Jaepheth wrote:Sikon, you may want to rethink the beginning of your rebuttal. A correlation between the beginning of the industrial age and the beginning of an increase in CO2 levels does not prove causation.
I don't know why you are talking about the beginning of the industrial age in particular. I showed data for a 30% to 40% increase in CO2 levels over the relevant timeframe up to now. It is known that there were not natural processes changing over that timeframe to release the corresponding amount of extra carbon dioxide. CO2 went from 280 ppm in 1750 to 380 ppm in 2006, for concentration by volume in parts per million. Since the molecular weight of CO2 is 44.01 g/mol compared to the 28.97 g/mol average for air, the preceding corresponds to an added mass of CO2 equal to about 150 millionths of the total mass of
earth's atmosphere.
Since earth's atmosphere masses about 5.15 quadrillion metric tons, the preceding equates to around 800 billion metric tons or around 900 billion short tons of extra CO2.
There are billions of tons of fossil fuels being burned per year worldwide, tens of billions of tons a decade. Each mole of carbon massing 12 grams becomes a mole of carbon dioxide massing 44 grams, for the resulting CO2 release to be several times the mass of carbon in the fuel. The effect is CO2 emissions were as follows:
The cumulative emissions from human-caused combustion correspond to the observed rise in the total mass of carbon dioxide in the atmosphere. It isn't precisely a perfect match, since the net change in CO2 in the atmosphere is simultaneously increased by some other factors and decreased by others. For example, there is absorption of a limited fraction of the extra CO2 by the oceans. But the general picture is apparent.
A lot of CO2 is released and absorbed by the biosphere and plants each year, in a natural cycle, but the bulk of the hundreds of billions of tons extra over the decades has a clear source. Human-caused carbon dioxide rise is unquestionable.
Jaepheth wrote:And I believe this is the absorption chart Akhlut was talking about:
That shows the absorption spectra of some components of the atmosphere, and it is interesting. It doesn't adjust for the relative amounts of each species, though.
Here's the radiative forcing from human emissions, not the total from each chemical species in the atmosphere but the extra anthropogenic effect:
Human emissions cause a mixture of heating and cooling, but the net effect is heating.
The relative amounts of radiative forcing are much different from the relative concentrations by mass. For example, the mass of halocarbons is a number of orders of magnitude less than the mass of carbon dioxide, but the former still causes substantial radiative forcing because the warming effect of halocarbons is far greater per unit mass.
For perspective, to illustrate the general principle in a different application, it is estimated
here that a mere 0.15 billion tons of suitable halocarbon gases intentionally artificially produced on Mars could raise the planetary temperature by 10 degrees Celsius, for that level of terraforming using only ~ 4.5 gigawatts of nuclear power, no more than the power consumption of a large metropolis on earth.
Likewise, among substances with negative radiative forcing, some cause far more cooling per unit mass than others. For example, on earth, stratospheric dust of the right size can cause orders of magnitude more cooling per unit mass than reflective dust at low altitude, due to factors including the former staying up for vastly longer, an average lifetime of around 1.25+ years.
Geoengineering calculations for earth have determined that the observed cooling effect of some volcanos could be more efficiently emulated by injection of appropriate-sized dust directly into the atmosphere, with merely on the order of 0.01 or 0.02 billion tons annually
being sufficient to counter ~ 2000 billion tons of carbon dioxide. Such geoengineering isn't a solution by itself, with need to switch away from infrastructure being based on fossil fuels for multiple reasons, but it illustrates what is possible.
As the preceding implies, mankind is capable of affecting a planet's climate rather readily, whether for cooling or heating, whether for good or bad. In fact, human-caused global warming can be considered a type of geoengineering, just one performed unintentionally, inefficiently, and causing undesirable effects.
A substantial segment of the general public doubts that human activities can much affect earth's climate compared to natural processes. However, really, the ability of human activities to affect a planet's temperature is so clear that it should come as no surprise that the hundreds of billions of tons of anthropogenic CO2 emissions and other warming pollutants have an effect.
