After Geoengineering is published by Verso Books, Oct 1 2019.

What is the best-case scenario for solar geoengineering? For author Holly Jean Buck and the scientists she interviews, the best-case scenario is that we manage to keep global warming below catastrophic levels, and the idea of geoengineering quietly fades away.

But before that can happen, Buck explains, we will need heroic global efforts both to eliminate carbon dioxide emissions and to remove much of the excess carbon we have already loosed into the skies.

She devotes most of her new book After Geoengineering: Climate Tragedy, Repair, and Restoration to proposed methods for drawing down carbon dioxide levels from the atmosphere. Only after showing the immense difficulties in the multi-generational task of carbon drawdown does she directly discuss techniques and implications of solar geoengineering (defined here as an intentional modification of the upper atmosphere, meant to block a small percentage of sunlight from reaching the earth, thereby counteracting part of global heating).

The book is well-researched, eminently readable, and just as thought-provoking on a second reading as on the first. Unfortunately there is little examination of the way future energy supply constraints will affect either carbon drawdown or solar engineering efforts. That significant qualification aside, After Geoengineering is a superb effort to grapple with some of the biggest questions for our collective future.

Overshoot

The fossil fuel frenzy in the world’s richest countries has already put us in greenhouse gas overshoot, so some degree of global heating will continue even if, miraculously, there were an instant political and economic revolution which ended all carbon dioxide emissions tomorrow. Can we limit the resulting global heating to 1.5°C? At this late date our chances aren’t good.

As Greta Thunberg explained in her crystal clear fashion to the United Nations Climate Action Summit:

“The popular idea of cutting our emissions in half in 10 years only gives us a 50% chance of staying below 1.5C degrees, and the risk of setting off irreversible chain reactions beyond human control.

“Maybe 50% is acceptable to you. But those numbers don’t include tipping points, most feedback loops, additional warming hidden by toxic air pollution or the aspects of justice and equity. They also rely on my and my children’s generation sucking hundreds of billions of tonnes of your CO2 out of the air with technologies that barely exist.” 1

As Klaus Lackner, one of the many researchers interviewed by Buck, puts it, when you’ve been digging yourself into a hole, of course the first thing you need to do is stop digging – but then you still need to fill in the hole.2

How can we fill in the hole – in our case, get excess carbon back out of the atmosphere? There are two broad categories, biological processes and industrial processes, plus some technologies that cross the lines. Biological processes include regenerative agriculture and afforestation while industrial processes are represented most prominently by Carbon Capture and Sequestration (CCS).

Buck summarizes key differences this way:

“Cultivation is generative. Burial, however, is pollution disposal, is safety, is sequestering something away where it can’t hurt you anymore. One approach generates life; the other makes things inert.” (After Geoengineering (AG), page 122)

Delving into regenerative agriculture, she notes that “over the last 10,000 years, agriculture and land conversion has decreased soil carbon globally by 840 gigatons, and many cultivated soils have lost 50 to 70 percent of their original organic carbon” (AG, p 101).

Regenerative agriculture will gradually restore that carbon content in the soil and reduce carbon dioxide in the air – while also making the soil more fertile, reducing wind and water erosion, increasing the capacity of the soil to stay healthy when challenged by extreme rainfalls or drought, and making agriculture ecologically sustainable in contrast to industrial agriculture’s ongoing stripping the life from soil.

Regenerative agriculture cannot, however, counteract the huge volumes of excess carbon dioxide we are currently putting into the atmosphere. And even when we have cut emissions to zero, Buck writes, regenerative agriculture is limited in how much of the excess carbon it can draw down:

“soil carbon accrual rates decrease as stocks reach a new equilibrium. Sequestration follows a curve: the new practices sequester a lot of carbon at first, for the first two decades or so, but this diminishes over time toward a new plateau. Soil carbon sequestration is therefore a one-off method of carbon removal.” (AG, p 102)

There are other types of cultivation that can draw down carbon dioxide, and Buck interviews researchers in many of these fields. The planting of billions of trees has received the most press, and this could store a lot of carbon. But it also takes a lot of land, and it’s all too easy to imagine that more frequent and fiercer wildfires could destroy new forests just when they have started to accumulate major stores of carbon.

Biochar – the burying of charcoal in a way that stores carbon for millennia while also improving soil fertility – was practiced for centuries by indigenous civilizations in the Amazon. Its potential on a global scale is largely untapped but is the subject of promising research.

