If the topic is ask anything, why not be a bit academically selfish. I have an interest in Physics and specially GeoPhysics. I have done B.Tech in IT is there any chance to do Phd in the GeoPhysics and if yes, what is the procedure. If not, how can I proceed for direct Phd?

I wish, i would want the earth ring to I could actually see the contamination underground instead of having to dig for it XD.

Do you ever call captain planet for help?

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Hi, thanks for doing this! I have a couple of questions. :)

1. What prompted you to study these topics in particular, and how do the conclusions you draw assist in combatting climate change in the present day?

2. Would you say your research has made you more pessimistic or optimistic about the ways in which governments/international organisations tackle climate change? Are we doing enough, and if not, what is our biggest drawback in this endeavour?

Thanks for your question! Whatever we do, over hundreds of millions of years there will probably be a mass extinction at some point, most simply because there have been 5 mass extinctions in the last 500 million years. That said, there appears to be an unprecedented rate of species loss today, and many would argue that we are already in the sixth mass extinction (see for example Elizabeth Kolbert’s book, or this paper).

Changes in land use probably account for much modern species loss. Climate change and ocean acidification (which we’ve focused on in our work) may eventually contribute to much more. The best way to prepare for this as a society is clearly to act in ways that limit disruptions to the global environment. At the individual level, the question becomes about how to best influence the actions of societies, which is unfortunately outside of our domain of expertise.

Phosgene gas a chemical weapon used in WWI is also a potential byproduct but I am unsure of the quantity that would be generated. It appears that those involved are aware of the potential and are monitoring those levels as well. I don't currently see any data that suggest that phosgene gas is of immediate concern but that may change with more data. If it is an issue it would have likely dissipated by now and may only be an issue in the upper atmosphere. I have never dealt with phosgene gas so I am not super confident on how it interacts or dissipates in the environment.

What other byproducts would you expect to find in the burn plume? Obviously it isn’t an ideal way to incinerate chemicals. They can’t be getting complete combustion.

This is awesome! Thank you so kuch for doing this.

I'm someone who runs Climate Adaptation training and education for an island community. Do you have any suggestions for maintaining a hopeful tone when discussing these big life changing topics?

Thank you!

Thanks for your question! Severe volcanic eruptions would be minor perturbations (in terms of CO2 injection) compared to the fossil-fuel burning. Chemical fires even more so, but clearly they are problems by themselves. Nuclear detonation would bring us towards an entirely new set of serious risks independent of climate change.

I will say that if you are a resident of Palestine, don't go out playing in rain any time soon, but otherwise there isn't too much to worry about down wind.

It is unlikely that HCL would have rained on anyone other than the residents in nearby Palestine. The most up to date measurements of atmospheric concentrations of the plume that escaped from the fire show insignificant concentrations of acid rain forming chemicals such as HCL.

Thanks for the great question! One interesting phenomenon that really matches the idea of the canary is that of “early warning signals”: basically, mathematical theory predicts that a system that’s about to cross a tipping point will start fluctuating more slowly, and this can be measured. There is a lot of work going into assessing elements of the climate system that might have tipping points, and searching for such early warning signals: one recent example is the Atlantic Meridional Overturning Circulation (AMOC; think Gulf stream). Recent work (e.g. Boers 2021) suggests that the AMOC is currently exhibiting early warning signals for collapse.

With respect to the global-scale disruption events, we could say that the canary is the historical record itself. Appropriately analyzed, the record suggests that there is a critical rate of CO2 perturbation at which mass extinction occurs, and that we are on track to cross the threshold by 2100 (see also this comment). Nevertheless, since it may take thousands of years for the ultimate consequences to play out, actions we take today to mitigate this could still have an effect.

What's the next mass extinction we are probably going to face? How soon? Best way to prepare oneself for it?

Everyone keeps getting worked up about how the burn off made hydrochloric acid in the atmosphere; is that really worth worrying about compared to the vinyl chloride itself and whatever other byproducts came off the burn? Like, HCL isn't carcinogenic. I have no chemical training to speak of, but I can buy a gallon of muriatic acid at the hardware store. My gut instinct is that I'd rather stick my hand in a beaker full of HCL than be in the same room with any visible quantity of vinyl chloride.

