Climate Change, Biodiversity, and the Importance of Prairie Conservation: an Interview with Dr. Peter Raven

June 1, 2020 | Blog, Missouri Prairie Journal Articles

By Carol Davit, Executive Director, Missouri Prairie Foundation 
Photo: Dr. Raven in his office by Carol Davit

Dr. Peter H. Raven, President Emeritus of the Missouri Botanical Garden and Honorary Board Member of the Missouri Prairie Foundation, has tirelessly dedicated more than 60 years of his life to conserving the world’s biodiversity. Officially retired from the Missouri Botanical Garden in 2010, Raven nonetheless continues to devote many hours of each day to this critically important mission.

Now an octogenarian, Raven is coediting a modern checklist of the plants of India, is writing his autobiography, maintains robust involvement with the National Geographic Society and its conservation work as a Trustee of the Society, and participates in the work of numerous other scientific and conservation organizations. What he finds especially satisfying, however, he says, “is connecting people to other people and resources to get conservation work done in ways they might not otherwise have happened.”

Dr. Raven took time out of his busy schedule this past July to talk with me about the importance of biodiversity conservation in an era of climate change.

DAVIT: You have said that climate change is not the definitive issue of our time, but rather, it is loss of biodiversity. Can you elaborate?

RAVEN: Yes, I have said this. The loss of biodiversity is permanent, with climate change one of the factors leading to this loss. We have about 12 million species on earth—not counting bacteria and other microorganisms—and we have given names to fewer than two million. Even of those, we know very little about the great majority, and thus very little about biodiversity as a whole. Then there are all those for which we have not even provided a name, most of them not known to exist. Despite this gaping hole in our knowledge, we must act to preserve as many of the existing species while there is still time to do so.

The relationships between the species and the inorganic elements that make up a given ecosystem are very complex and still poorly understood. Thus, when we eliminate individual species from a given ecosystem, we imperil the stability of the system as a whole. When we have lost enough of them, the ecosystems of which they are the key elements will not continue to function sustainably—and the analogy, unfortunately, applies to the earth as a whole. 

The organization Global Footprint Network estimates that the 70% of our planet’s sustainable productivity that we were consuming annually in 1970—when our total population was about 3.7 billion—has grown to about 175% of what the earth produces, with a current population of 7.7 billion. On about August 1 this year, we reached Earth Overshoot Day—the date on which we had consumed all of the resources available this year. For the rest of the year, we have been borrowing resources that would otherwise be available to us for future use. 

A great deal depends on the way we use resources, of course, with the consumption of fossil fuels contributing a great deal to our collective overshoot. In addition, rich countries consume far more that poor ones, which cannot in principle attain consumption rates equal to ours by cutting more from the same pie. A little thought quickly convinces us that, globally, inequality is the enemy of sustainability, and must somehow be rectified if we are to maintain a functioning planet that will support human beings with our civilization into a sound future. 

When our ancestors began to cultivate crops and domesticate animals, about 11,000 years ago, there were only about a million of us in the whole world. With the availability of stable supplies of food, however, our number swelled rapidly, to about 250 million at the time of Christ, one billion at the turn of the 19th century, and 7.7 billion today. Projections indicate that by mid-century, 30 years from now, there will be nearly 10 billion of us! How shall we then preserve the functioning of the world’s living systems, on which we all depend whether we think about it often or not.

Our extensive use of fossil fuels, including petroleum and coal, began in the first half of the 19th century. Eventually, Svante Arrhenius, a Swedish physicist and winner of the Nobel Prize in 1903, predicted that climate change and Earth warming would take place based on the increased density of the atmosphere. Humans cause much of this increase because of our production of pollutants tied to our activities, such as carbon dioxide, methane, and hydro- fluorocarbons.

By “thickening” the atmosphere, these gasses cause it to act as a heat trap, with the energy of the sun that reaches the surface of the earth prevented from escaping into space. Given this physical reality and the steady increase in these gasses in the atmosphere that we have chronicled for decades, it is no wonder that scientists are virtually unanimous in endorsing the validity of this relationship.

DAVIT: With the enormous challenges that climate change presents to life on Earth, how would you value the work of the Missouri Prairie Foundation, which is protecting as much biologically rich prairie as it can, even when only relatively small tracts of prairie remain in Missouri?

RAVEN: I would quote my friend Dan Janzen [University of Pennsylvania ecologist], who would say, “If we don’t save it now, we can’t save it later.”

