There are several subquestions here. Where I ask about temperatures, please use numbers (eg "2 or 3 degrees C", "5 degrees F", "less than 1 kelvin", whatever); for the last question, please give some kind of percentage or percentages.
1. What do you think has been happening to the average temperature of the planet over the last century or so?
2. What causal mechanism or mechanisms do you think are responsible for this behavior? (short answer is OK)
3. What do you think is going to happen to the Earth's average temperature over the next century, if we do not take any special measures to curb our greenhouse gas emissions or otherwise alter the climate?
4. What do you think is going to happen to the Earth's average temperature over the next century, if we take the most drastic anti-AGW measures you consider probable?
5. Short answer/broad outline, how do you think these projected changes will affect us, the ecosystem, et cetera, if they do in fact occur? If you did not think there were going to be changes, what do you think the effects would be if some kind of significant change *did* occur? (this can just be one sentence, eg. "It will be good/bad, except for (group X)")
6. If you had to assign betting odds, how accurate do you think your guesses for 3 and 4 are? And how confident do you feel about your answers to 1, 2, and 5?
Remember, I want answers with numbers in, not "more or less the same" or "rising catastrophically" or whatever. Ranges are fine (though please keep them small enough to be meaningful, saying that average global temperatures have stayed within 20 degrees of the same value is a fairly meaningless statement in this context)|||1 ) It has been rising; there is some natural variation of perhaps +/- 0.1C, also an underlying warming of around 0.8C.
http://en.wikipedia.org/wiki/File:Global鈥?/a>
Before this, the long term trend was one of gradual cooling of around 0.01C/century.
http://upload.wikimedia.org/wikipedia/co鈥?/a>
2 ) Mainly anthropogenic. Some of the warming in the early 20th century was probably due to an increase in solar activity, but with the sun cooling for the last 50 or so years, I think it doubtful that much of the present increase can be put down to 'solar'.
... and with everything else pretty stable, that only leaves the increase in GHG's ... and that is down to us!
Here is what should be happening if the world was in equilibrium energy wise. Energy in = energy out.
http://upload.wikimedia.org/wikipedia/co鈥?/a>
By increasing the amount of (mainly) CO2 in the atmosphere, we are slowing the rate that some infrared wavelengths are escaping to space, this putting the planet out of radiative balance. The response is the warming of the surface and this will continue until radiative equilibrium is restored.
3 ) For any combination of forcings and feedbacks, there will be an equilibrium temperature that the system will try to reach. The rate of warming is proportional to the difference between the actual temperature and the equilibrium value.
What I think is happening is that, while CO2 levels continue to rise, the rise in temps is being partly offset by the thermal inertia of the oceans. In other words the full increase is kept low, while we continue to push the equilibrium value higher and higher.
But the oceans can't damp down the increase without warming themselves. As this happens, they will be less effective as dampers; they will also start to emit CO2 rather than absorb it, thereby further raising the equilibrium temperature.
The net result will be an accelerating rate of increase, at least initially.
With a positive balance of other feedbacks, I think 6C or 7C is quite likely over several hundred years, but the bulk of that; 4C or 5C would occur this century.
4 ) If drastic measures were taken, the above would still occur, but the amount would be less. Even if we could stop all anthropogenic GHG's tomorrow, I think we have already committed ourselves to around 2C of warming and I would expect to see most of that in this century.
5 ) This is where I am less certain: Sea levels HAVE to rise; there's no way around that, and at a faster rate than we have seen so far. Similarly, global precipitation HAS to increase.
But what changes would occur regionally, I'm not so sure. I guess the bottom line is, can we afford to take a chance? Do we have the right to take the gamble? ... leaving future generations to pick up the tab?
My feeling is that we can't ... and we don't!
6 ) For 3 and 4; fairly confident, about 90% for both scenarios. I would be less confident if there was a credible alternative explanation for the warming we have already seen, but there isn't!
For 1 and 2; very confident, better than 95%.
For 5; I'm not so sure, I'll say 70% that it would be more bad than good, but within that 70% there is a real possibility that it would be really bad!
It is that possibility we need to avoid.
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Edit: There was a problem with the first links I used; these have now been replaced and seem to be ok. They are not significantly different from the originals.|||Thanks.
On reflection, I'm not quite as confident of (4) as I am of (3). Certainly, if we took active steps to recover the CO2, such that we had negative emissions, I'm sure we could zero out the warming fairly quickly.
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|||I'll just index the list: ~64%.|||. What do you think has been happening to the average temperature of the planet over the last century or so? Probably risen about a half degree F.
2. What causal mechanism or mechanisms do you think are responsible for this behavior? (short answer is OK). I don't think I know and I know no one else does either. Some think they do.
3. What do you think is going to happen to the Earth's average temperature over the next century, if we do not take any special measures to curb our greenhouse gas emissions or otherwise alter the climate? It is hard to say. We seem to heading into a cooling period but the jury is still out. That would be much worse than a continuation of moderate warming IMO, alarmists shrill cries to the contrary notwithstanding.
4. What do you think is going to happen to the Earth's average temperature over the next century, if we take the most drastic anti-AGW measures you consider probable?
Don't know. Drastic anti AGW will likely cause poverty and misery.
5. Short answer/broad outline, how do you think these projected changes will affect us, the ecosystem, et cetera, if they do in fact occur? If you did not think there were going to be changes, what do you think the effects would be if some kind of significant change *did* occur? (this can just be one sentence, eg. "It will be good/bad, except for (group X)")
I doubt that it will matter to your average butterfly if it is a degree warmer.
6. If you had to assign betting odds, how accurate do you think your guesses for 3 and 4 are? And how confident do you feel about your answers to 1, 2, and 5?
