By Amber Jenkins

I stumbled upon this video earlier today. It’s Isaac Asimov, famous science fiction writer and biochemist, talking about global warming — back in January 1989. If you change the coloring of the video, the facial hair style, and switch out Asimov for someone else, the video could pretty much have been made today.

Asimov was giving the keynote address at the first annual meeting of The Humanist Institute. “They wanted me to pick out the most important scientific event of 1988. And I really thought that the most important scientific event of 1988 will only be recognized sometime in the future when you get a little perspective.”

What he was talking about was the greenhouse effect, which, he goes on to explain, is “the story everyone started talking about [in 1988], just because there was a hot summer and a drought.” (Sound familiar, letting individual weather events drive talk of whether the Earth’s long-term climate is heating up or cooling down??)

The greenhouse effect explains how certain heat-trapping (a.k.a. “greenhouse”) gases in our atmosphere keep our planet warm, by trapping infrared rays that Earth would otherwise reflect back out into space. The natural greenhouse effect makes Earth habitable — without our atmosphere acting like an electric blanket, the surface of the earth would be about 30 degrees Celsius cooler than it is now.

The problem comes in when humans tinker with this natural state of affairs. Our burning of fossil fuels (coal, oil and gas) constantly pumps out carbon dioxide — a heat-trapping gas — into the atmosphere. Our cutting down of forests reduces the number of trees there are to soak up some of this extra carbon dioxide. All in all, our atmosphere and planet heats up, (by about 0.6 degrees Celsius since the Industrial Revolution) with the electric blanket getting gradually thicker around us.

“I have been talking about the greenhouse effect for 20 years at least,” says Asimov in the video. “And there are other people who have talked about it before I did. I didn’t invent it.” As we’ve stressed here recently, global warming, and the idea that humans can change the climate, is not new.

As one blogger notes, Asimov’s words are as relevant today as they were in 1989. “It’s almost like nothing has happened in all this time.” Except that Isaac Asimov has come and gone, and the climate change he spoke of is continuing.

Asimov’s full speech can be seen here.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

By Dr. David Diner

Tiny airborne particles, or aerosols, can affect the appearance of the moon during a total lunar eclipse, sometimes giving it a reddish hue. Copyright Ian Sharp

A lunar eclipse occurs when the Earth is positioned between the sun and the moon. Although the Moon passes through the Earth’s shadow, the lunar disk remains partially illuminated by sunlight that is refracted and scattered by the Earth’s atmosphere.

Refraction is the bending of light that occurs when the rays pass through media of different densities (our atmosphere is more dense near the surface and less dense higher up). Scattering of sunlight by molecules of air also deflects the light into different directions, and this occurs with much greater efficiency at shorter (bluer) wavelengths, which is why the daylight sky appears blue. As we view the sun near sunrise or sunset the light traverses a longer path through the atmosphere than at midday, and when the air is relatively clear, the absence of shorter wavelengths causes the solar disk to appear orange.

Tiny airborne particles, also known as aerosols, also scatter sunlight. The relative efficiency of the scattering at different wavelengths depends on the size and composition of the particles. Pollution and dust in the lower atmosphere tends to subdue the color of the rising or setting sun, whereas fine smoke particles or tiny aerosols lofted to high altitudes during a major volcanic eruption can deepen the color to an intense shade of red.

If you were standing on the Moon’s surface during a lunar eclipse, you would see the Sun setting and rising behind the Earth, and you’d observe the refracted and scattered solar rays as they pass through the atmosphere surrounding our planet. Viewed from the Earth, these rays “fill in” the Earth’s shadow cast upon the lunar surface, imparting the Moon’s disk with a faint orange or reddish glow. Just as we sometimes observe sunrises and sunsets with different shades of orange, pink or red due to the presence of different types of aerosols, the color of the eclipsed lunar disk is also affected by the types of particles that are present in the Earth’s atmosphere at the time the eclipse occurs.

By Amber Jenkins

You might think from the amount of “climate science debate” that is given airtime in the U.S. media that it’s undiscovered territory. But it’s not. The science is very well established and goes back a long way. Global warming is not a new concept.

The Victorians knew about it. John Tyndall (born 1820) knew about it. So did Svante August Arrhenius. In April 1896, Arrhenius published a paper in the London, Edinburgh and Dublin Philosophical Magazine and Journal of Science entitled “On the influence of carbonic acid in the air upon the temperature of the ground.” (Arrhenius referred to carbon dioxide as “carbonic acid” in accordance with the convention of the time.)

Arrhenius’ paper was the first to quantify how carbon dioxide contributed to the greenhouse effect — carbon dioxide warms up the Earth by trapping heat near the surface, a bit like swaddling the planet in an extra blanket. Arrhenius was also the first to speculate about whether changes in the amount of carbon dioxide in the atmosphere have contributed to long-term variations in Earth’s climate. He later made the link between burning fossil fuels and global warming.

Another person who “knew” some time ago was Frank Capra. Graduating from Caltech in 1918, he went on to become a famous filmmaker responsible for “It’s a Wonderful Life” and other movies. But one that stands out, at least for nerds like me or people with an interest in climate change is “Meteora: The Unchained Goddess”, released in 1958:

Made for Bell Labs, this most awesome educational film speaks of “extremely dangerous questions”:

Dr. Frank C. Baxter: “Because with our present knowledge we have no idea what would happen. Even now, man may be unwittingly changing the world’s climate through the waste products of his civilization. Due to our release through factories and automobiles every year of more than six billion tons of carbon dioxide, which helps air absorb heat from the sun, our atmosphere seems to be getting warmer.”

Richard Carlson: “This is bad?”

Dr. Frank C. Baxter: “Well, it’s been calculated a few degrees rise in the Earth’s temperature would melt the polar ice caps. And if this happens, an inland sea would fill a good portion of the Mississippi valley. Tourists in glass bottom boats would be viewing the drowned towers of Miami through 150 feet of tropical water. For in weather, we’re not only dealing with forces of a far greater variety than even the atomic physicist encounters, but with life itself.”

In 1958, they knew about the effects of heating up the planet. In the 1800s they knew about it. Today, the biggest challenge facing climate scientists lies in predicting how much our climate will change in the future. It’s not a trivial task, given how complicated the climate system is — we can barely predict in detail more than a week’s worth of weather. We’re not viewing Miami through bottomed-glass boats yet, but we’re already beginning to see some of the predictions of global warming — melting sea and land ice, sea level rise, more extreme weather events, changes in rainfall and effects on plants and animals — be borne out.

Thanks to OSS and Discovery News for the tip.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.