Carbon dioxide is a relatively weak warming substance per unit mass, particularly compared to halocarbons, but so much is released as to make its effect the single greatest component of radiative forcing from human emissions.
Jaepheth wrote:These sorts of charts will also frequent these debates:
I assume you are posting the graphs to point out that earth's temperature was far higher at some times millions of years ago. And, yes, it was.
Those graphs don't have a quantitative temperature scale, but here is an example where the right end of the graph is 5.5 million years ago:
In the still more distant past, the average temperature was higher than today by about 10 degrees Celsius, almost 20 degrees Fahrenheit hotter:
From a geological perspective, fossil fuel burning is releasing carbon that once was in the atmosphere before becoming vegetation that became coal, oil, and so on. Indeed, carbon dioxide levels in the atmosphere were once thousands of ppm instead of the four-hundred ppm of today:
Such is a good point if anyone predicts utter doomsday like the end of life on earth from global warming. That misconception is almost as irritating as the opposite error of disregarding the evidence for global warming or failing to recognize other problems with fossil fuel dependence.
But back then was a far different world, one rather undesirable from the perspective of mankind and a lot of ecosystems that evolved in more recent geological history. For example, if one goes far enough back, sea level was hundreds of meters higher than today:
Admittedly, if one gets into the details, it takes quite a long time for much of the total ice to melt, and I am not suggesting that much sea level rise in this century; the IPCC suggests
less. But the overall situation is that the higher temperatures in the distant past would only be a valid argument against "end of all life" extreme predictions rather than what I am saying about global warming being substantially undesirable.
Today's temperatures are fast approaching a point unprecedented in the past 400,000 years, as I discussed in an
old post.
Much of the world's population is rising out of poverty, and that will eventually lead to a number of times greater energy usage than today, along with corresponding greater trouble if there is too much attempt to still have that energy come from fossil fuels. Also, an undesirable future sociopolitical situation from fossil fuel dependence involves far more than global warming in itself, including peak oil, governmental reactions to it, and so on.
Jaepheth wrote:Personally, I don't think we're going to stop, much less reverse, global warming no matter what we do.
Too many people fall into the mindset of "no matter what we do." I agree that global warming will continue for a while in practice. In fact, it will vastly accelerate, for reasons expressed in this
old thread. Yet global warming is technically quite possible to stop. The problem is sociopolitical factors like the limited knowledge of the general public and a bias against massive focus on changing the energy source.
World energy usage is going to continue to increase, driven by total world
economic output and
industrial output rising at a rate of tens of percent per decade, due to fewer people remaining in utter poverty instead of most people in the world living on several dollars or less per day. For perspective, if the whole world had the per capita CO2 emissions of Americans, corresponding emissions would be 130+ billion tons annually. Even a quarter as much per person would still be 30+ billion tons annually, compared to 24 billion tons a year
now.
The overall picture will not be changed by population decrease in the relevant timeframe, as rather population
projections indicate increase for a long time, until the tendency of people to have fewer children after their countries become richer and industrialized may cause population to peak. It will be higher than now throughout this century at least. Even China which has had their "one-child policy" for decades has had no population decrease so far, actually some rate of continuing increase, such as 1.14 billion in 1990 versus 1.3 billion
in 2004. If major population decrease occurs someday, it is a very slow process of how long it takes for most people to die, still slower if continuing medical advancement improves life expectancy, like potentially some
life extension.
Even aside from the future increased rate of CO2 emissions, total carbon dioxide levels in the atmosphere would still be increasing even if there were just a few billion tons of new emissions annually. The past emissions still exist, as does the continuing build-up, as long as the fossil-fuel energy source isn't changed. One could debate the exact future emissions, but the net effect is an extreme carbon dioxide level in the atmosphere being reached sooner or later, whether in a certain number of decades or another number.
Unfortunately, most effort today is far more focused on extending slightly how long the present situation can be maintained rather than focusing much more on changing the energy source. For example, of U.S. military spending of $5+ trillion cumulatively per decade, a large fraction ends up being spent on Middle Eastern involvement, and expenditures indirectly related to the Middle Eastern oil supply have total expense amounting to cumulatively trillions of dollars over the decades.
