What this would not address is that global warming due to increased concentrations of greenhouse gases does not warm the world uniformly, but acts to reduce the temperature contrasts between the tropics and the poles and between the day and night sides of the earth.
Blocking sunlight could offset the increase in mean temperature, but would do nothing about the decrease in contrast. Thus, the polar regions would warm while tropics would cool and the world's weather systems and ocean currents, all of which are driven by heat flow from the tropics to the poles, could still be dramatically changed.
A single particle doesn't undergo fusion. Two particles must collide. The energy width of the beam is not relevant because you're not talking about collisions within the beam. For fusion, the relevant system is the system in which the collisions are occurring: the beam plus the target.
When you look at this system, you have an energy distribution (two narrow peaks, widely separated) that's manifestly out of equilibrium so it's neither low-temperature nor high-temperature. Temperature is not defined.
You could take a temperature to be whatever would produce a Boltzmann distribution with a width equal to the width of the particle distribution (target + beam), so for a keV beam hitting a stationary target, you'd take a width of 500 eV, or about 6 million Kelvin. I'd call that hot fusion.
What would it take to prove the existence of God from nature?
You're asking the wrong question. What would be needed would be to put the existence of God into a falsifiable hypothesis. Once you know how to disprove the existence of God, you can keep performing experiments to disprove God's existence. If even one of these experiments succeeded in disproving God, we'd definitely know He didn't exist.
On the other hand, the more experiments failed to disprove God's existence, the more faith we could have that his existence had been confirmed by scientific tests.
The biggest problem with addressing God's existence through science is coming up with a type of experimental test that believers could accept as disproving His existence.
Here's an analogy: you can't prove that the speed of light in vacuum is equal to all inertial observers. Any finite number of measurements of c does not prove that it's always the same for all observers. However, it would only take one reproducible experiment in which c is different for one inertial observer to disprove relativity.
The reason we believe the "laws" of physics is because they've withstood so many experimental tests that were capable of falsifying incorrect laws. Proving the existence of God would be similar: He'd have to survive a large number of experiments that were capable of disproving his existence.
By imminent decline in the production of fossil fuels, I am referring to the peak of oil and natural gas production scheduled to occur imminently, followed by a long decline. This represents a peril due to the fact that our industrial civilization depends almost exclusively on the ready availability of cheap oil and gas, entirely apart from what these fuels are doing to the climate we live in. The production of coal will not decline soon, but most of us don't use coal for transportation or heating, and switching from oil and gas for these uses to coal is not likely to constitute an improvement in any measurable sense.
As oil and gas become more expensive, we'll start producing gas and oil from coal (IGCC processes can produce gas and diesel fuel from coal fairly well). This suggests to me that running out of petroleum reserves will not disrupt civilization, but will merely lead us to use other, more expensive sources of fossil hydrocarbons. We'll adapt to new fuel sources quite well.
As to other sectors of our economy, coal is the fuel for 55% of electricity in the US, and with each year electricity becomes even more central to our economy.
As you correctly note, all of this is not a solution, but a further problem because switching to coal-intensive energy means ever more carbon in the atmosphere.
Of course, I could be wrong and President Bush's program to develop clean hydrogen fuel sources from coal and carbon sequestration technology could solve all our problems long enough for us to develop better nuclear and renewable energy sources. I'm just not holding my breath.
Actually there's an article in Scientific American this month, which refutes this claim using analysis of long-term climate data.
The article does not refute my statement. CO2 concentrations for the past 10,000 years remained fairly constant at typical interglacial concentrations. The article claims that they might have dropped slightly if not for human activity. Compare this to the observation that CO2 concentrations have increased by about 25% in the last 50 years so that they are now about 20% higher than they were at any point in the past 420,000 years. This is a climate forcing on a vastly greater scale both of magnitude and of time than the Scientific American article proposes for early human agriculture.
Nothing in the article you cite disagrees with the statement that most of the increase in CO2 concentrations occurred in the last 50 years and it occurred because of burning fossil fuels.
The fact that most climate forcing is due to CO2 from fossil fuels burned in the last 50 years does not refute the article's hypothesis that human activity caused climate change over the past 8,000 years. Just because humans might have caused gradual climate change over the past 8 millennia doesn't mean that recent activities might not cause much greater and more rapid changes.
It's important to keep straight here that climate forcing is a driving term. To understand the effect of this driving term on the climate, we must look at the total system response.
It's well known that because of the large thermal mass of oceans, the climate response to forcing lags the forcing by several centuries, so we won't see the full warming effect of the current forcing for 100 years or more. It's only by ignoring this time lag that you can claim early agriculture has had a larger effect on climate. If you look at the driving (forcing) terms, there is no doubt that fossil fuels outweigh the primitive agriculture terms.
BTW, What imminent decline in the production of fossil fuels do you mean? Oil and gas may become expensive, but we have enough coal to last our current use for two or three centuries. Of course burning it would increase atmospheric CO2 levels by a factor of ten, but we're not going to give up coal because we're running out.
