Past Seminars and Events 2017
Slow progress reducing greenhouse gas emissions has increased attention on solar geoengineering as a feasible and affordable tool to avoid dangerous climate change. Although gradual geoengineering implementation and termination combined with emissions cuts would be preferable, rapid implementation and termination (e.g., due to war) are significant inherent risks with potentially large effects on biodiversity and ecosystems. Climate responses to geoengineering have been studied in detail. However, the biodiversity and ecosystem impacts remain essentially unknown. We address this critical gap by estimating the effects of the rapid implementation, continuation and sudden termination of geoengineering on precipitation and temperature velocities—the speeds and directions that species would need to travel to track climates as they move. We find that rapid implementation is predicted to increase precipitation velocities by almost fivefold above velocities without geoengineering, as predicted for Representative Concentration Pathway (RCP) 4.5. Sudden geoengineering termination would more than double temperature velocities for the land and ocean, and would more than triple temperature velocities in multiple global biodiversity hotspots. These geoengineering-associated velocities exceed even the most optimistic dispersal rate estimates for many species, increasing local extinction risk. In addition, with sudden termination, 29% of the global land surface is predicted to have temperature and precipitation velocity vectors that are both very high and that diverge in direction by more than 90° from each other. Such rapid climate fragmentation could pull populations in divergent directions, with high potential for the rapid disassembly of ecological communities. Rapid geoengineering implementation and termination would significantly increase the threats to global biodiversity and ecosystems from climate change.