The seriousness of human-caused climate change came home hard Tuesday when scientists, one from the Defenders of Wildlife, acknowledged that our official goal to protect all endangered species is obsolete.

I have covered endangered species politics and science for more than 20 years and have rarely seen wildlife advocates take such a bold position. Defending the goal of saving all the parts has been one of the bedrock values of the environmental movement. It has been official federal policy since 1973 when the Endangered Species Act was passed and included Section 7.

In other laws, federal agencies are required to provide protection "where practicable." But Section 7 of the Endangered Species Act requires agencies to take “such action necessary to ensure that the actions authorized, funded or carried out by them do not jeopardize the continued existence of endangered species.”

With that one line Congress elevated protecting endangered species – preventing extinctions – to one of the government’s highest priorities.

In 1978 the reality of their action made Congress add an exception. It gave the President the authority to convene an Endangered Species Committee, known cynically as “The God Squad,” which has the power to override Section 7 and allow a federal action to go forward even if it may result in the extinction of an endangered species.

Every time since that someone has suggested amending Section 7 out of the law the environmental community has successfully stopped it. Dirk Kempthorne, now the interior secretary, and then a U.S. Senator introduced his first version of a reform bill back in 1995 that would have weakened Section 7 but quickly offered a new bill that did not challenge this central foundation of environmental protection in the United States.

The same year authors Charles Mann and Mark Plummer suggested in their book “Noah’s Choice,” that trying to save every endangered species is an impossible goal and intellectually dishonest public policy. They proposed the federal government set up a biodiversity trust fund to ensure funding for protecting species and then to develop a workable system to make “Noah’s Choice.”

That idea went against what biologists Aldo Leopold said in his classic 1940s essay, "Round River," Aldo Leopold made the case for conserving biological diversity: "saving all the parts’ of the natural world. "To keep every cog and wheel is the first precaution of intelligent tinkering," Leopold wrote.

Section 7 was the legal embodiment of what has been shortened to be described as the “precautionary principle.”

Unfortunately, “where practicable” had often failed as a protection for the environmental values that society shares. The Endangered Species Act was supposed to be the emergency room of wildlife and habitat protection.

But since the 1980s, the law, especially Section 7, has been the main tool for stopping or altering actions that kill species or destroy habitat. Judges have more often than not been the people who have been asked to make “Noah’s choice” and they have rightly deferred to Section 7.

But conditions have changed dramatically since 1995. The recognition that no matter what we do over the next 50 years we will lose between 20 and 40 percent of all know species forces a new debate.

If global warming is the crisis environmentalists say it is then the world is going to have to shift its priorities. If we take the actions climate scientists say we must and dramatically reduce greenhouse gases we can reduce the long term impacts, i.e. 100 to 200 years from now.

Environmental scientists like Jean Brennan, a climate scientist with the Defenders of Wildlife, say we have to focus our resources on protecting and preserving as many species as we can. We have to look forward, not backward. We have to protect corridors. We must, as author Rachael Carson did in the 1960s demonstrate that protecting biological diversity is necessary to preserve our own quality of life and indeed existence.

And now, she said we have to rebuild the institutions, laws and bureaucracies we’ve used in the past to meet this new challenge. She told Pacific Northwest resource managers, activists and others Tuesday that includes facing “Noah’s choice.”

But making society make the tough decisions without Section 7 is no more appealing. Somehow a system has to be created that is better that “where practicable.”

I expect environmentalists to react in the same way the Bush administration acted eight years ago when scientists told them that climate change was taking place and it should act. That makes her and Jeff Burgett, a biologist for the U.S. Fish and Wildlife Service, who said the same thing, as courageous as federal climate scientists like James Hansen, who stuck with their message despite the threat to their careers.

That Brennan and Burgett consider the threat to species so serious they would say what they did should be a signal to people who love the song birds, salmon, forest mammals and even game animals that enrich our lives, they too must be prepared to take risks to protect them.