1) You have to be able to predict CO2 levels as huge — which means making gross assumptions about technology that is not believable.
Your argument was left unfinished. What assumptions are not believable?
The oil and gas industry has proven adept at finding new reserves. Also, technology is being developed to supplant the most popular CO2-emitting fuels, crude oil and natural gas, with another, methane hydrates.
So, is it possible for humans to quadruple CO2 concentrations? It looks that way. (Especially since the projected worst-case increase in CO2 concentrations is not, IIUC, based on a completely linear relationship between emissions and atmospheric concentrations. It is thought that natural carbon sinks will absorb a less than linear fraction of atmospheric CO2 as time goes on and concentrations increase. If carbon sinks begin to “saturate” in this sense, future emissions will have a larger effect on the atmospheric CO2 concentration than current emissions do.)
But is a quadrupling likely? Certainly not.
Public and private research programs have a choice of whether to focus mainly on these technologies that could massively increase CO2 emissions, or on other technologies, such as LFTRs and solar panels.
This choice depends largely on whether people believe that raising CO2 emissions is acceptable or unacceptable.
So if we believe alarmists, the massive projected CO2 emissions will not occur. If we disbelieve them and mainstream scientists, those massive emissions are quite plausible.
Even if we are totally confident that we will reduce CO2 emissions, there’s nothing wrong with a scientist answering the “what if” question, “what if we keep doing business-as-usual?” Scientists are always answering “what if” questions because non-scientists and the media keep asking them.
Business-as-usual projections are in demand, so it would be downright bizarre for scientists to refuse to answer questions about it.
It would be like the MythBusters not figuring out how much X it takes to make Y explode. It would be like a supermarket not telling you the original price on a discounted item. People want to know! They keep asking! So scientists answer.
2) You have to be able to predict the temperature change from such CO2 which you have been extremely poor at doing and the climate MUST be extremely sensitive to CO2.
No. Mainstream estimates of climate sensitivity are not extreme, as I will explain.
First of all, 3°C is an absolute temperature change of only 1%, and it requires a modest feedback factor of 2.5x, based on the generally accepted CO2-without-feedbacks forcing of about 1.2°C from doubling CO2.
Setting that aside, I will simply extrapolate from observations below.
if co2 climbed 30% and produced 0.5C or 0.25C or 0.64C another 30% increase in CO2 will produce another quantity of that magnitude NOT 3C not 6C.
No mainstream climatologists claim 6°C, except a small minority who treat it as an “upper bound”. Typical best estimates are 2–4°C for “Charney climate sensitivity” with numbers close to 3°C being the most common by far (question 4a of Verheggen 2014).
Just as there’s a 3–9% minority saying “it’s a lot less than 2°C”, there’s another tiny minority of alarmists saying “it could be a lot more than 4°C”. As you know, I consistently side with mainstream scientists, so I would treat those alarmists with comparable skepticism as I treat the contrarians. Having said that, we only have one planet, so the possibility of unexpectedly large effects should not be dismissed entirely.
The Mainstream Scientific Case
Do numbers in the range 2–4°C make sense? Let’s do the math.
CO2 levels increased just under 25% between 1951 and 2010, the period on which the most recent IPCC report focuses (312 ppm to 389 ppm).
The temperature increase was 0.64C±0.06C in the same period.
Mainstream scientists estimate natural effects to be close to zero over that time period, because LIA ended 150 years ago, PDO had a 60-year period so its effect is neutral over the 60-year period, AMO is almost neutral as well, solar output has decreased slightly, and there is no large, natural reason for heat retention to increase, except for a small amount of CO2 from volcanoes which, on the other hand, also emitted copious amounts of cooling aerosols.
Therefore the increase is attributed entirely to humans, with CO2 as the most dominant factor by far, though there’s a small effect from methane and other things that aren’t coming to mind atm.
If we assume a simple logarithmic effect from increasing CO2, there should be an increase of around 1.99°C from doubling CO2 (that’s
log(2,1.25)*0.64 in my calculator).
That number may be a little high because CO2 is not the only anthropomorphic warming effect. So, IIUC, mainstream estimates in the range 2°C-3°C require the concept of committed warming.
The overall effect of CO2 is not instantaneous. Feedbacks can take decades to work themselves out, so we have not yet seen all the warming we are going to see. In other words, if we stopped all CO2 emissions tomorrow, the temperature would still rise for many years (edit: make that decades) afterward. Due to committed warming, most mainstream climatologists believe the temperature record alone understates the effect of CO2.
Here are two examples of time-delayed effects:
- Ocean warming: the ocean hasn’t “caught up” with CO2-induced warming. Every time cold water from deep in the ocean circulate to the surface, that water cools the surface. At the same time though, warm water at the surface goes downward. This warm water is (on average) about 0.64°C warmer than it was during older circulation cycles from 1950. Thus, the cold, deep water is slowly warming up. Consequently, future circulation events such as La Niñas will have slightly weaker cooling effects than they do now, so the result will be higher future global mean temperatures.
- Ice albedo: when sea ice and glaciers melt, the surface area of nearby bodies of water increase. This increases absorption of solar energy, causing some amount of warming, which in turn causes a little extra melting in later years, which in turn leads to other time-delayed effects.
(Note: pre-1950 emissions also have a time-delayed effect which has already taken place as part of the 0.64°C number; however, CO2 emissions are enormously bigger today. In 1950–1955, atmospheric CO2 increased 0.48ppm or 0.15% per year, but in 2006-2011 it increased 1.91ppm or 0.50% per year. Therefore, future committed warming from recent emissions should be much larger than the committed warming effect from pre-1950 emissions that we expect to have biased 1950–2010 measurements upward. Therefore, the net effect of committed warming has a strongly positive effect on estimates of climate sensitivity.)
Estimates of 3°C or higher require a second concept: aerosol cooling. The idea is that as we burn fossil fuels, especially coal and gasoline, we release SO2 and particulates that increase reflection of solar energy back to space.
Many climate scientists believe aerosols have a moderate cooling effect. This implies the warming effect of CO2 would be significantly higher without the aerosols — in the 3-4°C range. If this is true, it would not show up in observations of past warming! (or at least, not that strongly.)
The issue is important because aerosols dissipate much faster than CO2 (years vs centuries). Therefore, when we switch over to renewable energy and reduce emissions, the aerosols will quickly dissipate, but the CO2 will not. Paradoxically this will increase the warming effect of CO2.
So, that’s where estimates of 3°C-4°C come from, though there are probably other factors that might increase or decrease the sensitivity estimate slightly.
When you see estimates higher than 4°C, they either
- represent a change over extremely long time periods (because some smaller feedbacks might take centuries to play out),
- represent an upper bound (since mainstream scientists still admit a substantial amount of uncertainty in projected warming), or
- come from extreme alarmists that are hopefully safe to ignore.
I’m not telling you all this to change your mind.
I don’t expect you to.
Instead, the point I am making here is that climate science is logically consistent. The numbers make sense. Every part of it makes sense. It fits together into a coherent, cohesive whole. If you don’t believe that, try reading it again, more slowly and carefully.
One could decide to start from the physics of the atmosphere and information gathered before 1970 about the spectroscopy of CO2 and various other pieces of information that were gathered by non-climatologists, and derive a climate model from that without the need for any recent data. Then, you incrementally consider post-1970 information to build a more detailed picture. That’s what those originally proposing AGW did. This is hard though. Most people can easily understand the qualitative analysis, but making quantitative predictions requires very careful and detailed analysis that almost no one outside the field has the patience for.
Much more easily, one can start from observations of past warming and estimate sensitivity using straightforward arguments about natural forcings, feedbacks and aerosols.
Or, one can simply believe that there are at least, let’s say, 20% of climate scientists that have integrity and have checked the key findings of their peers.
The estimate of 2–4°C per doubling follows logically from all three lines of reasoning (well, it follows from the latter two; you can’t be sure about the first one unless you re-do all the science personally.)
