Friday, May 26, 2017

Ken & Ben on Climate & Engineering - A Reddit AMA

On March 23, 2017, Ken Caldeira, professor and climate scientist at Stanford University, and Ben van der Pluijm, Editor-in-Chief of AGU’s journal Earth’s Future, and professor and geologist at University of Michigan, hosted a Reddit Ask-Me-Anything on Climate Change and Climate Engineering.  

Ken Caldeira works on a broad array of issues including the physical climate system, global energy systems, ocean acidification, and geoengineering. Solar geoengineering involves trying to cool the Earth by deflecting some incoming sunlight away from our planet. Studies have shown that actions like putting small particles in the stratosphere could reflect some sunlight away from the Earth, potentially taking our climate back to a point similar to pre-industrial revolution. Of course, we know for sure about only one habitable planet, and toying around with this planet at the required scale would pose great risks -- but allowing the Earth to warm from our greenhouse gas emissions also poses grave risks.

Ben van der Pluijm works on societal resilience and the impacts of global change. Building on our human history of engineering applications to overcoming societal challenges, climate engineering should be included as a viable solution for reducing the impacts of global warming. Climate engineering takes two approaches: (1) Carbon dioxide removal, and (2) solar radiation management. The former addresses the cause of climate warming by removing a greenhouse gas from the atmosphere ("treat the illness"). The latter offsets the warming effects of greenhouse gases by allowing Earth to absorb less solar radiation ("treat the symptoms"). Given worldwide impact, planning for climate engineering must occur on a global scale, involving all nations, large and small, rich and poor, and not be limited to a few technologically advanced, wealthy countries.

The goal of the Reddit AMA was to advance the conversation about possible solutions to global warming by answering questions about climate change and whether geoengineering techniques can minimize the impacts for ecosystems and people.  Below are selected questions (in bold) and responses from over 200 questions that were posted in a 2-hour window.  Answers are minimally edited for clarity and brevity; questions are verbatim.  The full exchange is posted at and

What's the single most effective evidence of climate change when convincing skeptics?

Ken: I think the instrumental record of surface temperature is the most compelling evidence of temperature change. The fact that the stratosphere is cooling while the lower atmosphere warms is the most compelling piece of evidence that greenhouse gases are behind this warming. Almost everything else (solar variability, changes in ocean heat fluxes, etc) would cause both the stratosphere and near-surface temperatures to move together. The fact that stratospheric temperatures are moving in the opposite direction to surface temperatures is a real smoking gun pointing to our greenhouse gas emissions as the culprit.
Ben: Responses will vary, but I always highlight sealevel rise as evidence (more ice cap melting from warming) and as impact (coast-oriented human society).

Correct me if I'm wrong but climate change is not an issue at the national level, but more at the global level. With such ignorance and denial by leaders of some of those nations, United States particularly, it seems like changing ones worldview is a bigger problem than coming up with or implementing ideas to slow climate change. Nations like the United States were built on coal is it conscionable to tell another nation or enforce carbon tax on emerging nations doing the same?

Ken: Climate change is an issue at every level. The problem is that costs are borne by the individual in the here-and-now but benefits are to the whole world for thousands of years into the future. It is this game theoretic challenge that makes this such a difficult problem.
Ben: Climate change is a shared issue. As a large and wealthy nation, the US should take a lead in addressing the impacts and solutions to change, regardless of our past role. Past behaviors provide valuable lessons for the future. We are in this together.

I understandably get a sense of dread when I read headlines like, "CO2 LEVELS HAVE PASSED THE POINT OF NO RETURN". What does that mean quantitatively, and does it really mean that climate change as a result of carbon emissions is now out of our hands? Are there still steps that can be taken as a species to slow/stop/reverse it? How about on national level? How about on an individual level?

Ken: I am not a fan of these 'point of no return' declarations. Our CO2 emissions may cause damage and suffering, but humans will not go extinct as a result of our emissions. We will always deal with whatever conditions we have. The question is not one of how do we survive, but rather how do we want to live?
Ben: First, having CO2 in the atmosphere is good for us, making for habitable surface conditions. Modern CO2 increases will take decades to show their full impact. Adding more CO2 (and methane) will increase these impacts. We should try to minimize future increases as they have significant impact for human society, but perhaps also consider reducing CO2. The good news: we'll ultimately deal with change one way or another.

Carbon dioxide removal and solar radiation management are both likely to be useful and necessary tools for dealing with climate change - but how are we planning to pay for them? Do you envisage some sort of carbon tax in various countries to raise funds? Governments just deciding to do it on their own? Private donors? What is your most likely source of funding?

Ken: Carbon dioxide removal is thought to be expensive and paying for it will be at least as challenging as paying for CO2 emissions reduction. On the other hand, putting sulfate aerosols in the stratosphere is relatively cheap and would be in the noise of budgets of big countries. The main issue with solar geoengineering is adverse impacts and risk, not direct financial cost of deployment.
Ben: For starters, our changing climate is expensive already. I am not an economist, but do believe that full-cost accounting is the first step in understanding true environmental cost. Then, any remediation efforts may not look too bad. In today's economic world structure, a carbon tax certainly will have an impact. If governments don't step up, hopefully foundations are willing to support action. Also, industry can (and should) play a role.

