Tentative Programme Outline

MYLES ALLEN
University of Oxford

Myles Allen is Head of Atmospheric, Oceanic and Planetary Physics in the Department of Physics, University of Oxford, and Professor of Geosystem Science in the School of Geography and the Environment. His research focuses on how human and natural influences on climate contribute to climate change and risks of extreme weather. In 2005, Allen introduced the notion of a finite carbon budget, implying net zero emissions of carbon dioxide are necessary to halt global warming. He has been working on the implications ever since, most recently on the case for Geological Net Zero, or a balance between ongoing production of carbon dioxide from geological sources with carbon dioxide capture and geological storage. He has served on the Intergovernmental Panel on Climate Change, most recently as a Coordinating Lead Author on the IPCC Special Report on 1.5°C. He was awarded the Appleton Medal and Prize from the Institute of Physics “for his important contributions to the detection and attribution of human influence on climate and quantifying uncertainty in climate predictions", featured on the BBC’s “Life Scientific” as “the physicist behind net zero”, was awarded a CBE “for services to climate change attribution, prediction and net zero” and is a Fellow of the Royal Society.

Topic: Achieving Geological Net Zero in a fractious world

Although much appears to have changed over the past couple of years in the climate policy landscape, the underlying physics has not. The challenges of reducing fossil fuel use are increasingly evident, driving both countries and corporations to grapple with the precise definition of “net zero emissions”, and specifically what should be included in “removals by sinks” in Article 4 of the Paris Agreement. As one of the lead authors of the papers that established the cumulative impact of carbon dioxide emissions on global climate, I will explain what was meant by “zero net emissions” back in 2009, and why this is what it will take to halt global warming.

I will explain how a durable net zero must encompass Geological Net Zero, meaning for every tonne of carbon dioxide still produced from fossil sources through energy use or industrial processes, one tonne is captured, either at source or back out of the atmosphere, and safely disposed of, to geological-timescale storage. I will also explain how, in addition to achieving Geological Net Zero, resources must also be devoted to the protection of passive carbon sinks, meaning uptake of carbon dioxide by the oceans and land biosphere that is occurring as a consequence of past emissions and not because of any active ongoing human intervention. The protection of passive sinks must be additional to measures to achieve Geological Net Zero if net zero is to deliver a durable halt to global warming.

Recognising the need for Geological Net Zero, and how to get there, could be a unifying step for climate mitigation policy. Policies to encourage or mandate rapid reductions in fossil fuel use, however necessary, are increasingly seen as divisive, particularly when countries, corporations and citizens see no end in sight, and no prospect of the sacrifices they are being asked to make actually resulting in meeting the climate goal. Banning new fossil fuel exploration and investment in fossil fuel infrastructure, and/or requiring consumers to buy electric cars or heat-pumps, risk proving ineffective, divisive, or both.

A complementary framing is to focus on the need to reduce the net geological carbon intensity, or NGCI, of the fossil fuels we still use, rather than being prescriptive of the precise amount we use. The NGCI is the fraction of CO2 generated through fossil fuel use or industrial processes that is released to the atmosphere, as opposed to being captured at source or recaptured from the atmosphere and committed to geological-timescale storage. Unlike other intensity measures, the NGCI is sufficiently unambiguous to be impossible to manipulate. At present, the NGCI of global fossil fuel use is over 99.9%, and must be reduced to zero to stop fossil fuels from causing further global warming. Reporting the NGCI of remaining fossil fuel use in NDCs and long-term, low-carbon development pathways, and tracking the implications of Internationally Transferred Mitigation Outcomes for the global NGCI, are both essential to track progress to Geological Net Zero and hence to a durable halt to global warming: right now, however, not a single country or corporation reports the NGCI of the fuels it uses. Beyond reporting, we need policies that specifically drive down the NGCI of remaining fossil fuel use: an objective that traditional climate policies such as emissions pricing have so far signally failed to deliver.