The Climate Marathon Has Begun, Now Time for the Sprint

Alan S. Miller
7 min readJan 5, 2021
Measuring impact of black carbon in the Arctic

Alan S. Miller

Based on the forthcoming book, Cut Super Climate Pollutants, Now!, by Alan Miller, Durwood Zaelke, and Stephen O. Andersen

The election of President Biden provides — finally — a realistic hope the worst of climate change can be avoided. But, before we can throw ourselves into a marathon race to become carbon-neutral by 2050, we must reckon with one hard truth: once emitted, CO2stays in the atmosphere for centuries. We are now within a decade of climatic tipping points that may put us past a point of no return as soon as 2030.

But we are not doomed to fail. Reducing four super climate pollutants other than carbon dioxide (CO2) can cut the rate of global warming in half and avoid up to 0.6 °C of warming by 2050. Eliminating these pollutants in a ten-year sprint is the fastest way to slow the self-reinforcing feedback loops that are causing the earth to warm itself. This climate sprint can provide the time we need to achieve the slower reductions in temperature from reducing combustion of fossil fuels and eventually from removing CO2 from the atmosphere. Fortunately, actions to address these four climate super-pollutants have already begun.They now need to accelerated and brought to scale.

President Biden will soon recommit the United States to the Paris climate agreement and join a growing number of nations in the climate change marathon — the commitment to gradually, but steadily, reduce greenhouse gas emissions to “net zero” in coming decades. Like a long race, the climate marathon will require dedication and persistence, and to achieve success, countries will need to overcome many obstacles along the way. Interim goals are important, just as runners need to check their time at the halfway point. The European Union climate plan cuts emissions 55% by 2030, President Biden proposes to make US electricity production carbon-free by 2035, while China aims to peak its emissions by 2030 and achieve net zero by 2060

The fact that nations have begun this marathon is profoundly important. The continued use of fossil fuels risks the fate of humanity and much of life on earth, as scientists have known and warned about for decades. However, having waited so long to start the race, this marathon won’t finish in time to avoid dangerous warming.

Cutting fossil fuel emissions, while essential, will cause warming for a decade or more by reducing cooling sulfates along with CO2. Until at least 2050, a reduction in carbon emissions will achieve little reduction in warming; the atmospheric concentration will decline slowly over decades to centuries, while net warming will result from the faster decline in the concentrations of co-emitted sulfates, which fall out in days to weeks. Only dramatic reductions in CO2 emissions, on the order of 80 percent (thus the “net zero” target), will stabilize the atmospheric concentration.

The pandemic-induced economic shutdown reduced global carbon emissions by about seven percent. This did not reduce the atmospheric concentration — although in the unlikely event sustained, would go a long way toward meeting the Paris climate goals. While many coal plants have been shut down, the International Energy Agency recently pointed to new plants in China and concluded the fuel is not going away any time soon.

The addition of a ten-year sprint to the climate marathon can bring about a significant reduction in warming and do so rapidly enough to make a difference in the next decade. Fortunately, four sources of global warming that meet the bill.

· Hydrofluorocarbons (HFCs), chemicals widely used in refrigerators and air conditioners; 12,000 times more warming than CO2 (over 20 years), lasting up to 30 years in the atmosphere.

· Methane, or natural gas; 84 times more warming than CO2 (over 20 years), lasting 12 years in the atmosphere.

· Tropospheric ozone, the main component of smog, formed when methane, carbon monoxide, and other pollutants react in the presence of sunlight.

· Black Carbon, or soot, comprised of particles and some gaseous residues from the incomplete combustion of wood and charcoal used in cookstoves and diesel fuel used by trucks and other vehicles; 460–1,500 times more warming than CO2, lasting only days in the atmosphere. Their impact falls disproportionately on the Arctic by changing the surface reflectivity.

Fortunately, many of the needed actions have begun, although not yet rapidly enough to achieve the required sprint. An international agreement, the 2016 Kigali Amendment to the ozone depletion treaty (the Montreal Protocol) phases down use of HFCs. The United States, among the few major nations not to approve the amendment, remarkably approved comparable measures in the December 2020 stimulus bill with business and some Republicans in favor. In further support of HFC replacement, manufacturers can accelerate introduction of new technologies and federal and state governments can supply businesses and utilities with financial and technical assistance to retire old, inefficient cooling systems, replace HFC refrigerants, and reducing cooling loads by retrofitting buildings to energy efficient standards.

