This leaf beetle, which lives in the cloud forest on the east slope of the Andes Mountains in Ecuador, is from the family Chrysomelidae. Climate change could have a much bigger impact on such tropical species than scientists previously thought. (Credit: Kimberly Sheldon, University of Washignton)

Trouble In Paradise: Global Warming A Greater Danger To Tropical Species. ScienceDaily. Retrieved May 7, 2008, from

ScienceDaily (May 6, 2008) — Polar bears fighting for survival in the face of a rapid decline of polar ice have made the Arctic a poster child for the negative effects of climate change. But new research shows that species living in the tropics likely face the greatest peril in a warmer world.

A team led by University of Washington scientists has found that while temperature changes will be much more extreme at high latitudes, tropical species have a far greater risk of extinction with warming of just a degree or two. That is because they are used to living within a much smaller temperature range to begin with, and once temperatures get beyond that range many species might not be able to cope.

“There’s a strong relationship between your physiology and the climate you live in,” said Joshua Tewksbury, a UW assistant professor of biology. “In the tropics many species appear to be living at or near their thermal optimum, a temperature that lets them thrive. But once temperature gets above the thermal optimum, fitness levels most likely decline quickly and there may not be much they can do about it.”

Arctic species, by contrast, might experience temperatures ranging from subzero to a comparatively balmy 60 degrees Fahrenheit. They typically live at temperatures well below their thermal limit, and most will continue to do so even with climate change.

“Many tropical species can only tolerate a narrow range of temperatures because the climate they experience is pretty constant throughout the year,” said Curtis Deutsch, UCLA assistant professor of atmospheric and oceanic sciences and co-author of the study.

Why should we be concerned with the fate of insects in the tropics?

“The biodiversity of the planet is concentrated in tropical climates, where there is a tremendous variety of species,” Deutsch said. “This makes our finding that the impacts of global warming are going to be most detrimental to species in tropical climates all the more disturbing. In addition, what hurts the insects hurts the ecosystem. Insects carry out essential functions for humans and ecosystems — such as pollinating our crops and breaking down organic matter back into its nutrients so other organisms can use them. Insects are essential to the ecosystem.”

At least for the short term, the impact of global warming will have opposing effects. In the tropics, warming will reduce insects’ ability to reproduce; in the high latitudes, the ability of organisms to reproduce will increase slightly, Deutsch said. If warming continues, the insects in the high latitudes would eventually be adversely affected as well.

“Unfortunately, the tropics also hold the large majority of species on the planet,” he said.

Tewksbury and Deutsch are lead authors of a paper detailing the research, published in the May 6 print edition of the Proceedings of the National Academy of Sciences. The work took place while Deutsch was a UW postdoctoral researcher in oceanography.

The scientists used daily and monthly global temperature records from 1950 through 2000, and added climate model projections from the Intergovernmental Panel on Climate Change for warming in the first years of the 21st century. They compared that information with data describing the relationship between temperatures and fitness for a variety of temperate and tropical insect species, as well as frogs, lizards and turtles. Fitness levels were measured by examining population growth rates in combination with physical performance.

“The direct effects of climate change on the organisms we studied appear to depend a lot more on the organisms’ flexibility than on the amount of warming predicted for where they live,” Tewksbury said. “The tropical species in our data were mostly thermal specialists, meaning that their current climate is nearly ideal and any temperature increases will spell trouble for them.”

As temperatures fluctuate, organisms do what they can to adapt. Polar bears, for example, develop thick coats to protect them during harsh winters. Tropical species might protect themselves by staying out of direct sunlight in the heat of the day, or by burrowing into the soil.

However, since they already live so close to their critical high temperature, just a slight increase in air temperature can make staying out of the sun a futile exercise, and the warming might come too fast for creatures to adapt their physiologies to it, Tewksbury said.

