What caused the sea to inundate Beijing within the past 80,000 years?

[sneez]

Andre, i do not doubt your knowledge is about average and/or about mine on this issue. I even understand your frustration when you know (perceive) something contrary to majority. But I do not understand your conclusions and the way you present them (at least here). I read couple of links you posted. Not that i understood everything, no, but i am beginnig scientist and have a good understanding of what is a fact and what is not. 'Many' of the things you claim to be true as a fact are not a fact. If I was little more interested in putting you more substantial counter arguments I can see from the papers to be able to do so very easily, and it has been done by real scientists. (search JRE database on climate, and you find 'replies' as a title to deniers of HGW, not that GW is cause entirelly by humans or any implications of that, just a figure of speech)

Some of the papers are just research and not conclusions! You make them conclusion through your phiolosophy you pre-conceived. But i am not up to accusing you. I think you are good researcher. You basically claim to have 100% correct science in the field which is by its nature not possible to be so!

There is one fact alone, YOU DO NOT KNOW for a fact what you claim to know!

 

[Andre]

And what is this dwarfing hypothesis?

In terms of strategic settings I think I'm not ready yet to discuss new hypotheses and thus change from attacker into defender. It must be beyond any doubt that current paradigms about the last glacial transitions (and thus all 100ka cycle transitions) fail to explain the interaction between all events. Especially these:

http://home.wanadoo.nl/bijkerk/d18o-lh-ch4.GIF


The greenhouse potential of Methane is usually seriously overrated. Here is the theoretical effect in a blackbody setting. But I think I posted that before.

http://home.wanadoo.nl/bijkerk/modtran-rad-bal.GIF

The d13C excursions have been explained with local assumptions like a C3-C4 shift due to the Bolling warming. Problem is that this spike is no warming, which also shatters the explanation for the d18O spike as I explained elsewhere.

 

[Andre]

Andre, i do not doubt your knowledge is about average and/or about mine on this issue. I even understand your frustration when you know (perceive) something contrary to majority. But I do not understand your conclusions and the way you present them (at least here). I read couple of links you posted. Not that i understood everything, no, but i am beginnig scientist and have a good understanding of what is a fact and what is not. 'Many' of the things you claim to be true as a fact are not a fact. If I was little more interested in putting you more substantial counter arguments I can see from the papers to be able to do so very easily, and it has been done by real scientists. (search JRE database on climate, and you find 'replies' as a title to deniers of HGW, not that GW is cause entirelly by humans or any implications of that, just a figure of speech)

Some of the papers are just research and not conclusions! You make them conclusion through your phiolosophy you pre-conceived. But i am not up to accusing you. I think you are good researcher. You basically claim to have 100% correct science in the field which is by its nature not possible to be so!

There is one fact alone, YOU DO NOT KNOW for a fact what you claim to know!

Hold-it. I'm not claiming to know it all, otherwise I would not be talking about hypothesis, would I, or then it would be Andre's law, which exists here BTW.

Anyway if you need to combine the oceanic proxies, the ice cores, the geologic glacial paleobotanic and paleontologic data, the orbital cycles, the geophysic implications as a specialist you have a problem with the overview, as a generalist you have a problem with details but at least you can think of all simultaneously.

Remember that all I wanted to do is solve the extinction of the mammoth megafauna.

Anyway the hypothesis is here within the threads. Simple to find And I know that it's only the beginning of something very big that will take ages to understand as you can always continue to ask why. It's just the Popperian philosophy.

Perhaps have a look at a part of the NERC discussion that I uploaded when the site was down for recuperation.

http://home.wanadoo.nl/bijkerk/refuting%20the%20Greenland%20paleo%20thermometer1.pdf
http://home.wanadoo.nl/bijkerk/refuting%20the%20Greenland%20paleo%20thermometer.pdf

 

[sneez]

Thanx Andre, i went through some of the discussion, but its 200+ pages :D


Why do you put such an emphasis on BB computation of increasing some gass? It is important but the GW stuff is recognized comes from the coupling and potential positive feedbacks which is not well understood.

