, the PIs will analyze if the inclusion of dust climate feedback in paleoclimate simulations bring models into better agreement with observations. Results from the transient paleoclimate simulations will be made available online to facilitate paleoclimate model-data intercomparisons. Broader ImpactsThe project will establish linkages between the University of Miami, NCAR, and Cornell University through the use of CESM and the participation in the CESM Paleoclimate Working Group. Research activities will be presented at scientific conferences, workshops, and community outreach events, such as the science café (http://www.rsmas.miami.edu/info/seminar-archive/msg01683.html). Knowledge gained from this work will be used to prepare curriculum material for undergraduate and graduate courses taught at the University of Miami. The PIs participate in the Earth Science Women's Network (ESWN), a group that promotes mentoring, support, professional collaborations, and career development with other women working in science and technology. In addition, the PIs participate in the annual RSMAS Women in Science day. This program targets sixth and seventh grade girls, and female scientists from the Rosenstiel School lead hands-on activities in their scientific field to engage the young participants.