Sometimes we get so focused on our silos that we don’t see connections across silos or the broader context. At EPIC we spend a lot of time working on policies to reduce greenhouse gas emissions but during a recent project on carbon offset credits I learned more about the role of natural and working lands in California’s climate strategy. Add to that the recent activity related to carbon dioxide removal, particularly engineered solutions, and I began to see a more complete picture of climate action.
In hopes of making the complex work of climate policy a bit more digestible, consider a three-pronged framework for climate action: reduce emissions, preserve existing carbon stocks, and remove carbon from the atmosphere. This is nothing new. It basically summarizes California’s climate strategy, but I had to connect the dots to see it. This post summarizes each element of this framework.
The first prong is the most familiar and critical. According to the latest science, deep reductions in greenhouse gas (GHG) emissions are required by mid-century to prevent warming beyond 1.5° Celsius. We must reduce two types of GHG emissions: long-lived climate pollutants (e.g., carbon dioxide) and short-lived climate pollutants (e.g., methane and some refrigerants). As for long-lived climate pollutants, carbon dioxide (CO2) remains in the atmosphere for hundreds of years. Much of the activity to address climate change focuses on reducing CO2 emissions, which generally includes mitigating fossil fuel use through efficiency, decarbonizing energy systems, and electrifying vehicles and buildings.
Short-lived climate pollutants (SLCP) have higher high global-warming potential (GWP) than CO2 in the short term but last years to decades. So while SLCP represent a smaller fraction of overall GHG emissions than CO2, they cause a disproportionate amount of warming in the short-term due to their heat-trapping abilities. As Dr. Ram Ramanathan of Scripps Institution of Oceanography has pointed out for many years, reducing SLCPs can have a more immediate impact on global warming and have co-benefits of reducing air pollution.
California has recognized the role of SLCP. In March 2017 the California Air Resources Board (CARB) released its Short-Lived Climate Pollutant Reduction Strategy. It outlined activities to reduce SLCPs, including capturing methane from dairy operations and landfills and destroying or replacing high GWP gases, like HFCs.
Preserve Carbon Stocks
The second prong of this framework is to preserve the carbon stored in natural systems, including in forests and soil, preventing its release into the atmosphere. An article published recently in the journal Nature describes how the Amazon is shifting from carbon sink to emitter — a troubling trend. Recent fires in the Western U.S. remind us that forests are vulnerable in a changing climate and likely will be more prone to fire, disease, and insects. Preventing release of the carbon currently stored in natural and working lands will be an important part of the overall strategy to address climate change.
California Governor Gavin Newsome recognized this when he signed Executive Order N-82-20 in October 2020. This is often referred to as the “30 by 30” plan because it sets a goal for the State to conserve at least 30% of California’s land and coastal waters by 2030. In addition to helping prevent the release of stored carbon, such efforts have other co-benefits like enhancing biodiversity and recreational opportunities.
No matter how hard we try, we will not be able to squeeze all the GHG emissions from our economy. In particular there are some sectors like aviation and some industrial processes that will be difficult to decarbonize. To cancel out the emissions that remain after we do our best to reduce emissions and preserve carbon stocks, we will have to remove CO2 from the atmosphere. This can be done by natural processes like the CO2 absorption by trees and wetlands and by engineered processes like direct air capture. California has long identified CO2 removals from natural and working lands as an important component to a comprehensive climate strategy, but only recently has it begun to contemplate engineered solutions. As part of CARB’s 2022 Scoping Plan Update, it is hosting a Technical Workshop on Engineered Carbon Removal to explore its potential to help reach carbon neutrality.
Removed carbon must be stored. The longer the timeframe of storage the better. We will need to move from methods that can store carbon on the decadal timescale with a higher risk of reversal (e.g., trees) to those that can store it for at least 1,000 years and have a lower risk of reversal (direct air capture with geological storage).
Engineered removal technologies exist today but are in their infancy. Microsoft, Stripe, and Shopify have committed to purchase carbon removals to prime the market, and investors have turned their attention to these approaches. In the short run, we likely will have to rely on removals from natural and working lands and can phase in engineered solutions as technologies mature and costs decline.
Achieving the Right Balance
The figure below summarizes the reduce, preserve, and remove framework. Note that all three are required and there is an order of operations: reduce and preserve as much as possible first and then remove the rest. We cannot remove our way out of this. And a lot more work is required to reduce emissions enough to achieve deep cuts in the next couple decades. However, we cannot wait around to get started on the removal step, but don’t want to focus on removal at the expense of reducing and preserving. Achieving the right balance will be tricky. Also, there are many other aspects of this challenge, including equity and cost — not to mention adaptation and resilience — that are important but not covered here.
While this simple framework belies complexity and tough choices that lie ahead, it may help to conceptualize the path ahead and to put into context a range of activities that will be needed to avoid the worst impacts of climate change. It certainly has helped me to see the more clearly what needs to be done.