But, the temperature responds to the greenhouse gases much more quickly. It doesn't take years or decades for the temperature to change once you change the state of the atmosphere.
Actually it's more complicated than this. Temperature is measured from the snowflakes and that has a fairly good temporal resolution. The CO2 is measured from gas bubbles, but the top 100 meters of the glaciers are porous to air, so the bubbles give a average of hundreds of years worth of atmospheric change. So CO2 is always younger than the temperature, but they try to correct for this with diffusion models. The accuracy depend on how good the models are. But you never get a good time resolution of course...
Um, source? I am not a geologist, but my understanding was that a lot of the warming in the Cretaceous was due to CO2:
Nice summary.
Actually the precipitation was taking place in desertous areas, because it was too hot for trees to survive. Only small shrubs could live there.
We do know that historically, CO2 has not *triggered* rising temperatures.
The "trigger" is irrelevant in this case.
For example humans are a trigger for rising CO2, which in turn warms the earth.
The important thing is which physical process affects which aspect of the climate.
In some regions, a change in wind pattern or ocean current can make a big difference as well.
Earlier in this thread (repeatedly btw, over 6 months ago and on) I discussed how Cyanobacteria altered our climate by taking CO2 out of it and replacing it with oxygen. Then, dozens of comments later, Geo comes in and provides a bunch of links to me regarding that event as if I hadn't already discussed it in this thread. If the atmosphere of the earth goes from 17% CO2 to 0.4% (this was over many millions of years) you're going to indeed get an affect.
I thought that was an event 500 millions years ago or so...
I was talking about an event 50 million years ago (about 3,000 ppm down to 600 ppm, i.e. 0.3% down to 0.06%).
There is a very reasonable hypothesis that warming temperatures unlock carbon traps which results in more CO2 in the atmosphere which exacerbates the problem. That's fine. Warming temperatures unlock Co2, Methane and countless other carbon-based molecules. And those additional green house gasses magnify the warming trend.
Sure this is an interesting process.
When you see this set of physical processes which control the level of CO2, how do you then proceed to determine how much a certain level of CO2 affects the global temperature on Earth?
If your claim that temperature responds to greenhouse gases much more quickly were true, we should have seen very dramatic warming over the past 2 decades. That hasn't happened. And if historical data is too imprecise to be relied upon, why does IPCC do so?
If people would take the time to investigate exactly what this "delay" is all about, they would understand that the delay is due to the process of oceanic mixing and vertical heat transport. The ocean acts as a mitigating factor for temperature rise, and that mitigation effects occurs not only linearly but also in occasional bursts where large vertical overturn occurs.
The head slap remains appropriate because nothing you've cited demonstrates rising atmospheric CO2 concentration is the precipitating cause of higher global temperatures.
Only if you look doggedly at atmospheric temperatures.
For future temperatures, the oceanic heating is also very important, because a hotter deep ocean means hotter future temperatures, because vertical heat exchange will have less of a cooling effect.
Actually, it's quite material because we don't know how much, if any, measurable affect our CO2 production is having on the climate.
Actually, if you would forget your obsession with an "inexplicable" 1 degree celsius temperature offset in the Antarctic data set for a moment, you may find that other data sets show CO2-temperature correlations of 10 degrees celcius or even more, during several extreme catastrophic periods in the Earth's past.
Why CO2? Why is that the bogeyman? Why not methane? Methane has gone way way up and is a much worse greenhouse gas. What about all the extra water vapor our human cities produce? So why CO2? Co2 does aggravate the issue but we don't have any idea how much and what evidence we do have implies it has very little effect.
For greenhouse gases the variables that matter are: what concentration, its potential to capture and radiate heat, and how long it lasts in the atmosphere. Methane is more potent than CO2 in terms of its effect in trapping heat but lasts for only 1/10th the time of CO2. Methane currently has less of an overall radiative forcing effect than CO2 but this could change in the future as there large amounts currently trapped in permafrost that can be released as it melts.