 

[nesp]

<Quit emitting green houses gasses, wait another 100-200 years, and see if global warming continues or stops.>

And, if we're wrong, find out that we've destroyed the world's economy and the Earth is still warming? Wouldn't it be better to be certain before making drastic changes?

Peak oil, if true, is a more urgent driver for change. $5-10 dollar gas in the US might drop GHG emissions whether or not they caused GW. I say might because if the alternative is wood burning fires and electric cars from coal fired plants we may produce more GHG than from oil.

 

[Andre]

Thanx Andre, i went through some of the discussion, but its 200+ pages :D

Try the find functions for key words. "Model" would be a good one, "positive feedback" may work as well.

Why do you put such an emphasis on BB computation of increasing some gass? It is important but the GW stuff is recognized comes from the coupling and potential positive feedbacks which is not well understood.

It's not understood because it's non existent. Try the find function. I also posted that here earlier in the thread I think, the Karner Non-persistency study and the high resolution isotope-CO2 proxies of the EPICA Dome C ice core:

http://home.wanadoo.nl/bijkerk/epica5.GIF

 

[nesp]

<I also posted that here earlier in the thread I think, the Karner Non-persistency study ...>

Here's a related paper suggested to me from another forum. The authors model solar flare and temperature anomalies as related Levy processes. These are continuous time Markov processes that incorporate drift, Brownian motion, and jumps. They can also be considered as random walks with bigger jumps than Gaussian theory predicts. The important finding is that both solar flare activity and temperature anomalies might be related through a non-obvious process. The data is pretty limited though.

Solar turbulence in earth’s global and regional temperature anomalies
Nicola Scafetta, Paolo Grigolini, Timothy Imholt, Jim Roberts, and Bruce J. West

This apparent Lévy persistence of the temperature fluctuations is found, by using an appropriate model, to be equivalent to the Lévy scaling of the solar flare intermittency. The mean monthly temperature data sets cover the period from 1856 to 2002.

http://prola.aps.org/searchabstract/PRE/v69/i2/e026303?qid=e399f5dfccd56b56&qseq=2&show=25

 

[Andre]

There is a lot ongoing about the sun. For instance:

http://www.lps.umontreal.ca/~paquetteh/Maunder_SP.pdf

Bottom line, the ~1,5 W/m2 difference in solar output between the Maunder minimum and the current maximum falls way short to explain the difference in global temperature, before put into the Stefan Boltzman equation you'd have to divide that by 4 (diameter area versus surface of the globe) and multiply by 0.3 to account for albedo/reflectivity. I don't have my stuff around here to calculate the delta right now. Won't be significant.

Yet there appears to be a significant correlation between solar activy (flares, solar particles, induced solar magnetism and apparent global temperatures) but many things remain to be seen.

 

[sneez]

Using sun spot numbe as input and modeling evolution of magnetic flux ...

This is not something to subscribe to as a fact, Andre.., these processes are not even well understood as far as sun is concerned. The processes and relationship of sun-earth is being studied and many papers with conflicting opinions and inter-relationships are being presented.

Quote:
Yet there appears to be a significant correlation between solar activy (flares, solar particles, induced solar magnetism and apparent global temperatures) but many things remain to be seen.

As and researcher in this area I can tell you that far from any conclusions of long term changes are reached. Short term is more complicated than that. There is not know mechanism of long term change due to precipitation of solar particles. (In planetary science, it is being researched how the 'hot' plasma stays after the SPE event in the tail of the magnetic field of the earth, but that's a hard science on its own and its conclusion will depend on the theory that will be accepted and is not known as of now).

Upper atmosphere has a very efficient mechanism of getting rid of inputted energy from solar particles influx through NO, CO, CO2. There is no impact on surface temperature concluded. There is very delicate mechanism how this heating and cooling happens.

For CO2 issue, this is quote form Kerry Emanuel.
For example, doubling the concentration of CO2 would raise the average surface temperature by about 1.4°F, enough to detect but probably not enough to cause serious problems. Almost all the controversy arises from the fact that in reality, changing any single greenhouse gas will indirectly cause other components of the system to change as well, thus yielding additional changes. These knock-on effects are known as feedbacks, and the most important and uncertain of these involves water.

As far as this paper goes:"Solar turbulence in earth’s global and regional temperature anomalies"

Its missing the processes of the atmosphere specifically dynamics. Its concentrating on correlation, plus sun is not at its sol max but min. There are 11 and 22 year cycles of the sun. The current ideas about the amount of sunlight the Earth receives varies because of slight changes in the three parameters of the Earth's orbit, with periods of about 100,000, 41,000, and 23,000 years. But what causes the climate change over 1000,100, or 10? Many climatologists who study evidence of sun on our climate are not convinced that the connection exits. Its difficult to explain just how the sun might affect the Earth's atmos enough to make difference.

There are many ideas how these mechanisms happen, but no one dares to claim that we know it. The inherent NON-LINEARITY of the climate and contributing processes absolutely NEED to be included where they are not. The model of Wilson shows that non-linearity of sun's processes may cause the sun to switch into minimum activity (a Maunder effect). Correlation even for 400,000 years is nothing but guess work. (correlation does not imply causation). The mechanism is unknown, still. SO let's present it as it is, not as means to preconceived conclusion.

"Journey from the center of the sun', by jack b zirker, is nice book that explains what we know about sun and what are current ideas about how sun might/might not influence climate. (given on human scales the sun's output does not vary much for last 4 bilion years. Sol constant over 11 yrs cycle is 0.1% in change is too small for correlation. We need to know, if there is non-linear process which could drive this small change into climate change.)

 

[sneez]

"NERC discussion " - very good reading. I am glad i get to read it. Recommend it to all .

 

[verdigris]

"We need to know, if there is non-linear process which could drive this small change into climate change."

From the point of view of chemistry it would require a chain reaction and these are usually initiated by ultraviolet light.And chain reactions need
a high concentration of reactants to sustain the chain.

 

[sneez]

I am self-thought, self-interest in non-linear processes in geosciences. I do not know what processes could those be. If sol constant varies only by 0.1% over 11 year cycle, i cannot imagine any process that would make it into degrees of temp change on the surface. BUt I am not excluding the possibility.

 

[Andre]

Using sun spot numbe as input and modeling evolution of magnetic flux ...

This is not something to subscribe to as a fact, Andre..,

So did I? reread my post and see my judgement. Suggesting that I did is a strawman fallacy.

These knock-on effects are known as feedbacks, and the most important and uncertain of these involves water.

I have tried two times already in this thread to demonstrate that there is no trace of positive feedback.

The current ideas about the amount of sunlight the Earth receives varies because of slight changes in the three parameters of the Earth's orbit, with periods of about 100,000, 41,000, and 23,000 years.

This is an incredible error to me. Indeed you can read at virtually every site explaining Milankovitch that these are the correct numbers. Not your fault, But it aint. 100ka is NOT a Milankovitch cycle, it's just an incorrect oversimplification to avoid the discussion perhaps about the curious 100ka cycle. The major eccentricity cycle is 400ka with a much weaker 90 ka cycle superimposed. Richard Muller et al have tried to explain it as a inclination cycle, the Earth entering in a dust band every 100ka, obscuring the sun. But about every element of that idea has been falsified. It was a good try though.

So what is left is the suggestion that the 100ka cycle is some sort of superposition of the other cycles. But again major problems for that.

http://home.wanadoo.nl/bijkerk/41-100k-world-milankovitch.GIF

Showing the Milankovitch cycles for the last 5 million years with the 400ka cycle clearly visible. Also is visible the frequency shift of the Benthic foraminifera isotope stack that one million years ago something changed suddenly the major Earth cycle switching from 41ka to 100ka. If you explain that you hit the jackpot.

