The most important was simple water vapor H 2 O. Also effective were carbon dioxide CO 2 , although in the atmosphere the gas is only a few parts in ten thousand, and the even rarer methane CH 4.
Just as a sheet of paper will block more light than an entire pool of clear water, so a trace of CO 2 or CH 4 could strongly affect the transmission of heat radiation through the atmospheree. For a more complete explanation of how the so-called "greenhouse effect" works, follow the link at right to the essay on Simple Models of Climate. Keeling understood immediately that the curve is jagged because plants in the Northern Hemisphere take up CO 2 as they grow in Spring and Summer, and release it as they decay in Autumn and Winter.
Carbon Dioxide: Key to Climate Change? For the history of all measurements see the essay on the modern temperature trend. The history of these matters is described in essays on international cooperation and public attitudes.
The heat content of the upper layers of the world's oceans is the most comprehensive measure of changes in the temperature of the planet. For as new heat is added, far more goes into the oceans than into the thin atmosphere. Several independent analyses of hundreds of thousands of measurements of various kinds show that the oceans' store of heat energy, after a period of stability, began to rise in the s. That matches computer models of the effect of rising greenhouse gases.
For latest updates see NOAA's ocean heat content site. See Levitus et al. Back to earlier text. See also: graph of global surface air temperature since Callendar , little-known pioneer. The Discovery of Global Warming August The Carbon Dioxide Greenhouse Effect In the 19th century, scientists realized that gases in the atmosphere cause a "greenhouse effect" which affects the planet's temperature. Like many Victorian natural philosophers, John Tyndall was fascinated by a great variety of questions.
One possible answer was a change in the composition of the Earth's atmosphere. Beginning with work by Joseph Fourier in the s, scientists had understood that gases in the atmosphere might trap the heat received from the Sun. As Fourier put it, energy in the form of visible light from the Sun easily penetrates the atmosphere to reach the surface and heat it up, but heat cannot so easily escape back into space.
The warmed air radiates some of the energy back down to the surface, helping it stay warm. This was the effect that would later be called, by an inaccurate analogy, the "greenhouse effect. Yet the physics was straightforward enough to show that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. Tyndall set out to find whether there was in fact any gas in the atmosphere that could trap heat rays. The next major scientist to consider the Earth's temperature was another man with broad interests, Svante Arrhenius in Stockholm.
He too was attracted by the great riddle of the prehistoric ice ages, and he saw CO 2 as the key. Why focus on that rare gas rather than water vapor, which was far more abundant? Because the level of water vapor in the atmosphere fluctuated daily, whereas the level of CO 2 was set over a geological timescale by emissions from volcanoes. If the emissions changed, the alteration in the CO 2 greenhouse effect would only slightly change the global temperature—but that would almost instantly change the average amount of water vapor in the air, which would bring further change through its own greenhouse effect.
Again, for fuller discussion follow the link at right. But this idea could only answer the riddle of the ice ages if such large changes in atmospheric composition really were possible. Along the way he had come up with a strange, almost incredible new idea. Surprisingly, he found that human activities were adding CO 2 to the atmosphere at a rate roughly comparable to the natural geochemical processes that emitted or absorbed the gas. As another scientist would put it a decade later, we were "evaporating" our coal mines into the air.
The added gas was not much compared with the volume of CO 2 already in the atmosphere — the CO 2 released from the burning of coal in the year would raise the level by scarcely a thousandth part. But the additions might matter if they continued long enough.
So the next CO 2 change might not be a cooling decrease, but an increase. Arrhenius did not see that as a problem. He figured that if industry continued to burn fuel at the current rate, it would take perhaps three thousand years for the CO 2 level to rise so high.
One thing holding back the rise was the oceans. Anyway temperatures a few degrees higher hardly sounded like a bad idea in chilly Sweden. Another highly respected scientist, Walter Nernst, even fantasized about setting fire to useless coal seams in order to release enough CO 2 to deliberately warm the Earth's climate.
