The next 50 years will bring tech­no­log­i­cal, social and geopo­lit­i­cal change greater than we can imag­ine, says Astronomer Royal Mar­tin Rees, but the emerg­ing prob­lems of pop­u­la­tion growth and cli­mate change make this cen­tury arguably the most impor­tant in Earth’s 4.5 bil­lion year his­tory, even from the per­spec­tive of an astronomer.

It’s some­times wrongly imag­ined that astronomers, con­tem­plat­ing times­pans mea­sured in bil­lions, must be serenely uncon­cerned about next year, next week and tomor­row. But a “cos­mic per­spec­tive” actu­ally strength­ens my own con­cerns about the here and now.

Ever since Dar­win, we’ve been famil­iar with the stu­pen­dous times­pans of the evo­lu­tion­ary past. But most peo­ple still some­how think we humans are nec­es­sar­ily the cul­mi­na­tion of the evo­lu­tion­ary tree. No astronomer could believe this.

Our sun formed 4.5bn years ago, but it’s got 6bn more before the fuel runs out. And the expand­ing uni­verse will con­tinue — per­haps for ever — becom­ing ever colder, ever emp­tier. As Woody Allen said, “Eter­nity is very long, espe­cially towards the end”. Any crea­tures who wit­ness the sun’s demise, here on Earth or far beyond, won’t be human. They will be enti­ties as dif­fer­ent from us as we are from a bug.

But even in this “con­certi­naed” time­line — extend­ing mil­lions of cen­turies into the future, as well as into the past — this cen­tury is spe­cial. It’s the first in our planet’s his­tory where one species — ours — has Earth’s future in its hands, and could jeop­ar­dise not only itself, but life’s immense potential.

As Richard says (via), the arti­cle “seems to be a trun­cated ver­sion of his book Our Final Cen­tury”.