Also zooming in on the last half million years it is also clearly visible that the largest isotope spike some 430ka ago concurs with a minimum Milankovitch variation. It doesn't appear that this spike could have been caused by the insolation cycle. So why would any other?

http://home.wanadoo.nl/bijkerk/milanko3.GIF

Correlation even for 400,000 years is nothing but guess work. (correlation does not imply causation). The mechanism is unknown, still. SO let's present it as it is, not as means to preconceived conclusion.

Right, you need to find ALL the players. There is a biggy missing.

 

[sneez]

...changing any single greenhouse gas will indirectly cause other components of the system to change as well, thus yielding additional changes. These knock-on effects are known as feedbacks, and the most important and uncertain of these involves water.

Do you think, Andre, that increasing of CO2 does not have effect on other components of the system? Or how do i understand your point?

 

[verdigris]

ANDRE said:
"Also is visible the frequency shift of the Benthic foraminifera isotope stack that one million years ago something changed suddenly the major Earth cycle switching from 41ka to 100ka"


What causes the axial tilt to change under normal circumstances?

 

[Andre]

The difficult answer is in here.

The simple answer: different gravitation of sun and moon on the equatorial bulge creates a torque force which makes rotation bodies to perform a precession cycle, like the spin axis of an oblique spinning top slowly moving around in a circle. For Earth that is the precession of the equinoxes of 26,000 years, closely related to the precession of the perihelion, the Milankovitch cycle. The forces and torques involved are also causing the tilt of the axis to cycle with a 41,000 years cycle in a complicated way.

Talking about equatorial bulges and cycles, what, if the mysterious 100,000 years cycle was a http://www.space.com/scienceastronomy/equator_bulge_020801.html

 

[verdigris]

The pulsating equatorial bulge is thought to be caused by ocean currents bringing more sea water to the equator from higher latitudes.The cycle changes from 41000 to 100000 years - slowed by a factor of 2 and a half.There must have been material inside the Earth that had moved from the mantle to the core - a lot of it! What if the moon had developed a magnetic field that interacted with the Earth's? Would there be evidence in the
mid-atlantic ridge's magnetic record?

 

[nesp]

Might differential torque between unevenly distributed land masses riding on liquid sections of the core cause migration of the tilt axis? Not the axis itself, but the angle of the axis in relation to the continents -- ie, a gentler and slower form of continental drift.

 

[Andre]

Way to go, Nesp. That's it, the ability to step outside the thinking box and not considering anything outside ones own speciality for granted. The geophysicists know what Earth can do in terms of tectonic movements, mass balance, mantle core interaction, variation in spinning (length of day), etc etc but have no interest what that might do for climate. To paleo- climatologists Earth is a solid rock with fixed geography without any dynamics other than its orbit, spinning and known pertubations. You're one step short of inventing the True Polar Wander, if it wasn't for http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_62207.htm.

The idea is that the uneven mass distribution on Earth may cause the inertia tensor to drift away from the spinining axis. Realignment is taken place by the inertia tensor moving back to the spin axis, which means that the whole Earth displaces in regards to the stabilized spin axis.

Does that make sense?

It is calculated however that this is a very very slow effect, assuming ice age mechanisms.

I'm thinking of more dynamic processes like this:

http://www.agu.org/pubs/crossref/2001/2000JC000235.shtml.

This clearly thrashes everything we think we know about sea-level ice sheet dynamics, you know, large ice heets, low sea level and vice versa.

The alternative angle is: what moved? Was it the sea level or the sea floor below it? Try and stretch the thinking box.

 

[verdigris]

NESP said:

"Might differential torque between unevenly distributed land masses riding on liquid sections of the core cause migration of the tilt axis"

How much would this affect the mass distribution in the mantle.