The U.S. imports about 3.5 billion barrels of
crude oil a year, a factor also causing particular vulnerability to peak oil. And the coming of peak oil is not in much question, as some countries have already had oil production peak and decline due to the limited amount of it, with such going to happen sooner or later to all oil-producing countries. That equates to 150 billion gallons annually. Some just becomes asphalt and the like, but let's use that as an approximate upper limit for U.S. imports needing to be replaced.
In
another thread, I described how $1 trillion capital cost of mass-produced nuclear power plants could synthesize on the order of 140 billion gallons of gasoline and other fuel annually, in an environmentally friendly manner utilizing atmospheric CO2. Such is a better variation of the coal-based synthetic petroleum process used by Germany in WWII when its oil supplies were crippled by the Allies.
Of course, there would be more than the preceding cost, and the calculations are not exact. And they are not the only option. The more popular hydrogen economy idea is also possible, although such could cost much more due to replacing vehicles and the distribution system rather than starting by just using the existing gasoline-compatible infrastructure.
But the general picture is that obtainable cost is relatively moderate compared to U.S. GDP of $12.5 trillion annually, as U.S. GDP amounts to $600+ trillion in a 50-year period. Cost is also not excessive compared to government spending trying to maintain an oil supply which will run out sooner or later anyway.
Also, at the cost for suitably mass-producing nuclear power plants discussed in the
other thread, about $0.4 trillion would suffice for about 400 gigawatts, enough to replace all U.S. fossil-fuel powered electricity generation. Such is around 0.0016 of U.S. economic output over a 20-year period neglecting economic growth, equivalent to a cost per person on the order of $6 per month. Actually that is ignoring how much money is currently spent on the fossil-fuel power plants and their fuel, how much money would be saved, so the net cost could be zero or better.
Interestingly, 63% of Americans indicated in a 1998 poll that they would be willing to accept a far greater $25 per month extra expense in average electricity
bills if that was the cost of complying with the Kyoto treaty. The Kyoto treaty wouldn't do nearly as much as eliminating 100% of fossil-fuel electricity generation, so, if the public was logical and well-educated, they would also support the preceding nuclear power conversion. In an alternate universe where suggesting something like the preceding wasn't so politically incorrect and socio-politically unfeasible, such a switch away from fossil fuels could have already occurred.
Of course, the practical matter is that next to nobody suggests anything like the preceding, let alone supports it. Many don't even have any idea that switching away from fossil fuels is possible for everything important from fuel to plastics without vague future technology indefinitely decades away. Unfortunately, in the immediate future, there is greater likelihood of nations fighting future wars over dwindling oil supplies.
The situation is a little like a bunch of people on an island who are rationing a limited supply of food, while nearly nobody bothers to farm and produce more food. If some of them get killed, the lesser number of survivors may extend the remaining rations longer. If some of them beat up their neighbors and take their food, those may have food lasting a little longer, maybe Y years instead of X years. But it still runs out eventually. What really is the greatest solution is if they instead produce more food. It is something which has to be done sooner or later anyway for survival, let alone pleasant survival. That's not an exact analogy to the world's dependence on fossil fuels and the resulting environmental effects, but it is close enough.
There needs to be a change in the energy source, to power generation that is practically non-polluting rather than limited fossil fuels.
Anyway, my point is that mankind could stop global warming and switch away from fossil fuels, in terms of technical possibility if not for sociopolitical factors. But rather than write more here, I will reference an
old post, which suggests how much could be done with even a fraction of 1% of cumulative world GDP over a period of decades.
Of course, for the immediate future, the above is irrelevant to what actually happens, as the public does not think in a similar manner. Fossil fuel dependence will continue for a time, as well as increasing emissions and vastly increased global warming. But one should distinguish that from what is technically possible. Perhaps, once there is enough motivation, more people may someday learn about possibilities like those implied earlier, and then there may finally be serious change. Until major change, one can see where the following trend is headed:
