Communication between scientists and policymakers is critical for developing effective policies grounded in scientific evidence. However, actual communication between these two groups is often difficult, due to differences in training, communication styles, and motivation. While numerous “best practices” guides provide advice on science communication, many of these recommendations are based on personal experience rather than empirical data. To remedy this gap in the literature, researchers at the University of California, Davis conducted a literature review of scholarship on best practices in science communication, with an emphasis on finding reports based on empirical data rather than personal experience. The researchers synthesized their findings into a set of best practices for science communication and considered how scientific reputation affects engagement in the policy process.

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California and British Columbia transportation fuel carbon intensity (CI) standards have been in effect since 2011, and Oregon’s since 2016. Total transport energy consumption under the programs was over 23 billion gasoline gallon equivalents (gge) in 2019.

By 2019, the transport energy share from lower-carbon alternative fuels rose under each program to about 11%, 8%, and 7% in California, Oregon, and British Columbia, respectively.

Each program met its CI targets and accumulated a bank of credits, which represent greenhouse gas (GHG) emission savings beyond the annual target. Credits cover program deficits assessed for emissions above target levels and can be applied towards future compliance. California and British Columbia drew down their credit banks each year since 2017; Oregon’s credit bank grew since the 2016 program start.

Program credit prices in 2020 averaged $200/metric ton (MT), $132/MT, and $192/MT (all $USD) in California, Oregon, and British Columbia, respectively.

In California, growth of cost-effective diesel substitutes led to over-compliance with the diesel pool standard (a 25% CI reduction for California in 2020), more than offsetting under-compliance in the gasoline pool (a 3% CI reduction there). The same is true in Oregon and British Columbia to a lesser extent.

Renewable diesel (RD) generated a notable share of compliance credits in each jurisdiction, despite zero or near-zero volumes when the programs began. In 2019, RD accounted for more than 16% by volume of the liquid diesel pool in California and approximately 30% of alternative fuel energy and credits in British Columbia. RD was first credited in Oregon in 2019.

Biomass-based diesel from used cooking oil grew rapidly; 2019 consumption increased by at least 70% over previous year in all three programs.

Low-CI rated electricity (i.e., below the state grid average) accounted for approximately 4% of all credits in California beginning in 2019, after indirect accounting mechanisms that avoid the need for physical traceability became available. Oregon expanded its low-CI value electricity options in 2021 in a similar fashion to California.

California’s is the only program to track and penalize increasing CI of petroleum fuels. Additional deficits accrued in 2020, totaling 192,000 – 2.6% of the total – through Q2.

All three programs continue to adopt amendments, including extending targets and program durations (20% CI reduction by 2030 for all); opt-in credits for alternative jet fuel (California and Oregon); use of advanced crediting for electric vehicle (EV) charging (California and Oregon); an EV rebate program funded by residential charging credit revenue (California); infrastructure capacity crediting for zero emission vehicle (ZEV) fueling (California); third-party verification (California and Oregon), and carbon capture and sequestration protocol (California).o Washington state passed legislation adopting a Clean Fuel Standard to take effect in 2023.

An online visualization tool and data repository, available athttps://asmith.ucdavis.edu/data/LCFS, includes much of the data used in this report.

Many scientific projects are intended to inform public policy, however there are often difficulties transferring or translating research from scientists to policy makers. This paper reviews the existing literature on the quality of communication between scientists or field experts and policy makers and the challenges they face in conveying their research. A majority of best practice recommendations related to effective communication are rooted in anecdotal evidence and have not yet been subjected to systematic scientific study. This is, in part, because the nature of public policy makes data collection, randomization, or correcting for confounding factors extremely challenging. Studies that do put these recommendations to the test are most commonly fielded as national surveys of field experts and policy makers in comparative contexts. Few studies examine this subject in the United States, however, and most find mixed results as to the efficacy of well-accepted scientific communication strategies. Further, existing work often fails to account for the impact of reputation on the willingness of scientists to engage in policymaking and the willingness of political actors to seek and accept expert input in the policymaking process, unless it confirms pre-existing biases. The authors explain how this gap in the literature has important consequences for the quality of policies produced and suggest future avenues of research in the pursuit of sincere evidence-based policymaking.

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