Can somebody cite a period when climate HASN'T changed?
It all depends upon your time scale and your definition of what constitutes "climate change". My understanding of the Earth's climate history is that most of it has been slow transitions, and that fast transitions have been disruptive to life forms, and particularly disruptive to larger life forms, on our planet.
In terms of the current debate, the primary concern is the potential rate of climate change, specifically temperature increase. Mankind's ability to adapt depends not only on how much the climate may change but how quickly that change occurs. I have no doubt mankind can handle an increase of 5 degrees Celsius over 5,000 years. This has been the average rate of the Earth's natural temperature rise after an ice age, based upon the known temperature history of the last 800,000 years. However, we may already be within a few degrees of the warmest the Earth has been over that 800,000 year span. An additional 5 degree Celsius temperature increase over the next 100 to 200 years, as predicted by many climate models, would be much harder to handle.
Thanks for your explanation. Having lived for many years in the US "southwest" (I have lived in 3 of the "4-corners" states), I have encountered several "pre-historic" situations where the only explanation for a sudden failure of a society or "civilizations". Years ago, park rangers at Mesa Verde National Park and among the Pueblo, anthropologists at digs, and just plain old amateur hobbyists expressed that it didn't make sense that a seemingly thriving society just suddenly either disappeared or left their infrastructure, apparently going from the height of development to nothing in a period of only a very few decades. Evidence was that food sources disappeared or water was suddenly not sufficiently available after being there for centuries. they all said that such swift changes were unexplainable. Well, it's now apparent that such changes do and have occurred every few centuries. Such changes are only really evident in areas or zones that are on the fringe of being able to support larger population densities, like the southwest. Yes, these areas cover only a small fraction of the earth's surface, and may be isolated cases. But the evidence is there. Arguably, these conditions occurred in part because the society became too large or too successful, adding demand on the environment, and were at least in part man-made, but not unique to our current society and development.
What I find most interesting about this discussion on Global Warming/Climate Change, is that nobody seems to recognize that we are in an inter-glacial period that started about 11000-12000 years ago, when at least half of the Northern Hemisphere was covered with ice sheets up to a mile thick.
The natural expectation would be that the temperatures of the Earth SHOULD show a warming TREND, regardless of yearly temperature fluctuations, and study of any graphs will show that that is exactly what is happening. as the planet warmed, the rate of this trend became APPROACHED a relatively straight line. As for rapidity of climate changes, there have been periods where climate has changed significantly in less than a decade; I may be wrong, but the Younger-Dryas extinction relatively soon after the end of the last glaciation was one of these extreme events.
Another problem with emphasizing CO2 concentration as responsible for Global Warming/Climate Change is considering correlation to be causation. While CO2 may be involved, few people seem to consider the changes in land use not only since the start of the Industrial Revolution, but since the final evolution of homo sapiens. Just think of how many forests have been denuded, or actually just literally cleared not only since the industrial Revolution, but by thousands of years of human existence. Ironically, some of the sources of energy to replace fossil fueled power plants, particularly solar and wind farms, would just exacerbate the problem.
Hi, Steven Brecht. Even during the Last Glacial Maximum, which occurred about 24,500 BCE, nowhere near half of the northern hemisphere was covered in ice sheets up to a mile thick. Around 11,000 years ago, the northeast part of Canada and Greenland were covered in glaciers, with strips of glaciers elsewhere in North America. (http://www.historymuseum.ca/cmc/exhibitions/aborig/fp/fpz2f13e.shtml)
Human civilization started with the Holocene, ~12,000 years ago. In 2013 it was hotter than 90% of the Holocene (http://science.sciencemag.org/content/339/6124/1198).
Climate scientists are smart enough to know that climate changed in the past and that land use changes could affect climate. In fact, they use information about past climate change to learn about what is affecting today's climate and what future effects might be. There is a whole branch of paleoclimatology that focuses on previous rapid changes in climate.
