In a recent memo, Bill Gates declared that climate change “will not lead to humanity’s demise. People will be able to live and thrive in most places on Earth for the foreseeable future.” He decried a “doomsday outlook.” Similarly, climatologist Michael Mann and pediatrician Peter Hotez have denounced a “doomism” that is “marked by dramatic but unsupported claims of collapsing ice sheets, runaway warming, and imminent extinction.”
But is there valid evidence for a climate change trajectory that could lead to human extinction?
Central to such a trajectory would be a relentless rise in atmospheric carbon dioxide levels from fossil fuel burning. High emission levels are continuing, but regardless of whether carbon dioxide emissions go up or down, carbon dioxide levels will continue to rise. Such rise continues because a large fraction of emitted carbon dioxide has a hellishly long atmospheric lifetime—measured in centuries. And millennia will pass before the carbon emitted today will be thoroughly absorbed. Thus, carbon dioxide levels have steadily risen and will continue to do so. And this rise will produce an increase in global temperatures that is accelerating.
Driving this increase will be unabated production of fossil fuels, as well as high demand. Such demand will continue because no nation will take the enormous political and economic risk to cut back on fossil fuel production—as evidenced by the weak agreement from the international COP30 climate conference that did not even mention the role of fossil fuels in climate change. Fossil fuels will remain indispensable because they produce the vast majority of the energy that underpins the global economy, providing food, shelter, transportation, and other necessities. Only a small percentage of energy comes from renewable sources.
The climate consequences of the increases in global carbon dioxide level and temperature have been drastic. For example, wildfires are on the rise, The Great Barrier Reef faces demise, the Amazon rainforest ecosystem could rapidly collapse, and Antarctic and Greenland ice sheets and glaciers are melting.
Such looming catastrophes have led scientists to warn of “tipping points” beyond which those systems would not recover. However, those tipping points have already been passed due to the overwhelming momentum of such changes: Once the drought conditions driving vast wildfires arose, they will not fundamentally improve. Once increased ocean temperature and acidity began to kill coral reefs, they will not return to historically safe levels. Once deforestation and climate-caused drought began to destroy the Amazon rainforest, they will not reverse. Once global ice melting began, it will not stop. The Earth will not get cooler. Feedback loops accelerate these processes. Wildfires release carbon dioxide, increasing atmospheric concentrations. When rainforests die, they give way to hotter, drier savanna that generates less rain. Melting ice exposes darker heat-absorbing ocean water and land.
Unchecked fossil fuel production with the consequent rise in carbon dioxide levels will result in a temperature warming of from 2.1 to 3.3 degrees Celsius by the end of the century under current policies. This rise will continue, given past failures to reduce production. For example, with a 4-degree increase, wrote environmental biologist Rachel Warren, “The limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptation for natural systems would largely be exceeded throughout the world. Hence, the ecosystem services upon which human livelihoods depend would not be preserved.” If all known fossil fuel resources are burned, an up to 10 degrees of warming has been forecast by researchers Katarzyna Tokarska and colleagues.
Among the consequences of increasing temperatures: heat waves, megadroughts, wildfires, floods, superstorms, increased environmental toxicity and disease, war, and societal collapse.
So, why are Gates, Mann, and Hotez loath to entertain the possibility of human extinction from climate change? For one thing, scientists such as Mann and Hotez are neither engineers, economists, nor political scientists. They have an innately narrow expertise that leads them to discount the massive technological, economic, and political barriers to abandoning dependence on fossil fuels.
Gates recognizes his shortcomings, writing in his book How to Avoid a Climate Disaster, “I think more like an engineer than a political scientist, and I don’t have a solution to the politics of climate change.” He does recognize the unprecedented nature of the technological revolution he espouses, writing, “We need to accomplish something gigantic we have never done before, much faster than we have ever done anything similar. To do it, we need lots of breakthroughs in science and engineering. We need to build a consensus that doesn’t exist and create public policies to push a transition that would not happen otherwise. We need the energy system . . . to change completely and also stay the same.”
Besides their limited expertise, they may also seek solace in an anxiety-reducing “optimism bias,” in which people overestimate the likelihood of positive events and underestimate the likelihood of negative events. They may also experience “apocalyptic blindness”—a concept proposed by philosopher Günther Anders—in which we are unable to imagine the end of our history.
As journalist George Monbiot declared succinctly, such optimists “have failed to grasp the nature of either Earth systems or the political economy that bears upon them. These men are not climate deniers; they are politics deniers.” Monbiot charged that they spin “a simple story with a happy ending, telling power what it wants to hear, this is the Disney version of environmental science.”
In fact, given the stark realities of climate change, one can legitimately argue that a trajectory toward human extinction is the very one we are on now.
Dennis Meredith is author of The Climate Pandemic: How Climate Disruption Threatens Human Survival
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