Daily Archives: June 4, 2013

The 1970s Ice Age Myth and Time Magazine Covers – by David Kirtley

This is a guest post by David Kirtley. David originally posted this as a Google Doc, and I’m reproducing his work here with his permission. Just the other day I was speaking to a climate change skeptic who made mention of an old Time or Newsweek (he was not sure) article that talked about fears of a coming ice age. There were in fact a number of articles back in the 1970s that discussed the whole Ice Age problem, and I’m not sure what my friend was referring to. But here, David Kirtley places a recent meme that seems to be an attempt to diffuse concern about global warming because we used to be worried about global cooling. The meme, however, is not what it seems to be. And, David places the argument that Ice Age Fears were important and somehow obviate the science in context.


h3>The 1970s Ice Age Myth and Time Magazine Covers
– by David Kirtley

A few days ago a facebook friend of mine posted the following image:

From the 1977 cover we can see that apparently a new ice age was supposed to arrive. Only 30 years later, according to the 2006 cover, global warming is supposed to be the problem. But the cover on the left isn’t from 1977. It actually is this Time cover from April 9, 2007:

As you can see, the cover title has nothing to do with an imminent ice age, it’s about global warming, as we might expect from a 2007 Time magazine.

The faked image illustrates one of the fake-skeptics’ favorite myths: The 1970s Ice Age Scare. It goes something like this:

  • In the 1970s the scientists were all predicting global cooling and a future ice age.
  • The media served as the scientists’ lapdog parroting the alarming news.
  • The ice age never came—the scientists were dead wrong.
  • Now those same scientists are predicting global warming (or is it “climate change” now?)

The entire purpose of this myth is to suggest that scientists can’t be trusted, that they will say/claim/predict whatever to get their names in the newspapers, and that the media falls for it all the time. They were wrong about ice ages in the 1970s, they are wrong now about global warming.

But why fake the 1977 cover? Since, according to the fake-skeptics, there was so much news coverage of the imminent ice age why not just use a real 1970s cover?

I searched around on Time’s website and looked through all of the covers from the 1970s. I was shocked (shocked!) to find not a single cover with the promise of an in-depth, special report on the Coming Ice Age. What about this cover from December 1973 with Archie Bunker shivering in his chair entitled “The Big Freeze”? Nope, that’s about the Energy Crisis. Maybe this cover from January 1977, again entitled “The Big Freeze”? Nope, that’s about the weather. How about this one from December 1979, “The Cooling of America”? Again with the Energy Crisis.

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Now, there really were news articles in the 1970s about scientists predicting a coming ice age. Time had a piece called “Another Ice Age?” in 1974. Time’s competition, Newsweek, joined in with “The Cooling World” in 1975. People have collected lists and lists of “Coming Ice Age” stories from newspapers, magazines, books, tv shows, etc. throughout the 1970s.

But if it was such a big news story why did it never make the cover of America’s flagship news magazine like the faked image implies? Perhaps there is more to the story.

In the 1970s there were a few developments in climate science:

  • Scientists were finding answers to the puzzle of what caused ice ages in the past: variations in earth’s orbit.
  • Scientists were gathering data from around the world to come up with global average temperatures, and they found that temperatures had been cooling since about the 1940s.
  • Scientists were realizing that some of this cooling was due to increasing air pollution (soot and aerosols, tiny particles suspended in the air) which was decreasing the amount of solar energy entering the atmosphere.
  • Scientists were also quantifying the “greenhouse effect” of another part of our increasing pollution: carbon dioxide (CO2), which should cause the climate to warm.

The realization that very long cycles in earth’s orbit could cause the waxing and waning of ice ages, coupled with the fact that our soot and aerosols were already causing cooling, led some scientists to conclude that we may be headed for another ice age. Exactly when was still a little unclear. However, the warming effects of CO2 had been known for over a century, and new research in the 1970s was showing that CO2 warming would more than compensate for the cooling caused by aerosols, resulting in net warming.

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This, in a very brief nutshell, was the state of climate science in the 1970s. And so the media of the time published many stories about a coming ice age, which made for timely reading during some very cold winters. But many news stories also mentioned that other important detail about CO2: that our climate might soon change due to global warming. In 1976 Time published “The World’s Climate: Unpredictable” which is a very good summary of the then current scientific thinking: some scientists emphasized aerosols and cooling, some scientists emphasized CO2 and warming. There was no consensus either way. Many other 1970s articles which mention a Coming Ice Age also mention the possibility of increased warming due to CO2. For instance, here, here and here.