Finally, you can look at the many successful predictions of climatologists and conclude that while they didn’t get everything right, they clearly knew what they were talking about, given all their successful predictions. For example, J.S. Sawyer predicted in 1972 that an increase of 25 per cent in carbon dioxide would correspond to an increase of 0.6 degrees Celcius in world temperature. Early climatologists weren’t predicting that warming would “continue” — they were predicting an end to the cooling trend of the past 20 to 30 years:
Climatologists had many other successful predictions, too. With such a firm foundation, you can’t hope to sway AGW believers with rickety old evidence-free arguments for which rebuttals are easily found.
(Plus, one can observe that while mainstream scientists have a single consistent and unified theory, albeit with apparent disagreement about certain things like land use / albedo, skeptics do not have one unified theory, but several different ones. Having spoken to several skeptics, I have personal experience with their divergent views about both the causes of global warming and their predictions for the future. So even if one is suspicious of the mainstream theory, it’s not clear what to replace it with.)
3) You have to be able to predict the consequences of that temperature change from 2).
It’s a bit early to debate consequences of higher temperatures. It is too easy for you to say “higher temperatures are no big deal” when you don’t believe higher temperatures will happen in the first place.
They completely have ignored the positive effects of co2 and higher temperatures. They have completely miscalculated how things would react. A simple one is storms. They assumed more heat energy meant more storms.
If you want to claim they mispredicted something, you first have to find evidence that a prediction was made in the first place.
As I said, they do not predict more storms. They predict (apparently — some media sources are using that word anyway) — more intense storms. But most of that is in the future, so we cannot say the prediction is false. There are certainly those saying that recent extreme weather is caused by global warming (note that this link contradicts a NASA link I gave you earlier; not sure if the journalist simply misread the science or if there actually is some new study predicting more storms. I am not aware of any study that predicts “more storms”.)
They didn’t figure the huge benefit CO2 has on plant growth as well as drought resistance which one study showed completely negated all the negative effects of higher temps on food.
My understanding is that climate scientists do expect some increased plant growth from CO2. However, the improvements will be much smaller than the benefits claimed by skeptics, who refer to short-term benefits observed from artificially raising CO2 levels in greenhouses. There’s at least one study suggesting that the long-term effects are negative.
The combined long-term effects of CO2 + temperature increases + weather/precipitation changes + nitrogen changes are not simple to determine, and your skeptic literature is only going to emphasize benefits and ignore the drawbacks.
“3 things all of which must be true or the alarmism fails”
You didn’t define the word “alarmism”, but I am not interested in extreme climate predictions. Never have been. I’ll talk about mainstream climate science only. In mainstream science, the three issues are separate. All three are not required.
1) You have to be able to predict CO2 levels as huge
Climatologists do not predict “huge” CO2 emissions. There still a business-as-usual scenario in IPCC reports (RCP8.5) to remind us to change our ways, but there is also a best-case scenario with low emissions (RCP2.6).
Climatologists and the IPCC don’t predict which scenario will happen, or that any of them will happen. Predicting human behavior is not in their job description, although they do rely on estimates of the range of possible human behaviors because climate predictions are conditional on human behavior.
The scenarios are merely examples of what might happen. They are not conclusions, and they are not predictions.
I doubt climatologists thought that the best or worst case was very likely. “In between” scenarios like RCP6 and RCP4.5 are more likely — although solar technology is advancing faster than anyone expected, so maybe RCP2.6 is within reach after all.
2) You have to be able to predict the temperature change from such CO2 […] and the climate MUST be extremely sensitive to CO2.
Past predictions have been successful, the mainstream numbers make sense, and doubling CO2 could have a quite substantial effect without “extreme” sensitivity to CO2.
3) You have to be able to predict the consequences of that temperature change from 2).
“Alarmism” aside, if a prediction about consequences of rising temperatures turns out to be untrue, that doesn’t mean temperatures won’t rise in the first place.
