America’s moment to usher in a climate friendly aviation future
On July 22, 2020, I testified to the Senate Special Committee on the Climate Crisis about the aviation industry’s impact on climate change. Below is my prepared statement to the committee, lightly edited for clarity.
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It’s time to talk about aviation’s impact on climate change. Today I’ll tackle what this industry can and should do to reduce carbon emissions, and steps the US government can take to make sure that the flightpath of the aviation industry going forward helps us all arrive at a safe climate future.
“After COVID-19, a New Path for Aviation?”
Prior to the impacts of the coronavirus pandemic, aviation represented 2% of US domestic carbon emissions and 10% of overall US transportation emissions. That may not seem like a lot, but if we are to consider the full impact of aviation on the climate, we need to count the special chemistry of aircraft burning jet fuel in the upper atmosphere. These “non-CO2 effects” create an additional level warming and at least double the industry’s climate impact.
All industries need to make significant reductions in their emissions. In fact, according to the Intergovernmental Panel on Climate Change (IPCC), we need to reach net zero emissions globally by midcentury. Given long-term emissions growth projections for the sector, aviation could end up taking a quarter of the remaining carbon budget available to us if we are to keep warming below 1.5 degrees Celsius — the level that helps us avoid the worst impacts of climate change, including the near total collapse of key ecosystems.
At the moment, airlines are mostly in the news because of the historic drop in air travel as a result of the coronavirus pandemic. As a consequence, emissions from the industry are down too, temporarily.
Aviation industry modelers have examined various scenarios for air travel demand recovery. A key question is whether there will be significant structural changes to the industry, to the extent that the growth of aviation after the recovery is slower than it would have been before coronavirus. But in the grand scheme of things, industry experts anticipate long-term air traffic growth trends similar to what they expected prior to the coronavirus pandemic. This underscores that we still desperately need ambitious government policies to help transform the aviation industry to emit dramatically fewer greenhouse gases.
If airlines come back to the table for additional aid, any US Congressional support needs to ensure we are rebooting the industry to be more climate friendly, rather than spend taxpayer dollars in a way that lock in unsustainable levels of climate emission
The airlines can’t do it alone. The US Congress needs to step up.
A comprehensive climate plan for US aviation would start with setting both near-term and long-term compliance caps on emissions for US airplane operators. A credible near-term target would be a 30% reduction from 2019 levels by 2035; by 2050, aviation would have to reach net zero greenhouse gas emissions (GHGs).
Being net zero implies that airplane operators would either have to completely eliminate GHGs from their operations by 2050 or reduce their emissions to very low levels and then compensate for the remaining emissions by removing carbon from the atmosphere through biological (e.g., ecosystem restoration such as reforestation) or technological methods (e.g., directly capturing carbon from the atmosphere and storing it permanently).
To meet these targets, there are four essential mitigation levers:
1. Fuel efficiency:
The aviation industry has four main strategies by which to improve fuel efficiency: (1) replacing older aircraft with more fuel-efficient models; (2) improving operations to carry more passengers and/or freight per flight; (3) flying more directly to destinations; and (4) finding optimal flight paths and avoiding congestion near airports through advanced air traffic management.
Research and modelling show that the aviation industry could achieve up to 2.5% year on year CO2 efficiency improvements, especially if enabled by CO2 efficiency standards for aircraft, research and development funding for breakthrough aircraft designs, and other efficiency policies.
2. Shifting to other modes of transportation:
Policies that give consumers less energy intensive transportation options can decrease aviation climate emissions. These efforts could include support to modernize the US rail system, including providing grant funding for updates to America’s rail infrastructure.
3. Sustainable aviation fuels:
For the foreseeable future, aircraft will rely on liquid fuels for long-distance flights. Beyond fuel efficiency and flying less, the largest potential emission reduction opportunity is likely to be sustainable aviation fuels.
For a fuel to be cleaner, it must have lower lifecycle emissions than conventional jet fuel. Alternative liquid fuels can come from a variety of diverse and sustainable feedstocks: they can be bio-based, originate from waste streams, and — most promising on a large scale — “power-to-liquid” (PtL) synthetic fuels which can be made from renewable electricity, water and carbon dioxide. As an alternative to liquid fuel, hybrid or fully electric planes may service short- and medium-haul flight routes at scale in the coming decade or two, if national governments like the United States Government provide meaningful policy incentives.
These sustainable fuels are essential, but they are more expensive than fossil jet fuel. To incentivize uptake of sustainable aviation fuels in the United States, we would benefit from adopting policies like a national low carbon fuel standard. To build a large and long-overdue supply of ultra-low carbon fuels, Congress should also pass additional subsidies and appropriate R&D funding. In this instance, ultra-low carbon fuels can be defined as having at least 60% lower lifecycle emissions than fossil jet fuel.
Beyond emissions reductions, for sustainable aviation fuels to be truly sustainable they must also meet additional sustainability criteria to ensure that the production of these fuels is not exacerbating other environmental and social issues.
4. Removing carbon from the atmosphere:
The goal of net zero emissions for aviation by 2050 will also require carbon dioxide removal techniques that sequester carbon permanently without other adverse effects on the environment and people, for two reasons.
First, to achieve deep decarbonization in the aviation industry, “power-to-liquid fuels” will probably have to be a notable portion of the fuel mix by 2050. Additionally, to get the full carbon benefit of these fuels, they must be made with 100% renewable electricity and source carbon dioxide from direct air capture (DAC) systems.
Second, the aviation industry — or potentially government on behalf of the aviation industry — will need to use direct air capture systems or natural ecosystem restoration and soil carbon sequestration efforts to compensate for any residual emissions coming from their operations. The recent report from the House Select Committee on the Climate Crisis has provided a good summary of the overall policy response needed to develop a robust industry doing direct air capture: “To jumpstart a direct air capture industry in the United States, Congress should dramatically increase federal investment in carbon removal research and development; improve financial incentives for direct air capture technology; expand demonstration projects to safely store carbon below ground; and create markets for fuels made from carbon captured from the atmosphere.”
CO2 is just one part of the equation. Here’s how we might start solving for the rest.
While aviation’s impact on Earth’s climate is often referenced in terms of its CO2 emissions, studies indicate that burning jet fuel at altitude induces warming beyond the greenhouse gas effect of CO2. The science of aviation-related contrail formation and how it affects the climate is still evolving, though studies indicate that more than half of the aviation industry’s actual effect on climate may be due to non-CO2 climate forcers. Policies that focus only on CO2 released by aircraft are insufficient to align the industry with the Paris Agreement’s temperature goals, and therefore it is necessary to fully examine non-CO2 effects to allow their incorporation in climate policies.
A technical working paper submitted by the International Coalition for Sustainable Aviation to the 40th Assembly of the UN International Civil Aviation Organization best summarizes mitigation approaches to address non-CO2 effects from aviation:
While there are ways that non-CO2 effects can be reduced, there are significant challenges. Mitigation measures for non-CO2 effects include lowering cruise altitudes, restricting access to “climate-sensitive” airspace, or otherwise optimizing flight trajectory. Optimizing these actions (e.g., model-informed flight routes) to minimize the overall climate warming impact of the flight would benefit from funding for additional research. Aeroplane operators using PtL fuels could potentially reduce their non-CO2 effects as well. A 50% PtL fuel blend is estimated to reduce contrail formation (a key non-CO2 forcer) by around 20%.
Given the complexity of non-CO2 effect mitigation, the US Government should dedicate funding to explore how to set policies that would address non-CO2 emissions, with a focus on how to optimize flight trajectories to avoid “climate sensitive” airspace.
After COVID-19, a return to “business-as-usual” isn’t good enough.
To date, the US government has done very little to incentivize emissions reductions from US aviation, considering how significant the emissions reductions need to be for US and global aviation. In the near term, however, Congress may have an opportunity to start making up for lost time: While the airlines have already received emergency support from Congress under the CARES Act, they may need to come back to the table for additional aid if the coronavirus pandemic continues to disrupt air travel.
If Congress is going to use public funds to reboot the aviation industry, it should do so in a way that also works well for the aviation customer, the aviation worker, and the climate health of this and future generations. Federal financial assistance to the industry should come with conditions that protect the health of aviation workers and make sure they are able to support their families through this crisis.
We also need to build back a better and cleaner industry and not spend taxpayer dollars in a way that would lock in unsustainable levels of climate emissions from the sector. Many European governments are pivoting from the coronavirus crisis to rebuild aviation in a way that lines up with their national level climate goals and their economy. The US government should not sit on the sidelines and lose the opportunity to innovate in this sector and create the jobs required to get us to this new horizon for aviation.
The US aviation industry needs to get on a sustainable flight path now, because the climate crisis is not going away. With aviation emissions left unaddressed, we can expect major storm clouds ahead.
