What We Know about Climate Change

February 27, 2010

In the many responses I get to these videos, it appears that a number of people want to deny, or are not even aware, that there is a scientific foundation to the overwhelming consensus on climate change.

In fact, the science is built on thousands of publications and many decades of observation.

In this video we’ll go over some of the fundamental discoveries, the basic facts that we know beyond a doubt, about global warming.  Of course, many people will never believe science, because they believe that anything that challenges their world view, is all part of a secret, global conspiracy.

Script for this video

(voice of Dan Lundgren, US Congressman, Republican, California)

“We got to follow good science, not junk science. And I think, rather than committing ourselves to huge amounts of money, we ought to know what we’re talking about.”

(Triumph, the Dog)

“Global Warming, I think you know maybe it was made up by over-eager scientists, you know, the same scientists, maybe, that made up, things like evolution, and gravity — cuckoo! right?”

In the many responses I get to these videos, it appears that a number of people want to deny, or are not even aware, that there is a scientific foundation to the overwhelming consensus on climate change.

(voice:) “There is no scientific evidence that CO2 is a pollutant”

Many people want to see the single paper, the single bit of proof, the magic bullet, that seals the case for global warming.

Of course, that’s not how science works. The massive body of evidence for climate change has been built up from global observations over 150 years.

One might as well ask, show me the single proof that smoking causes lung disease. In fact, the science is built on thousands of publications and many decades of observation.

In this video we’ll go over some of the fundamental discoveries, the basic facts that we know beyond a doubt, about global warming. Of course, no amount of proof is sufficient for those that believe climate science is all a global conspiracy.

Obama: “Some Bolshevik plot!”

woman: “Damn Scientists”

In 1859, the English physicist John Tyndall, using equipment of his own design, showed that certain gases in the atmosphere, blocked and absorbed longwave, or heat radiation.

Four decades later, Svante Arrhenius, with thousands of manual calculations, made an estimate of the global warming power of CO2, that was very close today’s best models.

In the 1950s, American Charles Keeling began to measure accurately the steady increase of CO2 in the atmosphere. Spectrographic analysis soon showed that the new carbon was, without a doubt, man-made.

(Voice of Heidi Cullen:)

“The CO2 released by burning fossil fuels, like oil, coal, and gas, has a different chemical signature than CO2 released by living animals and plants. And the spectrometer shows that the increase in CO2, comes from burning all of those fossil fuels.”

A greenhouse gas like CO2, absorbs, and re-emits, wavelengths of light in the longwave spectrum, the energy of radiant heat.  Such a molecule will absorb and emit instantaneously, and in any direction. This is the simple, unambiguous physics of the greenhouse effect.

Richard Alley:

“Physics is straightforward, more CO2 has a warming influence, we can’t get around that, it’s out there, the rising CO2 should cause warming.”

The Primary greenhouse gases in the atmosphere include the most abundant one, water vapor, as well as carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons, as well as a few other more exotic new man-made compounds.

And overall, we like greenhouse gases. As radiation from the sun, mostly visible light, comes thru the atmosphere and warms the earth, greenhouse gases trap outgoing longwave radiation, and keep the planet 33 degrees centigrade warmer than it would otherwise be.

But as we have added more, especially CO2, the additional warmth is becoming a problem.

In recent decades, we have much more sophisticated ways to measure the energy that comes into, and out of, the planet, not just from ground based instruments, but also advanced satellites. We can measure accurately the incoming radiant energy from the sun, and we know how much energy the earth is radiating out as heat, and how much of that is absorbed and trapped by greenhouse gases.

Measurements of energy in and energy out have been tracked by scientists over recent decades.  This study [2] compared satellite measurements of outgoing longwave radiation over almost 3 decades.

Change in Outgoing radiation due to greenhouse gases between 1970 and 1997

After correcting for increased temperatures and humidity, this graph shows the change in outgoing radiation due to greenhouse gases between 1970 and 1997. The wavelengths for greenhouse gases show increased absorption. And the study concluded:

Our results provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.

woman: “Damn Scientists”

Obama: “Some Bolshevik Plot!”

If less energy is getting out, more energy must be coming back to warm the planet. And scientists have measured this as well.

In this study [5], data from 3200 ground stations collected over 25 years, showed increased downward longwave radiation, as predicted by atmospheric physics.