Other authors of the paper are Raymond Huey, Kimberly Sheldon, David Haak and Paul Martin of the University of Washington and Cameron Ghalambor of Colorado State University. The research was funded in part by the National Science Foundation and the UW Program on Climate Change.

The work has indirect implications for agriculture in the tropics, where the bulk of the world’s human population lives. The scientists plan further research to examine the effects of climate change, particularly hotter temperatures, on tropical crops and the people who depend on them.

“Our research focused only on the impact of changes in temperature, but warming also will alter rainfall patterns,” Deutsch said. “These effects could be more important for many tropical organisms, such as plants, but they are harder to predict because hydrological cycle changes are not as well understood.”

Adapted from materials provided by University of Washington.
Are many of the variables for the extinction of honey bees, in place, now?

SAN FRANCISCO, California (AP) — A survey of bee health released Tuesday revealed a grim picture, with 36.1 percent of the nation’s commercially managed hives lost since last year.
Photo by P.O Gustafson

Bees are dying at unsustainable levels, the president of the Apiary Inspectors of America says.

Last year’s survey commissioned by the Apiary Inspectors of America found losses of about 32 percent.

As beekeepers travel with their hives this spring to pollinate crops around the country, it’s clear the insects are buckling under the weight of new diseases, pesticide drift and old enemies like the parasitic varroa mite, said Dennis vanEngelsdorp, president of the group.

This is the second year the association has measured colony deaths across the country. This means there aren’t enough numbers to show a trend, but clearly bees are dying at unsustainable levels and the situation is not improving, said vanEngelsdorp, also a bee expert with the Pennsylvania Department of Agriculture.

“For two years in a row, we’ve sustained a substantial loss,” he said. “That’s an astonishing number. Imagine if one out of every three cows, or one out of every three chickens, were dying. That would raise a lot of alarm.”

The survey included 327 operators who account for 19 percent of the country’s approximately 2.44 million commercially managed beehives. The data is being prepared for submission to a journal.

About 29 percent of the deaths were due to colony collapse disorder, a mysterious disease that causes adult bees to abandon their hives. Beekeepers who saw CCD in their hives were much more likely to have major losses than those who didn’t.

“What’s frightening about CCD is that it’s not predictable or understood,” vanEngelsdorp said.

On Tuesday, Pennsylvania Agriculture Secretary Dennis Wolff announced that the state would pour an additional $20,400 into research at Pennsylvania State University looking for the causes of CCD. This raises emergency funds dedicated to investigating the disease to $86,000.

The issue also has attracted federal grants and funding from companies that depend on honeybees, including ice-cream maker Haagen-Dazs.

Because the berries, fruits and nuts that give about 28 of Haagen-Dazs’ varieties flavor depend on honeybees for pollination, the company is donating up to $250,000 to CCD and sustainable pollination research at Penn State and the University of California, Davis


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Photo by P.O Gustafson

Bees belong to the third largest insect order which also includes wasps and ants. The bee’s eyes, like those of other insects, differ greatly from human eyes. They consist of a pair of compound eyes made up of numerous six-sided facets (28,000 in some dragonflies, 4,000 in house flies) plus three simple eyes. Despite this, their vision is believed to be sharp only for a distance of about 1 m.

Bees, however, are capable of seeing ultraviolet light, which is invisible to humans. The bee is capable of navigating, even on a cloudy day, by cloud-penetrating ultraviolet light. Honey bees also use the sun as a reference point to communicate to other bees the angle of flight to be followed to arrive at newly discovered nectar-bearing flowers.

Bees are in danger of disappearing from our environment. Farming practices continue to disturb the natural habitats and forage of solitary and bumblebees at a rate which gives them little chance for re-establishment. The honeybee is under attack from the varroa mite and it is only the treatment and care provided by beekeepers that is keeping colonies alive. Most wild honeybee colonies have died out as a result of this disease.