ANDRE said:
"The geophysicists know what Earth can do in terms of tectonic movements, mass balance, mantle core interaction,"

Some people think the core is a fast-breeder nuclear reactor,others don't.Can the core shift its position relative to the crust i.e can the core be off-centre? Could nuclear reactions be the cause of this?Also,how quickly does the cycle go from 410000 years to 100,000 years - is the change sudden or gradual? If the Earth's core gets hotter because of nuclear fission,does this mean that more magma comes out at the sea floor and that the magnetic strips on the sea floor are wider -perhaps in a 100,000 year cycle?

 

[billiards]

Might differential torque between unevenly distributed land masses riding on liquid sections of the core cause migration of the tilt axis? Not the axis itself, but the angle of the axis in relation to the continents -- ie, a gentler and slower form of continental drift.

Apologies but some people's conception of the Earth and timescales can often be surprisingly misgiven. Land masses don't ride on the core, there's this thing that some people call the mantle that kind of makes up the bulk of the Earth's volume that sits between the core and the crust!

Furthermore, global geophysicists often disregard the crust, it's just some kind of sluggish lid that nobody quite understands. The effects of mass distribution heterogeneities at the crust are completely negligible in terms of any gross moment of inertia effect on the earth.

 

[heusdens]

After reading several papers and seeing gore's movie on GW I'm still searching for solid scientific causal evidence (versus correlations or circumstancial) that anthropogenic greenhouse gases are the cause of global warming in the post-industrial age. I accept we are in a warm epoch, atmospheric CO2 is higher than average, humans have made CO2 levels higher, and natural CO2 levels correlate historically with temperatures. This may be enough for some, but it still does not prove human causality. I'm not rejecting the thesis of human causality for global warming, just would like to read a scientific argument that doesn't rely on correlation, circumstances, or simulations. Is that's all there is?

It is known that the concentration of CO2 in the atmosphere between 1800 and 2005 has increased from 280 to 380 parts per million. It is known without doubt that this increase is due to human burning of fossil fuels, and not
to natural sources such as the oceans or volcanoes. Here are three arguments. First of all, there was a parallel decline of the 14C/12C ratio. Second, there was a parallel decline of the 13C/12C ratio. Finally, there was a parallel decline of the oxygen concentration. All three measurements independently imply that the CO2 increase is due to the burning of
fuels, which are low in 14C and in 13C, and at the same time decrease the oxygen ratio.
Natural sources do not have these three effects. Since CO2 is amajor greenhouse gas, the data implies that humans are also responsible for a large part of the temperature increase during the same period.

From: http://www.motionmountain.net/index.html
Motion Mountain
The adventures of physics.
p.867-868

 

[heusdens]

After reading several papers and seeing gore's movie on GW I'm still searching for solid scientific causal evidence (versus correlations or circumstancial) that anthropogenic greenhouse gases are the cause of global warming in the post-industrial age. I accept we are in a warm epoch, atmospheric CO2 is higher than average, humans have made CO2 levels higher, and natural CO2 levels correlate historically with temperatures. This may be enough for some, but it still does not prove human causality. I'm not rejecting the thesis of human causality for global warming, just would like to read a scientific argument that doesn't rely on correlation, circumstances, or simulations. Is that's all there is?

Below a quote from a Physics Text book, claiming that human caused carbon-dioxide levels are proven

It is known that the concentration of CO₂ in the atmosphere between 1800 and 2005 has increased from 280 to 380 parts per million. It is known without doubt that this increase is due to human burning of fossil fuels, and not to natural sources such as the oceans or volcanoes. Here are three arguments. First of all, there was a parallel decline of the ¹⁴C/¹²C ratio. Second, there was a parallel decline of the ¹³C/¹²C ratio. Finally, there was a parallel decline of the oxygen concentration. All three measurements independently imply that the CO₂ increase is due to the burning of fuels, which are low in ¹⁴C and in ¹³C, and at the same time decrease the oxygen ratio.
Natural sources do not have these three effects. Since CO₂ is a major greenhouse gas, the data implies that humans are also responsible for a large part of the temperature increase during the same period.

