Earth is doomed (eventually), UW scientists say

The world will come to an end at 12 o’clock. And it’s already 4:30. But before you dust off the Y2K bunker or dash for the duct tape, please be aware that not a person reading this article, or anyone currently alive anywhere on the planet, will be around to witness the Earth’s expiration. You see, this clock is measured not in minutes but in years, and not in single years—or decades, centuries, even millenniums—but in billions of years.

That’s four-and-a-half billion down, seven-and-a-half billion to go.

The math is straightforward; it’s the science that’s a bit drawn-out, according to UW Astronomy Professor Donald Brownlee. As that enormous ball of hydrogen we call the sun gets older, it also gets bigger and hotter and brighter-it is 30 percent brighter now than on the day Earth was formed. By the completion of the sun’s projected 12-billion-year life cycle, it will have evaporated our oceans, degraded our atmosphere and, in one final act, charred the Earth to its core, eradicating it, melting it and sending every last molecule shooting into space.

“People really should have an understanding of the fate that lies ahead,” says Brownlee, seated in his information-scattered office on the UW campus. “In 7.5 billion years Earth will either be swallowed up or survive only as a scorched planet. Most of us know the Earth is not flat. Most of us know it is not the center of the universe. But not many of us know that the sun won’t last forever. And we should, because just as it gave us life, it will bring us death.”

Brownlee and Peter Ward, a UW professor of Earth and space sciences and also of zoology, present the end-of-the-world thesis in their most recent book, The Life and Death of Planet Earth. The co-authors offer 213 pages of data that are equal parts biography and history, chronicling the planet’s first 4.5 billion years and providing scenarios for what may happen during what they call “the second half of life on Earth.”

“The dates can be criticized because saying exactly when is difficult,” says Ward, hours after returning from a New York City book-signing. “What we provide is not new research by us. It’s simply presenting a compilation of scientific literature.”

UW Professors Donald Brownlee (left) and Peter Ward have written a new book on “The Life and Death of Planet Earth.” Photo by Joel Levin.

Brownlee and Ward write: “We know that our planet is approximately 4.5 billion years old and that life is at least 3.4 billion years old. … We can predict that the last animals on this planet will die out as early as 500 million years from now.”

It will not be an expeditious death, analogous instead to the aging process of most human beings. Earth will lose one life-sustaining system after another-fuel, ice, oceans, plants and animals-until it meets its ultimate demise. The authors theorize that the existence of animals and plants is extraordinarily stunted on the Earth’s watch, beginning at 4 o’clock and ending right around 5.

“Most animals go extinct in a couple of million years,” Brownlee says. “No one has any idea of what it would take to totally drive the human race to extinction. I’m optimistic that we could be among the last survivors on the planet because we are adaptable. It may become too hot for large animals, but people could adapt somehow.”

Astronomer Brownlee is well-versed in the universe’s “other” worlds, while paleontologist Ward’s expertise is on that which has already ended: dinosaurs, fossils and rocks. To establish Earth’s fate, they relied on astrobiology, a fusion of biology, astronomy and paleontology, complementing our planet’s evolution with the life and history of other planets. By examining the Earth’s evolution, they conclude that only microscopic and bacterial organisms existed during Earth’s initial four billion years. They surmise that our planet’s biodiversity peaked as long as 300 million years ago.

“At one time the Earth was covered by ocean,” Brownlee says. “But land became important in that it plays a key role in the cycles that control the temperature. Much of the land mass in the world 250 million years ago was connected as a single continent. The continents today are basically bouncing around. The future Earth will go back to things of the past, and 250 million years from now the continents will have gone back to one another.” One result of this continental drift, Brownlee and Ward write, “may cause a mass extinction that kills off the majority of species on the planet.”

But should we care? If nothing else, it simply drives home the fact that we are all just a blip on the Earth’s lifetime radar screen.

“Why should we care that the Earth is flat if it didn’t matter 500 years ago?” Ward asks. “Do you have children? If so, your DNA is heading off toward that future. There’s a good chance your DNA will be around when it does happen.”

The unlikely literary coupling of the astronomer and the geologist began soon after Ward attended a Brownlee lecture on comets and meteorites of the solar system. Ward was already a prominent author of nine books, including the acclaimed The End of the Evolution, and conjured an instant paradigm: integrating his expertise of mass extinctions with Brownlee’s proficiency for all things universe.

Brownlee came with a decorated résumé. He is the principal investigator for Stardust, a seven-year NASA Discovery mission to capture comet particles and return them to Earth. Launched in February 1999 from Cape Canaveral, Fla., it is the first U.S. sample-return mission since Apollo 17 and the first ever designed to return material from outside the orbit of the moon.

“I went to Don with the proposal that we write a book together,” Ward remembers. “We went to lunch, and by the time we got back to his office, we had a title.”

Rare Earth was published early in 2000, laying out a synthesis that any life found on other planets is most likely to be crude microbes or the equivalent. Hailed in the New York Times, the London Times and Scientific American, Rare Earth reached No. 6 on Amazon’s best-seller list.

But Ward says the follow-up to Rare Earth was anything but exact science. “Don just said, ‘How about we write about the end of the world?’ We put together an outline and split up the chapters with eenie meenie minie mo. In two books we have killed off the aliens and we’ve ended the Earth, so what’s left to do?”

A study of the termination of the Earth is actually a study of the concept of the sun, which the authors describe as “a big ball of hydrogen gas with a nuclear reactor at its center.”

A star much like others we see on the clearest nights, the sun plays a much bigger role in our everyday lives. We are held in orbit by its gravity. We don’t freeze because of its heat. And we get food from plants thanks to the photosynthesis dependent on its energy-60 million watts of power for every square meter of its surface.

Hydrogen fuses with hydrogen to make helium, a process that releases nuclear energy to power the sun. As the amount of helium in the sun rises, the sun’s temperature also rises and it slowly becomes brighter.

“The temperature rises to keep the star stable against its own gravity,” says Brownlee. “The energy production increases because the fusion rate of hydrogen to helium is dependent on temperature. The hotter the gas, the harder hydrogens collide and the more likely they will undergo nuclear reactions to make helium.”

How slow is the process? Brownlee estimates that the hydrogen that exists in the center of the sun will last about 10 billion years before forming helium. In fact, all stars undergo the same process, becoming slowly brighter with time.

“The sun gets about 10 percent brighter every million years, which is about the equivalent of moving from Seattle to southern Oregon,” Brownlee says. “The increasing heat affects the Earth’s systems, such as the cycling of compounds between air, ocean and rock. The result is the decline of CO2 in the atmosphere.

“As the star get hotter, a water- and land-covered planet like Earth will have more and more of its CO2 put into carbonate rocks,” he continues. “It is all due to chemical processes. The carbon in us came from a star. But the very process that kills the Earth makes carbon for new stars.”

Once we lose the plants and animals, the oceans are not far behind, the latter’s downfall leaving the Earth a rust-colored planet like Mars instead of the blue planet seen from space today.

Still, the authors agree that despite the doom that lies ahead, there is no better place or time to be in the solar system than Earth, circa 2003.

“It’s likely that life just pops up on an oasis like Earth, then evolves and goes away,” says Brownlee. “An analogy would be an island in the Pacific. It forms in the ocean, and it’s a terrific place to be for a time. But one day it disappears below the waves, and any life that cannot either fly or float from the island is doomed.”

When the sun does reach its Armageddon sometime around high noon, it will have become one hundred times larger and several thousand times brighter than its current state. Mercury and Venus will be first to go, then Earth, leaving Mars the nearest planet to the sun.

Earth’s fate is an either-or proposition. Either the sun leaves our world a scorched planet orbiting a white dwarf star. Or it swallows the Earth whole, absorbing its atoms and spewing them into space to form new generations of stars and planets.