Bees belong to the same order as wasps. Like wasps, bees have mouth parts with a tongue longer than the wasps better suited for gathering nectar from a greater variety of flowers. Bees have feathery body hairs, also known as plumose. Females have brushes on their legs, and they use them to remove pollen that sticks to these body hairs. The pollen is then stored under the abdomen or on the hind legs. Bees are subdivided into several families on the basis of how their wings are veined, and other criteria. There are many unique species of bees, with some living below ground, and a few that even eat wood. One of the most fascinating bees, the giant Indian bee (Apis dorsata) builds a single comb as large as 5′ by 3′ attached to rocks, trees or buildings. Bees are very hard working creatures with a very rigid social order. Colonies kept in hives yield an average of 50 pounds of honey for the beekeeper. Unlike other bees, honeybees do not hibernate during cold weather.

Bees are world-class navigators. Honeybees communicate direction and distance from the hive to nectar sources through a sophisticated dance “language”. In 1973, Karl von Frisch received a Nobel Prize for deciphering this bee language, which consists of a circle dance and a tail wagging dance. It accurately tells other bees the angle from the sun and the distance to the nectar. Bees use the sun as a compass. Even when the sun is obscured by clouds, bees can detect it’s position from the light in brighter patches of the sky. Bees also can see ultraviolet designs in flowers like an airplane circling an airport sees the landing lights on a runway. Honeybees also have a built-in clock that appears to be synchronized with the secretion of nectar from flowers.

Honey Bee, Carpenter bee, Bumble bee, Africanized honey bees
Picture of Honey Bee Collecting Pollen

Bee pollen is the male seed of a flower blossom which has been gathered by the bees and to which special elements from the bees has been added. The honeybee collects pollen and mixes it with its own digestive enzymes. One pollen granule contains from one hundred thousand to five million pollen spores each capable of reproducing its entire species.

Bee pollen is often referred to as nature’s most complete food. Human consumption of bee pollen is praised in the Bible, other religious books, and ancient Chinese and Egyptian texts. Research studies document the therapeutic efficacy and safety of bee pollen. Clinical tests show that orally ingested bee pollen particles are rapidly and easily absorbed–they pass directly from the stomach into the blood stream. Within two hours after ingestion, bee pollen is found in the blood, in cerebral spinal fluids, and in the urine.
Bee pollen rejuvenates your body, stimulates organs and glands, enhances vitality, and brings about a longer life span. Bee pollen’s ability to consistently and noticeably increase energy levels makes it a favorite substance among many world class athletes and those interested in sustaining and enhancing quality performance.

Bee pollen contains most of the known nutrients, including all of those necessary for human survival. When compared to any other food, it contains a higher percentage of all necessary nutrients. Bee pollen is approximately 25% complete protein containing at least 18 amino acids. In addition, bee pollen provides more than a dozen vitamins, 28 minerals, 11 enzymes or co-enzymes, 14 beneficial fatty acids, 11 carbohydrates, and is rich in minerals, the full spectrum of vitamins, and hormones. It is low in calories. Bee pollen proves to be quite useful for activity enhancement and sports nutrition. It produces an accelerated rate of recovery, including a return to normal heart rate, breathing, and readiness for the next event. Bee pollen improves second and subsequent performances. Humans not receiving bee pollen show declining performances. It provides energy, stamina, and strength, and enhances performance levels. Bee pollen should not be confused with the pollen that is blown by the wind and is a common cause of allergies. Allergy-causing pollen is called anemophiles; it is light and easily blown by the wind. Bee pollen is heavier and stickier, and is collected off of bees’ legs by special devices placed at the entrance to hives. It is called entomophiles or “friends of the insects,” and will rarely cause allergy symptoms.

