How can the world respond to climate change? For a long time, answers to that question focused almost exclusively on mitigation – reducing the amount of carbon and other greenhouse gases emitted. Recently, adaptation has received more attention as the consequences of climate change have begun to manifest. But those two options – mitigation or adaptation – have been basically the only two answers to the question of how to respond to climate change.
That leaves aside a third – perhaps a third rail – option: geoengineering. Proposed geoengineering approaches to dealing with climate change take many forms but share the same basic premise of making large scale changes to the planet, or in space, that either drastically increase the absorption of CO2 or reduce the amount of solar radiation that reach the lower levels of the atmosphere.
Researching Solar Radiation Management
Of the various potential options for geoengineering, solar radiation management (SRM) is likely the most extensively studied. This approach involves injecting small aerosols into the stratosphere to reflect sunlight back into space, which would cool the planet in ways similar to what has happened after large volcanic eruptions in the past. It would also have impacts on global weather patterns that are not fully understood.
Better understanding of the impacts of SRM on global weather patterns is an important scientific question that researchers in the hard sciences are trying to answer. But developing a research agenda to examine the consequences of SRM was the focus of a recent workshop I was invited to attend. As an economist I was surprised to be invited because so many of the effects of SRM are questions for the physical sciences. But one of my main take-aways from the workshop is that understanding the consequences of SRM requires far more than a mechanistic understanding of the reaction of global weather patterns to aerosol injection. Economists can contribute important insights here.
What do economists have to say about SRM?
Much of the existing economics work on SRM (and geoengineering in general) has focused on questions of moral hazard, governance, and the implications of geoengineering for mitigation strategies. This work is important in helping to develop frameworks for managing the (potential) use of geoengineering but it does not contribute to our understanding of the effects of this use.
Literature in that space is much more nascent and, while economists have made some important contributions, it is much more likely to be found in scientific publications than traditional economics outlets. But the discussions at the recent workshop made it clear that economists can usefully contribute to the growing body of work on the effects of geoengineering.
Consider what are widely considered two of the most important consequences of SRM: its direct impact on temperature and its indirect impact on agricultural yields. While the effects of SRM per se have not been a focus of economists, there is a rich literature in economics on both the impacts of heat and the consequences of climate change on agriculture. The insights from these literatures may have important things to say about the consequences of SRM.
One example of this is a recent paper explicitly about the consequences of SRM for heat related mortality. Written by an interdisciplinary team of economists and scientists, it examines how SRM would impact temperature related mortality – a major consequence of unmitigated climate change – at the end of the century. They find that SRM could reduce temperature related mortality similarly to emissions reductions but with different spatial patterns of benefits. This is driven by the fact that SRM does not have globally uniform cooling effects.
But more important than the specific results, this paper provides an illustration of where economics can be usefully combined with geophysical modelling of SRM to provide a better understanding of the consequences of geoengineering for human outcomes. The methods used to estimate mortality outcomes would be familiar to any economist and, in fact, are based on work in a groundbreaking economics paper on temperature related mortality.
The case of SRM’s impacts on agricultural yields is a second area where economics could be usefully combined with models of the physical consequences of SRM to better understand its social impacts. As noted, SRM will not have uniform effects either on cooling the planet (it is likely to have larger cooling effects in the tropics) or on global weather patterns. That implies that its impacts on agricultural yields will be different in different locations. That, in turn, suggests that trade may play an important role in mitigating or exacerbating any negative yield impacts of SRM.
Economists have already made important contributions to our understanding of how trade will mediate the physical impacts of climate change on agricultural output. Similar work that incorporates models of the physical impacts of SRM would improve our understanding of spatial heterogeneity in the impacts of SRM.
A collaborative research agenda
One challenge with doing economics research on SRM is that the science of SRM is still very much in flux. That makes interdisciplinary collaboration important. The team behind the temperature mortality paper included an economist, a physicist, a climate scientist, and a physical oceanographer. Getting researchers from such different fields to speak the same language can be difficult but is necessary given the complexity of the modelling required to understand SRM’s effects.
If SRM is ever deployed it will generate substantial physical changes in the world’s weather systems. These changes will have important implications for human health and well-being, but the consequences of those physical changes will be mediated through a variety of socio-economic systems.
As a result, understanding the physical changes alone is not enough to understand the implications of SRM for human wellbeing. It also necessary to understanding how these socio-economic systems will respond to the changes generated by SRM (or other geoengineering). As the recent PNAS paper on heat and mortality shows, the response to SRM and the response to climate mitigation may not be the same. Examining those potential responses is a strength of economics and a place where economists can contribute to our growing knowledge of the effects of SRM.
source : World Bank blogs
