title: Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in CO2 emissions.
abstract: Current emissions of anthropogenic greenhouse gases (GHGs) have already committed the planet to an increase in average surface temperature by the end of the century that may be above the critical threshold for tipping elements of the climate system into abrupt change with potentially irreversible and unmanageable consequences. This would mean that the climate system is close to entering if not already within the zone of "dangerous anthropogenic interference" (DAI). Scientific and policy literature refers to the need for "early," "urgent," "rapid," and "fast-action" mitigation to help avoid DAI and abrupt climate changes. We define "fast-action" to include regulatory measures that can begin within 2-3 years, be substantially implemented in 5-10 years, and produce a climate response within decades. We discuss strategies for short-lived non-CO(2) GHGs and particles, where existing agreements can be used to accomplish mitigation objectives. Policy makers can amend the Montreal Protocol to phase down the production and consumption of hydrofluorocarbons (HFCs) with high global warming potential. Other fast-action strategies can reduce emissions of black carbon particles and precursor gases that lead to ozone formation in the lower atmosphere, and increase biosequestration, including through biochar. These and other fast-action strategies may reduce the risk of abrupt climate change in the next few decades by complementing cuts in CO(2) emissions.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0356, La Jolla, CA 92093, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Molina
authors.forename: Durwood
authors.initials: D
authors.lastname: Zaelke
authors.forename: K Madhava
authors.initials: KM
authors.lastname: Sarma
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Andersen
authors.forename: Veerabhadran
authors.initials: V
authors.lastname: Ramanathan
authors.forename: Donald
authors.initials: D
authors.lastname: Kaniaru
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002170:Canada; D002245:Carbon Dioxide / Q000032:analysis*; D057231:Climate Change; D004777:Environment; D005466:Fluorocarbons / Q000032:analysis; D017752:Greenhouse Effect; D006801:Humans; D010126:Ozone / Q000032:analysis; D012307:Risk Factors; D053260:Soot
chemical_list: D005466:Fluorocarbons; D053260:Soot; D002245:Carbon Dioxide; D010126:Ozone