When we talk about climate change, especially as it applies to the U.S. and public policy, the subject matter often seems to divide people into two strict, opposing camps: environmentalists and science deniers. But those of us who acknowledge the very real risks posed by climate change aren’t a monolith.

Even among climate realists, there are a variety of viewpoints, and naturally discussions can quickly become heated. One of the clearest divisions I’ve observed in recent times is a stark divide between optimists and “doomers,” with nearly every pundit arguing that the former mindset is going to be more efficacious in fighting climate change. The basic argument against climate pessimism makes intuitive sense: if we believe there’s no hope, we won’t try and will simply succumb to disaster. But I have to admit, it’s not the climate doomers who scare me—it’s the optimists.

Of course, I’d like to believe everything is going to work out in the end. But I find that often people are so completely placated by that belief that they continue to live their lives unexamined and without regard for some of the future’s darker possibilities. If we want to encourage the masses to make even small lifestyle changes like flying less or eating less meat—let alone vote for climate solutions that may come at the cost of higher taxes or other trade-offs—we need to make them understand that the stakes are very real. Both on a daily, individual basis and at higher levels, “Eh, whatever, it’s gonna be fine” is the kind of sentiment that inhibits action.

If people did grasp the urgency, I suspect we might see a big trend shift in one area: population. The decision of whether or not to have children is, obviously, a major one, with numerous contributing factors—one being the environment. Climate change, its progression, and our chances of ever stopping it are subjects that should influence population growth on both an individual level (Will this child have an adequate quality of life as the planet changes?) and a macro one (Will only the wealthy thrive on a warming planet?).

Optimists tend to reject “Malthusian” thinking, which is based on the idea that finite resources cannot support an exponentially growing population forever, instead advocating for more people instead of fewer.

It’s nice to think that more humans would mean more innovations and more chances to address the effects of climate change, but it’s just not supported by evidence. The rapid growth of our population over the past half century is correlated with a 69% drop in wildlife populations and the alteration of at least 70%—possibly up to 97%—of the world’s land. If history shows us anything, it’s that a growing human population has always meant more planetary destruction, even as new and better technologies have been developed. There’s little reason to think that this simply won’t be the case going forward.

Unfortunately, some prefer to ignore the grim reality. For example, I find self-identifying “pathological optimists,” like Elon Musk, are the ones most excited to bring humans to other planets before we’ve even figured out how to not wreck our own. This idea is bizarre for many reasons, one of which being that space colonization is supposedly an inevitable piece of our not-so-distant future. It’s not really a problem if the Earth’s resources are limited, the belief goes, because we’ll soon be expanding to other planets anyway.

Even if I were to accept that premise, this mindset still terrifies me. We haven’t yet figured out how to support the population we currently have, on the planet we currently inhabit, without causing irreparable damage to our environment and the other life forms with which we share it. Spreading the human population throughout the universe will only re-create these dire issues on a massive, universe-size scale.

To be fair, there is promising news from time to time—we learn that a certain environmental intervention did in fact make a difference for the better, or we hear of a developing technology that might offer solutions we never previously thought possible. I’m all for acknowledging our precious few victories, but we have to keep them in perspective and not invest too much faith in long-shot ideas.

Former Vice President Al Gore highlighted the risks of unfounded optimism in a recent TED Talk centered on possible climate solutions known as carbon dioxide removal (CDR) and direct air capture (DAC), which purport to remove greenhouse gases from the atmosphere once they’ve already been emitted. While a tempting idea, these technologies are pretty unfeasible at current—they don’t work as well as we need them to and they’re financially unviable.

But the most sinister effect of enthusiasm over CDR and DAC is the way oil companies seem to already be writing themselves free passes in terms of air pollution. Gore quotes an oil CEO who called these technologies a “license” for the oil industry to continue to operate as usual, indefinitely.

If the oil industry had its way, we’d abandon all efforts to cut emissions based on the (highly unrealistic) belief that we can just suck the pollution out of the air later. Listen, I desperately hope that DAC and CDR eventually become legitimate, lifesaving solutions to the climate crisis. But to assume that they will, and abandon other strategies as a result, is nothing short of magical thinking.

A recent Wall Street Journal piece calls “climate change obsession” a “mental disorder.” It’s just one piece of an aggressive gaslighting campaign—a term that’s overused but absolutely applicable in this context. For reasons ranging from economic to emotional, very legitimate fears are recast as not only inaccurate but also delusional, even a sign of insanity. If only that were true. The reality is that catastrophic thinking is completely appropriate in this case, when the effects of climate change—not only the predicted effects but the ones we’re already witnessing—are the definition of catastrophic.

When climate optimists critique panic-stricken climate-related communications as irresponsible, they of course have a point: If we’re paralyzed with fear and don’t believe that better outcomes are possible, we set ourselves up to succumb to despair rather than take action. This will mean something different for everyone, depending upon their interests and talents—organizing a protest, asking a school cafeteria to offer a vegan option, donating to an environmental charity, running for office, etc. All that matters is that we remain at least a little bit hopeful and do something.

As Michael E. Mann, professor and director of the Center for Science, Sustainability, and the Media at the University of Pennsylvania recently tweeted: “Concern, worry and alarm are often motivating. Doom and despair are not.” The sentiment of doom is that there is no hope, and that’s neither true nor useful. Sober, honest discussion about the climate should inspire concern, worry, and alarm—not enough to paralyze us, but enough to motivate us to take dramatic, unprecedented action.