As fall weather bleeds into winter, it can be hard to remember that humanity just experienced its hottest summer in recorded history. We now hear news of billion dollar climate disasters on a regular basis, whether it's heatwaves or flash floods or wildfires. Of course, all these things happened before the Industrial Revolution, but the amount of heat we've added to the planet has supercharged these natural events, making them more destructive and more common.
And things are just getting started. As humans continue to emit greenhouse gases from fossil fuels into the atmosphere, extreme weather events like heatwaves, floods and tropical storms will become increasingly common, according to climate models that we are sadly proving right.
But does that mean the entire Earth will literally become uninhabitable? Perhaps not, according to scientists who spoke with Salon, but at the very least, large sections of the planet will undergo radical, life-altering changes thanks to climate change. Indeed, we are already seeing the beginning of a future where highly populated regions are rendered — if not literally uninhabitable — then at the very least far more challenging to live in.
"Areas that are already experiencing significant heat will likely become uninhabitable but these locations will spread further north, such as into southern Europe and southern U.S. states," Julienne C. Stroeve, professor of polar observation and modelling at the University of Colorado Boulder, told Salon by email. She described a talk during the World Climate Research Programme meeting, "where scientists are looking at what a heat wave would have been in a 1° C [about 1.8° F] colder or say a 4° C [about 7.2° F] warmer world. And the example from Germany showed the heat wave recently experienced would have risen from 40° C [104° F] to 47° C [117° F], which would lead to people likely dying."
Jonathan R. Buzan, a postdoctoral climate researcher at the University of Bern, Switzerland, elaborated on the implications of rising heat, explaining that it is not easy to determine precisely how different regions will be impacted. Some areas will be more affected than others but we can begin to understand how using a metric called "wet bulb temperature," which is temperature measured by a wet thermometer in the shade as water evaporates off it. This is a better way of measuring heat stress than a regular thermostat. In some places not as used to extreme temperatures, wet bulb conditions can quickly become lethal.
"Above 40°C (104°F), dry heat impacts humans significantly, but below 40°C, high wet bulb temperatures can dominate," Buzan explained, emphasizing that this makes it hard to predict where will become uninhabitable. "The expected exposure to moist heat (high wet bulb temperatures) is supposed to increase exponentially relative to dry heat."
As a result, Buzan said, areas that will be harder to live in due to heat include "monsoonal regions (such as India/Pakistan/South East Asia) [that] have the highest combinations of moist and dry heat, and are likely to become physically straining first."
Bruce H. Raup from the National Snow and Ice Data Center at the University of Colorado warned about another factor that heavily bears on a region's inhabitability during climate change, namely "that once a place dries significantly (soil moisture drops and surface water evaporates), it can get a lot hotter quickly. That's because the energy that was going into evaporating water now goes into raising the temperature of the surface and near-surface air."
As all of these heat-related weather events build up one on top of the other, humans will struggle to survive in ways that are difficult to anticipate. Buzan drew attention to a recent study from the Journal of Thermal Biology which shows a growing epidemic of Chronic Kidney Disease in low latitude countries potentially caused by increased heat, as well as a study from the Annals of Medicine and Surgery which found an increase in disease outbreaks in flood-ravaged Pakistan.
"What I am wishing to highlight is that there are many unknown consequences of climate change in association with heat exposure; both short duration from heatwaves, but also long term exposure from seasonal, and with enough climate change, yearly exposure," Buzan explained to Salon.
Heat waves aren't the only factor making large regions of Earth harder to survive in. As Buzan also observed, "island nations are the first to be impacted by sea level rise. Agreements to relocate populations are already in effect. There is work towards development island rising to offset the effects of sea level change. But this isn’t to say that coastal areas are not impacted. Miami spends enormous amounts of money on pumping water out of the city due to sea level rise."
According to Walt Meier, a Senior Research Scientist at the CIRES/University of Colorado National Snow and Ice Data Center, sea level rise (SLR) will not be uniform around the world. There are global averages given in projections, but they can vary regionally "depending on local sea level and land subsidence or uplift."
Meier added that he would prefer the term "less inhabitable" rather than "uninhabitable," since humans could adapt to some of the changes they experience. Yet the questions remains of whether it is worth it to, for example, build levees and raise coastal elevation for areas that experience regular flooding due to sea level rise.
"These are very high cost adaptations," Meier wrote to Salon. "Is it just less expensive to abandon inhospitable environments? In many cases, probably yes."
Climate change will also pound regions of the Earth with intensified storms. Raup shared an analogy that "if you raised the floor of a basketball court by 4 inches, you'd expect more slam dunks. You expected some before, but now you expect more because the hoop is within easier reach of more players. Similarly, raising the average temperature of the atmosphere and the surface waters in the ocean provides a boost of energy to weather systems, and allows more water vapor to be in the atmosphere."
While Buzan said it is "extremely difficult" to anticipate which regions will become uninhabitable due to intensified storms, he observed that "hurricanes are likely the type of storms that will cause consistent problems. However, as we’ve seen with extreme rainfall recently in Pakistan or in Germany, one can have extreme rainfall that causes widespread damage, but that does not mean that it will happen again or frequently."
He added, "The connection to extreme rain and disease, however, should not be overlooked. Water that is not cleared efficiently can quickly become a breeding ground for disease and parasites."
While these sobering developments could trigger climate despair, the experts who commented for this article insisted that "uninhabitability" is a potentially damaging framework through which to view the question of climate change. Instead of "uninhabitable," it may instead be useful to think of the world as being "harder to inhabit."
"A strictly climate determinism perspective is limiting and distorts reality," Matthew Huber, professor at the Department of Earth, Atmospheric and Planetary Sciences at Purdue University, wrote to Salon. "From the perspective of severe weather/climate or drought, Northern Canada and Las Vegas are uninhabitable. Most of the Netherlands is below sea level, so it is uninhabitable by simple sea level metrics. But people can build the necessary infrastructure to make a region inhabitable."
According to Huber, the more important question is, "Do the regions that are negatively impacted by climate change have the resources (money, technology, institutions, culture, political will) necessary to keep regions habitable and will they make the decision to do so?"
While he acknowledged that in some cases a place like an island nation may literally become uninhabitable, Huber said use of the term is generally harmful because it can lead to writing off large parts of the globe.
"Once one has labelled a region as such, it leads to a cognitive switch in which many people will start blaming the people who live there for living in a region that 'everyone knows' is uninhabitable," Huber said. "This becomes a blame-the-victim situation which simultaneously erases the responsibility of those who can afford to provide the necessary resources to maintain habitability and agency of those who would attempt it."
CORRECTION: This story has been updated to include more accurate temperature conversions to Fahrenheit.