Honeybees use nectar to make honey. Nectar is almost 80% water with some complex sugars. In fact, if you have ever pulled a honeysuckle blossom out of its stem, nectar is the clear liquid that drops from the end of the blossom. In North America, bees get nectar from flowers like clovers, dandelions, berry bushes and fruit tree blossoms. They use their long, tubelike tongues like straws to suck the nectar out of the flowers and they store it in their “honey stomachs”. Bees actually have two stomachs, their honey stomach which they use like a nectar backpack and their regular stomach. The honey stomach holds almost 70 mg of nectar and when full, it weighs almost as much as the bee does. Honeybees must visit between 100 and 1500 flowers in order to fill their honeystomachs.

The honeybees return to the hive and pass the nectar onto other worker bees. These bees suck the nectar from the honeybee’s stomach through their mouths. These “house bees” “chew” the nectar for about half an hour. During this time, enzymes are breaking the complex sugars in the nectar into simple sugars so that it is both more digestible for the bees and less likely to be attacked by bacteria while it is stored within the hive. The bees then spread the nectar throughout the honeycombs where water evaporates from it, making it a thicker syrup. The bees make the nectar dry even faster by fanning it with their wings. Once the honey is gooey enough, the bees seal off the cell of the honeycomb with a plug of wax. The honey is stored until it is eaten. In one year, a colony of bees eats between 120 and 200 pounds of honey.

*Bees from the same hive visit about 225,000 flowers per day. One single bee usually visits between 50-1000 flowers a day, but can visit up to several thousand.

*Queens will lay almost 2000 eggs a day at a rate of 5 or 6 a minute. Between 175,000-200,000 eggs are laid per year.

*The average hive temperature is 93.5 degrees.

*Beeswax production in most hives is about 1 1/2% to 2% of the total honey yield.

*About 8 pounds of honey is eaten by bees to produce 1 pound of beeswax.

*Honeybees are the only insects that produce food for humans.

*Just a single hive contains approximately 40-45,000 bees!

*During honey production periods, a bee’s life span is about 6 weeks.

*Honeybees visit about 2 million flowers to make one pound of honey.

*A bee travels an average of 1600 round trips in order to produce one ounce of honey; up to 6 miles per trip. To produce 2 pounds of honey, bees travel a distance equal to 4 times around the earth.

*Bees fly an average of 13-15 mph.

The American Museum of Natural History


The American Museum of Natural History and Louis Harris and Associates, Inc., in conjunction with the opening of the Museum’s new Hall of Biodiversity, developed a nationwide survey titled Biodiversity in the Next Millennium. The survey reveals a startling gap in understanding between the scientific community and the general public concerning a current crisis in sustaining “biodiversity” – the variety and interdependence of the Earth’s plants and animals.


    Seven out of ten biologists believe that we are in the midst of a mass extinction of living things, and that this dramatic loss of

  • species poses a major threat to human existence in the next century.
  • In strong contrast to the fears expressed by scientists, the general public is relatively unaware of the loss of species and the threats that it poses.
  • This mass extinction is the fastest in Earth’s 4.5-billion-year history and, unlike prior extinctions, is mainly the result of human activity and not of natural phenomena.
  • Scientists rate biodiversity loss as a more serious environmental problem than the depletion of the ozone layer, global warming, or pollution and contamination.
  • Scientists overwhelmingly believe that we must act now to address the biodiversity crisis. The majority of scientists believe the crisis could be averted by a stronger stance by policymakers and governments and by individuals making changes in their daily lives.
  • Scientists believe some of the most important effects of this dramatic species loss are:
  1. Serious impairment of the environment’s ability to recover from natural and human-induced disasters.
  2. Destruction of the natural systems that purify the world’s air and water.
  3. Reduction of the potential for the discovery of new medicines.
  4. Increased flooding, drought, and other environmental disasters.
  5. Substantial contribution to the degradation of the world’s economies, thereby weakening the social and political stability of nations across the globe.
Rising Waters Are Pushing Out Refuge Wildlife
The coastal marshes are disappearing at the Blackwater National Wildlife Refuge on Maryland’s Eastern Shore. Rising sea levels are swamping so much of the marsh that the entire area could be open water in a few decades, making it unsuitable for migrating birds, fish and other animals that find shelter in the marshes.


