Clarification: This partly depends on the definition of "developed" and "developing," but the Centre for Global Development reports that developed countries are responsible for 79 percent of global emissions produced between 1850 and 2011: see here.
The estimate that rich countries are using up 60 percent of the global carbon budget is based on analyses showing that the world has used up roughly 85 percent of the global carbon budget, the total amount of carbon emissions that the world can emit while still staying below 1.5 degrees Celsius of warming (see the most recent Global Carbon Budget report here and a Carbon Brief analysis here).
Given that developed countries are responsible for 79 percent of the roughly 85 percent of the global carbon budget already used, this means that they have used up roughly 67 percent of the global carbon budget.
"The problem is that all of the aid in the world will not fund one-twelfth of the green transformation in developing countries."
Clarification: This one-twelfth estimate comes from two numbers: The total amount of foreign aid, specifically official development assistance (ODA), in 2022 was 204 billion dollars, and according to a 2022 report by the Independent High-Level Expert Group on Climate Finance, emerging markets and developing countries will need to spend 2.4 trillion dollars per year by 2030 to finance a green transformation. (204 billion dollars is about one-twelfth of 2.4 trillion dollars.) See here and here.
