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John Carlos Baez
To keep global warming below 2 °C we may need *negative carbon emissions* - sucking carbon dioxide from the air. I'm skeptical that this will happen in this century. But I'm more hopeful about the next few centuries. So, let's consider the tech:
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Eugene Seidel Mar 2
Replying to @johncarlosbaez
Trees.
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John Carlos Baez Mar 2
Replying to @EugeneSeidel
To suck up a typical person's emission of ~5 tonnes of CO2 per year we would need to plant about 3333 square metres of forest per person, and keep harvesting all the wood when the forest matures. Not gonna happen. And yet, preventing deforestation is very important!
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julesh Mar 2
Replying to @johncarlosbaez
I'm very happy you are talking about this. Many people are against geoengineering - they would doom us for their principles
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John Carlos Baez Mar 2
Replying to @_julesh_
Thanks! "Carbon capture" or "negative carbon emissions" is the least controversial form of geoengineering - at least until you pick a specific way to do it, and talk about the massive scale required. Most people save the word "geoengineering" for other things.
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Tom Andersen Mar 2
Replying to @johncarlosbaez
The only tech that could achieve this is known, safe, scalable and inexpensive. 25,000 GW of nuclear by 2060 would look like the graph you present. Another version of the graph should show required total energy (up 10x from today) and required carbon intensity (down 100x).
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John Carlos Baez Mar 2
Replying to @knobsturner
Nuclear power can dramatically reduce emissions, but only achieve *negative* carbon emissions if we use it to power a device of some sort. My ultimate goal, in future articles, is to investigate such a device.
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Tom Ruen Mar 2
Replying to @johncarlosbaez
My intuition says taking parts-per-million CO2 out of the air will take more energy than we extracted by burning the fossil fuels in the first place. (Removing CO2 from power plant gas effluents is a different story, but you're still stuck storing a stable gas for infinity.)
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Scott Leibrand Mar 3
I believe your intuition is incorrect there, but regardless, any fossil fuel power used to run direct air capture would be done with direct carbon capture of the combustion CO2 as well. The thermodynamics are proven, and it already costs less than $1/gallon of gas ($100/tCO2).
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Galen Wilkerson Mar 2
Replying to @johncarlosbaez
I don't think 'tech' is the solution to this. Many countries are planting trees. In the ecological domain, 'low tech' is the highest tech there is.
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Galen Wilkerson Mar 2
Replying to @johncarlosbaez
This seems true due to the basic fact that tech always sits on top of an energy intensive industrial process, while plants do not.
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