Wheat and other grains (corn is a grain, BTW) have the same problem as corn.
Wood can be different, but it grows much more slowly so unless you're talking about massive deforestation I'd think that it would be hard to start up a large-scale wood-based methanol operation. I'm less knowledgeable about wood, though.
On numbers, a quick look at the 1995 IPCC Mitigation report, pp. 695-7 estimates that full fuel-cycle GHG emissions from converting cars to methanol would range from 20% to 110% of simply continuing to use gasoline, depending on the details of how the crops are grown and how they are converted to methanol.
The most optimistic end of the range (20% as much GHG as gasoline) would still pose problems if you consider the developing world beginning to drive as much as Americans do. The IPCC also discusses the problem of energy crop production displacing other land use, such as forest carbon sinks and food production.
Some other data, from the IPCC 2001 mitigation report (pp. 222 ff.): Agriculture produces 21-25% of total CO2 emissions worldwide, 55-60% of CH4 emissions, and 65-80% of NO2 emissions. Together, these make up 20% of global GHG emissions.
The 2001 IPCC report also mentions in passing that Sweden's production of biomass fuels (methanol, etc.) from wood is less efficient than if the wood were burned directly for heating buildings and generating electric power (p. 245).
You can obtain the 2001 IPCC reports in HTML or PDF format at www.ipcc.ch.
I agree that it's hard to tell anything about what's happening from the limited data we have.
I would ask you to look at things another way:
Known fossil fuel reserves (mostly coal) add up to about 6 trillion tons of carbon.
The atmosphere contains about 0.76 trillion tons of carbon (almost all carbon dioxide).
While we don't know the details of the carbon sinks, we do know very well that about half the carbon emitted by burning fossil fuels remains in the atmosphere with a lifetime of around 100 years.
We know this by watching how the atmospheric CO2 levels have increased along with fossil fuel consumption in the last century. Atmospheric CO2 levels are now about 30% higher than they were at any other time between 500,000 years ago and the industrial era.
We know that carbon dioxide does tend to warm the climate. There are many complicating factors, but over history (e.g., during the ice ages), CO2 levels tend to correlate very well with temperature and we know that atmospheric carbon dioxide and water vapor can explain almost all of the differences in temperature between earth, mars, and venus.
However, as some climate skeptics point out, the earth has many complicated feedback mechanisms that we don't understand completely, so we have a hard time making detailed predictions of future climates.
Nonetheless, if we keep burning fossil fuels at current rates (assume that no one increases their consumption), we will burn the 6 trillion tons of fossil carbon in the next 200 to 300 yars.
Unless some hitherto unknown mechanism miraulously extracts this carbon from the atmosphere, we will end up with about 10 times the current levels of carbon dioxide in the atmosphere.
I find it very hard to imagine that increasing the amount of CO2 in the atmosphere by an order of magnitude would have no significant effect on climate.
Too many climate skeptics claim that we shouldn't do anything to slow global warming because we can't prove that some hitherto unknown negative feedback mechanism would not exactly compensate for this massive increase of CO2. The idea that such a mechanism would exist seems a bit magical---a bit deus ex machina for my mind. It violates the general scientific principle of looking for simple explanations based on what we've observed.
So I agree that we can't prove much about what the climate has done in the last 150 years. Where I disagree with you is that I don't think that's terribly relevant.
As an engineer I don't like the idea of taking my life-support system, adjusting one parameter an order of magnitude above the range at which it's been tested, and assuming that this is an acceptable risk.
We won't even have to get rid of our cars, since they can perfectly run* on ethanol, that can be made out of stuff we can grow.
Ethanol only looks attractive if you ignore the amount of petrochemical fertilizers used to grow the corn and the amount of energy used to cultivate, harvest, transport, and ferment it. Once you take those terms into account, you burn most of the ethanol you get from the corn just in the ethanol production operation.
When my wife was a child, her neighbors grew a small field of corn. They had a team of mules they used to cultivate the field. The mules ate most of the corn and only a little was left for other purposes (feeding their pigs). Biomass ethanol promises to be something like this.
You would produce a net surplus of ethanol, but you'd need to cut down a lot of forest worldwide to grow enough corn to supply the earth's petrol consumption and this would not be an environmentally benign operation!
First prove it beyond a reasonable doubt - these studies are very compelling, but are not proof.
CO2 lives in the atmosphere for a very long time. This is well-known. The more CO2, the longer the lifetime. Currently the lifetime of atmospheric CO2 is about 100 years.
Oceans warm up very slowly (on a timescale of 1000 years, which is determined by deepwater recycling times that can be measured very well.
Putting these two terms together implies that if global warming leads to unacceptable consequences, then by the time we have a clear and unambiguous observation of those consequences (remember that we're rejecting computer models that extrapolate from present trends) we will have set the earth on a course where those consequences will persist for another few centuries.
