The MIT Flood Vulnerability Study is one key part of a broader initiative led by the MIT Climate Resiliency Committee and the MIT Office of Sustainability to understand and recommend how MIT can continue to fulfill its mission in the face of intensifying climate risks over the next 100 years and beyond. Risks include precipitation flooding, sea level rise/storm surge and chronic heat stress. This study seeks to translate the science of campus-based flooding risk from climate change into operational and strategic guidance for informing campus planning and management.

Inspired by the MIT Plan for Action on Climate Change, one key research and academic objective of this study is to utilize the MIT campus as a test bed for climate innovation. The study engages MIT’s global research expertise in downscaling global MIT climate models for application testing on the MIT campus, as well as expertise and tools advancing the MIT Stormwater Management and Landscape Ecology Plan.

This Joint Program Report presents findings for Flood and Vulnerability Study Phase 1A – Evaluation of Precipitation Probabilities and Preliminary Campus Flood Risks. The primary purpose of Phase 1A is to quantify MIT Cambridge campus flood risks under current and future climate change conditions over a range of probabilities. Findings include predicted precipitation probabilities, campus flooding exposure from precipitation based on current and future climate conditions, campus flooding exposure from sea level rise and storm surges, and results from the testing of one potential flood mitigation solution. The co-authors conclude the report by outlining planning recommendations and next steps.

Diatoms are autotrophic siliceous unicellular eukaryotes believed to contribute ~40% of global depth-integrated marine primary production and export of organic carbon from the surface ocean. In addition to providing carbon to sustain ocean food webs they thus contribute significantly to its transfer to the deep ocean, i.e. to the biological carbon pump. Beyond the classical view of diatoms being abundant in nutrient-rich turbulent waters, observations and models both indicate their dominance in meso/submesoscale structures such as fronts and filaments, and as shade flora within the deep chlorophyll maximum. High-resolution observations and simulations, together with inferences from genomics, are changing our understanding of processes regulating and regulated by diatom diversity and abundance. Diatoms display wide variations in size, morphology, and elemental composition, all of which control the quality, quantity, and sinking speed of biogenic matter to depth. As regards carbon export diatoms are unique among the phytoplankton because of their silica shells which provide ballast to marine snow and faecal pellets. Evidence is growing that diatoms are not only efficient transporters of organic carbon to the mesopelagic layer, but can also transport it to the deep ocean. Herein we show that all diatoms are not equal, in that varying Si/C ratios and life strategies will modulate the transfer of carbon to the deep ocean. Except for the Southern Ocean, models predict a decline in the contribution of diatoms to primary production in the future ocean. However, we argue that to better predict the changes of the biological carbon pump in a warmer and acidified ocean we need to address the impacts of physical and chemical changes on diatom diversity, their interactions with other planktonic components, and their complex life histories.

Nine of the ten biggest blackouts in U.S. history were caused by hurricanes, whose sustained winds knocked out power lines over broad geographical areas. Topping the list is Hurricane Maria, which in October disabled the electric grid in Puerto Rico and the U.S. Virgin Islands, leaving the majority of the population without power for months. Climate scientists project that as the global average surface temperature continues to rise, so too will the frequency and intensity of major storms as well as of heat waves and high temperatures. As a result, we are likely to see even more widespread power outages—not only from hurricane winds but also from the effects of prolonged and extreme heat on a critical yet vulnerable component of the power grid: the large power transformer (LPT).     

LPTs are transformers rated at or above 100 MVA (Mega Volt-Amperes), and thousands are deployed across the U.S. But the current stock of LPTs is old; 70 percent or more are 25 years or older out of an expected lifetime of 40 years, and they are very costly and time-consuming to replace. Driven by global warming, more frequent and intense heat waves may degrade the operational lifetimes of LPTs and increase the risk of their premature failure. Overheating reduces the structural integrity of the electrical paper insulation used in LPTs, causing catastrophic short circuits; the failure rate becomes more pronounced as the temperature rises, causing more intense chemical reactions that age the insulation. Widespread LPT failure could lead to long-lasting grid disruption and major economic losses.

To assess the risk of LPT failure in coming decades, researchers from the MIT Joint Program on the Science and Policy of Global Change and MIT Lincoln Laboratory studied the potential impact of global warming and corresponding shifts in summertime “hot days” on LPT lifetime at an LPT location in the U.S. Northeast. They found that for a background 1 ̊C rise in temperature, the lifetime of the transformer decreases by four years, or by 10 percent. Therefore, end-of-century mean global warming projections of approximately 2 ̊C (a climate policy-driven scenario) and 4 ̊C (a business-as-usual scenario) would result in a mean reduction in expected transformer lifetime of 20 to 40 percent. The results are reported in Climatic Change.

The researchers also assessed the future changes in hot-day occurrence under these two climate scenarios, using two different approaches: a conventional method that detects the occurrence of hot days based on the projected daily maximum temperature from a suite of climate models, and a recently developed analogue method that instead uses a suite of model-simulated, large-scale atmospheric conditions associated with local extreme temperature. Both methods indicate strong decadal increases in hot-day frequency. By the late 21^st century, the median number of summertime hot days per year could double under the a 2 ̊C scenario and increase fivefold under the 4 ̊C scenario, along with corresponding decreases in transformer lifetime.

Most importantly, the analogue method showed far greater inter-model consensus—i.e., less uncertainty in the results. The improved inter-model consensus of the analogue method is a promising step toward providing actionable information for a more stable, reliable and environmentally responsible national grid.