I am inspired by students from Dalhousie University in Halifax who have been getting tattoos. These are simple tattoos, just three digits, placed somewhere conspicuous. The number is the concentration of carbon dioxide in the Earth’s atmosphere in their birth year. Were I inclined to get a tattoo, mine would be 319.
Since my birth year, I and billions of other humans on the planet have added carbon dioxide and other greenhouse gases to the atmosphere much faster than natural processes can remove them. Children born today would need a tattoo with the number 409. In my lifetime we have increased the CO2 concentrations nearly 100 parts per million. That concentration is now higher than it has been in at least hundreds of thousands, probably millions of years, if geologists are to be believed. And I believe the geologists.
The evidence is overwhelming and there is scientific consensus. Human behavior has changed the fundamental chemistry of the atmosphere resulting in changes in multiple global systems. Climate change deniers, including some in the current administration apparently, choose to ignore the science.
The other number I should have tattooed is 2.6 billion, the estimated size of the human population in my birth year. That number has nearly tripled and today stands at approximately 7.5 billion humans.
Concern about global population growth was a central tenet of the environmental movement of the 1970s, a time when I became aware of many of the issues that we continue to wrestle with today. There were famous fights among environmentalists about the significance of population growth, notably the one between Barry Commoner and Paul Ehrlich. Yet in the end, there was no question that there were limits to how many humans the planet could support without irreparable damage being done. When did we stop worrying about population growth?
The quality of the environment was, of course, not just a function of the numbers of humans. The fact is that more humans are living materially richer lives than at any time in our species history. And few humans in history have lived as well as the majority of Americans did over the past 65 years. We have been among the richest of the rich.
My two numbers are inextricably linked. The increase in CO2 concentrations from 312 to 409 parts per million in the atmosphere is a direct result of an extra 4.9 billion people, many living longer and more prosperous lives.
So the obvious place for me to have my tattoos is on my forehead:
312 — 2,600,000,000
Then, every time I look in the mirror I will be reminded of my role in creating global change. And the obvious place for your tattoo is your forehead. Then every time you and I see each other we will be reminded of our collective responsibility for changing the climate and other planetary processes.
Then we will remember that we got into this predicament together and it is only by working together that we fix the problems we have created. I had argued in an earlier blog that the Paris climate agreement was likely to fail. For me, the problem was that it did not go far enough to address the underlying forces creating global change. I do not believe walking away from global agreements is the answer.
No nation is more responsible for global change than we are and there is no more important ethical obligation facing us, collectively and individually, than accepting this responsibility.
So what numbers go on your forehead?