We don't have unambiguous proof today that human emissions of greenhouse gases will cause unacceptable damage to the environment. We can't predict future climates well enough to know with any certainty whether global warming is benign, catastrophic, or somewhere in between. We will not know this until we observe what the climate actually does.
Once we observe how the climate does change, it will be too late to alter its trajectory for a century or so, so deciding to wait until there is unambiguous proof is actually another way of deciding to do nothing. We should recognize that choosing to do nothing, choosing to take extreme action, or choosing some intermediate course of action will be done in a state of ignorance and uncertainty.
It may be that choosing to do nothing is the best course of action, but we should be honest that what we're doing is choosing to accept whatever climate change occurs in the next two centuries and not to sell it as though we would have the option of doing something about catastrophic climate change should we observe it 50 years from now.
As to nuclear power, I completely support you on this. Nuclear power is the only technology that has a hope of reducing CO2 emissions significantly in the next 30 years, so we should expand nuclear power as quickly as we can reasonably do.
But I don't see how Kyoto holds back the US at the expense of everyone else. Europe and Japan are committed under Kyoto to cut CO2 emissions more quickly than the US would be if we ratified the treaty.
Telling China that it would have to keep CO2 levels near its 1990 levels sounds good on paper, but even today, China emits only one sixth the amount of CO2 per person as the US does. Do you really think it would be a fair allocation of resources to freeze per-capita CO2 emissions with the US at about 6.5 tons per person per year, Europe at around 2.9 tons per person per year, and China at 1.2 tons per person per year?
Both sides of the debate are too set in their thoughts that no amount of data will change their opinions.
The same is true about many other debates:
Between Darwinian evolution and creationism.
Whether space aliens are abducting people from earth.
Whether cold fusion actually works.
Whether Jews and blacks are biologically inferior to "aryan" Europeans.
The fact that the two sides are sharply polarized and unwilling to look at new evidence with an open mind does not mean that they are equally right.
There is much more sound empirical evidence supporting Darwinian evolution, global warming, and racial equality and opposing space alien abductions and cold fusion than the other way around.
The phrase "caused by humans" is dangerous to use in this topic. It implies that global warming is directly caused by humans.
This is silly. A significant majority of anthropogenic climate forcing is due to CO2 produced directly by burning fossil fuels.
Indirect contributions to CO2, such as deforestation is very small in comparison. This can be seen by observing that during the 18th and 19th centuries, deforesting large areas of North America caused a measurable, but very small increase in atmospheric CO2. Burning fossil fuels in the 20th century caused a large increase in CO2 levels. There are several ways to tell where the carbon is coming from: isotope analysis shows that most of the additional carbon is old on the scale of the carbon 13 lifetime, so it has not come from organic material formed in the last couple of hundred thousand years. Second, the timing and magnitude of the increase coincides directly with the growth of fossil fuel use and not with any other anthropogenic or natural phenomenon.
Methane gets a lot of press, but it only lives for a decade in the atmosphere before it's oxidized, whereas carbon dioxide has a much longer lifetime (around a century) so it poses a much greater threat.
Even if we consider methane, cow farts are only a small fraction of total anthropogenic methane emissions.
You're right in principle, but can you give me a specific example of a chemical weapon where a bird can be contaminated with enough to kill many people and still travel a long distance?
I can't think of one off the top of my head and it always helps me to have specific examples to think of when trying to understand hazards I'm not familiar with.
Spanish flu wasn't a weapon. Bio weapons have an absolutely terrible record of effectiveness because it's so hard to make them do what you want them to.
A chemical weapon is easier to make, more deadly, spreads further, and is harder to clean up because it gets into the ecosystem. You end up having trouble with birds that have flown miles away.
If the chemical weapon is so deadly, how far would the bird fly, contaminated with enough toxic gunk to kill many people?
Look here for some more intuition.
The Heritage Foundation's intuition is based on the assumption that people follow simple rules of economic rationality. It would be nice if they did, but the hypothesis is testable and has been thoroughly refuted.
The Nobel Prize for economics a couple of years ago went to Daniel Kahneman, who demonstrated that
Kahneman also demonstrated that the Heritage foundation's intuition is poorly suited to understanding the economics and statistics of the real world.
Kahneman showed that people often prefer to choose a pair of gambles that equate to
25% odds of winning $240 and
75% odds of losing $760
over an alternative pair that equate to
25% odds of winning $250 and
75% odds of losing $750
which violates the fundamental postulates of economic rationality. Specifically, economic preferences are not rational: It is easy to set up choices where people consistently prefer a to b and c to d, but prefer (b+d) to (a+c) (see D. Kahneman and A. Tversky, Eds., Choices, Values, and Frames).
Kahneman's colleague Colin Camerer also demonstrated that taxi drivers work longer hours on nights when they make less money per hour and knock off early when they make more money per hour. In other words, the supply of cab drivers increases when the demand decreases and vice-versa!
