We’ve all seen those pictures of wilting cornstalks as a tough drought hits large parts of the country.

Is it just another hot summer?

I doubt it. I think it’s part of a more serious long-term trend that will require us to adjust our thinking sharply.

Most of us on this planet have been able to earn or produce enough of what we need to stay alive. We in the United States have been particularly lucky in that respect.

But we are being challenged to make a big shift.

The present pattern of economic activity on this planet goes something like this: Humans work to provide what they need — food and shelter, for example. By being technically inventive, well-organized and hardworking, we produce the basic necessities and enough extra for such services as schools, health care, transportation, and cultural and leisure facilities. The harder you work and the more ingenious you are, both as an individual and as a nation, the more you will advance in producing and enjoying these things.

One of the assumptions that underlies all this is the widespread availability of cheap natural resources. Water, fertile land, forests, fish, minerals, energy resources and more — all these are assumed to be available in large supply to draw on for economic activity.

That’s why, in traditional economic theory, no cost is assigned to them. One of the reasons gold has always enjoyed such high value is because it was not in large supply, and thus was an exception to this rule.

But today what used to be plentiful is becoming scarce.

Water tables are sinking in many parts of the world, and global warming is sending us more droughts. Many of the world’s principal fisheries are badly depleted.

Virtually all the high-quality land that can be farmed is already under cultivation, and the new land being claimed for farming is either second-rate or is obtained by cutting down forests — which depletes another critical natural resource that we need to produce rain and stabilize the climate.

Some of the forces behind these trends are well-known: For example, 3 billion people around the world are moving into the middle class, where they will use many more raw materials. The global car fleet is projected to double to about 1.7 billion by 2030.

We all know the oil story — shrinking reserves and rising prices. The pictures of wilting corn tell us that grain prices are going to go up sharply in the months ahead. That’s rough on us; it’s murderous on poor countries.

In his wonderful book “Collapse: How Societies Choose to Fail or Succeed,” Jared Diamond writes about past civilizations that did not survive. He finds they all shared two characteristics: First, they let natural-resource shortages get out of control; second, they failed to respond to new long-term trends that spelled trouble.

If those two characteristics typify our civilization today, and I think they do, then we’d better adjust our economic model — and our whole way of thinking about these things.

The evidence is clear that the squeeze is on. If that’s true, then there is only one way forward: to consume less, have population growth level off, recycle far more and fiercely increase efficiency in every domain to make the existing resource stock go further.

How can we finance this change? One logical place to look is the nearly $1 trillion spent annually worldwide on weapons. It would be smart to figure out how we can divert some of that from the arms race to the survival race.

All this is a tall order and a big change, and we humans don’t change easily. It’s not that I think it can’t be done. What I’m worried about is that we won’t buckle down and try.

Peter Goldmark, a former budget director for the state of New York, is a member of the State Budget Crisis Task Force.