Author Alan Weisman considers the effects of a world free of the burden of 6.6 billion humans in a speech at the Science Center yesterday.

What if humans were suddenly wiped off the face of this earth?

That is the question Alan Weisman tackled yesterday in a talk at the Science Center about his best-selling book, “The World Without Us.”

The book is an effort to reach out to people who are normally wary of reading about ecological problems, Weisman said.

“The idea was to get around the primordial fear that we all have when we hear about the environment and think, is this going to kill us,” Weisman said. “In my book, we get beyond this concern because we’re all dead by page one.”

Once it gets beyond the end of mankind, the book examines how the earth would react without the daily pressure of 6.6 billion humans.

After extensive travel and research, Weisman concluded that nature eventually would rehabilitate.

“No matter how much we have ravaged the landscape, no matter how contaminated, nature finds a way to make the world its own once again,” Weisman said.

During the talk yesterday, Weisman explained several examples of nature’s capacity for recuperation.

At the top of his list was the fate of New York City. According to subway operators, civil engineers, and botanists, Gotham would see its subways flooded within two to three days, bridges collapsed within two to three centuries, and thriving full fledged forests within two to three millennia.

Weisman also described the surprising state of the region around Ukraine’s Chernobyl nuclear power plant, which exploded in April 1986. Despite high levels of radioactivity in the area, biodiversity is flourishing and species are procreating.

For Weisman, these examples show that while humans have irrevocably altered the earth’s ecosystem, the evolution of life will continue.

Yesterday’s event was the first in a series of discussion-based talks called Green Conversations that are to be held this year by Harvard University Center for the Environment (HUCE). The goal of these conversations is to invite a broad variety of players in the environmental arena to come speak at the University, according to Daniel P. Schrag, director of HUCE.

When asked about the subtle moral message of his book, Weisman replied, “As a journalist I don’t preach, I simply show the facts, and the facts speak for themselves. Life will go on. My concern frankly is for us.”

At least one audience member seemed to share Weisman’s concern.

“We have hard times ahead of us, and need to come to terms with the fact that we’re not the only things in this universe,” said Scott Paradise, who lives in Cambridge.