Pete Irvine

Peter J. Irvine, David W. Keith, and John Moore. 7/27/2018. “Brief communication: Understanding solar geoengineering's potential to limit sea level rise requires attention from cryosphere experts.” The Cryosphere, 12, Pp. 2501-2513. Publisher's VersionAbstract
Stratospheric aerosol geoengineering, a form of solar geoengineering, is a proposal to add a reflective layer of aerosol to the stratosphere to reduce net radiative forcing and so to reduce the risks of climate change. The efficacy of solar geoengineering at reducing changes to the cryosphere is uncertain; solar geoengineering could reduce temperatures and so slow melt, but its ability to reverse ice sheet collapse once initiated may be limited. Here we review the literature on solar geoengineering and the cryosphere and identify the key uncertainties that research could address. Solar geoengineering may be more effective at reducing surface melt than a reduction in greenhouse forcing that produces the same global-average temperature response. Studies of natural analogues and model simulations support this conclusion. However, changes below the surfaces of the ocean and ice sheets may strongly limit the potential of solar geoengineering to reduce the retreat of marine glaciers. High-quality process model studies may illuminate these issues. Solar geoengineering is a contentious emerging issue in climate policy and it is critical that the potential, limits, and risks of these proposals are made clear for policy makers.
Andy Parker and Peter Irvine. 3/11/2018. “The Risk of Termination Shock From Solar Geoengineering.” Earth's Future, 6, Pp. 456-467. Publisher's VersionAbstract
If solar geoengineering were to be deployed so as to mask a high level of global warming, and then stopped suddenly, there would be a rapid and damaging rise in temperatures. This effect is often referred to as termination shock, and it is an influential concept. Based on studies of its potential impacts, commentators often cite termination shock as one of the greatest risks of solar geoengineering. However, there has been little consideration of the likelihood of termination shock, so that conclusions about its risk are premature. This paper explores the physical characteristics of termination shock, then uses simple scenario analysis to plot out the pathways by which different driver events (such as terrorist attacks, natural disasters, or political action) could lead to termination. It then considers where timely policies could intervene to avert termination shock. We conclude that some relatively simple policies could protect a solar geoengineering system against most of the plausible drivers. If backup deployment hardware were maintained and if solar geoengineering were implemented by agreement among just a few powerful countries, then the system should be resilient against all but the most extreme catastrophes. If this analysis is correct, then termination shock should be much less likely, and therefore much less of a risk, than has previously been assumed. Much more sophisticated scenario analysis—going beyond simulations purely of worst‐case scenarios—will be needed to allow for more insightful policy conclusions.
Peter J. Irvine, Ben Kravitz, Mark G. Lawrence, Dieter Gerten, Cyril Caminade, Simon N.Gosling, Erica J. Hendy, Belay T. Kassie, W. Daniel Kissling, Helene Muri, Andreas Oschlies, and Steven J. Smith. 1/24/2017. “Towards a comprehensive climate impacts assessment of solar geoengineering.” Earth's Future, 5, Pp. 93–106. Publisher's VersionAbstract

Despite a growing literature on the climate response to solar geoengineering—proposals to cool the planet by increasing the planetary albedo—there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current stateof knowledge about impacts of a solar-geoengineered climate and identify the major research gaps. We suggest that a thorough assessment of the climate impacts of a range of scenarios of solar geoengineering deployment is needed and can be built upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solargeoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solargeoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges, and risks presented by solar geoengineering.

David W. Keith and Peter J. Irvine. 11/30/2016. “Solar geoengineering could substantially reduce climate risks — A research hypothesis for the next decade.” Earth's Future, 4, Pp. 549–559. Publisher's VersionAbstract

We offer a hypothesis that if solar geoengineering (SG) were deployed to offset half of the increase in global-mean temperature from the date of deployment using a technology and deployment method chosen to approximate a reduction in the solar constant then, over the 21st century, it would (a) substantially reduce the global aggregate risks of climate change, (b) without making any country worse off, and (c) with the aggregate risks from side-effects being small in comparison to the reduction in climate risks. We do not set out to demonstrate this hypothesis; rather we propose it with the goal of stimulating a strategic engagement of the SG research community with policy-relevant questions. We elaborate seven sub-hypotheses on the effects of our scenario for key risks of climate change that could be assessed in future modeling work. As an example, we provide a defence of one of our sub-hypotheses, that our scenario of SG would reduce the risk of drought in dry regions, but also identify issues that may undermine this sub-hypothesis and how future work could resolve this question. SG cannot substitute for emissions mitigation but it may be a useful supplement. It is our hope that scientific and technical research over the next decade focuses more closely on well-articulated variants of the key policy-relevant question: could SG be designed and deployed in such a way that it could substantially and equitably reduce climate risks?

Jesse L. Reynolds, Andy Parker, and Peter Irvine. 12/13/2016. “Five solar geoengineering tropes that have outstayed their welcome.” Earth's Future, 4, Pp. 562–568. Publisher's VersionAbstract

In the last decade, solar geoengineering (solar radiation management, or SRM) has receivedincreasing consideration as a potential means to reduce risks of anthropogenic climate change. Some ideas regarding SRM that have been proposed have receded after being appropriately scrutinized, while others have strengthened through testing and critique. This process has improved the understanding ofSRM’s potential and limitations. However, several claims are frequently made in the academic and popular SRM discourses and, despite evidence to the contrary, pose the risk of hardening into accepted facts. Here, in order to foster a more productive and honest debate, we identify, describe, and refute five of the most problematic claims that are unsupported by existing evidence, unlikely to occur, or greatly exaggerated. These are: (A) once started, SRM cannot be stopped; (B) SRM is a right-wing project; (C) SRM wouldcost only a few billion dollars per year; (D) modeling studies indicate that SRM would disrupt monsoonprecipitation; and (E) there is an international prohibition on outdoors research. SRM is a controversial proposed set of technologies that could prove to be very helpful or very harmful, and it warrants vigorous and informed public debate. By highlighting and debunking some persistent but unsupported claims, this paper hopes to bring rigor to such discussions.

