Say it is man made. Here is your problem:
Sixty-three percent of annual emissions are produced by developing countries. The economic growth behind that is a very good thing, but it has a dangerous side effect—carbon emissions.
www.cgdev.org
Developing countries are responsible for 63% of total carbon emissions. The US is 13%. China and India combined are 28% of emissions with China being the bulk of that. China alone produces more carbon emissions than the US and and the EU combined.
"So what?" you will say, "We can still make an impact on our end and do what we can." OK, yes we can. However, that is where the disagreements lie. Access to energy, particularly cheap energy, is a major contributor to how "comfortable" life is for people on the planet right now. The US has made extraordinary strides to clean up our emissions. We can continue down that path and try an make an impact on global warming (something I am not convinced is wholly or even majority man made) without doing some of the drastic things being proposed. The GOP released a plan to plant more trees. Plants are the ultimate CO2 filters.
Anyways, there is always the social justice push attached to this conversation:
At the 2022 United Nations Climate Change Conference in Egypt, countries will gather to discuss how to reach net-zero carbon emissions targets. One issue will be whether developing countries should be expected to achieve the same targets as the wealthier high-emitting countries.
www.brookings.edu
It isn't fair to ask the people contributing nearly 2/3 of the carbon emissions to cut back so you are only looking to reduce 1/3 of the emissions down to 1/4? The developing countries have a point as well, why should we continue to not use our resources to pull our people up as you had done? That's a fair question.