By David A. Fahrenthold, The Washington Post – What has gone missing here is almost as spectacular as the 8,000 acres of swampy wilderness that remain. And that makes it Chesapeake Bay’s best place to watch climate change in action.

Visitors can see ospreys gliding overhead, egrets wading in the channels and Delmarva fox squirrels making their unhurried commutes between pine trees.

But then the road turns a corner, and Blackwater’s marsh yields to a vast expanse of open water. This is what’s missing: There used to be thousands more acres of wetland here, providing crucial habitat for creatures including blue crabs and blue herons. But, thanks in part to rising sea levels, it has drowned and become a large, salty lake. “If people want to see the effects” of Earth’s increasing temperature, refuge biologist Roger Stone said, “it’s happening here first.”

But not just here. Around the world, scientists have found that climate change is altering natural ecosystems, making profound changes in the ways that animals live, migrate, eat and grow. Some species have benefited from the shift. Others have been left disastrously out of sync with their food supply. Two are known to have simply disappeared.

If warming continues as predicted, scientists say, 20 percent or more of the planet’s plant and animal species could be at increased risk of extinction. But, as the shrinking habitat at Blackwater shows, the bad news isn’t all in the out years: Some changes have already begun. “This is actually something we see from pole to pole, and from sea level to the highest mountains in the world,” said Lara Hansen, chief climate change scientist at the World Wildlife Fund, a private research and advocacy group. “It is not something we’re going to see in the future. It’s something we see right now.”

The temperature increase behind these changes sounds slight. The world has been getting warmer by 0.2 degrees Fahrenheit every decade, a U.N. panel found this year, in part because of carbon dioxide and other human-generated gases that trap heat in Earth’s atmosphere.

By nature’s clock, the warming has come in an instant. The mechanisms that helped animals adapt during previous warming spells — evolution or long-range migration — often aren’t able to keep up. Scientists say that effects are beginning to show from the Arctic to the Appalachian Mountains. One study, which examined 1,598 plant and animal species, found that nearly 60 percent appeared to have changed in some way.

“Even when animals don’t go extinct, we’re affecting them. They’re going to be different than they were before,” said David Skelly, a Yale University professor who has tracked frogs’ ability to react to increasing warmth. “The fact that we’re doing a giant evolutionary experiment should not be comforting,” he said.

Some of the best-known changes are happening near the poles, where the air and the water are warming especially quickly. As they do, sea ice is receding. For some animals, this has meant literally the loss of the ground beneath their feet.

Polar bears, for instance, spend much of their life on the Arctic ice and use it as a hunting ground for seals. When ice on Canada’s western Hudson Bay began to break up earlier — three weeks earlier in 2004 than in 1974 — the effect was devastating. The bear population fell by 21 percent in 17 years. Shrinking ice has also been blamed for cannibalism among polar bears in the waters off Alaska, something scientists had not seen before 2004. This month, a U.S. Geological Survey report predicted that two-thirds of the world’s polar bears could die out in 50 years.

Walruses, too, rely on the ice; mothers stash their calves on it, then dive down to feed on the ocean floor. When ice recedes from prime feeding areas, mothers and calves can get separated.

In 2004, University of Tennessee professor Lee W. Cooper was off the north Alaskan coast when he saw about a dozen calves swimming toward his boat. His theory: The calves, alone and desperate without ice nearby, thought the boat might be a large iceberg.

There was nothing the scientists could do to help, Cooper said. “I think they were doomed.”

Other changes have been less deadly, but they show centuries-old patterns shifting. Scientists have noticed changes in the timing of seasonal migrations, presumably caused by the earlier onset of warm weather.

