In a post criticizing inaction on global warming, the Heritage Foundry writes:
Respectable economists don’t pretend to know what the world will look like much beyond 25 years, let alone 90.
While modeling requires assumptions like that, it’s probably true that "respectable economists" don't put a lot of faith in their assumptions over the very long term. But then, shouldn’t it also be the case for, say, economists who write about the long-term fiscal situation?
Medicare presents the greatest challenge to Congress and taxpayers, accounting for $36.3 trillion of the $46.9 trillion 75-year projected shortfall. Congress should take both short- and long-term approaches to solving the Medicare crisis.
Etc, etc, etc.
Certainly, the long-term economic outlook is extremely uncertain, but I’m not sure what “who knows!” is a better answer to cumulatively worsening climate problems than to cumulatively worsening fiscal problems.