So the Earth will die. It makes me sad -- like losing a good friend. Earth’s been good to me. Of course I may not be here for the memorial service – it looks to be a billion years out. As the sun brightens, average temperature will go up to 158 degrees, the oceans will evaporate and only a few microbes and bacteria will survive. It gets worse. Earth will then heat up to 842 degrees, wiping out all life on its way to melting. Ultimately, about five billion years from now, the sun will burn out – Earth exit stage left, curtain. So say Iain Stewart and John Lynch in “Earth The Biography” (page 224).
As far as a place to live, Earth is in its late middle age. Life began shortly after Earth was born about 4.5 billion years ago. So from a habitable perspective, translating into an 80-year human lifespan, the planet would be about 65 – just a little older than me.
But humans haven’t been around all that long. The authors cite three ways to put human existence into perspective (page 51). First, they reference Stephen Jay Gould’s translation of Earth’s history into a 24-hour day. Dinosaurs show up after 11:00 PM and are gone in 20 minutes. Modern humans show up two seconds before mid-night with civilization showing up in the last tenth of a second of the day. Second, they refer to John McPhee using the analogy of an old English yard – from the King’s nose to tip of the middle finger of his out-stretched hand. Human history is wiped out by one stroke of a nail file. Finally, Mark Twain, less mathematically precisely, equated man’s existence as the “skin of the paint on the pinnacle knob” of the Eiffel Tower and commented that “anyone would see that that skin is what the tower was built for.”
Obviously, the Tower wasn’t built for the skin of the paint and the Earth wasn’t made for human kind. But we act that way. We may not be able to avoid the sun brightening in a billion years, but let’s not do anything to accelerate the process, thank you.
Being a late middle-ager myself, I identify with the good old Planet Earth. I know that if I’m not careful, I won’t make it to the end of my optimal life span. Unlike me though, Earth will make it, somehow, to the end. Earth will be here, in some form, when the switch is flipped and sunlight goes off. Life forms will not be so lucky.
So, “Save the Earth” seems to be the wrong motto. I think it should be “Keep Earth Habitable.” Only by paying attention to and mitigating human impact on the atmosphere and the complex interactions of systems that affect it will we be able to take full advantage of the next billion years.
So, here’s to another five hours on the clock. Here’s to a foot-long fingernail. Here’s to some really thick paint. Here’s to a full life and a ripe old age – for me and for my good buddy Planet Earth.