As I travel around the United States giving presentations on human progress, I am encouraged by the enthusiasm with which the audiences receive my message of the improving state of the world. Still, someone in the audience invariably asks, “What worries you?” That’s understandable. Our species has evolved to see the glass of human existence as half empty. To plan for problems ahead, such as droughts, was a better survival strategy than expecting an eternity of bountiful harvests. Here I attempt to outline different types of problems that we will face in the future and evaluate the degree of “alarm” with which those problems should be treated.

First, consider known problems with known solutions. Global warming, for example, appears to be a problem that’s partly caused by excessive emission of carbon dioxide (CO2) into the atmosphere. A third of all U.S. CO2 emissions come from energy generation. But, much of that energy could be produced in a more environmentally friendly way with zero CO2-emitting nuclear power. Unfortunately, irrational fears of nuclear fission and excessive regulatory costs have prevented more nuclear power plants from being built. As a result, only 20 percent of U.S. energy needs are met by nuclear reactors. By contrast, that figure is 75 percent in France.

Similar known problems with known full or partial solutions include declining freshwater reserves, which could be tackled through greater use of desalination (50 percent of Saudi drinking water comes from desal plants) and recycling (Israel recycles over 90 percent of its waste water); excessive use of pesticides and fertilizer, which could be tackled through greater reliance on genetically-modified crops (Arcadia Biosciences’ rice uses 50 percent less fertilizer, while Monsanto’s Bt corn needs 45 percent less pesticide); overfishing, which could be tackled through greater reliance on aquaculture (already 50 percent of sea food consumed in the United States is farmed), etc.

I am not particularly worried about these types of problems. Once their gravity becomes apparent to a critical mass of humanity, solutions, which are currently either economically or politically unpalatable, will be actuated.

Second, consider known problems to which solutions are not only imaginable, but (probably) within reach. As a thinking species, we have already succeeded in solving serious problems that have bedeviled humanity for millennia. The earliest evidence for smallpox, to give one example, has been found on Egyptian mummies from the 18th dynasty (1549/1550 BC — 1292 BC). The disease, which destroyed hundreds of millions of lives, was fully eradicated in 1980. It is surely not much of a stretch to imagine that malaria—humanity’s greatest all-time killer—will eventually be defeated through a combination of genetic engineering, insecticide-treated bed nets, vaccines and drugs.

Much has been made about the rise of superbugs (i.e., strains of bacteria that have become resistant to antibiotic drugs) and the ease with which deadly viruses, such as coronavirus, can spread around the globe. Yet, hope may be on the horizon. Crispr technology, for example, allows researchers to easily alter DNA sequences and modify gene function. It “has typically been considered for macroscopic tasks: altering mosquitoes so they can’t spread malaria, editing tomatoes so they are more flavorful and curing certain genetic diseases in humans,” reports the New York Times. “Now researchers are harnessing Crispr to turn a bacterium’s machinery against itself, or against viruses that infect human cells.”

Obviously, these sorts of problems are bound to cause suffering until an appropriate solution is found. To that end, I am particularly concerned about attempts of some governments to make scientific research needlessly burdensome. The European Union’s enforcement of the precautionary principle (i.e., that the introduction of a new product or process whose ultimate effects are disputed or unknown should be resisted) is certainly worrisome.

Third, consider known problems without readily imaginable or implementable solutions. Take nuclear weapons. The number of active nuclear warheads fell from a high of 70,300 in 1986 to approximately 3,750 in 2019. That’s progress. Unfortunately, governments in possession of nuclear weapons are unlikely to give them up altogether. More importantly, the technology needed for the creation of additional nuclear weapons cannot be unlearned. The best we can hope for is that the total number of nuclear warheads is gradually reduced to a point where their intentional discharge does not lead to a nuclear winter and the end of civilization. Accidental nuke launch, however, can never be ruled out.

Consider, also, artificial intelligence. This technology has the potential to immensely improve the lives of our species and, if futurologists are to be believed, eventually put an end to work itself. How would we react to a world in which machines do all the jobs that people used to do before? Would we pursue arts and leisure, or be consumed by existential angst brought on by a sense of meaninglessness? And what if AI decides that the world would be better off without humans in it? The American neuroscientist Sam Harris is concerned, while Harvard psychologist Steven Pinker is more optimistic. This is not a place to go into details, but as the fascinating conversation between the two men shows, the future of AI raises a lot of questions.

In addressing these sorts of problems, we shall have to tread very carefully. Additional safety protocols aimed at preventing accidental nuclear conflict and universal ethical standards in AI development will help, but they will not dissuade rogue agents intent on sowing chaos.

The fourth type of known problem cannot be addressed by humans on Earth. They include the eventual exhaustion of hydrogen in the Sun and the star’s transformation into a red giant that will destroy the entire solar system; a sudden appearance of a black hole in our part of the cosmos that would consume everything in its path, including our planet; the explosion of one or many supervolcanoes that spew so much ash and CO2 into the atmosphere that life on Earth becomes impossible; a burst of gamma rays from a relatively close supernova that destroys our ozone layer thus exposing our planet to ultraviolet rays from the Sun; a related problem of a weakening or disappearing magnetic field during a geomagnetic reversal that would expose the Earth to cosmic ray bombardment; and a surprise asteroid strike that obliterates a large chunk of the planet and blacks out the Sun.

The only imaginable solution to the fourth type of problems rests in us becoming an interstellar species—a goal that’s unimplementable (due to the prohibitively great distances between stars) and pointless given the fifth kind of known problem, which was famously encountered by the neurotic New York comedian Alvy Singer in Woody Allen’s 1977 movie Annie Hall. Young Alvy is brought to see a doctor by his mother and the following conversation ensues:

Mrs. Singer: He’s been depressed. All of a sudden, he can’t do anything.

Dr. Flicker: Why are you depressed, Alvy?

Mrs. Singer: Tell Dr. Flicker. It’s something he read.

Dr. Flicker: Something you read, huh?

Alvy Singer: The universe is expanding.

Dr. Flicker: The universe is expanding?

Alvy Singer: Well, the universe is everything, and if it’s expanding, someday it will break apart, and that will be the end of everything.

Mrs. Singer: What is that your business? He’s stopped doing his homework.

Alvy Singer: What’s the point?

Mrs. Singer: What has the universe got to do with it. You’re here, in Brooklyn. Brooklyn is not expanding.

Dr. Flicker: It won’t be expanding for billions of years yet, Alvy. And we’ve gotta try and enjoy ourselves while we’re here. Huh? Huh? Huh?

There is much wisdom to Dr. Flicker’s recommendation. We cannot worry about everything all of the time. The best we can do is to try and address problems as they arise, and hope that people and (hopefully friendly) machines of the future will push the scope of human knowledge and progress ever further.

This originally appeared in Quillette.