There have been 25 conferences under the United Nations Framework Convention on Climate Change since the body first met in 1995.

Over that period, some 894 billion metric tons of carbon dioxide, about 37% of all greenhouse pollution in human history, has been emitted. What makes anyone think that the 26th meeting starting Oct. 31 — COP26 — will be any more effective?

The answer lies in the age-old challenges of forging major international agreements — and it may be more hopeful than you think.