Sea levels aren’t rising quickly yet because Antarctica’s land ice sheets are not melting quickly yet. As temperatures keep going up, we can expect this to change at some point. But sea level rise has already accelerated:
And Eric Rignot, glaciologist, says this:
the fuse is already blown. The idea is still probably a little bit of a shock for some people in our community, but I’ve been looking at this area long enough to be quite sure about that.
The time scale is the big issue. I think the community in general is very conservative with time scales. All the observations we’ve collected in the past decades is actually pointing towards shorter time scales than what the models are able to replicate. The models are not able to replicate that. It’s true for the decay of the glaciers and ice sheets. They’re going on a pace faster than what the models projected, faster than even the present day models are able to replicate, so, a lot of the changes we are witnessing we don’t actually have any reference in time to say we know how it happened in the past, we know at what pace these things can retreat. There’s no example of that. All the records of collapse of marine ice sheets have been bulldozed by re-advance of the glaciers. These records don’t exist. We know how fast some of the land terminating ice sheets can collapse; they can collapse pretty fast. The marine ice sheets, they can probably do it a lot faster. We are seeing that today in several parts of Antarctica and Greendand, but it’s a little bit shattering to say hey this is it. Even for the scientist looking at it. It’s kind of a big step to say I think this place is falling apart.
Plants may absorb more CO2 as concentrations rise, but oceans are less able to absorb CO2 as concentrations and temperatures rise. Which change is bigger? I’m not sure, the devil’s in the details, but the ocean is much larger than the forests.
One more thing. Ocean acidification.
Ocean acidification is completely separate from global warming. It would still happen even if all the AGW temperature projections were wrong. And it’s bad for lots of sea creatures. Many of them are fine-tuned to a very specific pH, as pH didn’t vary much before the 20th century. As long as the ocean keeps absorbing more CO2 than it releases, the pH will keep dropping. (Yet if it were to stop absorbing CO2, atmospheric concentrations would rise faster. There’s no upside scenario.)
surveys mean nothing.
i.e. the opinions of climate science experts mean nothing to you. But why would non-climatologists claiming AGW is BS be automatically more meaningful and trustworthy?
I also have no way of knowing how the numbers you quote are calculated. The term “contrary” is very subjective.
I don’t know which numbers you are referring to, and I did not use the word “contrary”.
As you must know we are seeing 15–30 centimeters in a century now. Which means over 7 centuries at most 2 meters.
You assume sea level rise will remain steady or decrease, but you give no reason to think so.
At this point, you and I debating sea level rise is ridiculous, in the same way as a Christian debating an Atheist about will happen hundreds of years after the second coming of Jesus Christ. Why debate the aftermath when one side rejects the very basis of the discussion?
They assume that co2 sensitivity is twice or three times what it actually is and the result is 10 times the temperature change
A 2x misestimate would cause a 2x difference in temperature change, not 10x.
we just spent 10 trillion dollars for nothing.
Where did you get that number? If you’re talking about 10 trillion over the next 50 years or something silly like that, the US GDP is $18 trillion so that would be about 1% of GDP. And carbon taxes don’t simply disappear, they recirculate in the economy. Fossil fuels will run out anyway, so we had to develop alternatives anyway. What’s wrong with doing it now instead of in 50–100 years?
By the way, what do ExxonMobil, Stephen Hawking, the Nature Conservancy, and Ronald Reagan’s Secretary of Treasury and Chief of Staff have in common? All have signed on as founding members to the Climate Leadership Council, which has met with the White House to propose a revenue-neutral carbon tax policy.
The group’s conservatives include cabinet members from the last three Republican presidential administrations (Ronald Reagan, George HW Bush, and George W Bush): two former Secretaries of State, two former Secretaries of Treasury, and two former chairmen of the President’s Council of Economic Advisors.
This is a filthy business David. Preaching religious crap as science.
Religious crap is very biased and isn’t based on data or evidence.
Religious crap cannot cite scientific sources except occasional cherry-picking.
So I agree, which is why I cite data, evidence, sources. You don’t and you never have. The religious crap is coming from you.