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LJWorld.com weblogs Global Warming from a Conceptual Standpoint

A Brief History

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In 1824, Joseph Fourier found that the earth was considerably warmer than it shoud be based on the work on thermodynamics (the study of energy exchanges) that he was conducting. If you are trained in mathematics or physics, you might recognize Fourier as the same person who gave us Fourier Analysis, and many other clever bits of science and math. In a nutshell, bodies radiant energy at a rate dependent on their temperature, and if you know how much energy is inbound (sunlight), you can calculate a temperature where energy outbound equals energy inbound. Earth was too warm, and Fourier deduced that Earth's atmosphere acted as a sort of insulation.

John Tyndall was also working on radiative energy transfer, a bit later in the 1850s. He also contributed many things that are now basic coursework in science classes, but the most relevant for the current topic is that he discovered that carbon dioxide absorbed and emitted radiation in the same part of the infrared spectrum as Earth emits. He was able to isolate the effect that various gases in the atmosphere have on radiated heat energy. This particular work was published in "On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction".

Svante Arrhenius was the first person to make the connection that human activities (mostly the burning of coal) increasing the carbon dioxide content of the atmosphere might, eventually, cause Earth to get warmer. Arrhenius was a pretty sharp guy as well; he taught himself to read at the age of three and, later of course, won the Nobel prize in chemistry, among other things. In 1896 he attempted to describe mathematically how much of an effect additional carbon dioxide should have. He incorporated his own work and built upon the earlier work of Fourier, Tyndall, Jožef Stefan, and Ludwig Boltzmann. (Those with a science or engineering background may be familiar with the Stefan-Boltzmann Law.) He did not have the refinement of knowing as much about feedback mechanisms, orbital mechanics, et cetera, as we do now, but his equation relating the content of carbon dioxide to the mean temperature of our planet serves as a first-order approximation and is still in use today.

In 1896, Arrhenius was a voice in the wilderness, and his idea was met with much derision at the time. Some decades later, in 1938, Guy Stewart Callendar revived and expanded upon the work of Arrhenius. He noted that industrial emissions of CO2 were already far greater than they were in Arrhenius' time, and that, even if the CO2 effect was pretty much saturated at sea level, the effect was a function of the density of the gas, and the density decreases with altitude. So, increasing the density overall rises the altitude at which it is not saturated, and that itself would increase the insulating effect and, therefore, the heat content would increase. Callendar was also met with debate, but this time the argument persisted. By the 1960s or so, the idea that people were impacting our planet's climate, and that CO2 was a prime driver, had won the debate, at least among scientists.

Charles Keeling was concerned about what might be happening to our planet, and in 1958 started measuring CO2 content in the middle of the ocean, far from industrial activities, and at the highest practical altitude in order to minimize the impact of daily cycles of plant growth on the measurements. Since 1958, there has been a continuous record of atmospheric CO2 content coming from the Mauna Loa Observatory on the big island of Hawaii. Many sites have been added to the record since then. They all tell the same story of an accelerating increase in CO2.

There are half a dozen or so institutions which have constructed records estimating the earth's surface temperature. The historical records are not nearly as complete as one would like to have for this undertaking, and the various institutions have used different math methods to minimise the effects of instrument bias, incomplete records, and the like. These different methodologies have yielded slightly different estimates for the mean temperature and rate of increase, but all the results show a marked and accelerating increase starting from the time that the industrial revolution started.

Recently, the concentration of CO2 in the atmosphere crossed 400 parts per million by volume (ppmv). This is not a magical number; it is not meaningfully different from 399ppmv or 401ppmv. However, people tend to gravitate to round numbers and this one has made the news lately. The last time CO2 levels were this high, about 3 million years ago, the planet had a very different climate. The continental ice sheets either did not exist or were much smaller than they are now, our ancestors were loosing body hair and learning to walk upright in the savannas of Africa, and pretty much none of the regions of earth had the same temperature and rain patterns that they do now. If you go back in time further, you will find the paleocene–eocene thermal maximum (PETM), another period of rapid CO2 increase and rapid temperature rise. The change in climate (and ocean pH) then was enough to destabilize ecosystems and cause the extinction of many ocean and mammal species. Rapid is a relative term; the PETM rise in CO2 and temperature took place over 20,000 years; we are on a path to cause the same changes in 200 years.

In summary, the basic foundations of the science related to global warming were laid down starting nearly 200 years ago. The prediction, based on science, that our activities would cause global warming was made about 100 years ago, and since then the planet has warmed. The debate about whether our use of fossil fuels would lead to a warming planet was over at least 50 years ago. For the last several decades, the vast majority of those that know the most about the subject have been saying that our use of fossil fuels will lead to changes in our environment that are dangerous to our way of life. Now it is past time to quit pretending we don't have a problem.

Postscript

I would encourage people not to take my word for what I have said about the history of the science. All of this can be verified independently, either in textbooks or on the web. I would caution that there is an awful lot of material on the web that is complete nonsense. Think of this like the game where a message is passed from person to person and comes out somewhat mangled at the other end. Try to get your information about the research as close to an original source as you can. If you can't trace your source back to some actual research, it is as valid as a rumor started by someone who was not there.

Comments

Chris Golledge 1 year, 5 months ago

Normally any mention of climate change creates a lively discussion, but not this time.

I'm curious if I simply missed the mark on something interesting to talk about, crossed the too-long-didn't-read threshold, or what.

George Lippencott 1 year, 5 months ago

Maybe the argument has changed from the scientific topic of the existence of climate change to the political issue of how to address it.

