It's so cool to see your old classmates published! It's also sad to see the conclusions be so dire.
It always amazes me that in the triumvirate of Environment, Politics, and Economics, it is so easy to discuss optimization of Political Economy, and so difficult to discuss Environmental Politics or Environmental Economics. I've come to the conclusion that the mental models in Economics and Politics both abstract further from the true underlying processes and make it easier to reason (and attempt to optimize for) the political economy models. Sadly, the environment resists simplified mental models because scientists actually understand the complexity, while political scientists and economists have a hard time developing policies, pricing structures, and cost models that can really handle the nuance of the environment as it actually exists.
I've seen the glaciers at Garibaldi first hand. Even now they're still awesome to look at. But before we went go there we took a look at some air photos from over the years and some of the first pictures ever taken of it. The difference was dramatic and fairly shocking. The lake itself was about half the size originally and even in the photos from 50-60 years ago the difference was pretty dramatic. The glacier was still twice the size as when I went and covered the whole side of the mountain down to the lake and pretty much the entire opposite side of the shore.
By the time I ended up going there the glacier was about half way up the side of the mountain, the opposite shore was mostly free of ice and had to be about half as wide. It was sad to see but i'm glad I got to see at least what I did.
Also, glacial lakes are fucking cool, Garibaldi lake is colour of ice blue koolaid.
What are the hypothetical options to stop/slow/reverse global warming? Assuming we could overcome any setback, what would we as a species have to accomplish and when?
Basically there are a number of pathways to reduce emissions sufficiently quickly (and then to suck out pollutants from the air) to limit climate change:
"The report finds that limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air."
> This means that any remaining emissions would need to be balanced by removing CO2 from the air.
This is the most important sentence in that paragraph.
If we're going to sit on our hands, waiting until 2030 to halve our emissions, and 2050 to zero them (Nobody has a plan for doing either of those things, by the way), we're then going to have to perform planet-scale carbon sequestration.
No affordable planet-scale carbon sequestration technology currently exists, nor are we close to developing one.
Trees are carbon neutral, not carbon sinks. You grow it, and it's a carbon sink. But then it dies. If by fire it's releases the CO2 quickly, if not it rots slowly and reduces the CO2 slowly. Neither are a fix for our short term problems.
Growing algae or plankton on the ocean, where most of them die and land on the (mostly inert) deep ocean floor would help. Not perfect, but at least the CO2 is likely be consumed on the ocean floor slower than it's produced on the surface thanks to the cold, dark, high pressure environment on the ocean floor.
One research claims that the limit for growth in many places in the ocean is a lack of iron. So spreading iron would lead to a huge increase in life. Unfortunately the impact seems to last days.
It's true that they are not a permanent carbon sink unless fossilised, but forests do store huge amounts of carbon, both in the living biomass and in the soil under them.
There is a strong seasonal variation in atmospheric carbon (several ppm) as the northern hemisphere biomass uptakes carbon in the summer growth season.
Right, so if you manage to start a healthy forest it is a carbon sink... as long as the biomass is increasing. After some decades it flattens out consuming land forever, but being mostly carbon neutral.
So to offset a non-zero amount of carbon emissions you have to steadily increase the number of acres of forest. Unfortunately this puts pressure on other things like farming, which causes them to be more energy intensive to get enough density.
From what I can tell the answers are things like nuclear, solar, and wind. Covering every parking lot with solar would be a good start.
Should perhaps add that the 2GT/y thing was in the context of tolerating a peak of 1.7 degrees and still being able to reach 1.5 by 2100 (since no scenario can stay below 1.5). It was not a bout a sustainable compensation for current emissions, if that was the impression.
Trees take years, and a lot of labour to grow, cut, and bury.
A tree takes out ~1 tonne of carbon out of the atmosphere, over a 40 year lifespan.
Since the industrial revolution, we've emitted 400 billion tonnes of carbon into the atmosphere. By 2050, we'll emit another 150 billion tonnes.
If we want to sequester half of that, we'll need to grow, log, and bury 275 billion trees. Who is going to pay for this?
Bonus points: Digging up coal, so you can burn it, at the same time that you're growing trees, so you can bury them, has got to be one of the worst ideas in the energy-economy space.
There are a number of strategies, each of which has pros and cons.
1. Hard switch away from fossil fuels for base energy generation. The only option for this is nuclear. Pros: This could reduce our emissions by ~60%. Cons: Everyone hates nuclear.
2. Transition to a steady state economy. Drastically reduce our net consumption of energy and raw resources, by taxing energy, resource extraction, or waste, while keeping the same mix of energy generation. Pros: You can reduce emissions by... As much as you want, with this. Cons: Everyone is banking on unlimited exponential growth, and this would cause an economic collapse/depression.
3. Invest hundreds of millions of people, and trillions of dollars into carbon sequestration. Pros: If we do enough of this, we can drive emissions negative. Cons: You can't do this cheaply. So, you get all the cons of #2. Also, you have to stop using fossil fuels, because there's no point to digging up and burning coal, at the same time that you're growing, and burying trees.
4. Do next to nothing, and let our children deal with the fallout. Pros: It's easy, and we're already doing it. Cons: Your grandchildren will inherit an ecological disaster.
For number 3 we already have very cheap solutions to carbon sequestration by artificially triggering algae blooms. The real questions is what kind of unintended consequences will come after.
I mean I think at this point it isn't unreasonable to say it's over for the ocean.
Either we start sequestering on a massive scale or the ocean is going to turn into a pool of acid anyway. I wouldn't be surprised if it was already too late right now and all life in the ocean is just currently in a slow death spiral because of what we have already done.
Sure, you just have to get in bed with both the fossil fuel lobby, environmentalists, and the cost-sensitive lower-classes. All at once.
Convince the three groups that their business is done, that they should do a 180 on the last four decades of their identity, and that they should pay twice as much for electricity, and you'll get them on board.
Only one of the three groups you mentioned needs to do an ideological 180. The masses don't care and the energy companies don't care so long as they stand to make money. Only (some) environmentalists activity dislike nuclear.
I'm curious about something closely related, which is: what are the practical things that need to be done to put brakes on the process? It feels like we've failed to articulate a concrete plan that we put to governments.
Buy solar (or even better buy into a share of large solar installation), don't fly, and don't eat meat seem to be the top things that individuals can do.
It always amazes me that in the triumvirate of Environment, Politics, and Economics, it is so easy to discuss optimization of Political Economy, and so difficult to discuss Environmental Politics or Environmental Economics. I've come to the conclusion that the mental models in Economics and Politics both abstract further from the true underlying processes and make it easier to reason (and attempt to optimize for) the political economy models. Sadly, the environment resists simplified mental models because scientists actually understand the complexity, while political scientists and economists have a hard time developing policies, pricing structures, and cost models that can really handle the nuance of the environment as it actually exists.