As a society, we have for millennia been converting natural communities to agriculture, either for crops or for grazing. We now grow crops on about 11% of the Earth’s land surface and graze more than another 20%. The grazing is mostly on natural or semi- natural grasslands, and if not managed very carefully, will ultimately destroy their sustainability. As a result of these activities, the vast prairies that extended once from southern Canada down through much of the middle of the US to northern Mexico have been reduced to a very small fraction of what they used to be because of the intensive use of the deep prairie soils for agriculture. 

As we destroy any part of the environmental mosaic that supports us—that supported us before we invented agriculture—we lose the chance to understand it and work with it constructively and sustainably. For us in the Midwest, the historical importance of our original prairies was so great that we naturally want to keep some of them simply to understand them better. The pioneers moved through these prairies and ultimately learned how to cultivate their wonderful, rich prairie soils. They remain intensely meaningful to us both for the memories they hold of our common past, and as incredibly rich reservoirs of some of the biodiversity that supports us—and will continue to do so to the extent that we hold back from destroying it. The work of the Missouri Prairie Foundation is an indispensable benefit to Missourians and will be recognized increasingly for its importance as the years pass.


DR. PETER RAVEN is a leading botanist and advocate of conservation and biodiversity with a notably international outlook. In addition, he is George Engelmann Professor of Botany Emeritus at Washington University in St. Louis, a Trustee of the National Geographic Society, and Chairman of the Society’s Committee for Research and Exploration.

For more than 39 years, Dr. Raven headed the Missouri Botanical Garden in St. Louis, an institution he nurtured to become a world-class center for botanical research, education, and horticulture display. During this period, the Garden became a leader in botanical research and conservation in Latin America, Africa, Asia, and North America, and cosponsored with the Missouri Department of Conservation a thorough revision of Steyermark’s Flora of Missouri, completed in August 2013.

Dr. Raven first realized in the mid-1960s that the rapid growth of the human population, the rate of natural resource consumption, and the spread of polluting technologies were threatening biological diversity seriously and that the threat was growing rapidly. He soon became an outspoken advocate of the need for conservation throughout the world based on efforts to attain sustainability and social justice everywhere.

He has been described by Time magazine as a “Hero for the Planet,” and has received numerous prizes and awards, including the National Medal of Science, the highest award for scientific accomplishment in the United States, and numerous other awards both nationally and internationally.

Dr. Raven has been president of the American Association for the Advancement of Science, Sigma Xi, the American Institute of Biological Sciences, and a number of other organizations. He served for 12 years as Home Secretary of the National Academy of Sciences, to which he was elected in 1977. He is also a member of the American Academy of Arts and Sciences and of the American Philosophical Society, as well as the academies of science in Argentina, Australia, Austria, Brazil, Chile, China, Denmark, Georgia, Hungary, India, Italy, Mexico, New Zealand, Russia, Sweden, Taiwan, Ukraine, the U.K. (the Royal Society), and of the Pontifical Academy of Sciences and the Academy of Sciences for the Developing World (TWAS).

In 2014, Dr. Peter Raven convened a group of scientists at Washington University to examine the effects of climate change on agriculture in the Midwest. One of the results of this meeting was an analysis of climate patterns and crop yield averages for 1971 to 2000, with projections for 2035 to 2065 based on particular climates shifting northward as the climate changes.

“Our prairie ecosystems evolved under the climates that developed following the retreat of the last continental scale ice sheet, and under the influence of native grazing mammals, fire, and eventually human beings,” said Raven. “By protecting and studying the remaining prairies, we can continue to unravel the mysteries of how those prairie plant communities functioned and apply the lessons that we learn to the development of the sustainable systems for the future. We can’t do that if we don’t have original prairie remnants to study.”

Critically important to preventing further loss of the planet’s biodiversity is the protection of biologically diverse sites, including original, unplowed prairies. Even if these remnant prairies are small, they are extremely important for many reasons, including what they have to teach us.

For example, at MPF’s 160-acre Penn-Sylvania Prairie in Dade County, with 289 recorded plant species, an astonishing 46 native plant species have been documented in a 20-inch by 20-inch plot––setting a new world record for plant species richness at this scale. As the U.S. National Academy of Sciences Proceedings reported in a 2018 paper, the preservation of small patches of original habitat are of key importance for biodiversity conservation. The article goes on to point out how serious the loss of such patches can be to the possibilities we have of preserving biodiversity.

Clearly MPF members and other financial supporters are making a positive difference in protecting global biodiversity, right here in Missouri.

This story originally appeared in the Missouri Prairie Journal’s Fall/Winter 2019 issue 

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