Camerer's results violate the Heritage Foundation's intuition and suggests that increasing taxes might well lead people to work harder because people often work until they earn a target, after which they decide to knock off early and enjoy their leisure.
In the real world, people's choices frequently violate in a fundamental manner the postulates of economic rationality and thus refute trite intuitive assumptions that people act to maximize their income, wealth, or other measures of utility.
Government affects the economy like a fish affects a bicycle. It can swim around it, but it can never true the wheels. Fortunately, the economy has a separate spoke wrench known as "Islamic fundamentalism." Government by itself can't straighten out the economy, but if it stays out of the way of the islamic fundamentalists, the economy can straighten itself out.
Thus, islamic fundamentalism can straighten out the economy.
Aren't metaphors fun? If you pick the right analogy you can prove anything and you don't even need to provide evidence!
Rather than looking at forcasts, if you look at the decrease in revenues, you'll find that that after the Bush tax cuts they INCREASED!
Wrong. Federal tax receipts have dropped from $2.05 trillion in the last Clinton year to $1.85 trillion in 2003.
No, you're wrong. The previous poster had it right. The "decrease in revenues" did increase. Revenues decreased by an even greater amount after Bush's tax cuts.
First I want to state that I always beleive in hiring the best person for the job no matter what. I hope that we can agree on that statement. If so then we both agree that afirmative action/quotas are bad.
Two objections:
First, is there an objective test that ranks people from best to worst? If not, how do we determine "best" in a way that is blind to the prejudices of those doing the hiring?
If prejudice does, however unconsciously, play a part in the hiring procedure, would it not be sensible to apply a correction (affirmative action) just as you would apply a correction to any other measurement susceptible to systematic error?
Employers may refuse to hire members of minority groups for certain types of jobs. This decision may not reflect irrationality of prejudice---but profit maximization. For race may serve as a good statistic for the applicant's social background, quality of schooling, and general job capabilities.... For an employer may make a rational decision not to hire any members of these groups in responsible positions---because it is difficult to distinguish those with good job qualifications from those with bad qualifications. This type of decision is clearly what George Stigler had in mind when he wrote, "... Enrico Fermi would have been a gardiner, Von Neumann a checkout clerk at a drugstore."
Thus, from a purely mathematical treatment of markets we find that the cost of acquiring information might lead rational employers to choose not to hire minority applicants, even if they are the best qualified. When the free market fails to give the best-qualified applicant a fair chance, affirmative action becomes necessary to correct for this systematic bias.
All we disagreed about was a minor point: we always agreed that the planet is warming up today because of human actions. We both agree that the world may enter an ice age in the future because of human action.
I want to call it climate change and you want to call it global warming. I think the changes to temperature contrasts are more important than the change in average temperature. You disagree with me on those minor points, but is anyone else interested enough in our argument to make it worth all the carbon dioxide that's being produced to power our computers while we type this?
The problem with global warming or climate change is less with people who believe that it doesn't exist than with people who understand that it does exist but don't want to give up computers, cars, airplanes, central heating, and modern medicine in order to avoid it. I have not found a good way to convince anyone, including myself, to stop using fossil fuels.
So the best we can hope for, even if we are tremendously optimistic about technology, is to slow down global warming by a few decades. We just can't stop it without shutting down everything separates us from the middle ages.
This is why many of the nations that will be hit hardest by global warming (I'll use your preferred term here), such as China and India, also are most eager to start burning as much fossil fuel as the US and Europe do. They would rather live a comfortable industrial life in a warm climate than to remain poor in a pristine one.
Re:global warming? No, global climate change....
on
BBC on Global Dimming
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· Score: 1
Remember that much of the southeastern United States has been a nice home for disease vectors (yellow fever, malaria, etc.) for all of its recorded history. As the climate changes, industrial nations will continue to deal with disease vectors the same way we always have. It's the poor nations that will be hit with the worst of the tropical diseases, just as they always have been.
The bigger problem than the wait-and-seers is the problem of people who understand that this is a real and imminent problem, yet wonder how we will tell the third world not to industrialize. It's not clear that there is any feasible alternative to burning fossil fuels in China, India, and Africa.
To put the discounting question in its starkest form, would you assert that it is better for people to die in poverty today and leave a pristine environment than to have children who would have to live in a world with a worse climate? Could you make this argument in a convincing fashion to someone living in poverty in a nonindustrial nation?
Personally, I have a big problem burning up lots of energy by using my computer to post to slashdot and then telling people in China that they can't burn as much coal or drive as many cars as we do in the US and Europe.
Aerosols have an atmospheric lifetime of a few years or less. CO2 has an atmospheric lifetime of about one hundred years. This means that while aerosols may offset greenhouse enhancement for a little while, over time the aerosols will precipitate leaving the CO2 behind.
"IT" is called global warming. "Climate change" is the vague spin term republicans and neoliberals use to deny that global warming exists and try to make it sound normal.