At 12 billion years, the authors write, “the energy generation rate briefly increases 10 billion times but the brightness of the sun, its energy radiated to space, paradoxically plummets. … The last and brightest flash may be the one that finally envelops the Earth, causing its complete destruction.”

According to Ward, not one human will be left to see it, hear it or feel it. “If plants and animals go away,” he says, “we don’t have to worry about what we eat, because we won’t be there either. The challenge is not to let them go away.”

Surely, the relentless and exploratory human race can come up with something to either expand the food chain or halt the end-of-the-world synopsis before it happens: heat shields, oxygen masks, food made of rocks, synthetic drinking water, even an invention that adds hydrogen back into the sun to prolong its life.

“Unless we turn out to be much more capable than I think, there’s not a snowball’s chance in hell of that happening,” Brownlee admits. “More than 400 million tons of hydrogen are used by the sun every second.”

Then, of course, there is space travel. Twenty-first century lore targets Mars as the most Earth-like planet available for human life to exist. Fifty percent farther from the sun than Earth, it also has half the sunlight, thus half the warmth. Think Antarctica without the air, water, energy or minerals.

But, Brownlee says, in a few billion years when the sun becomes twice as bright, it will leave Mars with the same solar energy per unit area as the Earth does at present. Eventually it will become more than 5,000 times as bright, leaving Mars so hot its surface rocks will melt.

As for living on other planets, Brownlee says television has left a great disconnect of what people believe about Earth and its life. “TV gives the impression that most planets are like Earth and most aliens are fantastically people-like,” he says. “There is nothing more ridiculous than the cantina scene in Star Wars (where Luke and Obi Wan Kenobi meet Han Solo and Chewbacca). Even if anyone develops star travel, it will take centuries to go from star to star.”

Ward agrees, noting that many who think space may be our savior don’t take distances into account. “One of anything doesn’t sound like a lot. But one light year? That is a long, long distance.

“Whether humans survive or don’t survive, this is going to happen to the Earth. That’s science,” Ward continues. “What humans might do, that’s not science, that’s fortune-telling.”

Brownlee says he and Ward haven’t encountered too many opposing views along the way because most of what they infer is nothing but cold, hard science.

“There’s a lot of time between now and the end of the world, and many things can be disproved in time,” he says. “Is broccoli good for you or bad for you? That will change back and forth as we learn more about it. But the fact that the sun will burn out in 7.5 billion years? That will never change.”

Seeking life on other worlds

They delved into the variety of life forms in space in their first book and speculated on Earth as simply a minuscule component of that space in their second.

Now, with the help of a $5.3 million grant from the National Aeronautics and Space Administration (NASA), Professors Peter Ward and Donald Brownlee are leading a University of Washington research team into discovering what inhabits the universe.

Ward, who traveled to Cambridge, England, in the spring to report on his group’s progress, says that NASA raised the original $4.9 million stipend in March. “The grant is renewable for another five-year term,” he says, “if we can continue to do good science.”

The funds allow UW researchers to investigate a series of critical factors, from the earliest life form in our world to the potential for planetary life outside the solar system. It also includes membership in NASA’s Astrobiology Institute.

“Astrobiology activities have been going on here at Washington since back in the late 1960s when (Microbiology Professor) Milton Gordon lectured on the universe and the origin of life,” says Brownlee. The unearthing of deep ecosystems living below Richland, Wash., along with the discovery of extra-solar planets, led NASA to initiate the grants program.

Ward says part of the grant money also goes to scientists from the University of Arizona and California Institute of Technology. Their investigations include the formation of habitable planets, mass extinctions due to comets or asteroids, and the evolution of single-cell life forms to more complex forms.

Brownlee believes the program will provide a remarkable bridge among various UW departments, serving as an umbrella to encourage people to think on larger, planetary scales and ponder the role of life in the cosmos.

“Even if extraterrestrial life is never found, astrobiology will have been a great success,” he says. “It works to stimulate us to think beyond our own fields. And it makes us consider all aspects of science that relate to the origin, evolution and fate of life on our planet and elsewhere.”