The US estimated 20.853 billion short tons (measured in BTU) of coal reserves as of 1980. However, the US now estimates recoverable reserves of 255 billion short tons.

OPEC reserves as of 1982: 467.3708 billion short tons. Note: OPEC reserve estimates are notoriously inflated, as for many years, quotas were related to reserves, so Iraq, when they were in the middle of their war with Iran, their reserves magically tripled so they could sell more oil. Iran's reserves almost doubled.

So yes, it may have been true, but not according to data available at the time.