Reposted from the Wilkes Center for Climate Science & Policy.
Climate scientist Myles Allen says the world could stop additional global warming within about 30 years - and limit total future warming to less than what has occurred since 2000 under the pathway he has developed. His argument adds a less familiar requirement to the usual energy transition playbook-storing carbon emissions underground.
In early October, Allen presented a series of lectures, including "Can We Fix Fossil Fuels? What It Would Take to Stop Global Warming," at the University of Utah's Wilkes Center for Climate Science & Policy. In addition to leading the Oxford Net Zero initiative, he is collaborating with oil and gas engineering faculty and students at Texas A&M.
Much of climate strategy has focused on rapidly reducing reliance on oil, gas, and coal-whose emissions are driving global warming-by making emission-free renewable energy cheaper and using it to meet global energy demand.
But that transition is unlikely to happen quickly enough to prevent further warming, argues Allen, a professor of geosystem science at the University of Oxford, where he also heads Atmospheric, Oceanic and Planetary Physics in the Department of Physics.
"For all the uses we have for fossil fuels, we're not going to make low-carbon energy technology cheaper than fossil fuels," he said. "Some of them we can - solar power has already beaten coal. But aviation fuel? Kerosene has a long way to run. There's a lot of applications of fossil fuels where it will be a very long time, if ever, that fossil fuel alternatives will actually be cheaper - even if you include the cost of carbon dioxide disposal."
Instead, he says, climate strategy needs a complementary approach for the fossil fuels that remain available.
"The world needs fossil fuels that don't cause global warming," said Allen, a proponent of a "carbon takeback obligation" policy. "America can supply them. America is the world leader in carbon capture technology."
Carbon credits won't save the climate; carbon storage can help
Scientists have long understood why Earth is warming: humans are burning fossil fuels for energy and releasing greenhouse gases into the atmosphere. We also understand what stopping that warming requires: bringing net CO₂ emissions to zero while also reducing emissions of other greenhouse gases, such as methane.
Since the Industrial Revolution, humans have burned coal, oil and natural gas to drive economic growth while releasing a long-lived greenhouse gas waste product, CO₂, into the atmosphere. The planet's oceans and forests have acted as "natural sinks," absorbing nearly half this waste. The rest has accumulated in the atmosphere, amplifying these gases' greenhouse effect.
One widely used approach has been carbon credits, some of which allow emitters to claim offsets by funding projects that avoid, reduce or remove emissions. But such schemes have faced criticism over whether they can reliably and measurably compensate for CO₂ emissions.
Meanwhile, the technology for capturing and storing CO₂ (CCS) in the United States grew out of early oil and gas practices. Commercial CO₂ enhanced oil recovery dates to 1972, when operators began injecting CO₂ into oil reservoirs to increase production.
More recently permanent underground CO₂ storage for climate purposes has begun to move toward commercial scale.
In one illustrative pathway, Allen argues that roughly 65% of "avoided fossil carbon combustion" to the atmosphere could be achieved by transitioning to less polluting, cleaner sources of energy for transportation, homes and industry. Yet, capturing CO₂ and restoring the carbon underground at "geological timescales" would comprise 25% of the solution. Reversing deforestation would account for the remaining 10%.
"Both of these actions are possible," Allen said. "They can be done, they are being done today, just not being done on a large scale."
Research at the U's Energy & Geoscience Institute (EGI), and elsewhere, has demonstrated how CO₂ can be compressed and injected deep underground, where it becomes a supercritical fluid and can be stored for geological timescales. Meanwhile, the Utah Geological Survey continues to map areas across the state where CCS could, in theory, be feasible.
Here's the plan
Allen says the world will need to dispose of more than one trillion metric tons of CO₂ over the course of this century. He argues that investment in CO₂ storage remains far below the scale required.
In many applications today, avoiding CO₂ emissions is cheaper than capturing and storing them. Allen argues that the economics could eventually shift: the cost of further emissions reductions will rise sharply, while the cost of expanding CO₂ storage should level off.
Allen illustrates the path to muting fossil fuels' impacts on the climate with a quadratic curve. The "transition duration" becomes apparent by plotting the time required to reduce fossil fuels' carbon intensity over time.
The Netherlands' Porthos Project and U.S. direct-air-capture projects such as 1PointFive's STRATOS facility offer examples of what this industrial-scale solution could look like.
Under Allen's proposed "Carbon Takeback Obligation," companies that profit from extracting and importing oil, gas, and coal would take responsibility for a rising share of the CO₂ associated with the fuels they sell, ultimately reaching an equivalent quantity stored geologically.
Who pays?
The proposal would shift more of the responsibility upstream to fossil fuel producers and importers. Under Allen's formulation, fossil fuel producers and importers would surrender "Carbon Storage Units" (CSUs) representing a rising fraction of the CO₂ generated by their products and activities.
The system would require fossil fuel extractors and importers to cover the costs to ensure the verified capture and permanent storage of CO₂ through the trading of CSUs. Over time, producers would have to capture and store an increasing share of the carbon associated with their products.
Some of those costs would likely be passed on to consumers. Allen says a carbon disposal fee on fossil fuel producers wouldn't necessarily add much to what consumers already pay for energy.
In Allen's example, a hypothetical incremental carbon disposal cost introduced in 2000, and gradually increased to 70 cents per liter - about $2.65 per U.S. gallon - by 2025, still would have tracked below what gasoline consumers in the U.S., Canada and the U.K. paid at the pump.
As costs have fallen and deployment has expanded, cleaner technologies have become more affordable and widespread. In many markets, new utility-scale solar and battery storage can compete with coal generation, while electric vehicles can have lower fuel and maintenance costs than gasoline-powered cars.
"The difference between what we pay for oil and gas, and what they actually cost to extract, process and deliver to our cars and homes would pay for carbon air capture. That money is going somewhere," Allen asserted.
Will it work?
The proposal faces substantial scientific, economic and policy questions.
Critics argue that allowing continued fossil-fuel production could become a "Capture it later" policy that slows substitution and prolongs dependence. Others worry whether DAC and CCS can scale sufficiently and at competitive cost, as neither technology has been demonstrated at the massive global scale required. Still, others say prioritizing money for carbon storage reduces funds available for investments in other clean technologies.Allen counters that a fossil-fuel phaseout is unlikely to occur quickly enough to stop further warming. He argues that climate policymakers should also engage with fossil fuel producers to "fix" their products by ensuring that any remaining fossil-fuel use no longer adds CO₂ to the atmosphere.
The problem is fixable, he contends, but what's needed now is to get on with it. The test will be whether carbon takeback can actually deliver verified geological storage at the required scale and cost, without slowing the world's transition toward cleaner energy substitutes.
