Planet Ocean-Cloud or Daisy World?
Around the halls of the Geophysical Institute, where many scientists are researching the effects of global climate change in the Arctic, Professor of Physics Glenn Shaw is famous for taunting them with his own theory about worldwide warming, or the potential lack of it.
"We should not call this ground we stand on the Earth," Shaw has said one more than one occasion. "We should call it Planet Ocean-Cloud."
From space, Shaw explains, the Earth can only be seen through a cloak of white. In fact, in all the space pictures he's seen, clouds are the Earth's most dominant feature. As Shaw sees it, clouds could be the key to climate regulation. They could be the reason the climate of our planet has remained relatively stable, despite the fact that most scientists believe the sun has increased in intensity by over 20 percent since life sprung up here about 4 billion years ago.
Shaw speculates that clouds act as climate regulators by bouncing reflecting Earth-warming sunshine back into space. With clouds taking this role, the Earth could be a self-regulating body, much like British scientist James Lovelock described with his theory of the "Gaia hypothesis," in which he portrayed the Earth as a living, self-sustaining organism.
Lovelock explained the Earth's ability to keep itself at a constant temperature with a computer model he called "Daisyworld." Daisyworld is a planet the same size and the same distance from the sun as the Earth. The only living things on Daisyworld are white, black and gray daisies.
As with our planet, Daisyworld's sun grows hotter over billions of years. Because there are no clouds over Daisyworld, the temperature is determined largely by the reflectivity of the surface. Early in Daisyworld's history, black and white daisies live in equal numbers. But as the sun heats up over millions of years, the black daisies absorb too much heat, and die. The white daisies, with their ability to reflect sunlight and keep cool, then begin to thrive. They bounce much of the incoming sunshine back to the sun and they stabilize the climate, acting much like an automatic thermostat.
Shaw speculates that clouds covering our Earth might act like the white daisies in the computer model by creating feedback loops that make sure our planet is covered at all times with a certain amount of cloud cover. Clouds bounce incoming solar radiation back toward the sun and keep the Earth's surface cool enough for life to exist here.
Phytoplankton, microscopic organisms living in the ocean that represent most of the living mass on Earth, may be part of the negative feedback loop that keeps the world from burning up, Shaw said. As the climate gets warmer, he explained, so does the ocean. Phytoplankton thrive in warmer temperatures, reproducing at amazing rates. They emit sulfur gas that converts to aerosols, or fine particles. The aerosols serve as condensation nuclei for water vapor to cling to, and clouds are born. In a phenomenon sometimes called "the parasol effect," more clouds reflect more sunshine out to space, and the planet gets cooler as a result of being warmer.
Shaw said there are many other systems affecting global climate, but thinks systems such as the relationship of phytoplankton to cloud formation may be the key to the Earth's amazing ability to cover itself with a fairly constant layer of clouds, and thereby regulate its own temperature, at least so far.
Perhaps the Earth takes care of itself, just like Daisyworld, but even if it does, Shaw says self-regulating systems such as Daisyworld and the phytoplankton-cloud relationship can't be counted on to save the planet because we, by pumping greenhouse gases and other forms of pollution into the atmosphere, can cause the systems to slip out of their patterns. And any deviation from a natural state could result in extreme worldwide warming or cooling, creating conditions that ultimately could be disastrous for life on Earth, including both daisies and human beings.
