At the intersection of physical sciences and policy, our researchers work to find solutions for hunger, environmental degradation, emerging energy markets and more.
Research Spotlight
Economic Policy Challenges Facing California's Next Governor: Electricity Policy Reform
Because Californians are likely to want to continue to lead the energy transition, the relevant policy design question is: How can the state achieve these low-carbon energy goals in a more cost- effective manner?
Climate Change is Increasing the Risk of Extreme Autumn Wildfire Conditions Across California
The climate model analyses presented here suggest that continued climate change will further amplify the number of days with extreme fire weather by the end of this century, though a pathway consistent with the UN Paris commitments would substantially curb that increase.
Sight for Sorghums: Comparisons of Satellite- and Ground-Based Sorghum Yield Estimates in Mali
Leveraging a survey experiment in Mali, this study uses plot-level sorghum yield estimates, based on farmer reporting and crop cutting, to construct and evaluate estimates from three satellite-based sensors.
In addition to habitat loss and fragmentation, demographic processes—the vagaries of births, deaths and sex ratio fluctuations—pose substantial threats to wild giant panda populations. Additionally, climate change and plans for the Giant Panda National Park may influence (in opposing directions) the extinction risk for wild giant pandas. The Fourth National Giant Panda Census showed pandas living in 33 isolated populations. An estimated 259 animals live in 25 of these groups, ~14% of the total population. We used individual-based models to simulate time series of these small populations for 100 years. We analysed the spatial pattern of their risk of extinction under current conditions and multiple climate change models. Furthermore, we consider the impact of the proposed Giant Panda National Park. Results showed that 15 populations face a risk >90%, and for 3 other populations the risk is >50%. Of the 15 most at-risk populations, national parks can protect only 3. Under the Representative Concentration Pathway 8.5 climate change scenario, the 33 populations will probably further divide into 56 populations. Some 41 of them will face a risk >50% and 35 face a risk >90%. Although national parks will probably connect some fragmented habitats, 26 populations will be outside national park planning. Our study gives practical advice for conservation policies and management and has implications for the conservation of other species in the world that live in isolated, fragmented habitats.
Stanford health law experts Michelle Mello and David Studdert discuss the ongoing pandemic, proof of vaccination “passports” at the state and federal levels, and a July 19 ruling that Indiana University could require that its students be vaccinated.
Crop productivity is potentially affected by several air pollutants, although these are usually studied in isolation. A significant challenge to understanding the effects of multiple pollutants in many regions is the dearth of air quality data near agricultural fields. Here we empirically estimate the effect of four key pollutants (ozone (O3), particulate matter (PM), sulfur dioxide (SO2), and nitrogen dioxide (NO2)) on maize and soybean yields in the United States using a combination of administrative data and satellite-derived yield estimates. We identify clear negative effects of exposure to O3, PM, and SO2 in both crops, using yields measured in the vicinity of monitoring stations. We also show that while stations measuring NO2 are too sparse to reliably estimate a yield effect, the strong gradient of NO2 concentrations near power plants allows us to more precisely estimate NO2 effects using satellite measured yield gradients. The presence of some powerplants that turn on and others that shut down during the study period are particularly useful for attributing yield gradients to pollution. We estimate that total yield losses from these pollutants averaged roughly 5% for both maize and soybean over the past two decades. While all four pollutants have statistically significant effects, PM and NO2 appear more damaging to crops at current levels than O3 and SO2. Finally, we find that the significant improvement in air quality since 1999 has halved the impact of poor air quality on major crops and contributed to yield increases that represent roughly 20% of overall yield gains over that period.
Quantification of the sector-specific financial impacts of historical global warming represents a critical gap in climate change impacts assessment. The multiple decades of county-level data available from the U.S. crop insurance program – which collectively represent aggregate damages to the agricultural sector largely borne by U.S. taxpayers – present a unique opportunity to close this gap. Using econometric analysis in combination with observed and simulated changes in county-level temperature, we show that global warming has already contributed substantially to rising crop insurance losses in the U.S. For example, we estimate that county-level temperature trends have contributed $US2017 23.9 billion – or 17% – of the national-level crop insurance losses over the 1991-2017 period. Further, we estimate that observed warming contributed approximately one third of total losses in the most costly single year (2012). In addition, analyses of a large suite of global climate model simulations yield very high confidence that anthropogenic climate forcing has increased U.S. crop insurance losses. These sector-specific estimates provide important quantitative information about the financial costs of the global warming that has already occurred (including the costs of individual extreme events), as well as the economic value of mitigation and/or adaptation options.
This essay is a part of an exchange based on Francis Fukuyama’s “Making the Internet Safe for Democracy” from the April 2021 issue of the Journal of Democracy.
