A “fast-action” climate agenda including reducing non-CO2 climate change agents such as black carbon soot, tropospheric ozone, and hydrofluorocarbons (HFCs), as well as expanding bio-sequestration through biochar production, can forestall fast-approaching abrupt climate changes, according to Nobel Laureate Dr. Mario Molina (Chemistry, 1995) and co-authors in a paper published in the Proceedings of the National Academy of Sciences (PNAS).
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, the authors write. This would mean that the climate system is close to entering if not already within the zone of “dangerous anthropogenic interference” (DAI).
|“We intend our paper as a call to action.”|
—K. Madhava Sarma
Noting the references in scientific and policy literature to the need for fast-action mitigation to help avoid DAI and abrupt climate changes, the authors 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.
Cutting HFCs, black carbon, tropospheric ozone, and methane can buy us about 40 years before we approach the dangerous threshold of 2°C warming.
—co-author Dr. Veerabhadran Ramanathan, Scripps Institution of Oceanography, UCSD
HFCs. HFCs are powerful greenhouse gases originally developed as substitutes for ozone-depleting chemicals. They are poised to become a larger part of the climate problem over the next few decades. (Earlier post.) HFCs are used primarily as refrigerants and in making insulating foam, and emissions are expected to grow dramatically due to increased demand for air conditioning in developing countries.
By 2050, HFC emissions could equal up to 19% of global CO2 emissions under business-as-usual scenarios. A binding legal agreement exists that can cut HFCs now—the Montreal Protocol ozone treaty—and many alternatives to HFCs have already been developed and are waiting for the right regulatory incentive from the Montreal Protocol to be deployed.
The Montreal Protocol has already delayed climate change by seven to 12 years, and put the ozone layer on the path to recovery later this century. The Montreal Protocol is critical for avoiding abrupt climate change. We have to take advantage of the proven ability of this legally binding treaty to quickly phase down HFCs.
—Dr. Mario Molina
(Dr. Molina received the Nobel Prize in Chemistry in 1995 for his path-breaking work in 1974 that sounded the alarm on ozone-depleting CFCs.)
The small island nations of Micronesia and Mauritius submitted a joint proposal in April to phase down production and consumption of HFCs under the Montreal Protocol. North American leaders followed suit with their own joint proposal, which builds on the islands’ submission. The Montreal Protocol is an essential strategy for the island nations to achieve fast mitigation to slow sea-level rise that is already starting to destroy their countries.
Black Carbon. A neglected fast-action strategy presented in the paper is reducing black carbon soot, an aerosol produced largely from the incomplete combustion of diesel fuels and biofuels, and from biomass burning. It is now considered to be the second or third largest contributor to climate change. (Earlier post.)
Black carbon is responsible for almost 50% of the 1.9°C increase in warming of the Arctic since 1890 as well as significant melting of the Himalaya-Tibetan glaciers that feed the major rivers of Asia, providing fresh water to billions of people. (Earlier post.)
Researchers consider black carbon an ideal target for achieving quick mitigation because it only remains in the atmosphere a few days to a few weeks and can be reduced by expanding the use of diesel particulate filters for vehicles and clean-burning or solar cookstoves to replace those burning dung and wood. With indoor air pollution killing 1.6 million people a year, global action to cut soot emissions would reap major benefits for both public health and climate.
If we reduce black carbon emissions worldwide by 50 percent by fully deploying all available emissions-control technologies, we could delay the warming effects of CO2 by one to two decades and at the same time greatly improve the health of those living in heavily polluted regions.
Tropospheric ozone. Like black carbon, ground level or tropospheric ozone doubles as a major climate forcer and health hazard. It also lowers crop yields. A recent study reported that ozone’s damage to crop yields in 2000 resulted in an economic loss of up to $26 billion annually.
It is formed by ozone precursor gases such as carbon monoxide, nitrogen oxides, methane, and other hydrocarbons, many of which can be reduced by improving the efficiency of industrial combustion processes. Reducing tropospheric ozone by 50% could buy another decade’s worth of time for countries to start making substantial cuts in CO2, the authors said.
Biochar. Biochar is one of the few promising “carbon-negative” strategies that can drawdown existing concentrations of CO2. The fine-grained charcoal product is a stable form of carbon that can be plowed into soil where it remains for hundreds to thousands of years, also serving as a natural fertilizer. Biochar comes from cooking biomass waste at low temperatures with minimal oxygen (pyrolysis).
The other fast-action strategies can quickly mitigate emissions, but to back away from the cliff of abrupt climate change, we need biochar.
—co-author Durwood Zaelke, President of the Institute for Governance & Sustainable Development
Climate policy. Although most of the world is focused on CO2 in the months leading up to Copenhagen, the authors of the paper hope that policymakers will recognize the advantages of implementing these fast-action strategies to complement reductions in CO2.
These fast-action strategies will support the long-term CO2 solution by stopping near-term climate change with non-CO2 solutions. This will bring momentum to those negotiating the international agreement and the US legislation.
—Dr. Stephen Andersen
The paper is part of a “Tipping elements in Earth systems” special feature to be published in PNAS later this year.
Mario Molina, Durwood Zaelke, K. Madhava Sarma, Stephen O. Andersen, Veerabhadran Ramanathan, and Donald Kaniaru (2009) Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in CO2 emissions. PNAS doi: 10.1073/pnas.0902568106