In some cases, migrating animals suddenly find themselves out of rhythm, missing the weather conditions or the food they need. In parts of the Rocky Mountains, American robins arrive two weeks earlier than they used to — and often discover the ground snow-covered and little food to be found.

In other cases, an animal’s entire territory that shifts, as old habitats become too warm. In many cases, this means a move north. In others, it means a move up.

The American pika, a small rodent that lives on the slopes of mountains in the western United States, can overheat when temperatures hit 80 degrees. Over the past century, these creatures have kept climbing, reaching new ranges that can be 1,300 feet up the slope.

In some cases, there is no escape. In Costa Rica’s Monteverde Cloud Forest, a famous region that is kept damp by fog and mist, climate change has brought more variable weather and less of the clouds that some animals need.

Two amphibian species — the golden toad and the Monteverde harlequin frog — have not been seen since the late 1980s. These may be some of the first extinctions linked to climate change, said cloud forest researcher Alan Pounds. “It’s been an interesting puzzle to work on,” Pounds said. “But, at the same time, very alarming and frightening.”

At the Blackwater refuge, it is rising waters, not rising temperatures, that are eliminating habitat. A quirk of geology means that water rises especially fast here: Paradoxically, the land in this area is sinking as North America slowly unbends from the weight of glaciers during the last ice age.

Add that to the effect of melting polar ice, and scientists expect that most of the marsh will become open water by 2030. When it goes, there could be a shortage of habitat for the Eastern Shore’s marsh animals and migratory birds, said Stone, the refuge biologist.

“Birds will return for spring migration, and they’ll be looking for territory, and there just won’t be enough territory to go around,” he said.

So what happens then?

“They’ll . . .” he paused, looking for the right word, “. . . die. They’ll disappear.”

Not all animals, of course, will suffer. There are examples of creatures that are thriving in a warmer world. Fish such as pollock and pink salmon have begun moving into now-warmer Arctic waters. In the northern woods of North America, some tick species are making it through the winter in record numbers.

Livestock herds might increase in a warmer world, an analysis by the Agriculture Department found. That’s because food crops such as corn and rice could become harder to grow if the fields dry out, leaving more land for grazing. Researchers say that, even if all greenhouse-gas emissions were shut off today, the gases already in the atmosphere will cause Earth to warm for years to come. But, many say, it’s still imperative to reduce these emissions to head off even more warming.

“Unfortunately, it takes a generation or two to turn this supertanker around,” said Stephen Schneider, a professor at Stanford University, talking about the climate change already in progress. But still, he said, it is important to start trying. “What we’re looking at is a planetary environmental train wreck if we don’t start some compromising here.”

Already, some are trying to make it easier for wild animals to adjust. In Australia, conservationists are trying to set aside a north-south cordon of open land so animals can move if they need to. In the western United States and Canada, environmentalists are trying to create a similar corridor between Yellowstone National Park and the Yukon Territory.

Overall, scientists say, the news of climate change will not be bad for all animals. But, they say, that’s cold comfort for the rest — and for humans, as well, if it means that we watch some of the planet’s most beloved species decline or disappear.

“Yeah, the earth will recover,” said Scott Wing, who studies the biology of previous eras at the Smithsonian Institution. But, he said, “would you have wanted to be one of the dinosaurs when the asteroid hit? No.”

ScienceDaily (Mar. 2, 2008) — Biologists at the University of California, San Diego have developed a series of global maps that show where projected habitat loss and climate change are expected to drive the need for future reserves to prevent biodiversity loss.
In the face of impending global change, some regions are more in need of protected lands than others. The map shows regions color-ranked by how much area is projected to change by 2100 in relation to how much area is currently protected (“Conservation Risk”). Many of the tropical, but not temperate regions with greatest risk (red) are also of highest conservation value as indicated by their higher number of globally unique amphibians, birds, mammals and reptiles. (Credit: Image courtesy of University of California – San Diego)

Their study, published online February 28 in the journal Proceedings of the Royal Society B, provides a guide for conservationists of the areas of our planet where conservation investments would have the most impact in the future to limit extinctions and damage to ecosystems due to rapid human-driven climate and land-use change.