Arrhenius brought up the possibility of future warming in an impressive scientific article and a widely read book. By the time the book was published, , the rate of coal burning was already significantly higher than in , and Arrhenius suggested warming might appear wihin a few centuries rather than millenia.
Yet here as in his first article, the possibility of warming in some distant future was far from his main point. He mentioned it only in passing, during a detailed discussion of what really interested scientists of his time — the cause of the ice ages. Arrhenius had not quite discovered global warming, but only a curious theoretical concept. An American geologist, T. Chamberlin, and a few others took an interest in CO 2.
How, they wondered, is the gas stored and released as it cycles through the Earth's reservoirs of seawater and minerals, and also through living matter like forests?
Chamberlin was emphatic that the level of CO 2 in the atmosphere did not necessarily stay the same over the long term. But these scientists too were pursuing the ice ages and other, yet more ancient climate changes — gradual shifts over millions of years. Very different climates, like the balmy age of dinosaurs a hundred million years ago, puzzled geologists but seemed to have nothing to do with changes on a human time scale.
Nobody took much interest in the hypothetical future warming caused by human industry. Experts could dismiss the hypothesis because they found Arrhenius's calculation implausible on many grounds.
In the first place, he had grossly oversimplified the climate system. Among other things, he had failed to consider how cloudiness might change if the Earth got a little warmer and more humid. A still weightier objection came from a simple laboratory measurement. The assistant "Herr J. Koch," otherwise unrecorded in history put in rather less of the gas in total than would be found in a column of air reaching to the top of the atmosphere.
The assistant reported that the amount of radiation that got through the tube scarcely changed when he cut the quantity of gas back by a third. Apparently it took only a trace of the gas to "saturate" the absorption — that is, in the bands of the spectrum where CO 2 blocked radiation, it did it so thoroughly that more gas could make little difference.
Still more persuasive was the fact that water vapor, which is far more abundant in the air than carbon dioxide, also intercepts infrared radiation. In the crude spectrographs of the time, the smeared-out bands of the two gases entirely overlapped one another.
More CO 2 could not affect radiation in bands of the spectrum that water vapor, as well as CO 2 itself, were already blocking entirely. These measurements and arguments had fatal flaws. He failed to understand that the logic of the experiment was altogether false.
The greenhouse effect will in fact operate even if the absorption of radiation were totally saturated in the lower atmosphere. The planet's temperature is regulated by the thin upper layers where radiation does escape easily into space. Adding more greenhouse gas there will change the balance.
The logic is rather simple once it is grasped, but it takes a new way of looking at the atmosphere — not as a single slab, like the gas in Koch's tube or the glass over a greenhouse , but as a set of interacting layers. The full explanation is in the essay on Simple Models, use link at right. The subtle difference was scarcely noticed for many decades, if only because hardly anyone thought the greenhouse effect was worth their attention. Arrhenius responded with a long paper, criticizing Koch's measurement in scathing terms.
He also developed complicated arguments to explain that absorption of radiation in the upper layers was important, water vapor was not important in those very dry layers, and anyway the bands of the spectrum where water vapor was absorbed did not entirely overlap the CO 2 absorption bands.
Other scientists seem not to have noticed or understood the paper. Theoretical work on the question stagnated for decades, and so did measurement of the level of CO 2 in the atmosphere. A few scientists dissented from the view that changes of CO 2 could have no effect. An American physicist, E. Hulburt, pointed out in that investigators had been mainly interested in pinning down the intricate structure of the absorption bands which offered fascinating insights into the new theory of quantum mechanics "and not in getting accurate absorption coefficients.
Hulburt was an obscure worker at the U. Naval Research Laboratory, and he published in a journal, the Physical Review , that few meteorologists read. Their consensus was stated in such authoritative works as the American Meteorological Society's Compendium of Meteorology : the idea that adding CO 2 would change the climate "was never widely accepted and was abandoned when it was found that all the long-wave radiation [that would be] absorbed by CO 2 is [already] absorbed by water vapor.
Even if people had recognized this was untrue, there were other well-known reasons to deny any greenhouse effect in the foreseeable future.
These reasons reflected a nearly universal conviction that the Earth automatically regulated itself in a "balance of nature. Fifty times more carbon is dissolved in seawater than in the wispy atmosphere. Thus the oceans would determine the equilibrium concentration of CO 2 , and it would not easily stray from the present numbers. If somehow the oceans failed to stabilize the system, organic matter was another good candidate for providing what one scientist called "homeostatic regulation.
Just as seawater would absorb more gas if the concentration increased, so would plants grow more lushly in air that was "fertilized" with extra carbon dioxide.
Rough calculations seemed to confirm the comfortable belief that biological systems would stabilize the atmosphere by absorbing any surplus. One way or another, then, whatever gases humanity added to the atmosphere would be absorbed — if not at once, then within a century or so — and the equilibrium would automatically restore itself.
As one respected expert put it baldly in , "The self-regulating mechanisms of the carbon cycle can cope with the present influx of carbon of fossil origin. Yet the theory that atmospheric CO 2 variations could change the climate was never altogether forgotten. An idea so simple on the face of it, an idea advanced however briefly by outstanding figures like Arrhenius and Chamberlin, had to be mentioned in textbooks and review articles if only to refute it.
Arrhenius's outmoded hypothesis persisted in a ghostly afterlife. The greenhouse warming theory found a lone advocate. In an English engineer, Guy Stewart Callendar, tried to revive the old idea.
An expert on steam technology, Callendar apparently took up meteorology as a hobby to fill his spare time. When Callendar compiled measurements of temperatures from the 19th century on, he found they were right.
He went on to dig up and evaluate old measurements of atmospheric CO 2 concentrations. This rise, Callendar asserted, could explain the observed warming. For he understood perhaps from Hulburt's calculation that even if the CO 2 in the atmosphere did already absorb all the heat radiation passing through, adding more of the gas would raise the height in the atmosphere where the crucial absorption took place.
That, he calculated, would make for warming. Although he understood that industrial emissions were already far greater than in Arrhenius's day, Callendar never imagined the exponential climb that would make a doubling possible as soon as the late 21st century.
He did hint that over the centuries the rise might trigger a shift to a self-sustaining warmer climate which did not strike him as a bad prospect. But future warming was a side issue for Callendar. Like all his predecessors, he was mainly interested in solving the mystery of the ice ages.
Callendar's publications attracted some attention, and climatology textbooks of the s and s routinely included a brief reference to his studies. But most meteorologists gave Callendar's idea scant credence. In the first place, they doubted that CO 2 had increased at all in the atmosphere. The old data he had sorted though were untrustworthy, for measurements could vary with every change of wind that brought emissions from some factory or forest.
Already in the nineteenth century scientists had observed that the level of the gas rose, for example, near a flock of sheep busy exhaling the gas, and dropped in London during the inactivity of a bank holiday. If in fact the level was rising, scientists felt that could only be detected by a meticulous program stretching decades into the future.
The objections that had been raised against Arrhenius also had to be faced. Wouldn't the immense volume of the oceans absorb all the extra CO 2? Callendar countered that the thin layer of ocean surface waters would quickly saturate, and it would take thousands of years for the rest of the oceans to turn over and be fully exposed to the air.
According to a well-known estimate published in , even without ocean absorption it would take years for fuel combustion to double the amount of CO 2 in the atmosphere. There was also the old objection, which most scientists continued to find decisive, that the overlapping absorption bands of CO 2 and water vapor already blocked all the radiation that those molecules were capable of blocking.
Callendar tried to explain that the laboratory spectral measurements were woefully incomplete. Some scientists found this convincing, or at least kept an open mind on the question. But it remained the standard view that, as an official U.
Weather Bureau publication put it, the masking of CO 2 absorption by water vapor was a "fatal blow" to the CO 2 theory. Therefore, said this authority, "no probable increase in atmospheric CO 2 could materially affect" the balance of radiation.
Most damaging of all, Callendar's calculations of the greenhouse effect temperature rise, like Arrhenius's, ignored much of the real world's physics.
For example, as one critic pointed out immediately, he only calculated how heat would be shuttled through the atmosphere by radiation, ignoring the crucial energy transport by convection as heated air rose from the surface this deficiency would haunt greenhouse calculations through the next quarter-century. Worse, any rise in temperature would allow the air to hold more moisture, which would probably mean more clouds that would reflect sunlight and thus preserve the natural balance.
Callendar admitted that the actual climate change would depend on interactions involving changes of cloud cover and other processes that no scientist of the time could reliably calculate.
Few thought it worthwhile to speculate about such dubious questions, where data were rudimentary and theory was no more than hand-waving. Better to rest with the widespread conviction that the atmosphere was a stable, automatically self-regulated system.
The notion that humanity could permanently change global climate was implausible on the face of it, hardly worth a scientist's attention. The scientists who brushed aside Callendar's claims were reasoning well enough. Subsequent work has shown that the temperature rise up to was, as his critics thought, mainly caused by some kind of natural cyclical effect, not by the still relatively low CO 2 emissions.
And the physics of radiation and climate was indeed too poorly known at that time to show whether adding more gas could make much difference. Yet if Callendar was mistaken when he insisted he could prove global warming had arrived, it was a fortunate mistake. Research by definition is done at the frontier of ignorance. Like nearly everyone described in these essays, Callendar had to use intuition as well as logic to draw any conclusions at all from the murky data and theories at his disposal.
Like nearly everyone, he argued for conclusions that mingled the true with the false, leaving it to later workers to peel away the bad parts. While he could not prove that greenhouse effect warming was underway, he had given sound reasons to reconsider the question.
We owe much to Callendar's courage. His claims rescued the idea of global warming from obscurity and thrust it into the marketplace of scientific ideas. Not everyone dismissed his claims. Their very uncertainty attracted scientific curiosity. The complacent view that CO 2 from human activity could never become a problem was overturned during the s by a series of costly observations. This was a consequence of the Second World War and the Cold War, which brought a new urgency to many fields of research.
American scientists enjoyed massively increased government funding, notably from military agencies. The officials were not aiming to answer academic questions about future climates, but to provide for pressing military needs.
Almost anything that happened in the atmosphere and oceans could be important for national security. Among the first products of these research efforts were new data for the absorption of infrared radiation, a topic of more interest to weapons engineers than meteorologists. The early experiments that sent radiation through gases in a tube, measuring bands of the spectrum at sea-level pressure and temperature, had been misleading.
The bands seen at sea level were actually made up of overlapping spectral lines, which in the primitive early instruments had been smeared out into broad bands. Improved physics theory and precise laboratory measurements in the s and after encouraged a new way of looking at the absorption.
Scientists were especially struck to find that at low pressure and temperature, each band resolved into a cluster of sharply defined lines, like a picket fence, with gaps between the lines where radiation would get through.
Instead of two overlapping bands, there were two sets of narrow lines with spaces for radiation to slip through. So even if water vapor in the lower layers of the atmosphere did entirely block any radiation that could have been absorbed by CO 2 , that would not keep the gas from making a difference in the rarified and frigid upper layers.
Those layers held very little water vapor anyway. And scientists were coming to see that you couldn't just calculate absorption for radiation passing through the atmosphere as a whole, you had to understand what happened in each layer — which was far harder to calculate. Digital computers were now at hand for such calculations. Agriculture is another proponent of greenhouse gas emissions.
The planting of crops and rearing of animals releases several types of greenhouse gases into the air. For example, cattle herds produce methane when they pass gas, and this methane is 30 times more powerful than carbon dioxide. The crop fertilizers used by farmers contain nitrous oxide that is nearly times more potent than carbon dioxide. Deforestation occurs when trees are cut down to make way for agriculture or grazing or chopping down trees to use the timber for fuel, manufacturing and construction.
Forests contain trees that naturally remove and store carbon dioxide from our atmosphere. Trees also release the carbon they were storing when we burn them, so the damage is even more severe. Many situations often cause deforestation, but the most damaging process is beef production. The damage done by beef production is more than double the damage done by soy, palm oil, and wood production combined. Global warming occurs when carbon dioxide and other pollutants accumulate in the atmosphere.
This radiation would normally escape into space, but these pollutants can last for centuries in the atmosphere, trapping the heat and causing the nearby planet to heat up. These pollutants trap heat and are referred to as greenhouse gases. Their negative impact on the planet is known as the greenhouse effect. Here in the US and in most other areas of the world , the biggest contributor is the burning of fossil fuels. Every time we burn a fossil fuel it releases more harmful gases that contribute to the greenhouse effect.
If you want to contribute less to this issue, there are two important actions you can take. Inspire helps its members do just that in many states around the country. If you want to see if we can help you, click her e.
The other option you have is to use eco-friendly transport. If your lifestyle allows for it, consider switching to a vehicle with a high MPG miles per gallon will help you save money and get further on less fuel. Each year, we discover more about the consequences of global warming through evidence of its worrisome impact on the planet and its inhabitants.
Climate change causes heatwaves, fires, droughts, and floods, and as they become more frequent and dangerous, people and animals suffer. Why are carbon emissions a global problem? These devastating effects will likely also force million people into extreme poverty by In countries that already have high levels of suffering and poverty, this could have disastrous effects that we cannot afford to risk.
So, given the concerning outcomes of carbon emissions worldwide, carbon emissions are certainly not exclusive to certain countries. Environmental NGOs Non-Governmental Organizations began advocating global environmental protection to curb further global warming. Global warming soon became a hot news topic that was repeated all over the world. It may be surprising that this information became public knowledge so late, but before then, the idea of global warming was simply a theory.
Pretty much every sector of the global economy, from agriculture and manufacturing to power production and transportation, contributes to releasing greenhouse gases. To avoid the worst effects of large-scale climate change, all of these sectors must shift away from fossil fuels. The changes are vital for the biggest emitters, with twenty countries causing around three-quarters of global greenhouse gas emissions, with the US, China and India in the top three.
We already have the technology needed to reduce greenhouse gas emissions. Climate action is synonymous with any policy, measure or programme that works to reduce greenhouse gases, builds resilience to climate change or supports and finances those objectives. The Paris Agreement was the first major international agreement towards those ends. Skip to main content.
You are in Environment Consequences of the greenhouse effect. Share in Twitter. Share in Facebook. Whatsapp Whatsapp. The consequences of the greenhouse effect: from desertification to floods Human action is causing an increase in global temperature.
Numerous gases that are part of the atmosphere absorb the Earth's infra-red radiation, producing an increase in the temperature of the surface of our planet and the atmospheric layer that surrounds it.
Radiation escaping into space. Evolution of CO 2. CO 2 is the gas that contributes the most to the greenhouse effect. We present the history of emissions in the world during the last decade. Let's find out about the main consequences of this phenomenon: Thawing of glacial masses Glaciers retreat also has its own consequences: reduced albedo — the percentage of solar radiation that the earth's surface reflects or returns to the atmosphere —, a global rise in sea level and the release of large methane columns are only some of them, however, they are all dramatic for the planet.
Flooding of islands and coastal cities According to Intergovernmental Panel on Climate Change IPCC, , during the period the global average sea level rose 19 centimetres. It is estimated that by the sea level will be between 15 and 90 centimetres higher than it is now and will threaten 92 million people. Hurricanes will be more devastating The intensification of the greenhouse effect does not cause these extreme climatic events, but it does increase there intensity.
Hurricanes formation are connected with sea temperature — they only form over waters that have a temperature of at least
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