In acknowledging the many uncertainties in under-researched areas, Buck does offer some slender threads of hope here. Scientists say that “rocks for crops” techniques – in which certain kinds of rock are ground up and spread on farmland – could absorb a lot of carbon while also providing other soil nutrients. In the lab, the carbon absorption is steady but geologically slow, but there is some evidence that in the real world, the combined effects of microbes and plant enzymes may speed up the weathering process by at least an order of magnitude. (AG, p 145-146)

The cultivation methods offer a win-win-win scenario for carbon drawdown – but we’re on pace to a greenhouse gas overshoot that will likely dwarf the drawdown capacity of these methods. Buck estimates that cultivation methods, at the extremes of their potential, could sequester perhaps 10 to 20 gigatons (Gt) of carbon dioxide per year (and that figure would taper off once most agricultural soils had been restored to a healthy state). That is unlikely to be anywhere near enough:

“Imagine that emissions flatline in 2020; the world puts in a strong effort to hold them steady, but it doesn’t manage to start decreasing them until 2030. … But ten years steady at 50 Gt CO2 eq [carbon dioxide equivalent emissions include other gases such as methane] – and there goes another 500 Gt CO2 eq into the atmosphere. That one decade would cancel out the 500 Gt CO2 eq the soils and forests could sequester over the next 50 years (sequestered at an extreme amount of effort and coordination among people around the whole world).” (AG p 115)

With every year that we pump out fossil fuel emissions, then, we compound the intergenerational crime we have already committed against Greta Thunberg and her children’s generations. With every year of continued emissions, we increase the probability that biological, generative methods of carbon drawdown will be too slow. With every year of continued emissions, we increase the degree to which future generations will be compelled to engage in industrial carbon drawdown work, using technologies which do not enrich the soil, which produce no food, which will not directly aid the millions of species struggling for survival, and which will suck up huge amounts of energy.

Carbon Capture and Sequestration

Carbon Capture and Sequestration (CCS) has earned a bad name for good reasons. To date most CCS projects – even those barely past the concept stage – have been promoted by fossil fuel interests. CCS projects offer them research subsidies for ways to continue their fossil fuel businesses, plus a public relations shine as proponents of “clean” energy.

A lignite mine in southwest Saskatchewan. This fossil fuel deposit is home to one of the few operating Carbon Capture and Sequestration projects. Carbon from a coal-fired generating station is captured and pumped into a depleting oil reservoir – for the purpose of prolonging petroleum production.

Buck argues that in spite of these factors, we need to think about CCS technologies separate from their current capitalist contexts. First of all, major use of CCS technologies alongside continued carbon emissions would not be remotely adequate – we will need to shut off carbon emissions AND draw down huge amounts of carbon from the atmosphere. And there is no obvious way to fit an ongoing, global program of CCS into the framework of our current corporatocracy.

The fossil fuel interests possess much of the technical infrastructure that could be used for CCS, but their business models rely on the sale of polluting products. So if CCS is to be done in a sustained fashion, it will need to be done in a publicly-funded way where the service, greenhouse gas drawdown, is for the benefit of the global public (indeed, the whole web of life, present and future); there will be no “product” to sell.

However CCS efforts are organized, they will need to be massive in order to cope with the amounts of carbon emissions that fossil fuel interests are still hell-bent on releasing. In the words of University of Southern California geologist Joshua West,

“The fossil fuels industry has an enormous footprint …. Effectively, if we want to offset that in an industrial way, we have to have an industry that is of equivalent proportion ….” (AG, p 147)

Imagine an industrial system that spans the globe, employing as many people and as much capital as the fossil fuel industries do today. But this industry will produce no energy, no wealth, no products – it will be busy simply managing the airborne refuse bequeathed by a predecessor economy whose dividends have long since been spent.

So while transitioning the entire global economy to strictly renewable energies, the next generations will also need enough energy to run an immense atmospheric garbage-disposal project.

After Geoengineering gives brief mentions but no sustained discussion of this energy crunch.

One of the intriguing features of the book is the incorporation of short fictional sketches of lives and lifestyles in coming decades. These sketches are well drawn, offering vivid glimpses of characters dealing with climate instability and working in new carbon drawdown industries. The vignettes certainly help in putting human faces and feelings into what otherwise might remain abstract theories.

Yet there is no suggestion that restricted energy supplies will be a limiting factor. The people in the sketches still travel in motorized vehicles, check their computers for communications, run artificial intelligence programs to guide their work, and watch TV in their high-rise apartments. In these sketches, people have maintained recognizably first-world lifestyles powered by zero-emission energy technologies, while managing a carbon drawdown program on the same scale as today’s fossil fuel industry.

