WASHINGTON — The world has long talked about the importance of preserving the diversity of life on Earth for the sake of beauty and wonder, or in the hopes of new medical discoveries, or for moral reasons.
Now a group of scientists reports that biodiversity helps sustain human life.
There are direct measurable impacts on human prosperity and human well being, said Bradley Cardinale of the University of Michigan, the lead author of a team of 17 ecologists who reviewed hundreds of experiments conducted over the past 20 years. That places conservation in a whole other ballpark.
The report cited a number of ways in which biodiversity the variety of species, genes and traits has practical value.
For example, genetic diversity within a species can increase the yield of commercial crops. Diversity of tree species increases production on timber plantations. More fish species mean more stable yields for fishermen.
Diversity in the types of plants that grow together also can make the plants more resistant to disease and invasive species, and in some cases make them pull more carbon dioxide out of the atmosphere.
The first Earth Summit, in Rio de Janeiro, Brazil, in 1992, warned that human actions were destroying habitats and reducing biodiversity at an alarming rate. New evidence has shown that biodiversity loss is continuing, often at increasing rates, the report said. At this pace, scientists estimate that one-third to one-half of all species could be lost permanently in about 100 years.
Cardinale said that the report was meant as a warning. The journal Nature published it this week in advance of an international conference on sustainable development, known as Rio+20, later this month.
The rate of extinction for organisms weve been able to document is about 1,000 times faster than what occurs in the fossil record, Cardinale said in an interview.
Our paper is basically saying, look, if those hundreds of thousands of species go extinct, youre going to feel it in your pocketbook. Its going to affect food production, its going to affect climate all those things we care about, he said. And theres overwhelming scientific evidence to support it.
David Hooper of Western Washington University, another one of the authors, said he hoped it would influence world leaders.
Where I live, around Puget Sound in Washington state, its one of the most beautiful areas in the world and, in fact, that natural beauty is a source of local pride, tourism dollars, and natural resources, such as clean water and fisheries. Even so, we have at least 25 species threatened with extinction, ranging from small wildflowers to Chinook salmon and Orca whales, Hooper wrote in an email.
Many other species are declining as a result of habitat loss, overharvesting and environmental degradation caused by humans, he added. While some of those species might disappear with barely a whisper, others are hugely important ecologically, economically and culturally.
In the past, theres been some controversy among scientists about what the impacts of biodiversity loss will be, Hooper said. The authors of this report come from across the spectrum of perspectives on these issues, he said. They drew together results from many studies to arrive at the key findings and questions for future work.