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The impacts of global climate change are here with soaring temperatures, stronger hurricanes, intensified floods and more severe wildfire season. Scientists warn, ignoring global climate change will yield “untold suffering” for humanity. But if things are getting that much worse, could global climate change make humans go extinct?
Scientists predict a variety of devastating scenarios if global climate change isn’t kept under control, but if we consider the direct impacts and then there’s some good news; it’s unlikely to cause our extinction.
“There is no evidence of climate-change scenarios that might render human beings extinct,” said Michael Mann, a distinguished professor of Atmospheric Science at Penn State & author of “The New Climate War: The Fight to require Back Our Planet“ (PublicAffairs, 2021).
However, it’s possible that global climate change will still threaten the lives of hundreds of millions of people, like by resulting in food & water scarcity, which has the potential to trigger a societal collapse and set the stage for global conflict, research finds.
Too hot to handle?
Humans are increasing the quantity of greenhouse gases like carbon dioxide (CO2) & methane (CH4), within the atmosphere through the burning of fossil fuels & other activities. These gases trap & hold heat from the sun, causing global temperatures to rise and therefore, the climate to vary much faster than it otherwise would, putting humanity on a dangerous path.
A runaway greenhouse effect is the only way global climate change impacts could directly cause human extinction, consistent with Luke Kemp, a Search Associate at the Centre for the Study of Existential Risk at University of Cambridge in United Kingdom. This effect happens when a planet is caught in an unstoppable, positive-feedback loop of warming & absorbs more heat than it loses, until the planet’s oceans evaporate and it can no longer sustain life.
Fortunately, runaway greenhouse effect isn’t a plausible global climate change scenario on Earth. For the effect to occur, a planet needs CO2 levels of a few of thousand parts per million (Earth features a little over 400 parts per million) or an enormous release of methane, and there is no evidence for that at this point, Brian Kahn, a Search Scientist at NASA’s Reaction Propulsion Laboratory, told NASA in 2018.
Venus has the runaway greenhouse effect, but it’s much closer to the sun & features a much thicker, carbon dioxide rich atmosphere that traps more heat than Earth’s. The science does not support the notion of runaway warming scenarios, although climate doomists often make such claims, Mann said. “There is no reason to exaggerate the climate threat. The truth is bad enough & reason enough to take dramatic action.”
According to Mann, global temperature increases with 5.4 degrees Fahrenheit (3 degrees Celsius) or more could lead on to a collapse of our societal infrastructure and large unrest & conflict, which in turn, could lead on to future that resembles some Hollywood dystopian films.
One-way global climate change could trigger a societal collapse by creating food insecurity. Warming the earth features a range of negative-impacts on food production, including increasing the water deficit and there-by reducing food harvests. Food production losses can increase human deaths & drive economic loss & socio-political instability, among other factors, which will trigger a breakdown of our institutions and increase the danger of a societal collapse, consistent with a study published Feb. 21 in the journal Climatic Change.
Past extinctions & collapses
Kemp studies previous civilization collapses, and the risk of global climate change. Extinctions & catastrophes almost always involve multiple-factors, he said, but he thinks if humans will extinct, global climate change would likely be the most culprit.
“If I am to say, what do I think is that the biggest-contributor to the potential for human extinction going towards the future? Then climate change, no doubt,” Kemp said.
All of the main mass-extinction events in Earth’s history have involved some kind of climatic change, consistent with Kemp. These events include cooling during Ordovician-Silurian extinction about 440 million years ago that exhausted 85 percent of species, and warming during the Triassic-Jurassic extinction about 200 million years ago that killed 80% of species. And more recently, climate change affected the fate of early human relatives.
While Homo sapiens are obviously not extinct, “we do have a track-record of other hominid species going extinct, like Neanderthals,” Kemp said. “And in each of those-cases, it appears that again, climatic-change plays some kind of role.”
Scientists do not know why Neanderthals went extinct about 40,000 years ago, but climatic fluctuations seem to broke their population up into smaller, fragmented groups and severe changes in temperature affected the plants & animals they relied on for food, consistent with Natural Museum in London. Food loss, driven by global climate-change, may have also led to a small drop by Neanderthal fertility-rates, contributing to their extinction.
Climate change also played a role in the collapse of past human civilizations. A 300-years long drought, for instance, contributed to the downfall of ancient Greece about 3,200 years ago. But Neanderthals disappearing & civilizations collapsing don’t equal human extinction. After all, humans have survived climate fluctuations in the past & currently live everywhere the planet despite the increase & fall of various civilizations.
Homo sapiens proven themselves to be highly adaptable & ready to deal with many various climates, be they hot, cold, dry or wet. We will use resources from many various plants & animals and share those resources, along with information, to help-us survive during a changing world, consistent with the Smithsonian’s National Museum of Natural History.
Today, we live in a global interconnected civilization, but there’s reason to believe our species could survive its collapse. A study published on July 21 within the journal Sustainability identified countries presumably to survive a global societal collapse & maintain their complex way of life. Five island countries, including New Zealand & Ireland, chosen as they might remain habitable through agriculture because of their relatively cool temperatures, low weather variability and other factors that make them more resilient to climate-change.
New Zealand would be expected to hold-up the simplest with other favorable conditions, including a low population, large amounts of good-quality agricultural land & reliable, domestic energy. So, even-if climate change triggers a global civilization collapse, humans will likely be ready to keep going, at least of in some areas.
Turning on ourselves
The last scenario to think about is climate-driven conflict. Kemp explained that in the future, a scarcity of resources that diminish due to climate change could potentially create conditions for wars that threaten humanity. “There’s reasons to be concerned that as water resources dry up & scarcity becomes worse and general conditions of living today become much worse, then suddenly, threat of potential nuclear war becomes much higher,” Kemp said.
Put another way, global climate change impacts won’t directly cause humans to go extinct, but it could lead on to events that seriously endanger many millions, if not billions, of lives. A 2019 study published in the journal Science Advances found that a nuclear conflict between just India & Pakistan, with a small-fraction of the world’s nuclear weapons, could kill 50 million to 125 million people in those two countries alone. Nuclear war would also change the climate, like-through temperature drops as burning cities fill the atmosphere with smoke, threatening food-production worldwide and potentially causing mass starvation.
What’s next?
While avoiding complete extinction does not sound like much of a climate-change silver lining, there’s reason for hope. Experts say, it is not too late to avoid the worst-case scenarios with significant cuts to greenhouse gas emissions.
“It is up to us,” Mann said. “If we fail to-reduce carbon emissions substantially in the decade ahead, we’re likely committed to a worsening of already dangerous extreme weather events, inundation of coastlines round the world due to melting ice & rising sea-level, more pressure on limited resources as a growing global population competes for less food, water & space due to climate-change impacts. If we act boldly now, we’ll avoid the worst impacts.”