There are multiple lines of evidence that point to human-caused CO2 resulting in climate change. An extremely partial list:
We know from physics that increasing the concentration of CO2 and other greenhouse gases in the atmosphere affects the earth's energy balance
We know that levels of CO2 and other greenhouse gases are high and rising: CO2 is the highest it's been in the last 780,000 years (for the last 400,000 years see http://cdiac.ornl.gov/trends/co2/graphics/vostok.co2.gif, for recent measurements see http://blog.ucsusa.org/wp-content/uploads/2014/03/mlo_full_record.png)
We know that global temperatures are increasing (http://data.giss.nasa.gov/gistemp/graphs_v3/)
We know the temperature increase is from greenhouse gases because if it wasn't, the vertical temperature profile of the atmosphere would look different (http://onlinelibrary.wiley.com/doi/10.1029/2004JD005075/full)
We know that the increase in greenhouse gases in the atmosphere is from combustion of fossil fuels, because it isn't from other sources and they're depleted in 13C (http://www.realclimate.org/index.php/archives/2004/12/how-do-we-know-that-recent-cosub2sub-increases-are-due-to-human-activities-updated/)
We also know that if we exclude anthropogenic sources of greenhouse gases, the climate models don't work (and they do work very well) (also from Santer et al 2004)
I went over this last week on a similar topic. Global Climate change is nothing more than an unsteady state radiant heat transfer problem. The Energy balance between the Sun and the Earth is not at steady state due to CO2 and the "greenhouse" effect. The "models" that a previous poster referenced are about how fast temperature will change. That may be an interesting exercise but does nothing about the problem. We know when the rise will stop and that will be when the Sun-Earth Energy balance in in equilibrium. I have seen data that estimates the imbalance. Using radiant heat transfer equations, it should be a simple task to estimate how high the temperature of the Earth will rise to radiate the excess energy into space. Of course, the temperature get higher as we increase the CO2 concentration in the atmosphere.
Here is a graph of how the temperature of the Earth has varied over the last 400,000 as a function of the CO2 concentration in the atmosphere:
I'd say the correlation between temperature and CO2 concentration is pretty strong. Since we have tons of data on how CO2 interacts with light, I'd say that CO2 concentration in the atmosphere is very likely the controlling factor in maintaining a climate suitable for life. We're not going to adopt to this. That's like thinking the body will adopt to lung cancer if the patient continues smoking. Possible? I guess, but what are the odds?
Researches have been at this for 40 years. The energy companies have an economic incentive to solve this problem and keep us addicted to fossil fuels. Nothing has come of it. A miracle solution is always possible, but, at this point, as likely as hitting the powerball.
I’ve been following this thread for some months now, trying to divine the truth about Global Warming. While I’m still not 100 percent convinced of the accuracy of the forecasts, no doubt unmitigated increases in CO2 will lead to warming, all other things equal. That said, I wonder if we were to take a look at the long view – might there be a win/win in terms of collecting CO2 today for use in the future.
What if we consider the situation when the next Ice Age commences, which some scientists believe is overdue? At that point, if the past several cycles are any indication, average global temperatures will drop perhaps 6⁰C, as I understand the history. Furthermore, those temps will stay down for a very, very long time – perhaps 100K years or so. I think such a change will cause major disruptions in our ability to feed the planet, amongst other things. What will we do then?
What if we could simply open the valves on underground formations in which we’ve stored CO2 collected in the past, starting, say, in the 21st century, and create just the right amount of green-house effect to offset the orbital forcing leading to the cool-down? If our current rate of production of CO2 is driving a 2⁰C increase in such a relatively short time, a mere couple of centuries of collecting and storing CO2 should build enough inventory to prepare for the inevitable chill down. Of course, in that event, someday even further down the line mankind will be faced with challenge of recollecting the CO2 thus released as yet another interglacial period starts. But that’s a really long time out.
So … perhaps we should redirect our energies to the longer view, begin to collect and store CO2 now, so that we have a knob to turn as the next big chill commences. Now, while there is still a certain practicality to it – being able to collect the gas from relatively concentrated stack gas in fossil-fueled energy plants and fixed industrial vents. In so doing we could mitigate today’s threat of global warming even as we prepare for that colder future. A classic win/win. Has such a scenario been considered by the climate change community? As the debate rages, are we allowing an important asset to dilute into the atmosphere?
I’m by no means an expert – just an old-style ChemE hoping we get this one right. My remains will long since be at a comfy 55⁰F by the time future ChemE’s know the truth of this issue. But is there a win/win that we’re letting slip away?
I never said CO2 is the cause. The pre-historic data I presented makes it a likely suspect. Certainly someplace to look.