Since I am confident of my ignorance as well as everyone else I would give it high confidence.|||1. I think global average temperatures have been rising by perhaps as much as 1C.
2. I believe there two main causes: solar and human. I'm not entirely sure of the exact solar mechanism however evidence for Henrik Svensmark's cosmic ray theory may be one of several plausible solar mechanisms. For the human mechanism, it is a combination of land use change, urbanization and altering the atmosphere composition (i.e. especially CO2 levels). Out of all of the possible and plausible warming mechanisms, I put a percentage on CO2 emissions as a range of 2-30%.
3. Well I don't think there is any significant effect we can cause by limiting CO2 emissions. And I mean that from the perspective of not being able to reduce them greatly (enough) and what we do reduce will have much less effect than natural variability. As far as natural variability, I'd look to the Sun again. I don't like the prediction that's it's going to enter a prolonged minimum. If that happened, I'd think we'd see temperatures gradually drop perhaps up to .5C over the next 60 years.
4. Not much different that answer #3 other than perhaps we would make it slightly colder by say .1C.
5. If what I say in answer #3 is close to be correct, then it will be very bad. Much worse than if temperatures went up by the same amount.
6. Betting odds: 1. 90%. 2. 50%. 3. 50%. 4. 50%. 5. 80%.|||I'll refer to my last answer of this question for the accuracy of any predictions. But given you are asking for guesses and estiamted levels of certainty, I'll give it a whirl, wtih little to no confidence.
1. and 2) Aaverage temp of the planet has increased over the last century by about 0.8 degrees celsius, with about 50% being caused by man's increased production of CO2. Other fall under normal fluctuation and coming out of the little ice age, some warming is to be expected.
In the next century, given that we do absolutely nothing to curb the CO2 production (or nothing more) the temps will continue to rise by about 1.3 degrees for each doubling of CO2. I would expect to double once around 2050 adding about 1.3 degrees to be felt by 2070. At around 2050, I would expect that we will be forced to move to more renewable resources or nuclear due to the cost of fossil fuel extraction. This will cause a decrease in CO2 production. Now I think a good estimate of the half-life of CO2 in the atmosphere (the general cycle, not one atom of CO2) is about 25 years. so that by 2100 we will be at our current levels of atmospheric CO2. Now given that it takes time for the temps to come back down upon less CO2 in the air, I estimate this to follow a half-life of about 25 years as well. So by quarter century (assuming that today is +0.4 degrees higher that what should normally be the case, I would estimate the following:
2010: +0.4
2025: +0.8
2050: +1.4
+1.7 as high between these 2
2075: +1.5
2100: +1.1
2125: +0.6
2150: +0.2
The above is the warming caused by man. Now the effect would be slightly bad, but manageable. I am not convinced of negative weather pattern changes, but there will certainly be less agrable land due to ocean rises, but more due to higher elevation and latitude land becoming available. The effect will largely be monetary due to movement of the populations from more established location to less. The human life toll would be dependent upon man's actions, which is entirely to variable to guess.
My confidence in my prediction is obviously low due mostly to the specificity of the numbers provided. In fact meeting all of the numbers within the significant digits used I would only give a %26lt;0.1% chance. My justification for such numbers, however, should be intuitively obvious. I doubt many warmers would argue against my numbers if I stated that these were the effects of CO2 warming alone minus all of the positive feedbacks. Simply put, I do not believe that the positive feedback outnumber the negative feedbacks, or more specifcally the huge negative feedback of the oceans. Simply put, the oceans serve as an extremely huge capacitor. One look at the amount of energy that the oceans can hold, with raising even 1 degree would give us all a clue as to their ability to serve as a capacitor. It would take a lot more evidence than the warmers have currently provided for me to believe that the positive feedback have overcome the negative feedback of the oceans. That being said, my confidence in my overall rationale is high. Following the logic of human-caused change in temps and follwoing within say 0.3 degrees of all the numbers I have used, I would put as up to 40% likely. That is to say this 40% is my belief and can certainly be changed by new information or information I do not know.
Hey Dook,
What are you talking about? You act like this question does not have meaning when it has more meaning than all of your questions. Clearly no one knows the future, but this really gets at the heart of where you stand on the issue. You want to pretend we "must" do such-and-such yet you can't answer this question? You want me to sacrifice for your "something bad may happen" garbage? No! In fact, how can I tell if you are scare-mongering some garbage about the world being uninhabitable if you are unwilling to at least hazard what you would consider an educated guess. Further, how much value does my answer provide you, if you paid attention? You might notice that I don't completely disagree and would be willing for some change, which would certianly be a start from the current stalemate.
Edit again for Dook: What lies have I told? I suppose you do not want to use CO2 taxes or really want the govt to regulate any changes at all. I also suppose that preparing for a 5 ft tidal wave and a 20 foot tidal wave requires the same level of preparation, at least according to you.|||Too many subquestions, Chem. It is more like questionaire than a question with subparts. Whatever it is, however, it is far from your best post here.
If you build a child-size sand castle near the ocean's edge shortly after low tide, it is of little use asking about the average velocity of the last 5 incoming waves, the speed and predicted direction of the wind, how many minutes longer the walls around the castle will last if you use the most drastic available little plastic shovel to make the walls higher and thicker, or how the projected changes in the tide level will affect the height and shape of the castle.
In other words, Chem, this question strikes me as bogus. You can get at best a wide range of numbers on all these sub-points, if you consult IPCC etc., so what is the point of asking the deniers, arm-chair scientists, and high school students here, for their obviously much less reliable "numbers"?
Edit to Expel: How about limiting your lies to science, and stop lying about other answers. I never said anything like what you falsely claim: that "we "must" do such-and-such"
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