Pete Irvine

Pete Irvine

Postdoctoral Research Fellow, Harvard John A. Paulson School of Engineering and Applied Sciences

Pete Irvine is a Postdoctoral Research Fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences. Pete conducts research on the climate and broader impacts of solar geoengineering and works to put those findings into perspective with the risks posed by climate change. He works with researchers from a range of disciplines to explore the implications of solar geoengineering as a potential means of reducing the risks of climate change. Current work includes evaluating the potential effectiveness of different solar geoengineering proposals at reducing sea-level rise to determine whether solar geoengineering deployment could be optimized to increase this effectiveness.

Pete Irvine, Ben Kravitz, Mark Lawrence, and Helene Muri. 7/2016. “An overview of the Earth system science of solar geoengineering.” Wiley Interdisciplinary Reviews: Climate Change. Publisher's VersionAbstract

Solar geoengineering has been proposed as a means to cool the Earth by increasing the reflection of sunlight back to space, for example, by injecting reflective aerosol particles (or their precursors) into the lower stratosphere. Such proposed techniques would not be able to substitute for mitigation of greenhouse gas (GHG) emissions as a response to the risks of climate change, as they would only mask some of the effects of global warming. They might, however, eventually be applied as a complementary approach to reduce climate risks. Thus, the Earth system consequences of solar geoengineering are central to understanding its potentials and risks. Here we review the state-of-the-art knowledge about stratospheric sulfate aerosol injection and an idealized proxy for this, ‘sunshade geoengineering,’ in which the intensity of incoming sunlight is directly reduced in models. Studies are consistent in suggesting that sunshade geoengineering and stratospheric aerosol injection would generally offset the climate effects of elevated GHG concentrations. However, it is clear that a solar geoengineered climate would be novel in some respects, one example being a notably reduced hydrological cycle intensity. Moreover, we provide an overview of nonclimatic aspects of the response to stratospheric aerosol injection, for example, its effect on ozone, and the uncertainties around its consequences. We also consider the issues raised by the partial control over the climate that solar geoengineering would allow. Finally, this overview highlights some key research gaps in need of being resolved to provide sound basis for guidance of future decisions around solar geoengineering.

Caitlin G. McCormack, Wanda Born, Peter Irvine, Eric P. Achterberg, Tatsuya Amano, Jeff Ardron, Pru N. Foster, Jean-Pierre Gattuso, Stephen J. Hawkins, Erica Hendy, W. Daniel Kissling, Salvador E. Lluch-Cota, Eugene J. Murphy, Nick Ostle, Nicholas J.P. Owens, R. Ian Perry, Hans O. Pörtner, Robert J. Scholes, Frank M. Schurr, Oliver Schweiger, Josef Settele, Rebecca K. Smith, Sarah Smith, Jill Thompson, Derek P. Tittensor, Mark van Kleunen, Chris Vivian, Katrin Vohland, Rachel Warren, Andrew R. Watkinson, Steve Widdicombe, Phillip Williamson, Emma Woods, Jason J. Blackstock, and William J. Sutherland. 2016. “Key impacts of climate engineering on biodiversity and ecosystems, with priorities for future research.” Journal of Integrative Environmental Sciences, Pp. 1-26. Publisher's VersionAbstract

Climate change has significant implications for biodiversity and ecosystems. With slow progress towards reducing greenhouse gas emissions, climate engineering (or ‘geoengineering’) is receiving increasing attention for its potential to limit anthropogenic climate change and its damaging effects. Proposed techniques, such as ocean fertilization for carbon dioxide removal or stratospheric sulfate injections to reduce incoming solar radiation, would significantly alter atmospheric, terrestrial and marine environments, yet potential side-effects of their implementation for ecosystems and biodiversity have received little attention. A literature review was carried out to identify details of the potential ecological effects of climate engineering techniques. A group of biodiversity and environmental change researchers then employed a modified Delphi expert consultation technique to evaluate this evidence and prioritize the effects based on the relative importance of, and scientific understanding about, their biodiversity and ecosystem consequences. The key issues and knowledge gaps are used to shape a discussion of the biodiversity and ecosystem implications of climate engineering, including novel climatic conditions, alterations to marine systems and substantial terrestrial habitat change. This review highlights several current research priorities in which the climate engineering context is crucial to consider, as well as identifying some novel topics for ecological investigation.

Ben Kravitz, Douglas MacMartin, Alan Robock, Philip Rasch, Katharine Ricke, Jason Cole, Charles Curry, Pete Irvine, Duoying Ji, David Keith, Jon Egill Kristjánsson, John Moore, Helene Muri, Balwinder Singh, Simone Tilmes, Shingo Watanabe, Shuting Yang, and Jin-Ho Yoon. 2014. “A multi-model assessment of regional climate disparities caused by solar geoengineering.” Environmental Research Letters, 9. Publisher's Version