Scientists have also looked at other potential causes of warming, or forcings, in the system [3]. Accurate measurements are available of solar irradiance, which has been flat since the 1950s.  We’ve also measured the effects from the ocean, like El Nino, and the influence of volcanic eruptions.

When scientists put all these forcings together, they can make an estimate of the effects on climate over time [8].  Using what we know about climate forcings, scientists have checked to see if they can recreate known temperature conditions of the past. This series of multiple climate model recreations over the last 120 years, tracks accurately with the known temperature record over that time, proving that our models are realistic.

But more important than temperature readings or climate models, are the ways the earth itself is showing us the indications of climate change.

Chris Fields:

“The clearest ones are in shifts in the way that ecological systems work, when spring arrives, when flowers bloom, when birds fledge.”

Richard Alley:

“Where critters and plants live and when they do things in the year are moving toward colder places and towards colder seasons as they respond to the warming. Most of the indicators are saying the same thing, it’s getting warmer.”

Scientists have gathered an enormous volume of data from physical and biological systems. In this famous study by NASA researchers [6], the available data was gathered together.  All over the planet, physical systems and living things are showing us a trend.

The seasons when birds migrate, the blooming of flowers and plants, the migration and mating of fish and animals, the peak flow dates of glacial streams, the days when ice breaks on frozen rivers and lakes, the onset of winter and spring. Altogether, this study looked at more than 29000 sets of physical and biological data. Of those, almost 90 percent were changing in a direction consistent with global warming. Birds and bees don’t have a political agenda.  At least, we think not.

This is a headache, for Climate deniers who want you to believe it’s all some kind of giant conspiracy, and the birds are in on it.

woman: “Damn Scientists!”

Obama: “Some Bolshevik plot!”

The plot gets thicker. The great lakes have lost most of their winter ice over the last 3 decades.

Sea level rise

The Ocean is in on it too. If temperatures are rising, then ocean waters should be expanding, and sea level should rise, and we do see that rise.

The change is evident to farmers and gardeners, as growing seasons and hardiness zones for plants have moved steadily northward over several decades.

As more snow melts in northern regions, the outflow of arctic rivers to the ocean has increased.  Northern polar sea ice has been in steady decline over the last 3 decades.

from World Glacier Monitoring Service

The great ice sheets of Antarctica and Greenland are losing more mass than anyone would have predicted just a few years ago.  Glaciers all over the planet are melting and shrinking at increasing rates.

Boots on the ground observations, from both American, and International teams have shown the same long term decline, now extending over many decades.

With more moisture in the atmosphere due to warming, precipitation events are getting more extreme, both in northern, and tropical areas.

The evidence is clear, overwhelming, from multiple lines of evidence, and consistent world wide, as demonstrated in 150 years of scientific research.

woman: “damn scientists”

Obama: “some Bolshevik plot!”

The Physicist Richard Feynman said, “Science is what we do to keep from lying to ourselves.”  There will always be those who prefer comfortable lies to uncomfortable truth, and no shortage of those willing to tell those lies. Real science sometimes upsets our preconceived notions of the world, and that’s not always bad.

But you can always count on getting the real documented information, on real science, here at Climate Denial Crock of the Week.

References

  1. Stable isotope ratio mass spectrometry in global climate change research, Ghosh, 1 July 2003
  2. Increases in greenhouse forcing inferred from outgoing longwave radiation spectra of the Earth in 1970 and 1997, Harries, et al, Nature, 15 March, 2001
  3. Cycles and trends in solar irradiance and climate, Lean, Wiley InterScience Journal, 2010
  4. Radiative forcing – measured at Earth’s surface – corroborate the increasing greenhouse effect, Philipona, et al, Geophysical Research Letters, 6 February 2004
  5. Global atmospheric downward longwave radiation over land surface under all-sky conditions from 1973 to 2008, Wang, Journal of Geophysical Research, Oct 2009
  6. 29000 data sets: Attributing physical and biological impacts to anthropogenic climate change, Rosenzweig, et al, Nature, 15 May 2008
  7. 29000 data sets, press release: Earth Impacts Linked to Human-Caused Climate Change
  8. Earth’s Energy Imbalance: Confirmation and Implications, Hansen, et al, Science, June 3, 2005

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One Response to “What We Know about Climate Change”


  1. [...] (Script, graphs and links to some of the relevant papers here) [...]


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