Obviously you haven't been paying attention to the concern among environmentalists that anthropogenic climate change could trigger a mini-ice-age by altering north atlantic deep-water formation.
Even apart from this possibility, calling the phenomenon global warming is misleading because the biggest problem is not the increased average temperature, but the change in temperature distribution: warming is expected to be more pronounced in the polar regions. Meridional temperature contrasts, which produce our global weather patterns, are expected to become smaller. It's these changes to the climate pattern rather than the increase in average temperature that cause most concern. Thus, climate change is a more accurate description than global warming, even for a die-hard environmentalist.
For those of you that were still in diapers or elementary school, prior to 1988, the scientific community was touting the fact that the world was recovering from a mini-ice age from 1450 to about the 1850s. The sweltering summer of 1988 led a small minority of "scientists" to postulate a "global warming" idea.
Wrong by about 100 years. Global warming was first proposed by Svante Arrhenius in 1895. More recently, serious councern over warming began with Wallace Broecker's 1975 paper, "Climate Change: Are We on the Brink of a Pronounced Global Warming?," (Science 189, 460).
How many people know that Krakatoa, in the eruption of 1883 released more "greenhouse" gases than all of mankind has released since?
Wrong again. Human activity has released something like 200 billion tons of carbon into the atmosphere. This is much more than Krakatoa released. One way to find this out is to look at the amounts of greenhouse gas in the air over history: levels have risen much more since 1950 than they did over the previous 10,000 years. Carbon concentrations in the atmosphere over the past thousand years almost exactly parallel the consumption of fossil fuels.
If you're talking about water vapor emissions from Krakatoa, you're either being disingenuous or you're just ignoreant. See my comments below about the difference between water vapor and carbon dioxide.
Water vapor accounts for 95% of the "greenhouse" effect.
Water does account for most of the greenhouse effect, but there is an important difference: water is a vapor, so water vapor mixing ratios are always close to equilibrium in the atmosphere. If we add more, it precipitates out very rapidly. Carbon dioxide is a gas, and is not at equilibrium, so if we add more CO2, it will remain in the atmosphere for around a hundred years. It's well known that water vapor acts as a positive feedback that amplifies warming due to other factors. This has been verified with observations taken after the Mt. Pinatubo eruption.
I hate to say it, but 100 years ago, 60 years ago, even 40 years ago, there weren't SUVs driving around.
Have you heard of the industrial revolution? People were not driving SUVs, but they were certainly burning lots of coal. Beyond this, it's a silly syllogism to say that because Al Gore said something dumb about global warming that this disproves global warming. It's like what Michael Moore does on the left: Paul Wolfowitz says something dumb about the war in Iraq. Therefore the war in Iraq is dumb.
Slashdot Mirror
Blocking sunlight could offset the increase in mean temperature, but would do nothing about the decrease in contrast. Thus, the polar regions would warm while tropics would cool and the world's weather systems and ocean currents, all of which are driven by heat flow from the tropics to the poles, could still be dramatically changed.
When you look at this system, you have an energy distribution (two narrow peaks, widely separated) that's manifestly out of equilibrium so it's neither low-temperature nor high-temperature. Temperature is not defined.
You could take a temperature to be whatever would produce a Boltzmann distribution with a width equal to the width of the particle distribution (target + beam), so for a keV beam hitting a stationary target, you'd take a width of 500 eV, or about 6 million Kelvin. I'd call that hot fusion.
they couldn't get into Caltech: Soldering while eating pizza is just this side of eating paint chips.
You're asking the wrong question. What would be needed would be to put the existence of God into a falsifiable hypothesis. Once you know how to disprove the existence of God, you can keep performing experiments to disprove God's existence. If even one of these experiments succeeded in disproving God, we'd definitely know He didn't exist.
On the other hand, the more experiments failed to disprove God's existence, the more faith we could have that his existence had been confirmed by scientific tests.
The biggest problem with addressing God's existence through science is coming up with a type of experimental test that believers could accept as disproving His existence.
Here's an analogy: you can't prove that the speed of light in vacuum is equal to all inertial observers. Any finite number of measurements of c does not prove that it's always the same for all observers. However, it would only take one reproducible experiment in which c is different for one inertial observer to disprove relativity.
The reason we believe the "laws" of physics is because they've withstood so many experimental tests that were capable of falsifying incorrect laws. Proving the existence of God would be similar: He'd have to survive a large number of experiments that were capable of disproving his existence.
As oil and gas become more expensive, we'll start producing gas and oil from coal (IGCC processes can produce gas and diesel fuel from coal fairly well). This suggests to me that running out of petroleum reserves will not disrupt civilization, but will merely lead us to use other, more expensive sources of fossil hydrocarbons. We'll adapt to new fuel sources quite well.
As to other sectors of our economy, coal is the fuel for 55% of electricity in the US, and with each year electricity becomes even more central to our economy.
As you correctly note, all of this is not a solution, but a further problem because switching to coal-intensive energy means ever more carbon in the atmosphere.