From: http://www.motionmountain.net/index.html
Motion Mountain
The adventures of physics.
p.867-868

 

[nesp]

<Below a quote from a Physics Text book, claiming that human caused carbon-dioxide levels are proven>

Please reread my original post. The question was how much those human caused CO2 levels impact global temperature. The answer appears to around 1K in steady state, as mentioned by Andre. Projections above or below that are the result of feedback factors not well understood.

 

[Andre]

That 1K is a standard basic black body sensitivity for doubling CO2. in the real world things are more complex, it could be more but it's likely far less.

So if we assume 280ppmv preindustrial around 1850AD, and 380 now we are far from doubling yet the temp has already increased 0,6 degrees. Most of that happened however prior to 1940 after which some cycles came in more pronounced. So you cannot attribute that warming to dramatic increase of CO2. It's clear that natural factor play the dominant role at that time, so why not now?

 

[heusdens]

I disagree. Science is above all a matter of finding the truth.

Abusing it, to force the world upon changing its energy habits may be a most exemplary good cause corruption, but it kills the science and brings us back to the dark ages with devils and dragons at will of those who want to rule.

Recheck http://www.positiveatheism.org/hist/quotes/mencken.htm .

Science is practical.

And what is more practical as doing an experiment?

The scientific debate (is there a debate? the human-caused carbo levels and global warming effect is not in any doubt any more) can go forever, without resolvin anything.
By the way, so-called "scientists" are paid by oil companies to spread disinformation about the CO₂ issue.

By the way... my post was a bit of cynism of course, as if what I suggested (stopping fossil fuel usage) could be done...

This does not prevent us however for inventing measures that can reduce the problem.

 

[joema]

Like Nesp, I'm just a guy trying to figure this out. Re the textbook quote:

"CO2 in the atmosphere between 1800 and 2005 has increased from 280 to 380 parts per million. It is known without doubt that this increase is due to human burning of fossil fuels, and not to natural sources such as the oceans or volcanoes."

If the increase is "without doubt" caused by human burning of fossil fuels, does that mean decreased carbon sink capacity from human deforestation is not a factor? If it is a factor, what's the relative contribution of deforestation vs anthropogenic CO2 emissions in increasing CO2 levels?

I often see increasing atmospheric CO2 levels described as a simple imbalance between emission and absorption capacity.

But I read all anthropogenic CO2 output is just about 3% of natural CO2 output. Is that number right? If so, why are atmospheric CO2 levels increasing so rapidly? That implies the biosphere has virtually no adaptability -- no excess carbon sink capacity. If bumping the total CO2 output (natural + anthropogenic) by 3% creates this, doesn't that imply the solution is to reduce it by an almost equal amount?

This may be naive, but if the Earth's carbon cycle is that delicate, it seems the required solution is far more drastic than cutting anthropogenic emissions by 20%. Atmospheric CO2 started increasing at the beginning of industrialization when anthropogenic emissions were a fraction of today. If global CO2 emissions were reduced by 70%, the historical graphs I've seen imply atmospheric levels would still be increasing, only slower.

Do we have any idea what reduction in global anthropogenic CO2 emissions is required to achieve equilibrium in atmospheric CO2 levels? If so, what's the basis for and confidence in that number?

I've looked through a bunch of GW stuff, and can't find clear answers to these. Would appreciate any explanations or pointers.

 

[Andre]

A neat little http://earthobservatory.nasa.gov/Library/CarbonCycle/Images/carbon_cycle_diagram.jpg here.

The most important part of the carbon cycle is the balance at the sea surface. Changes in ocean - atmosphere fluxes, with an order of magnitude more substance than anthrpogenic CO2, would have a strong effect on the atmospheric CO2. But then again, even before the K/T boundary some more than 65 million years ago the atmospheric the pCO2 (of leaf stomata proxies)was between 300-500ppmv, where it is still today:

http://home.wanadoo.nl/bijkerk/CO2-KT-PETM.GIF

 

[joema]

The argument that increased atmospheric CO2 levels are anthropogenic based on C14/C12 ratios seems pretty good. I'd be interested if anyone has a contrary opinion to that argument.

