Astronomers warn "There's no planet B"

Astronomers usually look to the stars and think about time in terms of billion of years, but recently thousands of them joined together to call for climate action now to preserve the habitability of our one and only Planet Earth.

Last July, under the aegis of Astronomers for Planet Earth, more than 2750 astronomers and astrophysicists from 87 countries signed an open letter focusing attention on and urging immediate and substantial steps to address our current climate crisis.

Earth from Space (Credit: NASA)

"Comprehensive scientific evidence clearly demonstrates that we are living in a climate emergency that calls for urgent action," they warn. If we fail to significantly and continuously reduce global carbon emissions "... we will face both a biodiversity crisis through mass extinctions, and a humanitarian crisis from increasingly inhospitable living conditions."

They add that "... at our current rate of emissions... we are failing to prevent this disaster."

The astronomers also point out that while there may be billions of potentially habitable planets in our galaxy, the Milky Way, not one is within our reach, and even if one were, we have no way to move Earth's 7.75 billion people to it. As one of the signatories, Travis Rector, at the University of Alaska Anchorage explains, "Unfortunately the term 'habitable zone' does not necessarily mean that a planet in this zone is habitable. It simply means that it could in principle have the right conditions for liquid water to be on its surface. It doesn't mean that there actually is water, or that there is life, or that we could actually live there. And even if we could, these exoplanets are so far away we couldn't possibly relocate to them. Mars at its closest is about four light minutes away from us. The nearest star is over four light years. Compare four minutes to four years and you'll get a sense of how much bigger that is. And we can't even yet get one human to Mars, much less all of humanity! It is clear that there truly is 'no Planet B'."

To lead by example, the signatories, who read like a Who's Who of researchers in the field, urge astronomers and their institutions to reduce their own carbon footprint, for example by minimizing the large amount of energy used in computation, and to make environmental sustainability an immediate and primary goal.

Beyond setting an example in their own field and institutions, the astronomers warn that similar steps to reduce carbon emissions and move towards sustainability are urgently needed worldwide. "The climate crisis reaches beyond country borders and individual communities," they point out.

Perhaps nobody has said this more eloquently than the late Carl Sagan, who wrote, "When you look at the Earth from space, it is striking. There are no national boundaries visible. They have been put there, like the equator and the Tropic of Cancer and the Tropic of Capricorn, by humans. The planet is real. The life on it is real, and the political separations that have placed the planet in danger are of human manufacture. They have not been handed down from Mount Sinai. All the beings on this little world are mutually dependent. It's like living in a lifeboat. We breathe the air that Russians have breathed, and Zambians and Tasmanians and people all over the planet. Whatever the causes that divide us, as I said before, it is clear that the Earth will be here a thousand or a million years from now. The question, they key question, the central question, in a certain sense the only question, is, will we?"

Who better to urge us to act now to preserve our only home, Earth, than those who study the stars?