Of course, I could be wrong and President Bush's program to develop clean hydrogen fuel sources from coal and carbon sequestration technology could solve all our problems long enough for us to develop better nuclear and renewable energy sources. I'm just not holding my breath.
The article does not refute my statement. CO2 concentrations for the past 10,000 years remained fairly constant at typical interglacial concentrations. The article claims that they might have dropped slightly if not for human activity. Compare this to the observation that CO2 concentrations have increased by about 25% in the last 50 years so that they are now about 20% higher than they were at any point in the past 420,000 years. This is a climate forcing on a vastly greater scale both of magnitude and of time than the Scientific American article proposes for early human agriculture.
Nothing in the article you cite disagrees with the statement that most of the increase in CO2 concentrations occurred in the last 50 years and it occurred because of burning fossil fuels.
The fact that most climate forcing is due to CO2 from fossil fuels burned in the last 50 years does not refute the article's hypothesis that human activity caused climate change over the past 8,000 years. Just because humans might have caused gradual climate change over the past 8 millennia doesn't mean that recent activities might not cause much greater and more rapid changes.
It's important to keep straight here that climate forcing is a driving term. To understand the effect of this driving term on the climate, we must look at the total system response.
It's well known that because of the large thermal mass of oceans, the climate response to forcing lags the forcing by several centuries, so we won't see the full warming effect of the current forcing for 100 years or more. It's only by ignoring this time lag that you can claim early agriculture has had a larger effect on climate. If you look at the driving (forcing) terms, there is no doubt that fossil fuels outweigh the primitive agriculture terms.
BTW, What imminent decline in the production of fossil fuels do you mean? Oil and gas may become expensive, but we have enough coal to last our current use for two or three centuries. Of course burning it would increase atmospheric CO2 levels by a factor of ten, but we're not going to give up coal because we're running out.
The most optimistic end of the range (20% as much GHG as gasoline) would still pose problems if you consider the developing world beginning to drive as much as Americans do. The IPCC also discusses the problem of energy crop production displacing other land use, such as forest carbon sinks and food production.
Some other data, from the IPCC 2001 mitigation report (pp. 222 ff.): Agriculture produces 21-25% of total CO2 emissions worldwide, 55-60% of CH4 emissions, and 65-80% of NO2 emissions. Together, these make up 20% of global GHG emissions.
The 2001 IPCC report also mentions in passing that Sweden's production of biomass fuels (methanol, etc.) from wood is less efficient than if the wood were burned directly for heating buildings and generating electric power (p. 245). You can obtain the 2001 IPCC reports in HTML or PDF format at www.ipcc.ch.
I would ask you to look at things another way:
We know this by watching how the atmospheric CO2 levels have increased along with fossil fuel consumption in the last century. Atmospheric CO2 levels are now about 30% higher than they were at any other time between 500,000 years ago and the industrial era.
We know that carbon dioxide does tend to warm the climate. There are many complicating factors, but over history (e.g., during the ice ages), CO2 levels tend to correlate very well with temperature and we know that atmospheric carbon dioxide and water vapor can explain almost all of the differences in temperature between earth, mars, and venus.
However, as some climate skeptics point out, the earth has many complicated feedback mechanisms that we don't understand completely, so we have a hard time making detailed predictions of future climates.
Too many climate skeptics claim that we shouldn't do anything to slow global warming because we can't prove that some hitherto unknown negative feedback mechanism would not exactly compensate for this massive increase of CO2. The idea that such a mechanism would exist seems a bit magical---a bit deus ex machina for my mind. It violates the general scientific principle of looking for simple explanations based on what we've observed.
Ethanol only looks attractive if you ignore the amount of petrochemical fertilizers used to grow the corn and the amount of energy used to cultivate, harvest, transport, and ferment it. Once you take those terms into account, you burn most of the ethanol you get from the corn just in the ethanol production operation.
When my wife was a child, her neighbors grew a small field of corn. They had a team of mules they used to cultivate the field. The mules ate most of the corn and only a little was left for other purposes (feeding their pigs). Biomass ethanol promises to be something like this.
You would produce a net surplus of ethanol, but you'd need to cut down a lot of forest worldwide to grow enough corn to supply the earth's petrol consumption and this would not be an environmentally benign operation!
CO2 lives in the atmosphere for a very long time. This is well-known. The more CO2, the longer the lifetime. Currently the lifetime of atmospheric CO2 is about 100 years.
Oceans warm up very slowly (on a timescale of 1000 years, which is determined by deepwater recycling times that can be measured very well.
Putting these two terms together implies that if global warming leads to unacceptable consequences, then by the time we have a clear and unambiguous observation of those consequences (remember that we're rejecting computer models that extrapolate from present trends) we will have set the earth on a course where those consequences will persist for another few centuries.