Fake-skeptics read these stories and only focus on the Coming Ice Age angle, and they enlarge the importance of those scientists who focused on that angle. They totally ignore the rest of the picture of 1970s climate science: that increasing CO2 would cause global warming.

The purpose of the image of the two Time magazine covers, and of the Coming Ice Age Myth, is not to show the real history of climate science, but to obscure that history and to cause confusion. It seems to be working. Because today, when there really is a consensus about climate science and 97% of climatologists agree that adding CO2 to the atmosphere is leading to climate change, only 45% of the public know about that consensus. The other 55% must think we’re still in the 1970s when scientists were still debating the issue. Seems newsworthy to me, maybe Time will run another cover story on it.

To learn more see:

Linking Weather Extremes to Global Warming

Global Warming is the increase in the Earth’s temperature owing to the greenhouse effects of the release of CO2 and other gasses into the atmosphere, mainly by humans burning fossil fuel, but also by the release of Methane from oil wells and melting of Arctic permafrost, natural gas from leaky pipes, and so on. This increase in temperature occurs in both the atmosphere and the oceans, as well as the land surface itself. During some periods of time most of the increase seems to happen in the atmosphere, while during other times it seems to occur more in the oceans. (As an aside: when you use passive geothermal technology to heat and cool your home, the heat in the ground around your house is actually from the sun warming the Earth’s surface.)

ResearchBlogging.org“Weather” as we generally think of it consists partly of storms, perturbations in the atmosphere, and we would expect more of at least some kinds of storms, or more severe ones, if the atmosphere has more energy, which it does because of global warming. But “weather” is also temperature, and we recognize that severe heat waves and cold waves, long periods of heavy flooding rains, and droughts are very important, and it is hard to miss the fact that these phenomena have been occurring with increasing frequency in recent years.

We know that global warming changes the way air currents in the atmosphere work, and we know that atmospheric air currents can determine both the distribution and severity of storms and the occurrence of long periods of extreme heat or cold and wet or dry. One of the ways this seems to happen is what is known as “high amplitude waves” in the jet stream. One of the Northern Hemisphere Jet Streams, which emerges as the boundary between temperate air masses and polar air masses, is a fast moving high altitude stream of air. There is a large difference in temperature of the Troposphere north and south of any Jet Stream, and it can be thought of as the boundary between cooler and warmer conditions. Often, the northern Jet Stream encircles the planet as a more or less circular stream of fast moving air, moving in a straight line around the globe. However, under certain conditions the Jet Stream can be wavy, curving north then south then north and so on around the planet. These waves can themselves be either stationary (not moving around the planet) or they can move from west to east. A “high amplitude” Jet Stream is a wavy jet stream, and the waves can be very dramatic. When the jet stream is wavy and the waves themselves are relatively stationary, the curves are said to be “blocking” … meaning that they are keeping masses of either cold (to the north) or warm (to the south) air in place. Also, the turning points of the waves set up large rotating systems of circulation that can control the formation of storms.

So, a major heat wave in a given region can be caused by the northern Jet Stream being both wavy (high amplitude) with a big wave curving north across the region, bringing very warm air with it, at the same time the Jet Stream’s waves are relatively stationary, causing that lobe of southerly warm air to stay in place for many days. Conversely, a lobe of cool air from the north can be spread across a region and kept in place for a while.

Here is a cross section of the Jet Streams in the Norther Hemisphere showing their relationship with major circulating air masses:

Jet Stream Cross Section
Cross section of the atmosphere of the Northern Hemisphere. The Jet Streams form at the highly energetic boundary between major circulating cells, near the top of the Troposphere.

Here is a cartoon of the Earth showing jet streams moving around the planet:

The Jet Streams moving around the planet.  Not indicated is the Intertropical Convergence Zone (ITCA) around the equator which is both not a Jet Stream and the Mother of All Jet Streams.  This post mainly concerns the "Polar Jet."  Note that the wind in the Jet Streams moves from west to east, and the Jet Streams can be either pretty straight or pretty curvy.  Curvy = "high amplitude." This figure and the one above are from NOAA.
The Jet Streams moving around the planet. Not indicated is the Intertropical Convergence Zone (ITCA) around the equator which is both not a Jet Stream and the Mother of All Jet Streams. This post mainly concerns the “Polar Jet.” Note that the wind in the Jet Streams moves from west to east, and the Jet Streams can be either pretty straight or pretty curvy. Curvy = “high amplitude.” This figure and the one above are from NOAA.