The Trump EPA weakened regulations to control methane leakage but can be reversed by the Biden Administration. Most oil and gas companies support reducing methane leakage — it saves them money — and some states are leading the way, including Colorado’s Renewable Portfolio Standard program and California’s Cap-and-Trade program. Other measures to reduce methane emissions include stricter regulation of coal mines, wider adoption of programs to reduce meat consumption (methane is emitted from cows and other ruminants) and food waste, improving manure management to control release of gases, and in developing countries with rice-intensive diets, improved paddy irrigation practices

Regulating methane is a “two-fer” — it also reduces formation of tropospheric ozone, a potent health hazard and greenhouse gas due to its absorption of solar radiation. Tropospheric ozone also affects the climate through impacts on evaporation rates, cloud formation, precipitation levels, and atmospheric circulation. Among its final acts, the Trump EPA ignored expert advice and declined to set more stringent ozone standards. After an early period of smog-free days due to the pandemic induced reduction in driving, in 2020 Los Angeles had its worst ozone pollution in decades — ironically due to intense heat waves that increase ozone formation. Reversing this decision will take time, perhaps two years or more because of the formalities of the regulatory process.

The primary strategies for reducing black carbon are replacing inefficient and highly polluting wood-burning cookstoves in developing countries and better controlling pollution from diesel trucks, passenger cars, and off-road vehicles. The World Bank and multiple UN agencies are working to support the introduction of modern cookstoves in poor developing nations, but their efforts require much greater funding. Roughly half the world’s population, or about 4 billion people, still rely to some extent on dirty cooking fuels. Air pollution regulations on heavy duty trucks also work — California regulation has cut black carbon emissions by 90%, although soot and smoke from the state’s record wildfires reversed this progress. The Trump Administration recently rejected tougher regulations to control fine particulates, among the sources of black carbon, another decision that may take some time to reverse due to legal requirements.

Reducing the four climate pollutants with shorter atmospheric lifetimes will create substantial additional health, environmental, and economic benefits. Indoor air pollution from cookstoves causes more than four million premature deaths every year — 50 percent of which are children under the age of five. Air pollutants including fine particulates exacerbate the effects of asthma, contribute to tens of thousands of American deaths annually, and may be linked to COVID-19 death rates. Reducing black carbon and tropospheric ozone would increase crop production by more than 50 million tons, worth US$4–33 billion year. Food waste, a substantial source of methane, results in greenhouse gas emissions equivalent to the third largest country behind only China and the United States; reducing it will also avoid the need for large amounts of water and fertilizer and make a large contribution to meeting the food needs of a projected population of more than 9.5 billion people in 2050.

The climate sprint is thus not a single event but a collection of efforts in which individuals as well as governments at all levels need to engage. The need for action must be understood as urgent and among the highest global priorities. The first and most fundamental requirement: a vocal, focused, public call for action to reduce the four short-lived climate pollutants. Individuals can do their part by reducing food waste and meat consumption, while calling on governments at all levels to regulate and incentivize reductions in methane emissions and tropospheric ozone pollution. Developed countries also must provide financial and technical assistance for developing country efforts to take parallel action and to reduce black carbon emissions from dirty cookstoves.

According to ancient legend, the marathon originated with a Greek messenger who raced from Marathon to Athens, about 25 miles, with news of an important military victory. Unfortunately, according to legend, running alone and without support, he collapsed and died after he delivered the message. The climate marathon with global cooperation can end more happily — if joined by a climate sprint.

Alan S. Miller is a consultant on climate finance and policy who has worked on global environmental issues for more than 40 years, including 16 years in the World Bank Group. This blog is the second in a series on practical solutions to climate change. The first, “The Case for a Climate Change Operation Warp Speed,” is available on Medium:



Alan S. Miller

Alan S. Miller is co-author of “Cut Super Climate Pollutants Now!”. His full bio and links to writing are available at