We don't have unambiguous proof today that human emissions of greenhouse gases will cause unacceptable damage to the environment. We can't predict future climates well enough to know with any certainty whether global warming is benign, catastrophic, or somewhere in between. We will not know this until we observe what the climate actually does.
Once we observe how the climate does change, it will be too late to alter its trajectory for a century or so, so deciding to wait until there is unambiguous proof is actually another way of deciding to do nothing. We should recognize that choosing to do nothing, choosing to take extreme action, or choosing some intermediate course of action will be done in a state of ignorance and uncertainty.
It may be that choosing to do nothing is the best course of action, but we should be honest that what we're doing is choosing to accept whatever climate change occurs in the next two centuries and not to sell it as though we would have the option of doing something about catastrophic climate change should we observe it 50 years from now.
As to nuclear power, I completely support you on this. Nuclear power is the only technology that has a hope of reducing CO2 emissions significantly in the next 30 years, so we should expand nuclear power as quickly as we can reasonably do.
But I don't see how Kyoto holds back the US at the expense of everyone else. Europe and Japan are committed under Kyoto to cut CO2 emissions more quickly than the US would be if we ratified the treaty.
Telling China that it would have to keep CO2 levels near its 1990 levels sounds good on paper, but even today, China emits only one sixth the amount of CO2 per person as the US does. Do you really think it would be a fair allocation of resources to freeze per-capita CO2 emissions with the US at about 6.5 tons per person per year, Europe at around 2.9 tons per person per year, and China at 1.2 tons per person per year?
The same is true about many other debates:
- Between Darwinian evolution and creationism.
- Whether space aliens are abducting people from earth.
- Whether cold fusion actually works.
- Whether Jews and blacks are biologically inferior to "aryan" Europeans.
The fact that the two sides are sharply polarized and unwilling to look at new evidence with an open mind does not mean that they are equally right. There is much more sound empirical evidence supporting Darwinian evolution, global warming, and racial equality and opposing space alien abductions and cold fusion than the other way around.This is silly. A significant majority of anthropogenic climate forcing is due to CO2 produced directly by burning fossil fuels.
Indirect contributions to CO2, such as deforestation is very small in comparison. This can be seen by observing that during the 18th and 19th centuries, deforesting large areas of North America caused a measurable, but very small increase in atmospheric CO2. Burning fossil fuels in the 20th century caused a large increase in CO2 levels. There are several ways to tell where the carbon is coming from: isotope analysis shows that most of the additional carbon is old on the scale of the carbon 13 lifetime, so it has not come from organic material formed in the last couple of hundred thousand years. Second, the timing and magnitude of the increase coincides directly with the growth of fossil fuel use and not with any other anthropogenic or natural phenomenon.
Methane gets a lot of press, but it only lives for a decade in the atmosphere before it's oxidized, whereas carbon dioxide has a much longer lifetime (around a century) so it poses a much greater threat.
Even if we consider methane, cow farts are only a small fraction of total anthropogenic methane emissions.
You're right in principle, but can you give me a specific example of a chemical weapon where a bird can be contaminated with enough to kill many people and still travel a long distance?
I can't think of one off the top of my head and it always helps me to have specific examples to think of when trying to understand hazards I'm not familiar with.
Spanish flu wasn't a weapon. Bio weapons have an absolutely terrible record of effectiveness because it's so hard to make them do what you want them to.
If the chemical weapon is so deadly, how far would the bird fly, contaminated with enough toxic gunk to kill many people?
The Nobel Prize for economics a couple of years ago went to Daniel Kahneman, who demonstrated that
Kahneman also demonstrated that the Heritage foundation's intuition is poorly suited to understanding the economics and statistics of the real world.
Kahneman showed that people often prefer to choose a pair of gambles that equate to
- 25% odds of winning $240 and
- 75% odds of losing $760
over an alternative pair that equate to- 25% odds of winning $250 and
- 75% odds of losing $750
which violates the fundamental postulates of economic rationality. Specifically, economic preferences are not rational: It is easy to set up choices where people consistently prefer a to b and c to d, but prefer (b+d) to (a+c) (see D. Kahneman and A. Tversky, Eds., Choices, Values, and Frames).Kahneman's colleague Colin Camerer also demonstrated that taxi drivers work longer hours on nights when they make less money per hour and knock off early when they make more money per hour. In other words, the supply of cab drivers increases when the demand decreases and vice-versa!
Camerer's results violate the Heritage Foundation's intuition and suggests that increasing taxes might well lead people to work harder because people often work until they earn a target, after which they decide to knock off early and enjoy their leisure.
In the real world, people's choices frequently violate in a fundamental manner the postulates of economic rationality and thus refute trite intuitive assumptions that people act to maximize their income, wealth, or other measures of utility.
Government affects the economy like a fish affects a bicycle. It can swim around it, but it can never true the wheels. Fortunately, the economy has a separate spoke wrench known as "Islamic fundamentalism." Government by itself can't straighten out the economy, but if it stays out of the way of the islamic fundamentalists, the economy can straighten itself out.