Methane is negligible in total quantity, it is converted into CO2 within a few decades. To have enough methane in the atmosphere to influence the climate during thousands of years, that would require an impossibly large level of yearly methane production.
It's just not possible.
The only candidate would be a catastrophic methane-hydrate release could be big enough to cause a temperature jump, but it would have to be absolutely massive.
More likely is a gradual release of methane, which is then transformed into CO2, which can then affect climate for many thousands of years.
I think that the release of methane from permafrost will be too slow (not enough methane release / year) to have a noticeable effect, because permafrost melts very very slowly - it takes a long time before 100 meters of soil have melted. I think that the prolonged release of methane during thousands of years of melting will result in higher levels of CO2, which will just keep accumulating (because it's produced much faster than it can be removed by life) and this will be important.
What about all the extra water vapor our human cities produce?
Water vapor is even harder to maintain in the atmosphere. It creates rain and is washed out of the atmosphere within a few days. To maintain an artificial high water vapor level, humans would have to produce hundreds of billions of tons of water vapor every day. That's just no doable, we don't produce enough energy to produce so much water vapor.
But it gets worse, IF temperature was heavily affected by CO2, we'd already be screwed beyond all recall. You'd need to decrease CO2 back down to less than 300 just to approach historical norms and there is no way that's going to happen. So be thankful that CO2 isn't a significant driver of temperature.
Yes the whole point of climate research is to understand exactly how screwed we are.
We haven't seen massive climate changes over the last few decades because current CO2 changes are still small compared to those in say, the Cretaceous. It takes time for the CO2 to build up from our industrial processes, so the effect is cumulative and it will get worse over time for that reason. It's not like it was a sudden impulse in 1950 or something.
Well actually it is already pretty important for our climate (for example the poles and the shifitng deserts), but I agree that it takes a while. The ocean still acts as a heat buffer, mitigating heating. China's aerosol polution acts as a mitigating factor too.
We are definitily not in an equilibrium situation yet (for the current levels of CO2) where we can see NOW what the temperatures will be like THEN. That's just not the case, but we've got models for that, to estimate what the future temperatures will be.
I've been one of the people linking to the IPCC report. Anyone claiming they've read this thread while suggesting that I (or others) haven't done plenty of googling during the course of it are being disingenuous.
Apart from the link to the Antarctic data set, I have seen no evidence to support your point.
There are no lab experiments for example that show that CO2 does not absorb energy.
Or perhaps you're refering to the cloudiness hypothesis ... but that one's been investigated heaviliy by modeling and so far, the dice could go either way: will global warming create extra clouds, or will it just create the same number of clouds which just contain more rain, or will there be fewer clouds?
It's hard to say from a modeling viewpoint, and it surprises me that deniers somehow know this for a "fact".
Especially since ancient data have shown hot-house earths, so I think that clouds are definitely not a fool-proof mechanism to avoid global warming.
So a big spike in CO2 levels can have a fairly small change in temperatures at first, especially since you have a big temperature baseline that is dominated by effects that are not related to greenhouse gasses in the first place. But that doesn't imply that there is no relationship between greenhouse gasses and atmospheric temperatures. It just means that things in reality can be nonlinear (not surprising in reality), and that things can have multiple causes (also not surprising in reality).
Well said.
Why don't we want the earth to get warmer anyway? I mean if the earth got warmer canada could be like,. a real country. Or even greenland!
Because in the end-game (extreme heating) only the polar regions would be habitable and these regions, even without a 100 meter sea level rise, have less land area than the equator and cannot house and feed 7 billion people.
In any case it couldn't possibly be worse for humanity than the effect of stopping fossil fuel usage which would basically send us back to some pre-industrial hell that no one wants to live in.
In the early stages it would cost a lot of money to move cities and agriculture.
It will be similar to the rise and fall of civilizations, except that those will occur on a massive scale, all together in a short period of time.
In the end-game it would cost billions of lives.
These things are very very costly.
My country would disappear, it would be almost priceless for me if the Netherlands would somehow be saved... or maybe the future Dutch will have to move elsewhere, as one of the worlds first climate refugees.