A certain fluffy-headed optimist posed the following question:

“What tiny change could the whole world make right now to make a huge impact on the rate of climate change in the next decade?”

I’m sure it was aimed at provoking answers like “walk to work” or “plant a tree”, maybe “use less plastic” or just “consume less”. Which would all be good things; I won’t argue that; we should do them all, absolutely. But this sort of question obscures the true answer, which is:

None.

Climate is not small scale and it’s not short-term. As well, the environment is not a simple thing, but rather an intensely complex system with massive redundancies. If you were to actively try to change it by concentrating the entire work output of humankind on the job, that’s maybe enough for the task as stated, but maybe not.

Let explain by example: One of the most compelling historical instances of local manmade climate change was the Great Smogs of London. In the worst event, a thermal inversion coupled with virtually the entire population of the city burning low-grade high-sulfur coal led to a thick enough smog in 1952 that thousands of people died before it lifted. The changes in its aftermath were massive, but even so it was not enough to prevent a further smog of the same sort a decade later.

In the throes of forced industrialization, China repeated this not once but twice in 2013 — and not in one single city, but across the entire eastern region. The effects lasted weeks and were likely quite deadly; reports on that vary. What is beyond debate, however, is that the government instituted a massive program to stop air pollution in February of 2014 that has altered not only theirs, but the entire world’s economy.

Both of these were mere events; both were temporary. They were weather coupled with pollution. And, at least in London, it could not repeat today because the climate has been altered to make it impracticable. In order to reproduce those conditions, tens of thousands of people would need to burn masses of sea coal for years, which would first need to be mined and transported; the process would take a decade and cost a mint. And that’s to create a small local disruption; try doing it in reverse.

In order to create measurable lasting change, thousands of minor personal behaviors will need to be altered in addition to major industrial fixes. Fortunately for the world, many of these are already being done. But the present weather trends have so much momentum that they will only gradually slow over the next decade, and it will be twenty years before we see a return to even present conditions. It must also be observed that our (heh) fixation on carbon emissions is oversimple; in time, unless standards are broadened, sulfur will do as much damage or more.

I’ve tried to arrange both thoughts and sources in a somewhat longer article, which can be read here:
https://gnerphk.wordpress.com/2019/04/13/climate-change-for-skeptics/

But remember: We’re not trying to save the Earth; the Earth is in no danger. It has survived worse than us and will continue to do so. Instead, if we’re willing, we have a decent chance to save our civilization from the massive social and economic impacts that will otherwise prove inevitable.