If we could have picked a single person in the world to back 350.org, it might well have been Desmond Tutu.

The former Anglican archbishop of South Africa, and Nobel Peace Prize laureate, is not only perhaps the planet’s leading moral voice, but also the exemplar of global unity on tough topics. While most of South Africa’s anti-apartheid activists were in exile or underground during that nation’s struggle, Tutu used his pulpit to rally worldwide sentiment that helped turn the tide.

This morning–in USA Today, with an essay that will be reprinted in the next 24 hours in newspapers across the globe–he makes the case that the 350 movement is much the same. "People in almost all the nations of the earth are involved — it’s the same kind of coalition that helped make the word "apartheid" known around the world," he writes.

When you are in the middle of last-minute organizing for your action, or if you get out of bed tomorrow on Saturday and it’s raining and you wonder if you should bother attending an event, remember these words from Archbishop Tutu:

"In South Africa, we showed that if we act on the side of justice, we have the power to turn tides. Worldwide, we have a chance to start turning the tide of climate change with just such a concerted effort today."