The End of the World in Numerical Terms: a +2°C climate scenario in the year 2100

This is the way that it starts.

A rise in two degrees Celsius, a difference imperceptible on the skin. A globally
determined target maximum, it should be noted, with a predicted five percent chance of success
by the end of the century. In other words, in words not numbers: this is if things go improbably well.

First, we’ll see it in the oceans. They’ll rise, by several meters, as higher temperatures
cause seawater to expand and ice mass from land to melt increasingly faster, and the forty
percent of the US population that lives in coastal areas (say, Miami; say, Boston) will first be
inconvenienced with nuisance flooding, contaminated water, faulty sewage systems and stalled
public transit. Then nuisance will shift, impalpably or otherwise, to danger, and danger will give
way to mass evacuations, migrations with no determined point of arrival. Low-lying countries
like the Maldives will be entirely submerged, and cities like Bangladesh that have suffered
disproportionately rapid sea-level rise will see fifty million people displaced. (As you read this,
forget your address. Burn the things you own and have held onto, or drown them, or leave them.
Tell no one where you’re going.)

As the ocean absorbs more carbon dioxide, it will also acidify by an estimated 170%.
Ocean biodiversity will plummet as the pH of the ocean becomes its most acidic in 200 million
years, and the pH of marine animals’ brains will accordingly change. The black-finned
clownfish, for instance, will lose its hearing and sense of smell, and with both, its ability to
detect predators. Most reefs, habitat to a million species and a fourth of all fish, will be eroded
faster than they can grow, and will die. (As you read this, turn on all your faucets and plug your
drains. Leave home, leave the water running. If you’re too exhausted, isn’t everyone exhausted?Lie on the floor of your living room and wait.)

As permafrost melts, mountain ranges will become increasingly susceptible to landslides.
Natural disasters will multiply and strengthen; tropical regions in Central and South America
will face up to six separate climate hazards at the same time. Twenty to thirty percent of global
land surface will become arid, priming new regions for wildfires and drought. Parts of the US
Southwest, Iran, India, Bangladesh, Ethiopia, Libya, Australia and China will become too hot to
safely live in. So much as standing outside for a few hours in cities like Dubai and Abu Dhabi
will be deadly. (As you read this, cup the soft of your palm around your apartment’s pipes, the
ones that clang with unpredictable jolts of heat. Keep your hand there until you smell burning,
don’t pull away.)

At least ten percent of the world’s population will be displaced: climate refugees (of
whom there will already be two hundred million in the next thirty years) will need legal
recognition and basic resources. A third of all life on Earth will face extinction. This is if all
things go well, shockingly well. (As you read this, tread water. Keep treading.)

This is the way that we end the world. (Are you underwater yet?)