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In the US, electricity + transportation makes up 56% of anthropogenic emissions and agriculture makes up 9%: https://www.epa.gov/ghgemissions/sources-greenhous

In the US, electricity + transportation makes up 56% of anthropogenic emissions and agriculture makes up 9%: https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis... The European Union reports aggregates a bit differently, but agriculture is only 10% there too (see Figure 3): http://ec.europa.eu/eurostat/statistics-explained/index.php/Greenhouse_gas_emission_statistics http://ec.europa.eu/eurostat/statistics-explained/index.php/... Neither the USA nor the EU are undergoing deforestation at present, and electrical heating can substitute for the vast majority of applications currently served by fossil-combustion heat. That's why most research and headlines about GHG reductions in the developed world focus on transport electrification and electricity decarbonization. In poorer parts of the world, where automobile use is less common and/or fewer people have grid tied electrical service, deforestation and agricultural emissions make up a larger share of total anthropogenic emissions. But most of the world's anthropogenic emissions, and most of the low-hanging mitigations for emissions, come from geographic regions that commonly have grid tied electrical service and other modern amenities.

the8472 9y ago
But those replacements, electrical heating and industrial processes, are also holes. Basically, if we replaced 100% of the current electricity production with renewables that wouldn't even provide the energy needed for electric vehicles. So we already have to go >100%. And then we need to overhaul heating and energy-intensive industries too. And even if we get to that point we still would not be carbon-neutral due to the remaining sectors. And possibly due to new natural sources (permafrost) we're already locked into due to the warming that is already in progress. So the point is that just inventing our way to replace the current grid with green sources is insufficient for meeting the climate budget within a few decades.
- philipkglass 9y ago
  I think we're all making slightly different points. OP said "We will end our reliance on fossil fuels ... by developing green energy tech that is simply more efficient and cost effective than fossil fuels. Once this happens the transition away from carbon based energy sources will be swift." You replied pointing out that electricity and transportation are not the only sources of emissions -- not sure if it was intended as a rebuttal because OP didn't say they were. I noted that electrical heating can generally substitute fossil heating, that the developed world isn't undergoing deforestation, and that agriculture is a much smaller source of developed-world emissions compared with fossil combustion. Neither I nor OP said or implied that "just inventing our way to replace the current grid with green sources is sufficient for meeting the climate budget." We're obviously going to blow past the "safe" 2-degree-rise-by-end-of-century cumulative emissions target. In the long term, if complex civilizations survive, I expect large scale atmospheric carbon removal efforts (enhanced silicate weathering and similar). Otherwise feedback processes and anthropogenic emissions apart from fossil combustion are probably going to amplify ~4 degrees of end-of-century warming to more like 7-9 degrees of warming by end-of-millennium. After that it'd take ~100k years to restore the pre-industrial atmospheric CO2 concentration status quo by natural sinking mechanisms alone.

the8472 9y ago

But those replacements, electrical heating and industrial processes, are also holes. Basically, if we replaced 100% of the current electricity production with renewables that wouldn't even provide the energy needed for electric vehicles. So we already have to go >100%. And then we need to overhaul heating and energy-intensive industries too. And even if we get to that point we still would not be carbon-neutral due to the remaining sectors. And possibly due to new natural sources (permafrost) we're already locked into due to the warming that is already in progress. So the point is that just inventing our way to replace the current grid with green sources is insufficient for meeting the climate budget within a few decades.

philipkglass 9y ago
I think we're all making slightly different points. OP said "We will end our reliance on fossil fuels ... by developing green energy tech that is simply more efficient and cost effective than fossil fuels. Once this happens the transition away from carbon based energy sources will be swift." You replied pointing out that electricity and transportation are not the only sources of emissions -- not sure if it was intended as a rebuttal because OP didn't say they were. I noted that electrical heating can generally substitute fossil heating, that the developed world isn't undergoing deforestation, and that agriculture is a much smaller source of developed-world emissions compared with fossil combustion. Neither I nor OP said or implied that "just inventing our way to replace the current grid with green sources is sufficient for meeting the climate budget." We're obviously going to blow past the "safe" 2-degree-rise-by-end-of-century cumulative emissions target. In the long term, if complex civilizations survive, I expect large scale atmospheric carbon removal efforts (enhanced silicate weathering and similar). Otherwise feedback processes and anthropogenic emissions apart from fossil combustion are probably going to amplify ~4 degrees of end-of-century warming to more like 7-9 degrees of warming by end-of-millennium. After that it'd take ~100k years to restore the pre-industrial atmospheric CO2 concentration status quo by natural sinking mechanisms alone.