A total shutdown of the entire world economy on an unprecedented scale still doesn't track enough to prevent climate change.
If that isn't a clear indicator of how severe the situation is then I don't know what else is.
GDP has barely taken a hit the world over. Trade is virtually unchanged. Hell, some indicators went positive though the pandemic.
I don't really think there was a "shutdown". Passenger car miles might have gone down, but I suspect deliveries and cargo went way up.
I'm still optimistic. Just replacing coal with renewable power would put emission levels back to like the 1960s (maybe 1970s, trying to find that damn statistic), and that's likely to happen in the US in a few decades just by market forces.
The economy never came close to a “total shutdown.” In most places, the overwhelming majority of jobs were classified as essential—maybe 2/3rds—even while certain sectors did shut down. You can look at various stats, but a very simple one is the output gap, estimated to be 6%, which is potential GDP minus actual. This is a fair proxy for how shut down the economy was. The severe shutdowns were relatively brief.
Mostly, we massively changed the mix of activities we engage in, substituting relatively cleaner ones for more polluting ones. Maybe you purchased more manufactured goods and used more electricity, while driving less. A different conclusion from yours is that simple behavior changes—like more telework—can have significant impacts on emissions.
It proves that we can cut emissions without living a prehistoric lifestyle. And given that renewable energy sources are cheaper than polluting ones, this gives me reason to be optimistic.
Some napkin math: the Sedan test was optimized to dig a big hole, was buried almost 200 meters deep, and moved about 11 million tons of earth, leaving a crater of 0.005 cubic kilometers. The 1815 eruption of Mount Tambura, which caused a 'year without summer', ejected 160-213 cubic kilometers of material into the stratosphere, something like 32 thousand times as much as the Sedan blast. I'm guessing each strike against a nuclear silo would probably create craters a fraction the size of Sedan.
Where did that happen? US GDP is down a few percent, yet emissions plummeted far far further.
Changing weather and vegetation patterns is going to be a big event. We're going to see some previously fertile areas (Mesopotamia, Northern Europe, sub-Saharan Africa) suffer from decade-long droughts, while other previously uninhabitable areas (Canadian & Russian taiga and the Sahara, for example) become fertile grasslands. This will drive widespread migration, which has a tendency to destroy political stability and lead to mass wars. Nature isn't going to kill us; we're going to kill each other because some of us are going to starve and others are going to get fabulously wealthy.
The idea that you can gain anything from denying climate change and skip out on preventative measures is just wrong. The economics alone tell you that this is a losing play and I am not even talking about the impact on the climate, just the potential for economic growth that you end up denying by denying climate change.
There's some additional work for things like replacing steam reformation with electrolysis or thermochemical hydrogen production. Decarbonization of air and sea transportation presents a bigger challenge but it's not unsolvable.
There are serious and legitimate concerns about albedo modification research which have nothing to do with politics. I don’t think that anyone in the field is concerned that this small-scale experiment will lead to global catastrophe, but it’s a stepping stone to something which could lead to those bad outcomes—and it’s not clear that a small test like this would be able to answer the most important questions that we’d need answered before actually embarking on a global albedo modification programme.
Of the various issues already covered by the Daily Mail story, one thing it doesn’t really talk about is that albedo modification requires a functioning human civilisation capable of injecting aerosols to the atmosphere to exist, without ever stopping, for thousands of years. A single disruption could cause up to 0.7°C of warming in one year[0].
About the only case in which something like this makes sense is if we’ve solved the emissions problem, but a bit too late, so only need a bridge for a few decades while we are actively pulling CO2 from the atmosphere.
If you want to learn more, away from the sensationalism of the Daily Mail, the podcast Brave New Planet had an episode about this last October[1], which is where most of my current knowledge comes from.
[0] https://iopscience.iop.org/article/10.1088/1748-9326/4/4/045...
[1] https://www.bravenewplanet.org/episodes/a-radical-approach-c...
But I've spent a good deal of time studying game theory and situations where the behavior of the whole is significantly dumber than the behavior of each individual actor, because the individual actors' interests are not aligned. I think global warming is going to be one of those. Sure, if we could come to a rational collective-action agreement, we could solve it. The history of collective-action as a solution is pretty dismal.
I think the costs of a changing climate are real, but I think the benefits are too often overlooked. For instance, most landmass on earth is not at the equator, but it's in the northern hemisphere. Much of it is uninhabitable at present but will become habitable as the climate changes. Canada, Sweden, Finland, and others will become more than 100km tall. A lot of Russia, and Northern Europe, as well as Mongolia and South America will become more habitable. Further, according to Lancet, very cold weather kills more people than very hot weather, so as winters become more mild and summers become hotter, the net effect will be fewer deaths.
> The fusion-fission blast had a yield equivalent to 104 kilotons of TNT (435 terajoules)
That is a quite small fusion-fission bomb. If your calculation is right, we are talking about some hundreds of more normal ones, not tens of thousands.
It'll take a lot more than climate for those areas to become productive. Glaciers have scraped away most of the topsoil in the Canadian shield[1], for instance. The Sahara desert's sand isn't a great growing medium. And so on.
And yet in Israel people managed to employ advanced AgTech to grow food in areas with much worse soil than Berlin-Brandenburg & with less abundant water reserves (and they also did this back when Israel was a much poorer country than Germany). In fact aside from some grains import Israel is mostly self-sufficient in food production. Germany is not despite being less densely populated and having much better natural conditions for growing food, because it is more expensive than importing food.
If need be these areas can produce food if the climate is suitable, it will just not be as cheap as the food we can currently get elsewhere (but then again AgTech continues to advance and economies of scale kick in). Anecdotally as a consumer groceries in Israel cost about 2-3x as much as in Germany but both countries suffer a lot more from obesity than hunger.
Also as an unintended result of the above Israel is today a significant exporter of AgTech.
We've shut down the most we could, essentially. Which means most things need to stay open and active.
What could we possibly do to make a bigger impact?