The tipping point on global warming has been passed. That was three decades ago when the world, collectively, might have been able to do something about global warming. It is now too late. We are on a path to reach more than 10 billion people in the world by 2100. There will be more than 2 billion fossil fuel-burning cars and trucks by 2100. The proven reserves of fossil fuels are presently worth more than $20 trillion. Can we afford to see that not spent?

It is impossible to tell all couples they can have only one child. India and China tried it without success.

Manufacturers will not respond to an edict that they can only produce vehicles getting more than 100 miles per gallon on fossil fuel. Oil and coal companies will spend billions fighting any edict that they can’t mine their multitrillion-dollar investments.

And what about the investments needed to protect U.S. East Coast communities from the rising sea levels (between 3 to 6 feet by 2100)? It is likely that 10 million future U.S. citizens will need to be relocated away from the flooding coasts at an estimated cost of $7 trillion. From where will this money come?

We are facing a sixth extinction, which probably will occur in the 22nd century. Do I care? Am I ashamed of all the political, corporate and personal greed in the world that will cause this? Were my early activist activities misplaced? Yes, yes and yes!

So, what to do? Unfortunately, I have no answers other than to have my children write in my obituary that I am sorry I didn’t leave them a better world.

Arthur Humphrey

member, National Academy of Engineering; former president, American Institute of Chemical Engineers; former dean of engineering, University of Pennsylvania; former vice president for academic affairs, Lehigh University