Before I saw the doctor, the nurse checked my vital signs. Blood pressure: 118 over 72. Pulse: 68 beats per minute. Temperature: 98.2. All normal. In fact, 98.2 degrees Fahrenheit is as average as it gets.
"Have you considered getting a flu shot?" the nurse asked. "We're expecting it to be a bad year."
I thought back to the last time I had seasonal influenza: fever, chills, dehydration, slightly delirious thoughts. My temperature then was just a few degrees above normal, but what would have happened if it had risen a few degrees beyond that? A fever below 104 degrees isn't usually dangerous for adults, but 108 degrees can cause brain damage. That difference of 4 degrees Fahrenheit equals a little more than 2 degrees Celsius—that is, the amount of global warming that scientists and world leaders have agreed would be unsafe for our planet's health.
Two degrees Celsius doesn't sound like much, but the world's average temperature has risen less than 1 degree Celsius since the pre-industrial age, and already many regions are experiencing feverish heat waves, inexplicable cold spells, droughts, and other debilitating symptoms. Earth is a finely tuned system that can only take so much increased heat—interestingly, about the same amount as the human body can tolerate—before there are irreversible consequences.
The habitable zone. Like our own bodies, our planet is best suited to human life when it stays within a relatively narrow range of temperatures: not too hot, not too cold. Scientists scanning the heavens with NASA’s Kepler Space Telescope have detected more than 3,500 possible planets, but so far only five have been confirmed as bodies that orbit at a sufficient distance from their suns to potentially have liquid water. And even these “habitable” planets may not fall within the Goldilocks zone for human life, where the temperature is just right.
Astronauts gazing down upon our blue marble from the International Space Station have remarked on the “thin blue line” of atmosphere that traps heat and makes life on Earth possible. If humans continue to pollute that fragile layer separating Earth from the rest of the universe, we will cross a thin red line between health and suffering. Already, warming-induced disruptions in natural systems are increasing the spread of diseases such as cholera, malaria, West Nile virus, and Lyme disease.
The point of no return. Periodically, the members of the Bulletin's Science and Security Board meet to discuss the existential threats facing the world and whether they merit moving the hands of the iconic Doomsday Clock. The clock is a powerful metaphor, but its evenly spaced minutes may suggest a linear progression toward midnight. Global warming, however, may tick along incrementally and then reach a tipping point beyond which changes occur suddenly and catastrophically. At that point it may no longer be possible to pull back from the brink, as we might if faced with a looming threat from nuclear weapons. Like the frog brought slowly to a boil, we may fail to comprehend our situation until it is too late to jump out of the pot.
Climate change is already an emergency, but the White House and US Congress are not calling 911. Preoccupied with health care, they ignore the world's biggest threat to human health. They refuse to champion the radical lifestyle changes that are necessary to avoid disaster, the things your doctor would tell you: Stop smoking those fossil fuels. Eat your vegetables. Ride your bike to work. Your doctor does not advise you to wait until your health gets worse before doing anything, or quit smoking only if your neighbor agrees to do the same.
An ounce of prevention. I decided to get that flu shot, even though it wasn't covered by my health insurance. At $31.99, it seemed like a bargain if it could help me avoid missing even one day of work—and spare me from a day of misery. Perhaps more important, I wanted to avoid infecting someone more vulnerable. The CDC estimates that seasonal flu kills up to 49,000 people annually in the United States alone; seniors and young children are at greater risk. Climate change will also hit the most vulnerable people hardest: the elderly, the babies, the poor, the sick, the citizens of nations already threatened by water scarcity and crop failures and rising seas.
Like getting a flu shot, taking preventive action to reduce greenhouse gas emissions is a good investment. According to a new study by scientists at the Potsdam Institute for Climate Impact Research, delaying the implementation of comprehensive international climate policies from 2015 to 2030 would triple the short-term costs of mitigation, which would be more expensive because it would have to happen faster.
One drawback to this framing, though, is that it places economics above other goals that might conceivably unite humanity to take action on climate: justice, peace, stewardship, human health. Climate-minded politicians, business leaders, and environmentalists rarely question the supremacy and inviolability of economic growth; to the contrary, they keep up a steady drumbeat of assurances that ceaseless growth and environmental protection are compatible. In health care, however, ceaseless growth is what occurs when a person has cancer—a disease in which cells divide endlessly until they take over the body.
A healthy adult, like Mother Nature, exists in a steady state. Her weight and blood pressure and pulse do not continue to rise year after year. Her temperature remains at 98.2 degrees. Her respiratory and circulatory systems are stable. She may have some wear and tear in her joints, but it’s nothing that a little physical therapy can't help. At least that's what my doctor tells me.