Re amt of increase from anthropogenic emissions vs reduction in carbon sink capacity due to deforestation, the new IPCC report indirectly addresses this. http://www.ipcc.ch/SPM2feb07.pdf

It says annual anthropogenic emissions are about 7 GtC per year, whereas "land use changes" create about 1.6 GtC per year. Don't know if that's effective creation due to reduction of sink capacity or actual emissions from burning. Either way the % contribution of land use changes vs hydrocarbon emissions seems small.

However -- there may be a fundamental math error in the new IPCC report. Could someone please cross-check me on this?

On page 12, it says "model studies suggest that to stabilize at 450 ppm carbon dioxide, could require that cumulative emissions over the 21st century be reduced from an average of approximately 670 [630 to 710] GtC to approximately 490 [375 to 600] GtC."

I think they forgot to account for the annual increase in hydrocarbon consumption for the nominal "no change" case. Unless I'm mistaken, this is a fundamental error that greatly impacts the calculation of required emission reduction, and any related planning.

E.g, current world anthropogenic CO2 emissions are about 7 GtC per year. If it was capped at that level tomorrow, over the 21st century cumulative emissions would be about what IPCC says: 670 GtC. They apparently just multiplied 93 years by 7 GtC/yr.

However world energy use (of which hydrocarbons make about 85%) increases at about 1.5% to 2% per year, as it's keyed to economic output and development. Like compound interest on a bank account, that makes a vast difference over time.

Thus the baseline number is NOT 670 GtC cumulative emissions over the 21st century, but 7 GtC/yr increasing at a 1.5% to 2% compounded annual rate.

I don't know the formula, but it's the same one to calculate final balance of a non-interest-bearing bank account assuming annual contributions increase at x%. It doesn't matter whether annual growth rate in energy consumption is 1%, 1.5% or 2%. Over a century the difference is vast.

At 1.5% annual growth, the actual "no change" case would be thousands of cumulative GtC released over the 21st century, NOT 670 GtC.

My question is did IPCC model that, or just 670 GtC. This affects everything -- how bad the perceived problem is, amount of required reduction to achieve a given benefit, etc.

It can't be such a simple error. Have I missed something?

 

[joema]

OK I found the formula. It is:

FV = D * ((1+r)^T - 1) / r , where:

FV = Cumulative carbon emissions in GtC over 93 yrs (2007-2100)
D = 1st yr emissions (7.0 GtC)
r = annual % increase of emissions
T = time in yrs (93 yrs)

So rather than the baseline IPCC number of 670 GtC over the remaining 21st century, the actual baseline emissions would be:

1857 GtC @ 2% annual growth
1396 GtC @ 1.5% annual growth

The EIA projects about an approx. 2% annual growth in hydrocarbon energy consumption over the next quarter century. If that continued over the remainder of the 21st century, the baseline number is 1857 GtC.

Hence the reduction required is NOT from 670 GtC down to 490 GtC, but from 1857 GtC down to 490 GtC.

That is a big difference. I'd be very interested in knowing which input value was modeled -- 1857 GtC or 670 GtC.

This affects everything -- climate modeling, how achievable the needed reductions are, etc.

That superficially looks like a 74% reduction in hydrocarbon energy consumption is required. But it's worse than that. You'd have to virtually eliminate hydrocarbon energy. Why?

Because no matter what technology or how ambitious the plan, it takes time to implement. Hence the 1st few decades you're still burning hydrocarbons at the current rate (inc'l annual increase). All that counts against the IPCC 21st century cumulative limit of 490 GtC.

That means in later decades of the 21st century, much greater reductions are needed than 74%. The entire globe would have to mostly run on fusion or something like that, otherwise you'll go over 490 GtC cumulative emissions. And even that results in atmospheric CO2 increasing to 450 ppm, significantly above current levels.