Phoghorn 1 year, 5 months ago

That is the big issue. If you look at the history of the planet, you see that it is a story of global tropical conditions interrupted by the occasional ice age and temperate conditions as we have had for the last few thousand years. Thus, while humans may have a miniscule affect, it is negligible in the grand scheme of things.

I have to live on this planet, so I want it to be as healthy as possible. That being said, I am not convinced that the warming trend of the last couple decades is anything to worry about. Give it enough time, and we will likely go back into a period of cooling.

There is not much we can do about Milankovich Cycles.

Chris Golledge 1 year, 5 months ago

Phoghorn, you haven't been paying much attention. We are still in a cooling period as far as Milankovich cycles are concerned.

avarom 1 year, 5 months ago

Very true....Global Warming, then Climate Change....they had to change to the wording to fit the picture.....funny how that work out. People should be more worried about the frack drilling that is happening....which is poisioning our drinking water, creating earthquakes and damaging our food sources from animals drinking bad water. Chemical induced in fracking is a very bad deal for humans.

avarom 1 year, 5 months ago

Land owners, take a serious look at your Mineral Rights and don't sign them off....

Chris Golledge 1 year, 5 months ago

Except people are still voting for people like Inhofe and Rick Perry, and any Republican who admits to the reality, like Jon Huntsman, faces being ostracized by his constituents.

avarom 1 year, 5 months ago

Using the Milankovitch cycles to predict future climate changes is like trying to use reruns of Gilligans island to predict what is going to happen on American idol. The only thing those 2 shows have in common is that they were on TV, the only thing the Milankovitch climate cycle and our current climate have in common is that they occur on earth. The climate under the Milankovitch cycle is predictable because the only things which can disrupt it are major geological or cosmological events, Milankovitch's cycle became useless to predict climate the first day we (mankind) began to alter the earth's atmospheric content. Major temperature changes take place over thousands of years in his cycle because of the cumulative effects of all the different models (axial, orbital, etc.) interacting with each other to produce GRADUAL cooling or warming trends with the mean average temperature not fluctuating more than 4-5 degrees C over a 20 to 50 thousand year period.

Using the data available today, we would be experiencing that increase over the next 3-4 hundred years..... there aren't any naturally occuring variables to account for a change that is both this drastic and this rapid. The current warming trend may have been initiated as a naturally occuring Milankovitch shift 10,000 years ago, but there can be no doubt about the amplification of the warming trend by the millions of tonnes of greenhouse gases being belched into the atmosphere every year by humankind that wouldn't normally be there.

The point is this, attempting to argue against human induced global warming using naturally occuring events, although the events are proven to alter climate, is futile because cyclical climate change simply doesn't occur as rapidly as what is happening right now and a naturally occuring event which could have produced the current trend would have happened during the last 2000 years and would have to have been documented somewhere by someone. True there have been well documented climatic anomalies which have been severe, but also shortlived and the causes for them have been recognized. This current warming trend has been global and constant over the last century and the cause has also been recognized, by everyone who doesn't have a financial stake in the engines that drive our current economy remaining unchanged......so in other words...... The Sky Isn't Falling.......

Ken Lassman 1 year, 5 months ago

Avarom, In school, if you copy and paste someone else's words without attributing it to that other person, you are given a "zero" for your paper and given a warning never to plagiarize again. That sin of omission is even worse than your usual "link-without-a-point" posting. For others who read "Avarom's" unusually cogent post (with the odd statement that contradicts the plagiarized portion above it tacked on to the end), here is the unattributed source: http://www.physforum.com/index.php?showtopic=11529

Chris Golledge 1 year, 5 months ago

I was thinking the same thing, that this comment made an unusual amount of sense for Avarom, except there was no connection between the underlying facts and the conclusion that was drawn. I did not think to check for plagarism.

Ken Lassman 1 year, 5 months ago

By the way, thanks, cg, for laying out the basic untrammeled science that underlies the whole issue of greenhouse gases and how they relate to climate change and how they connect human activities to those changes. With Obama set to make a statement on taking measures to curb greenhouse gas emissions, your post is a timely one that folks should read to inform themselves on this important background as to why it's an issue in the first place.

One piece of the puzzle that I've been paying attention to of late is the role that the oceans are playing in the absorption, retention and circulation of heat on our planet. A particularly good summary of this dynamic can be found here:

http://www.skepticalscience.com/clarifying-continuation-global-warming.html

Chris Golledge 1 year, 5 months ago

Similar thoughts. I've been meaning to write another post for a while; now seemed like an opportune moment to set some background context for whatever Obama has to say.

A rhetorical question for doubters, regarding the recent slowdown, is: In the past, similar periods of low solar activity and predominately La Nina conditions have seen downturns in the temperature record; why do you think there has been no downturn this time?

jafs 1 year, 5 months ago

Generally speaking, the same folks who are concerned about CO2 emissions are also concerned about the environmental effects of things like fracking.

It's the ones who deny the effect of CO2 emissions who also push for fracking.

jafs 1 year, 5 months ago

The point of my comment was that you say we should be more concerned about fracking, and oppose climate change concerns.

But, the same folks concerned about climate change are concerned about fracking.

So, if you're concerned about the effects of fracking on the environment, you'd be better off aligning yourself with environmentalists, who are also concerned about CO2 emissions.

Trumbull 1 year, 5 months ago

America has the opportunity to be the leader in developing and using renewable energy sources and to show the world we are not a declining power who outsources jobs. We are the America who declared Independence in 1776 and rose to the top during the Industrial Revolution, and did much good in the 20th century by protecting democracy in WWI and WWI.

Perfect opportunity. What do we do? We blow it. We give way to vested interests who do not want to lose their slice of the pie. Right now America reminds me of a fat man in a Tuxedo chewing and smoking a dirty cigar....not the world leader we are capable of being.

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