Twenty-five years ago a group of 1,700 independent scientists, most of them Nobel laureates, joined the Union of Concerned Scientists in issuing a manifesto called the “World Scientists’ Warning to Humanity.” It was pretty much as dire as it sounds. Gathering together the latest data on environmental destruction and future projections, the paper noted that “a great change in our stewardship of the earth and the life on it is required if vast human misery is to be avoided.”

So how have things gone since 1992?

Pretty dismally.

An update to the manifesto was published in BioScience on November 13 of this year, and the data isn’t looking so great. The main dangers today are pretty similar to what they were then: climate change, population growth, deforestation, species extinction, and access to clean water. Human numbers have increased by 2 billion (35 percent). Close to 121 million hectares (300 million acres) of forest have been cut down. The amount of fresh water available per person has dropped by 26 percent. So there’s a lot going wrong in the environment.

It’s not all doom and gloom, though. For one thing, ozone depletion since 1992 has declined, proving that positive actions can have an effect on the environment when they’re thoughtfully and systematically carried out. The researchers also note that world poverty and hunger have decreased. Education of women and girls has increased. And there’s been rapid growth in the renewable energy sector.

The 15,000 scientists from 184 different countries who signed the “second notice” readily admit that change can’t happen without buy-in from a variety of areas. Civil-society pressure, evidence-based advocacy, political leadership, and an understanding of the market drivers behind our environmental choices all have an impact on what policies are put into place. Still, they remain cautiously optimistic.

“With a groundswell of organized grassroots efforts, dogged opposition can be overcome and political leaders compelled to do the right thing,” the manifesto states.

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