The researchers found that many of the regions that face the greatest habitat change in relation to the amount of land currently protected —such as Indonesia and Madagascar—are in globally threatened and endemic species-rich, developing tropical nations that have the fewest resources for conservation. Conversely, many of the temperate regions of the planet with an already expansive network of reserves are in countries—such as Austria, Germany and Switzerland—with the greatest financial resources for conservation efforts, but comparatively less biodiversity under threat.

“There’s a huge discrepancy between where the world’s conservation resources are concentrated and where the greatest threats to biodiversity are projected to come from future global change,” said Walter Jetz, an assistant professor of biological sciences at UC San Diego, who headed the study. “The developed nations are where the world’s wealth is concentrated, but they are not the future battlegrounds for conservation.”

“While many details still have to be worked out, our study is a first baseline attempt on a global scale to quantitatively demonstrate the urgent need to plan reserves and other conservation efforts in view of future global change impacts,” he added. “Reserves have often been set up haphazardly, following some national goal, such as to preserve 10 percent of a country’s area, or in response to past threats. But little consideration has been given to the actual geography of future threats in relation to biodiversity. Yet it’s those future threats that expose biodiversity to extinction.”

To conduct their study, the researchers examined the impact of climate and land use changes on networks of biological reserves around the world and contrasted them to four projections of future global warming, agricultural expansion and human population growth from the global Millennium Ecosystem Assessment. They discovered that past human impacts on the land poorly predicted the future impacts of climate change, revealing the inadequacy of current global conservation plans.

“The past can only guide you so much in the future,” said Tien Ming Lee, a graduate student and the first author of the study. “This is why we may have to change our future conservation priorities if we want to be effective in conserving biodiversity in the long run.”

Lee said the study also confirmed the longstanding argument that wealthy countries with few threats to future biodiversity loss would do better to spent their conservation dollars on underdeveloped countries with greater threats of future extinctions than in their own backyards.

“Tropical countries are currently sitting on vast tracts of forests that are substantial carbon sinks and if they can get adequate financial help to protect these habitats, both global climate change and biodiversity loss could be mitigated,” he said.

Funding for the study was provided by the National Science Foundation.

Adapted from materials provided by University of California – San Diego.

Stephen M. Meyer

Dr. Stephen M. Meyer, who died recently, was a professor of political science at MIT and the director of the MIT Project on Environmental Politics and Policy.

For the past several billion years evolution on Earth has been driven by small-scale incremental forces such as sexual selection, punctuated by cosmic-scale disruptions—plate tectonics, planetary geochemistry, global climate shifts, and even extraterrestrial asteroids. Sometime in the last century that changed. Today the guiding hand of evolution is unmistakably human, with earth-shattering consequences.

The fossil record and statistical studies suggest that the average rate of extinction over the past hundred million years has hovered at several species per year. Today the extinction rate surpasses 3,000 species per year and is accelerating rapidly—it may soon reach the tens of thousands annually. In contrast, new species are evolving at a rate of less than one per year.

Over the next 100 years or so as many as half of the Earth’s species, representing a quarter of the planet’s genetic stock, will either completely or functionally disappear. The land and the oceans will continue to teem with life, but it will be a peculiarly homogenized assemblage of organisms naturally and unnaturally selected for their compatibility with one fundamental force: us. Nothing—not national or international laws, global bioreserves, local sustainability schemes, nor even “wildlands” fantasies—can change the current course. The path for biological evolution is now set for the next million years. And in this sense “the extinction crisis”—the race to save the composition, structure, and organization of biodiversity as it exists today—is over, and we have lost. . . .

Stephen M. Meyer is a professor of political science at MIT and the director of the MIT Project on Environmental Politics and Policy.