What are some struggles with renewable power integration? Say we wanted to go 100% renewable by 2050, what would be the biggest obstacle during the transition?

Ken: One of the biggest challenges is dealing with the intermittency of wind and solar electricity generation. Another big challenge is how to decarbonize things like aviation, which today depends on dense liquid fuels. Ultimately, it is largely a question of willingness to pay more for something that works a little less well, but is better for the environment.
Ben: Our current infrastructure is based on fossil fuel energy. In the US, 80+% of energy is still produced this way. Once the obstacle for an energy transition was technology, but today the obstacle is mostly infrastructure (transportation, grid, etc) and embedded interests (industry, job sectors, etc). Price is no longer a large issue.

Solar radiation management (particularly through the injection of sulphate aerosols in the stratosphere) is a form of geoengineering that has seen significant interest among researchers as a potential way to buy time of society can't get its act together to reduce emissions quickly enough. As researchers who have worked extensively on the subject, what do you see as the relative pros and cons of this geoengineering approach?

Ken: The pros are that solar geoengineering with stratospheric aerosols is pretty cheap and easy, and we know from volcanic eruptions that it will basically will work and not cause the world to end. The main cons are that there are likely to be both environmental and sociopolitical downsides that are hard to predict. Risk aversion suggests we would do better to try to reduce our interference in complex Earth-system processes, and that increasing our interference is likely to lead to unforeseen problems.
Ben: Solar Radiation Management, as you describe, would allow us to turn action on and off at will. That is good. However, we must also be sure that neighbors agree with such action. This requires dialogue and shared decision-making.

I recently read a paper that found fracking was producing more leaks than we had previously thought. Is methane in the atmosphere a problem that should be talked about more? Also what damage are we doing to the Earth by using fracking and what consequences might we see? Thank you very much for your time and I wish you the best of luck in your mission.

Ken: There are several issues with fracking. To me, the central question is whether we want to be expanding fossil fuel industries that depend on dumping waste CO2 into the sky at a time when we know that we need to be phasing out such industries. Methane releases associated with fracking are substantial, but with good management policies these emissions can be curtailed. It is much harder to prevent the CO2 from combustion of that methane from reaching the atmosphere. Of course, when fracking is poorly implemented, there is the potential for substantial local environmental hazard.
Ben: Fracking targets the release of the greenhouse gas methane that is buried in geologic (typically shale) formations. The goal is to catch this released gas, but, yes, some escapes. Such leaks are tracked by EPA and NASA agencies, for example. Other issues with fracking are subsurface pollution (like groundwater) and continued fossil fuel reliance. Methane is converted to CO2 for energy production, a greenhouse gas, which contributes to atmospheric warming. As a geologist I also mention the role of human-induced earthquakes from fracking, but that is for another AMA.

How do you feel about Naomi Klein's book 'This Changes Everything' and its conclusion that capitalism is at the Crux of the climate issue and can only be solved by reevaluating that part of our society?

Ken: If we wait to save the climate problem until capitalism is overthrown, we will be waiting too long. The climate problem is not that hard to solve technically. We just need to decide that we are willing to pay for it. Economists estimate that solving the climate problem might cost 2% of GDP. Compare this with the 17% of GDP the US now spends on health care or approximately half of that it spends on the military. We could be more efficient on delivering health care or spend less on the military and easily have enough resources to solve the climate problem.
Ben: I have not read the book, but heard the arguments. One could also argue that capitalism will support change if you and I decide to make our choices accordingly. Oil companies find and sell oil only because we buy it.

What tipping point do you think will end the corporate-sponsored mass denier movements in the west? Or are the courts likely to do it first?

Ken: I push back on the "tipping points" framing. Most changes in the climate system will, I think, be fairly progressive and continuous. Tipping points can happen in social systems, where there is a phase change in human attitudes towards something. It is, of course, challenging to try to create that social tipping point. I guess that I am doing a little but to try to create that tipping point by doing this Reddit AMA.
Ben: The problem with the notion of "tipping points" is that climate change is gradual on the human scale. Perhaps looking back we will see the aggregate of impacts as a tipping point, but day-to-day we see mostly annoyances. Their costs might be the ultimate driver for changing our practices. My fellow geologists in a future, far, far away will likely see a tipping point in our reaction.

Curbing CO2, methane, etc is politically and practically very, very hard. Will geoengineering be our only option? How smart are we to pull this off?

Ken: Phase changes in social systems are possible. People used to accept slavery and no longer accept slavery. Few people foresaw the fall of the Soviet Union. Few people thought Congressional Republicans would be supporting protectionist trade policies and support a pro-Russian President. So, the unexpected can and does happen. I am still hoping for and working towards a change in social attitudes towards using the sky as a waste dump for our CO2 pollution. I am hoping this will result in a major transformation of how we obtain and use energy. But, I don't want to put all of my eggs in one basket, so I also want to understand whether and how geoengineering options might be able to reduce suffering and damage in both human and natural systems.
Ben: If we stop producing atmospheric CO2 and methane today we will still see climate change for decades to centuries, because the atmosphere is slow to react. So, first, we have to live with change, and, second, we want to minimize further change. The latter can occur by greenhouse gas emission reduction policies, and by geoengineering, the topic of this Reddit-AMA. Either way, we are smart enough to deal with change.

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