You touch on one of the great difficulties of international negotiations to lower carbon dioxide and methane emissions. Countries fight over whether to deal in percentage reductions from today's values, a reduction to a level of emissions per capita, a reduction to a total emission per capita budget over all of history, a system by which rich countries must pay for the reductions by poorer countries, etc.
Still, at the end of the day, elimination of fossil fuels requires everyone to be at 0, regardless of the above, beyond the debate over subsidies for poorer nations.
The generally bruited about year for 0 emissions is 2050. That is the predominant year cited by governments around the world pushing for a solution to global warming. The Green New Deal is ridiculous, because it chooses the year 2030. That is an unattainable date, it is like saying if a supertanker is ordered to turn around by a naval vessel that it must be going the 180 degree opposite of its prior direction such that it doesn't travel more than 100 yards in the direction it was traveling, or it can be blown out of the water. Well, supertankers simply cannot turn around in that short a distance. An advanced industrial economy can't turn around in 10 years and no longer use fossil fuels.
The sponsors of the Green New Deal seem to recognize this objection and that millions of Americans would be thrown out of work as our economy becomes totally noncompetitive. That's why they include the provision so that everyone is guaranteed a well-paying government job. Presto! no danger to you from the inevitable industrial collapse.
Since we are not the largest carbon dioxide emitter,, and since other nations are rapidly increasing their emissions (China, India, etc.) or achieving little reduction, even if we went to zero by 2030, global warming problems would not be averted. THE WHOLE WORLD MUST CUT EMISSIONS. So, the n umber one need is an enforceable global agreement. What is a reasonable goal. A 75% reduction from today's total emissions to 2050, in a linear fashion, seems workable. Adaptation to and mitigation of the effects of warming will also be required.
Now, how is it best (most likely) to gain this international agreement in a competitive nationalistic world in which countries seek military/geo-political-economic advantage over each other and in which China does so very aggressively? Well, we can look to past agreements. The huge number of nuclear weapons has been an on-going problem. What do you think would have happened if our government declared "we will destroy all of our nuclear weapons within a year, diluting the uranium to 5% enrichment". Would they say "great, we'll do the same" or will they slap each other on the back and declare "we just won"? We know what did work. We negotiated discrete, step-by-step reductions, which the United States and the USSR then both eliminated. What doesn't work? Ozone destroying CFC refrigerants were dangerously thinning the Earth's ozone layer. The wealthy nations agreed to eliminate production, allowing China to continue to produce the refrigerants for local production. China increased production and illegal CFCs were smuggled from China to the United States and Europe.
I don't like the setting of unattainable goals (like zero fossil fuels by 2030), because they just cause people to throw up their arms and do nothing. Start with reasonable steps, with a reasonable end goal (like elimination of 75% of fossil fuel use by 2050) and require discrete, pre-agreed reductions in emissions to be made each year. Start with what is doable today: nonew coal plants and a schedule to close existing ones, increased energy efficiency standards and subsidies to retrofit existing homes etc, a carbon tax, subsidies for electric cars, solar, wind, encouragement of nuclear with a legislated solution to nuclear waste storage (Yucca Mountain was fine).
I agree that global warming is an existential threat. Environmentalist warriors don't act as if it is. They are still playing NIMBY games to stop projects which would help reduce carbon dioxide emissions, like solar energy projects and the electrical lines to connect them to the power grid, and natural gas pipelines. Virtual ALL of the huge amount of natural gas produced in northern Alaska was flared -- all of its carbon dioxide value was added to the atmosphere, with close to zero value from the energy released. The same for most of the natural gas produced with the oil from West Texas: burnt, all of its carbon dioxide released, no benefit either economically or in displacing highly polluting coal. Its beyond stupid.