If you lean strongly towards optimism you may hope for that outcome – but how can anyone feel realistically confident in that outcome?

The lack of a serious grappling with this energy challenge is, in my mind, the major shortcoming in After Geoengineering. And big questions about energy supply will hang in the air not only around carbon sequestration, but also around solar geoengineering if humanity comes to that.

Shaving the peak

Solar geoengineering –  the intentional pumping of substances into the upper atmosphere into order to block a percentage of incoming sunlight to cool the earth – has also earned a bad name among climate activists. It is, of course, a dangerous idea – just as extreme as the practice of pumping billions of tonnes of extra carbon dioxide into the atmosphere to overheat the earth.

But Buck makes a good case – a convincing case, in my opinion – that in order to justifiably rule out solar geoengineering, we and our descendants will have to do a very good job at both eliminating carbon emissions and drawing down our current excess of carbon dioxide, fast.

Suppose we achieve something which seems far beyond the capabilities of our current political and economic leadership. Suppose we get global carbon emissions on a steep downward track, and suppose that the coming generation manages to transition to 100% renewable while also starting a massive carbon drawdown industry. That would be fabulous – and it still may not be enough.

As Buck points out, just as it has proven difficult to predict just how fast the earth system responds to a sustained increased in carbon dioxide levels, nobody really knows how quickly the earth system would respond to a carbon drawdown process. The upshot: even in an era where carbon dioxide levels are gradually dropping, it will be some time before long-term warming trends reverse. And during that interim a lot of disastrous things could happen.

Take the example of coral reefs. Reef ecosystems are already dying due to ocean acidification, and more frequent oceanic heat waves threaten to stress reefs beyond survival. Buck writes,

“Reefs protect coasts from storms; without them, waves reaching some Pacific islands would be twice as tall. Over 500 million people depend on reef ecosystems for food and livelihoods. Therefore, keeping these ecosystems functioning is a climate justice issue.” (AG, p 216)

In a scenario about as close to best-case as we could realistically expect, the global community might achieve dropping atmospheric carbon levels, but still need to buy time for reefs until temperatures in the air and in the ocean have dropped back to a safe level. This is the plausible scenario studied by people looking into a small-scale type of geoengineering – seeding the air above reefs with a salt-water mist that could, on a regional scale only, reflect back sunlight and offer interim protection to essential and vulnerable ecosystems.

One could say that this wouldn’t really be geoengineering, since it wouldn’t affect the whole globe – and certainly any program to affect the whole globe would involve many more dangerous uncertainties.

Yet due to our current and flagrantly negligent practice of global-heating-geoengineering, it is not hard to imagine a scenario this century where an intentional program of global-cooling-geoengineering may come to be a reasonable choice.

Buck takes us through the reasoning with the following diagram:

From After Geoengineering, page 219

If we rapidly cut carbon emissions to zero, and we also begin a vast program of carbon removal, there will still be a significant time lag before atmospheric carbon dioxide levels have dropped to a safe level and global temperatures have come back down. And in that interim, dangerous tipping points could be crossed.

To look at just one: the Antarctic ice sheets are anchored in place by ice shelves extending into the ocean. When warming ocean water has melted these ice shelves, a serious tipping point is reached. In the words of Harvard atmospheric scientist Peter Irvine,

“Because of the way the glaciers meet the ocean, when they start to retreat, they have kind of a runaway retreat. Again, very slow, like a couple of centuries. Five centuries. But once it starts, it’s not a temperature-driven thing; it’s a dynamic-driven thing … Once the ice shelf is sheared off or melted away, it’s not there to hold the ice sheet back and there’s this kind of dynamic response.” (AG, p 236)

The melting of these glaciers, of course, would flood the homes of billions of people, along with a huge proportion of the world’s agricultural land and industrial infrastructure.

So given the current course of history, it’s not at all far-fetched that the best option available in 50 years might be a temporary but concerted program of solar geoengineering. If this could “shave the peak” off a temperature overshoot, and thereby stop the Antarctic ice from crossing a tipping point, would that be a crazy idea? Or would it be a crazy idea not to do solar geoengineering?

These questions will not go away in our lifetimes. But if our generation and the next can end the fossil fuel frenzy, then just possibly the prospect of geoengineering can eventually be forgotten forever.


1 Greta Thunberg, “If world leaders choose to fail us, my generation will never forgive them”, address to United Nations, New York, September 23, 2019, as printed in The Guardian.
2 In the webinar “Towards a 20 GT Negative CO2 Emissions Industry”, sponsored by Security and Sustainability Forum, Sept 19, 2019.