Solar geoengineering offers a speculative means to cool the planet by reflecting solar radiation into space. While some research suggests that awareness of solar geoengineering could reduce public support for decarbonization through a moral hazard mechanism, other studies indicate that it could serve as a “clarion call” that motivates further action. Using a pre-registered factorial design, we assess how sharing balanced information on solar geoengineering affects attitudes toward decarbonization policies and climate attitudes among 2,509 US residents. We do not find that solar geoengineering information affects support for decarbonization on average, though it may increase support among initially less supportive subgroups; moreover, this information tends to increase the perception that climate change is a daunting problem that cannot be resolved without decarbonization. Our results suggest that concerns about moral hazard should not discourage research on solar geoengineering – as long as the public encounters realistic messages about solar geoengineering’s role.

The troublesome weed Johnsongrass [Sorghum halepense (L.) Pers.] is predicted to expand its range under climate change. In the process, it is likely to become more competitive in corn (Zea mays L.) production areas of the northeastern United States and southern Canada. A replicated greenhouse experiment was conducted to measure interspecific and intraspecific competition between a S. halepense biotype from central New York State (northern range edge) and corn under drought and well-watered conditions. Drought stress significantly reduced the biomass and height of corn and S. halepense in both rounds of the experiment (P < 0.001). Drought stress increased the root-to-shoot ratio of S. halepense (P < 0.001) and reduced the root-to-shoot ratio of corn (P < 0.001). In one run of the experiment, corn produced 19.3% more aboveground biomass (P < 0.001) and 6.6% more height (P < 0.001) when competing with a S. halepense plant (interspecific competition) than when competing with a second corn plant (intraspecific competition). Drought conditions increased the advantage of corn plants grown under interspecific relative to intraspecific competition (P = 0.012). In that round of the experiment, biomass of S. halepense was 12.9% higher under intraspecific competition than interspecific competition in the well-watered treatment and 15.5% higher under intraspecific competition than interspecific competition in the drought treatment (main effect of competition, P = 0.002). Differences between competition treatments were smaller in the other round of the experiment (P > 0.05). Our findings suggest that the New York S. halepense biotype used in this study may not be as competitive as biotypes found in this weed’s core range in more southern regions of the United States. However, anticipated effects of climate change may increase the abundance and competitiveness of this species in the northeastern United States.