written 2 July 2023
published 9 July 2023
Last week, another round of Canadian wildfire smoke poured southward into Midwestern US and then moved east, affecting 1/3 of the country with unhealthy air quality. Record heat attacked the southern US like a blowtorch, bringing temperatures comparable to the Sahara or the Persian Gulf. Northern Mexico experienced 122°F, with 10 Mexican states reporting power shortages, leaving tourists and locals without air conditioning or fresh water. For the first time, there have already been two tropical storms in the Atlantic in June.
The book "Climate Restoration" makes the case that, for a habitable planet, we must not only completely decarbonize the economy, but also aggressively sequester much of the carbon already in the atmosphere. Synthetic limestone, kelp cultivation, and fertilized ocean phytoplankton are all systems that use natural living systems to bring us back to historically proven habitable levels. However, there is another significant greenhouse gas that must also be addressed: methane.
Methane is 40 times more potent than carbon dioxide, but naturally breaks down within a decade. Atmospheric methane concentration, now two and a half times preindustrial levels, increased 0.1ppm in the last decade, the warming equivalent of 4ppm of CO2. Since CO2 grew 25ppm last decade, this addition is another 16 percent increase.
Methane comes from melting permafrost, natural wetlands, rice paddies, landfills (1/4 of Ukiah's greenhouse gas contribution), cow burps, and the production and transportation of oil and natural gas. Such diversity makes reducing methane at the source difficult.
Climate Restoration reports on a process that accelerates the natural methane oxidation rate: Enhanced Atmospheric Methane Oxidation (EAMO). A fine aerosol mist of iron-chloride is added to the air. Wind mixes it with methane, and sunlight powers the oxidization reaction. This is 100,000 times more efficient than any other oxidation technology. EAMO could restore pre-industrial methane levels by 2028 by doubling the rate of natural methane oxidation, addressing both natural and human-made methane.
While current methane production rates are problematic, a more serious concern is methane stored in the seafloor of the Arctic Ocean. The East Siberian Arctic Shelf (ESAS), with an average depth of 120 feet, is estimated to hold at least 1,400 billion tons of frozen methane hydrate, kept solid by the cold temperature of the Arctic sea floor.
Frozen methane is like dry ice (frozen CO2), in that it changes directly from solid to gas. As climate change warms the Artic, summer sea ice has diminished, allowing the dark ocean water to warm. This area is now "violently boiling", as methane begins reaching the surface. The concern is that at some point large amounts of frozen methane will warm into gas, and burst to the surface.
Geologic record indicates this happened about 56 million years ago, during the Paleocene-Eocene Thermal Maximum. Carbon dioxide level were rapidly rising, melting seafloor permafrost, and a methane burst produced a severe and rapid temperature spike, leading to the extinction of about 30 percent of life forms alive at the time. Carbon dioxide levels are rising 10 faster today.
If just 50 billion tons of methane, less than 4 percent of that estimated in the shallow ESAS, were to burst into the atmosphere, global temperatures would rapidly spike by another 50 percent. Bursts could be 2 or 3 times this size. Like predicting an earthquake, timing is anyone's guess, with expert opinion ranging from within the next decade to beyond our lifetime. But given the magnitude of impact, it is worth humanity considering what can be done to prepare. By developing an EAMO system now, building the capacity to cut existing methane in half, we would be in a better position to ramp up to respond to an Arctic seafloor burst, preventing methane from building to extinction levels.
Development is underway to build simple ship born systems, injecting iron-chloride into the exhaust stacks to facilitate mixing. There is good reason to think EAMO is safe, as it mimics natural processes, and the same method is used to purify drinking water. Funding is estimated at $1 billion a year, which is modest enough to appeal to the insurance industry, which has an economic stake in preventing climate disasters.
As the climate crisis builds, people are beginning to see this is real, despite Republican and industry obstructionism. The good news is, working with natural systems, we can restore the planet to insure human habitability. Are we intelligent enough, with sufficient political will, to make the effort?