Here is a depiction of the Jet Stream being very curvy. The waves in the Jet Stream are called Rossby waves.

The Jet Stream in a particularly wavy state.
The Jet Stream in a particularly wavy state.

(See also this animation on Wikicommons, which will open in a new window.)

Research published in the Proceedings of the National Academies of Science last February, in a paper titled “Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes,” links global warming to the setup of high amplitude waves in the Jet Stream, as well as relatively stationary, blocking, waves that cause extreme warm or cold conditions to persist for weeks rather than just a few days. According to lead author Vladimir Petoukhov, “An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions. So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic…What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks. So instead of bringing in cool air after having brought warm air in before, the heat just stays.”

So how does global warming cause the northern Jet Stream to become wavy, with those waves being relatively stationary? It’s complicated. One way to think about it is to observe waves elsewhere in day to day life. On the highway, if there is enough traffic, waves of cars form, as clusters of several cars moving together with relatively few cars to be found in the gaps between these clusters. Change the number of cars, or the speed limit, or other factors, and you may see the size and distribution of these clusters (waves) of cars change as well. If you run the water from your sink faucet at just the right rate, you can see waves moving up and down on the stream of water. If you adjust the flow of water the size and behavior of these “standing waves” changes. In a baseball or football field, when people do “the wave” their hand motions collectively form a wave of silliness that moves around the park, and the width and speed of that wave is a function of how quickly individuals react to their fellow sports fan’s waving activity. Waves form in a medium (of cars, water molecules, people, etc.) following a number of physical principles that determine the size, shape, speed, and stability of the waves.

The authors of this paper use math that is far beyond the scope of a mere blog post to link together all the relevant atmospheric factors and the shape of the northern Jet Stream. They found that when the effects of Global Warming are added in, the Jet Stream becomes less linear, and the deep meanders (sometimes called Rossby waves) that are set up tend to occur with a certain frequency (6, 7, or 8 major waves encircling the planet) and that these waves tend to not move for many days once they get going. They tested their mathematical model using actual weather data over a period of 32 years and found a good fit between atmospheric conditions, predicted wave patterns, and actual observed wave patterns.

The northern Jet Stream originates as a function of the gradient of heat from the Equatorial regions to the Polar regions. If air temperature was very high at the equator and very low at the poles, the Jet Stream would look one way. If air temperatures were (and this is impossible) the same at the Equator and the poles, there would probably be no Jet Stream at all. At various different plausible gradients of temperature from Equator to the poles, various different possible configurations of Jet Streams emerge.

One of the major effects of global warming has been the warming of the Arctic. This happens for at least two reasons. First, the atmosphere and oceans are simply warmer, so everything gets warmer. In addition, these warmer conditions cause the melting of Arctic ice to be much more extreme each summer, so that there is more exposed water in the Arctic Ocean, for a longer period of time. This means that less sunlight is reflected directly back into space (because there is less shiny ice) and the surface of the ice-free northern sea absorbs sunlight and converts it into heat. For these reasons, the Arctic region is warming at a higher rate than other regions farther to the south in the Northern Hemisphere. This, in turn, makes for a reduced gradient in the atmospheric temperature from tropical to temperate to polar regions.

Changing the gradient of the atmospheric temperature in a north-south axis is like adjusting the rate of water flowing from your faucet, or changing the number of cars on the highway, or replacing all the usual sports fans at the stadium with stoned people with arthritis. The nature of the waves changes.

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In the case of the atmosphere of Earth’s Northern Hemisphere, global warming has changed the dynamic of the northern Jet Stream, and this has resulted in changes in weather extremes. This would apply to heat waves, cold snaps, and the distribution of precipitation. The phenomenon that is increasingly being called “Weather Whiplash” … more extremes in all directions, heat vs cold and wet vs. dry, is largely caused by this effect, it would seem.

This study is somewhat limited because it covers only a 32 year period, but the findings of the study are in accord with expectations based on what we know about how the Earth’s climate system works, and the modeling matches empirical reality quite well.

See also: Killer Heat Waves and Floods Linked to Climate Change by Stephen Leahy and Slowing Rossby Waves Leading to Extreme Weather? by Stuart Staniford.

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Petoukhov, V., Rahmstorf, S., Petri, S., & Schellnhuber, H. (2013). Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes Proceedings of the National Academy of Sciences, 110 (14), 5336-5341 DOI: 10.1073/pnas.1222000110