> Where are you getting the idea that personal footprints have to be reduced to zero or less? That assumption only holds if there are no carbon sinks.
This is not really correct thinking, because you need to account for both sinks and sources of carbon. For instance, you could emit methane locally enough to, say, intensify a forest fire or dissolve methane clathrates. Then a forest somewhere else absorbs the original weight in carbon dioxide. This is net zero emissions for you, but certainly causes more warming. The best way to think of it is as a system with sources, sinks, and feedbacks.
But really, the biggest adjustment to your life to reduce carbon emissions is to get involved in politics. Everyone reducing to net zero at home would make a tiny dent in the problem. The big users are transportation and concrete and metals.
I was just giving a concrete example (pun intended). There’s still some rock crushing for aggregate, but the energy is mostly in cement. Concrete uses most of the cement, so it’s a good target. Japan uses something like four times the concrete of California, despite similar population, land area, and geography.
I've heard similar about concrete as well, but have had a difficult time putting it in context.
"Cement (3%): carbon dioxide is produced as a byproduct of a chemical conversion process used in the production of clinker, a component of cement. In this reaction, limestone (CaCO3) is converted to lime (CaO), and produces CO2 as a byproduct. Cement production also produces emissions from energy inputs – these related emissions are included in ‘Energy Use in Industry’."
Unfortunately, it doesn't further breakdown what percentage of the cement energy inputs contribute to GHG emissions.
This is not really correct thinking, because you need to account for both sinks and sources of carbon. For instance, you could emit methane locally enough to, say, intensify a forest fire or dissolve methane clathrates. Then a forest somewhere else absorbs the original weight in carbon dioxide. This is net zero emissions for you, but certainly causes more warming. The best way to think of it is as a system with sources, sinks, and feedbacks.
But really, the biggest adjustment to your life to reduce carbon emissions is to get involved in politics. Everyone reducing to net zero at home would make a tiny dent in the problem. The big users are transportation and concrete and metals.