Scientists: Humans cause global warming

CNN ^ | 7/21/05

[Crackingham]

Global warming is caused primarily by humans and "nearly all climate scientists today" agree with that viewpoint, the new head of the National Academy of Sciences -- a climate scientist himself -- said Wednesday.

Ralph Cicerone's views contrasted with Bush administration officials' emphasis on uncertainty about how much carbon dioxide and other industrial gases warm the atmosphere like a greenhouse.

"Carbon dioxide in the atmosphere is now at its highest level in 400,000 years and it continues to rise," said Cicerone, an atmospheric scientist who left as chancellor of University of California-Irvine to become academy president this month. "Nearly all climate scientists today believe that much of Earth's current warming has been caused by increases in the amount of greenhouse gases in the atmosphere, mostly from the burning of fuels."

Cicerone, testifying before a Senate Commerce subcommittee on global climate change, cited data from weather stations and ships indicating the surface of the Earth is generally hotter by about seven-tenths of 1 degree Fahrenheit just since the early 1970s.

The administration officials stressed the $5 billion spent yearly on U.S. climate programs, mostly research. David Conover, a principal deputy assistant energy secretary, said President Bush would lead on the issue though "the scientific and technology challenges are considerable."

James Mahoney, assistant commerce secretary for oceans and atmosphere, said, "We know that the surface of the Earth is warmer, and that an increase in greenhouse gases caused by humans is contributing to the problem." But he did not go further than that.

"We see economic growth, addressing the climate change problem and energy security as integrally related," said Daniel Reifsnyder, director of the State Department's Office of Global Change.

[snarks_when_bored]

I always knew my temper was going to get me the world into trouble...

[Indy Pendance]

Just think of all that power you wield.

[RightWhale]

"nearly all climate scientists today"

How many are there? As a guess, a dozen, and they don't agree on much except they would accept a gov't grant to refine their global climate models.

[RayChuang88]

That chart you posted is true demonstration that Earth is actually reaching one of its natural periodical temperature peaks. Note that the CO2 level some 375,000 years ago is actually higher than today.

Many scientists have said that Earth was actually warmer during the time dinosaurs ruled the Earth.

[Windcatcher]

Nah, the periodicity in the Earth's orbit doesn't have something to do do with that pattern...

The next time a wacko environmentalist screams this nonsense, go fetch your friendly neighborhood astrophysicist. I'm sure he would welcome the chance to give the enviro-wacko a thorough smacking.

If you want to see something *really* scary, go look up the Gould belt, especially the time of origin. Yes, galactic-scale events *do* affect life on earth.

[Indy Pendance]

You don't even have to get that technical, just ask them why the glaciers melted. They get all weird.

[snarks_when_bored]

Just think of all that power you wield.

Scary, very scary. (Serenity now...serenity now...)

[Indy Pendance]

I looked up 'Gould belt, especially the time of origin' and that's fascinating, the brief scan I did. Thanks for the tip. I've never studied this, it'll be interesting to learn about it.

[Indy Pendance]

LOL!

[Ichneumon]

["Carbon dioxide in the atmosphere is now at its highest level in 400,000 years]

Wow. I didn't know they were measuring it 400,000 years ago.

It's actually relatively straightforward to determine CO2 levels at various points in the past.

CO2 levels at a particular time affect a lot of things which leave measurable traces that can be analyzed in modern times, such as geochemical composition, plant densities, soil chemistries, and so on. Atmospheric bubbles trapped in ancient ices can even be used as "samples" of ancient atmospheres which allow direct measurement (as well as validition/calibration of the aforementioned methods).

[Snoitan5]

That's what I thought I'd heard some time ago... Cows. But these scientist could be on to somthing here, as a certain senator from New York comes to mind. Connection?

[Wombat101]

I guess it was all us nasty humans, with our industry and automobiles, our CFC's and aerosol cans, that managed to melt the two mile thick sheet of ice that New York City was buried under 12,000 years ago.

One question that has never been adequately answered to my satisfaction by the global warming nuts: isn't it a matter of scientific fact that the Earth has endured several Ice Ages in it's geologic past, and that the warming that ended those Ice Ages occurred without the internal combustion engine and steel mills?

[elfman2]

Nice graph, thanks!

[HereInTheHeartland]

BREAKING HARD,
After reevaluating their data, these same scientists have concluded that the sun is the cause of global warming.

[AaronInCarolina]

I have been reading a lot lately about the earth's "albedo"... the overall reflectivity of the earth. Generally, the more reflective the earth is, i.e. a higher albedo, the earth absorbs less of the sun's heat. This is very critical in whether the earth heats up or cool down. The following web site (a NASA one at that) illustrates the albedo and reveals that the the earth's albedo is currently in decline. That means that less of the sun's light is reflected back and more is absorbed at the surface. This is largely because, with the exception of Inda and China, the atmosphere is becoming less polluted, due to decades of reduction of pollution in most modern countries. The unintended consequence is that more of the earth's sunlight reaches the ground and oceans and causes more heating.

If you think that humans are causing this warming, consider this fact from the NASA web page:

On average, the Sun shines on Earth 341 watts of energy per square meter of surface area. The Sun beams more energy to our planet every hour than humanity uses in a whole year.

One hour!!! There are over 61,000 hours in a year. That means that the sun provides more than 61,000 times as much energy to this planet than the total of all human energy production. Our puny effect on this planet is miniscule compared to what the sun does to the planet. Combine this overwhelmingly larger sun effect with a decrease in the earth's albedo (reflectivity), and you have a recipe for a warming trend. I have also read that the sun is currently experiencing a spike in intensity. That helps explain why the polar ice caps on Mars are receding similar to the Earth's ice caps.

Earth's Albedo in Decline

Also, this quote from the NASA web page:

A drop of as little as 0.01 in Earth’s albedo would have a major warming influence on climate—roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area.

[coconutt2000]

Oh yeah, I know that. I was just pointing out why I think they chose 400,000 years ago as the date to compare with.

It isn't a valid comparison on many levels. Too many variables, so much scientists don't know about the mechanics of equilibrium that are how our planet functions.

[William Tell]

From the article: "Nearly all climate scientists today believe that much of Earth's current warming has been caused by increases in the amount of greenhouse gases in the atmosphere, mostly from the burning of fuels."

For "scientists" these guys seem mighty uncurious about why the CO2 levels have been cycling with dramatic increases of 50% over the last 400,000 years during times when human activities could not possibly have been responsible.

[SkyDancer]

I read an old Time magazine from the 1970 that said we were going to have global cooling and it was a crisis and that in twenty years we'd all be wearing fur coats in Texas in the summer ....

Regards,
J

[Windcatcher]

Hear, hear. This is what happens when environmentalists are louder than astrophysicists (or any other physicist, for that matter). The amount of energy exchanged in our solar system on a daily basis is truly staggering compared to anything that we can wield, and the problem is that the enviro-wackos aren't interested in seeing the larger picture. Physicists can't help but notice little things like the fact that if the wrong star dies at the wrong time, we're dead. Not "might be dead", "might survive", "might survive with lots of deaths", but D-E-A-D—all of us, from the largest Elephant to the smallest bacterium.

In ~3Gyr, it's all moot. Andromeda will collide with the Milky Way, and right as rain some gravitational force will throw our solar system all asunder, long before the Sun exhausts enough hydrogen to go nova. It's a certainty (though, of course, solar output will have increased enough to make the Earth unlivable 2Gyr before then anyway).

One way or another, we're leaving this rock.

[stboz]

I think global warming causes humans. Otherwise, it's too damn cold to do anything.