Only fast action can curb planetary heating in time

Curbing CO2 emissions gets most of the attention and getting to net zero emissions by midcentury is essential in the long run to abate climate change. But that’s not enough. To bend the warming curve, we must drastically reduce the less appreciated short-lived “super-pollutants” — mostly methane, HFCs coolants, and black carbon soot. Together, these pollutants, along with the ozone in the lower atmosphere caused by them, are responsible for at least 40 percent of the warming that is happening right now. The need to get them under control is the more immediate and most urgent.

Methane, HFCs, black carbon soot and lower atmosphere ozone are called super pollutants because they are such potent trappers of the earth’s heat. Per ton, methane and ozone have about 90 times the warming effect of CO2. And HFCs and black carbon soot have about 2,000 times the warming effect of CO2.

The good news is that their lifespans in the atmosphere are about 10 to 1000 times shorter than CO2. That means that the effect of reducing them is more immediate atmospheric cooling. The faster cooling of the atmosphere from reducing super pollutants is itself critical, and it has two important co-benefits.

First, immediate results will increase public confidence in the effectiveness of climate actions.

Second, decreasing super pollution also decreases air pollution and boosts environmental justice.  Emission sources for methane and black carbon soot are also major sources of air pollution that leads to over 5.5 million deaths and over 52 million tons of crop losses every year, worldwide. According to the emerging evidence, air pollution also increases the risk of dying from COVID. Since the poor suffer more exposure to air pollutants and farmers bear the brunt of crop losses, super pollutant reductions will be a major step towards addressing environmental justice, as well.

Our atmosphere is currently burdened with a blanket of carbon dioxide that has been built up since the nineteenth century. That blanket now weighs about one trillion tons and it will keep trapping the earth’s heat for a very long time because CO2 stays in the atmosphere for a very long time. To be clear, we absolutely must bend the carbon dioxide emission curve as aggressively as we can to stabilize climate in the long term. But even as we achieve zero emissions by 2050, reducing CO2 can’t deliver any cooling for decades.

And fighting CO2 is not just about limiting future emissions. In the longer term, to reduce the risk of catastrophic climate change beyond 2050, we need to develop ways to retrieve CO2 from the air and either store it underground or repurpose the carbon for commercial use. We can also enact policies to enhance the ability of forests, grasslands, wetlands, and agricultural soils to store more carbon. And, we can support the development of technologies that can extract carbon from the air. We must remove at least 500 billion tons of CO₂ from the air by 2050.

But now, we must attack super pollutants. During the last 20 years, the warming curve has steepened and is causing record-breaking floods, storms, fires, and other impacts. In 2020, a record 12 tropical storms made landfall over the U.S. with $40 billion in damages. We also suffered our most destructive wildfire season. If we don’t bend the warming curve immediately, every coming decade will bring ever more devastation.

To cut the rate of warming by half within 20 years and thus avoid the risks of crossing the 2C threshold before 2050, we have to curb emissions of methane by 50 percent, black carbon soot by 75 percent and HFCs with high global warming potential by 100 percent. The good news is we have shovel-ready technologies and policy proposals at hand. Some of the quickest actions we can take include:

Require climate-friendly refrigerants and cooling equipment that are super energy-efficient. John Kerry, who now leads the climate agenda in the Biden White House, led the charge to use the Montreal Protocol to cut HFCs and avoid up to 0.5C of future warming in the waning days of the Obama administration via the Kigali Amendment.

Deploy soot free diesel. Retrofit all diesel vehicles fueled by ultra-low sulfur diesel with diesel particulate filters, on the way to electric vehicles and perhaps hydrogen for trucking.

Ban food waste from landfills. Fully one-third of food waste is dumped in landfills. It, along with other organic waste, is one of the largest sources of methane, equivalent to the emissions of 37 million cars. The edible part of the food should be used to feed the hungry while the non-edible processed through biodigesters to produce renewable fuels.

Develop manure free farms. Reduce methane and other climate pollutants produced by cattle and other farm animals through feed additives and manure management including biodigesters that can produce renewable fuel as we shift our diet to depend less on farm-raised animals.

Produce leak free gas pipes, to reduce methane from transmission and distribution of natural gas.

To ensure a fast start, we propose the U.S. Congress enact a fast mitigation, “Bend the Warming Curve Initiative” that includes legislation to enact these measures. It would jump start a 10-year sprint to prevent spiking temperatures long enough to achieve net zero emissions, remove the excess CO2, and restore a safe climate.

The future of our planet — and the safety of our children — is at stake. We must act with urgency.

V. Ram Ramanathan is a presidential professor of Climate Stability at the University of California San Diego and editor and co-author of the book: Bending the Curve: Climate Change Solutions. Congressman Scott Peters represents the 52nd District of California. He who has authored laws pertaining to super pollutants and carbon removal technologies and serves on the House Energy and Commerce Committee. Durwood Zaelke is president of the Institute for Governance & Sustainable Development and an adjunct professor at the Bren School of Environmental Science and Management, University of California, Santa Barbara.