Thus, islamic fundamentalism can straighten out the economy.
Aren't metaphors fun? If you pick the right analogy you can prove anything and you don't even need to provide evidence!
Wrong. Federal tax receipts have dropped from $2.05 trillion in the last Clinton year to $1.85 trillion in 2003.
No, you're wrong. The previous poster had it right. The "decrease in revenues" did increase. Revenues decreased by an even greater amount after Bush's tax cuts.
Two objections:
If prejudice does, however unconsciously, play a part in the hiring procedure, would it not be sensible to apply a correction (affirmative action) just as you would apply a correction to any other measurement susceptible to systematic error?
I want to call it climate change and you want to call it global warming. I think the changes to temperature contrasts are more important than the change in average temperature. You disagree with me on those minor points, but is anyone else interested enough in our argument to make it worth all the carbon dioxide that's being produced to power our computers while we type this?
The problem with global warming or climate change is less with people who believe that it doesn't exist than with people who understand that it does exist but don't want to give up computers, cars, airplanes, central heating, and modern medicine in order to avoid it. I have not found a good way to convince anyone, including myself, to stop using fossil fuels.
So the best we can hope for, even if we are tremendously optimistic about technology, is to slow down global warming by a few decades. We just can't stop it without shutting down everything separates us from the middle ages.
This is why many of the nations that will be hit hardest by global warming (I'll use your preferred term here), such as China and India, also are most eager to start burning as much fossil fuel as the US and Europe do. They would rather live a comfortable industrial life in a warm climate than to remain poor in a pristine one.
The bigger problem than the wait-and-seers is the problem of people who understand that this is a real and imminent problem, yet wonder how we will tell the third world not to industrialize. It's not clear that there is any feasible alternative to burning fossil fuels in China, India, and Africa.
To put the discounting question in its starkest form, would you assert that it is better for people to die in poverty today and leave a pristine environment than to have children who would have to live in a world with a worse climate? Could you make this argument in a convincing fashion to someone living in poverty in a nonindustrial nation?
Personally, I have a big problem burning up lots of energy by using my computer to post to slashdot and then telling people in China that they can't burn as much coal or drive as many cars as we do in the US and Europe.
Aerosols have an atmospheric lifetime of a few years or less. CO2 has an atmospheric lifetime of about one hundred years. This means that while aerosols may offset greenhouse enhancement for a little while, over time the aerosols will precipitate leaving the CO2 behind.
What do you propose doing about this? Please give details.
Obviously you haven't been paying attention to the concern among environmentalists that anthropogenic climate change could trigger a mini-ice-age by altering north atlantic deep-water formation.
Even apart from this possibility, calling the phenomenon global warming is misleading because the biggest problem is not the increased average temperature, but the change in temperature distribution: warming is expected to be more pronounced in the polar regions. Meridional temperature contrasts, which produce our global weather patterns, are expected to become smaller. It's these changes to the climate pattern rather than the increase in average temperature that cause most concern. Thus, climate change is a more accurate description than global warming, even for a die-hard environmentalist.
Wrong by about 100 years. Global warming was first proposed by Svante Arrhenius in 1895. More recently, serious councern over warming began with Wallace Broecker's 1975 paper, "Climate Change: Are We on the Brink of a Pronounced Global Warming?," (Science 189, 460).
How many people know that Krakatoa, in the eruption of 1883 released more "greenhouse" gases than all of mankind has released since?
Wrong again. Human activity has released something like 200 billion tons of carbon into the atmosphere. This is much more than Krakatoa released. One way to find this out is to look at the amounts of greenhouse gas in the air over history: levels have risen much more since 1950 than they did over the previous 10,000 years. Carbon concentrations in the atmosphere over the past thousand years almost exactly parallel the consumption of fossil fuels.
If you're talking about water vapor emissions from Krakatoa, you're either being disingenuous or you're just ignoreant. See my comments below about the difference between water vapor and carbon dioxide.
Water vapor accounts for 95% of the "greenhouse" effect.
Water does account for most of the greenhouse effect, but there is an important difference: water is a vapor, so water vapor mixing ratios are always close to equilibrium in the atmosphere. If we add more, it precipitates out very rapidly. Carbon dioxide is a gas, and is not at equilibrium, so if we add more CO2, it will remain in the atmosphere for around a hundred years. It's well known that water vapor acts as a positive feedback that amplifies warming due to other factors. This has been verified with observations taken after the Mt. Pinatubo eruption.
I hate to say it, but 100 years ago, 60 years ago, even 40 years ago, there weren't SUVs driving around.
Have you heard of the industrial revolution? People were not driving SUVs, but they were certainly burning lots of coal. Beyond this, it's a silly syllogism to say that because Al Gore said something dumb about global warming that this disproves global warming. It's like what Michael Moore does on the left: Paul Wolfowitz says something dumb about the war in Iraq. Therefore the war in Iraq is dumb.