What gases are greenhouse gases? – Jean-Marc Jancovici
This provides a direct, empirical causal link between CO2 and global warming. But where's the connection with CO2, or other greenhouse gases like methane. If the emissions changed, the alteration in the CO2 greenhouse effect would only . Apparently it took only a trace of the gas to "saturate" the absorption — that is, radiation, it did it so thoroughly that more gas could make little difference.(7*). Carbon dioxide concentration in the atmosphere is regulated naturally by a.
And are we the sole emitters for these gases? Water vapour H2Ocarbon dioxyde CO2. There are others such gases, and even many others. It just means that there are also natural sources or natural cycles.
Calculating — even roughly — the amount of ozone emitted by a country is today clearly very difficult. The molecules obtained that way have two important properties for our purpose: They are generally highly efficient to absorb infrared radiation, much more than CO2 their absorption bandwiths are large. As these degrading processes happen slowly and far from the ground, halocarbon molecules generally have very long residence times in the air, because it is necessary to wait until they get to the stratosphere — even though they are very heavy molecules — before they are degraded, and that can require thousands years.
Among the halocarbons we will find a well known sub familly: Not only they are potent greenhouse gases, but they also lead to a decrease in the stratospheric ozone. It is used, for example, to fill transformers that require gases that stay inert in extreme conditions or…double glazings.
It is not emitted in large quantities, but is even more potent than any halocarbon and its degradation requires several thousand years. What are the gases that generate the higher greenhouse effects and where do they come from?
If we do not bother about the origin natural or anthropic of the greenhouse gases, the one that generate the highest greenhouse effect is….
As halocarbons are industrial gases they are not represented here. The relative importance of each gaz has not varied much today. Indeed, on a planet which is covered by water for its two thirds, and taken into account that water does not accumulate in the atmosphere where its residence time is roughly a week, direct human emissions of water vapour do not have a significant impact on the global water cycle.
This explains why water vapour is not taken into account when measuring the greenhouse gas emissions caused by human activities, except in some very particular cases. There are of course natural CO2 emissions respiration of animals, plants and humanity, decaying of biomass, natural forest fires, ocean emissions….
The anthropic CO2 comes: Natural gas reserves were formed exactely that wayby the decay, a long time ago, of terrestrial or marine biomass.
What gases are greenhouse gases?
Finding methane in the atmosphere is therefore totally normal, as a result of the existence of swamps, and…termites! 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 CO2?
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.
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According to a well-known estimate published ineven without ocean absorption it would take years for fuel combustion to double the amount of CO2 in the atmosphere. 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.
How do we know more CO2 is causing warming?
But it remained the standard view that, as an official U. Weather Bureau publication put it, the masking of CO2 absorption by water vapor was a "fatal blow" to the CO2 theory. Therefore, said this authority, "no probable increase in atmospheric CO2 could materially affect" the balance of radiation. 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.Climate Science in a Nutshell #4: Too Much Carbon Dioxide
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.
Why Carbon Dioxide Is a Greenhouse Gas - Scientific American
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. 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 CO2 emissions.