This is a complex problem with a lot of parts to consider, but I will attempt to address it with a back of the envelope evaluation. Global CO2 emissions were approximately 2.5 billion metric tons in 1900 and as of 2020 were around 33 billion metric tons according to the Center for Climate and Energy Solutions (https://www.weforum.org/agenda/2022/11/visualizing-changes-carbon-dioxide-emissions-since-1900/). CO2 emissions account for 76% of the total greenhouse gas emissions worldwide. In order to reach 1900 levels we would need to sequester around 30.5 billion metric tons per year.

It is estimated that about 55% of our current level of emissions are absorbed back or sequestered naturally through plant respiration and absorption into our oceans (which causes its own problems), but that leaves us with about 45% of 30.5 billion tons to sequester manually or about 13.725 billion tons. There was a recent technique that came out which is the cheapest method of sequestering carbon as of right now at $39 USD/ metric ton (https://www.cnbc.com/2023/01/24/new-technique-from-us-national-lab-to-remove-co2-at-record-low-cost.html). To capture that carbon, the top of the line models will use up to 30% of a power plants capacity to reduce 90% of the carbon output. Given that the majority of direct CO2 emissions are from power plants, lets simplify the problem a little bit by assuming that all carbon emissions come from power plants and to reduce carbon emissions we use this carbon capture technology.

EPA estimates that approximately 884.2 lbs of CO2 are emitted per megawatt-hour for a coal fired power plant (https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references#:~:text=The%20national%20average%20carbon%20dioxide,EPA%202021%3B%20EIA%202020b). For the 13.725 billion tons we discussed before, that would be about 15,522,506 mega-watt hours of generation capacity. Assuming the 30% from before, it would take 4,656,751 mega-watt hours of power to reduce the 13.725 billion tons by 90% (which would bring us down to 1.23525 billion tons). With the cost estimate of $39 USD/metric ton from before, it would cost about $482 billion USD and that is just operating costs, not including upfront costs of manufacturing the amount of systems that would be needed and installing them.

I need to throw in a disclaimer that this is a gross simplification of the problem and please don't quote me on this because I had to make a lot of simplifying assumptions.

Thank you for doing this. Do you think that humanity should engage in climate change mitigation and adaptation, rather than attempting to reduce carbon emissions?

To be clear, I understand the science and PPM calculations, but I don't foresee a world where all countries, particularly China, India, and Russia will promote a carbon-free or low-emission economy...and I doubt that the U.S. has the willpower to do so any time soon.

What are some ways we can encourage thriving ecosystems in the surrounding areas we live? (Individually, or community/city efforts).

EDIT: Also, have you read Greta Thunberg's new book? Thoughts on it?

Thanks for the question! Unfortunately the question of how well equipped we are to survive the coming changes is pretty complex and somewhat outside of our specific expertise (we’ve been focusing more on the changes themselves). Understanding this involves not just scientific knowledge from a range of disciplines but also knowledge from social sciences about how societies will respond, what’s possible in terms of economics and policy, and so on.

We agree with you that the food question is a really important one. We’re also not experts on agriculture, but there are some other researchers and research institutes doing great work on this. Off the top of our heads, one prominent recent study is that of Gerten et al. (2020): they argue that it should in principle be possible to transform the global food system to feed 10 billion people in away that’s relatively globally sustainable. Whether this is going to be possible in practice, of course, is another matter.

For more AMAs on this topic, subscribe to r/IAmA_Science, and check out our other topic-specific AMA subreddits here.

The present rate of CO2 increase is much larger than in past disruption events. However, the critical rate of change seen in past events is only part of the story. First. the timescale of the current situation (about a century) is much shorter than past events. Second, natural processes in the oceans tend to damp perturbations of CO2, at a roughly 10,000 year timescale. The upshot is that the critical rate of the modern event must be rescaled by a factor of about 100/10000 = 0.01 to be compared to past catastrophes. When that rescaling is done, our modern disruption event, if it continues throughout this century, looks fairly similar to the runup to extreme warming events of the past, including those associated with mass extinction. A rough estimate is that the tipping point would occur late in this century. For more detail, see our papers here and here.

But that too is only part of the story. If the tipping point is real, our own calculations suggest a roughly 10000-yr trajectory during which things become progressively worse—but only if there were no negative feedbacks beyond those we currently understand that would act to arrest the trajectory. And we would imagine that new technologies—or simply improved scientific understanding—might contribute towards goading the Earth system in the right direction.

How long have we got?

Thank you!
I see you mentioned 2100 as a year of a potential turning point. Can this estimate be cut dramatically by external forces such as nuclear detonations, chemical fires (ohio train) or even a severe volcanic eruption?

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