Let's put aside the mountain of scientific data, and experiments that point to CO2 as the cause of Climate Change. I need you to explain why the Internal Energy of the Earth has been increasing. I presented this graph last week:
If it were weather variation that caused what we we're seeing, that curve would be relatively flat. Something else is going on. the First Law of Thermodynamics is pretty clear what is going to happen. The temperature of the Earth will keep rising until that curve goes flat. The Earth has to get hot enough to radiate the excess energy into space.
Does the cause really matter? No, the result will be the same. Let's look at the possible causes of an imbalance in the Earth-Sun Energy Balance. The Sun could be radiating more energy than usual. We measure that and that is not the case. Maybe it's due to man-made energy generation. Not likely. The energy from the Sun dwarfs what we generate here on Earth. It wouldn't take much of a temperature rise for the Earth to radiate that energy into space. That leaves something blocking the Earth's ability to radiate energy into space. Can you think of something else?
BTW you tried to make an argument that the atmosphere is big and therefore the CO2 we dump into the atmosphere is not going to make much of a difference. It really doesn't matter the quantity that we dump in. What matters is that we are dumping it in faster than the processes that remove it can take it out. It will continue to build and the CO2 ppm will continue to rise. Your argument is only relevant in the context of how fast the rise will occur.
You also commented how pleased you are the AICHE is not "politicizing" Climate Science. The AICHE is a feckless organization. I suspect many of the organization's directors and executives have ties to the energy industry. I suspect the energy industry provides financial support for many of the AICHE's activities. It doesn't surprise me at all that they have taken no position on Climate Change. Not an act worthy of praise.
Here another organization that believes in Climate Change. A tree hugging member of the Sierra Club? Not exactly
"The deep ocean storage of heat is an interesting graph, but there havebeen many frauds in climate "science" and I would want to know moreabout the data..."
I haven't head that argument in quite awhile., Scientists have been taking climate data for the past 30 years. Even the "scientists" who are avowed climate deniers stopped trying to attack the data. Of course there is ancillary evidence. The Earth's ice mass is decreasing and the oceans are rising. This isn't a recent phenomena. It has been happening consistently over years. That wouldn't be happening if the Internal Energy of the Earth wasn't rising.
"but my best intuition would be something todo with cloud formation/destruction."
Water vapor is a greenhouse gas. The difference between water vapor and CO2 is that water vapor does not build up in the atmosphere. It has a very efficient removal process called rain. Since it can't build up in the atmosphere it's effect on the continuing rise of the Internal Energy of The Earth is non-existent. That leaves the ability of clouds to reflect solar radiation. This has a cooling effect and won't cause the Internal Energy of the Earth to rise. Clouds are not a plausible explanation for what we are seeing.
"Rather a libellous accusation, especially since there is an innocentexplanation of defending free speech and the scientific process."
Ridiculous! I wouldn't call the AICHE feckless if they took a stand either way. No, their "position" is that they have no position. This is supposedly an organization rooted in science. They should be able to look at the record and make a judgement. Their problem is if they take a position against Climate Change, they will be taking a stance against the overwhelming opinion of the scientific community and wind up looking stupid. If they take the opposite position, they fear angering their sponsors in the energy industry. So, they pretend there is a "controversy". Calling the AICHE "feckless" is being generous. Reckless is closer to the truth.
"You cannot have it both ways -- if the energy industry supports AGWand a carbon tax, why would they pressure the AIChE to remain open?Corporations are legally required to make decisions in theirshareholders best interests. I am not at all surprised to seeExxon embrace Climate Change. A contrary position probably coststhem some marginal sales and profits. Notice their advertising."
I don't think Exxon Mobil or the oil industry in general is making statements warning about the dangers of CO2 out of a sense of morality or profits. The thing they are worried about is litigation. Look at what happened to Big Tobacco after it was discovered that they covered up their knowledge of the effects of tobacco. That only affected a small portion of the population. What do you think the energy industry will have to pay for covering up something that has a negative impact on every person on the planet? Hence, the change of heart. Exxon is currently a defendant in a suit concerning Climate Change.
Even as I write, the oil industry is making plans to exploit oil reserves in the Artic made available by Climate Change. How cynical is that?
Yes Michael, this process is currently implemented by some emitters that wish to claw back some carbon tax and also cash in on government subsidies.
The process is called Carbon Capture and Sequestration (CCS) which is a misnomer because it is actually Oxygen Capture and Sequestration – 2.67 tons of Oxygen are taken out of the atmosphere and injected downhole for every ton of carbon that originally came from downhole.
Trees do a better job of capturing carbon from the atmosphere and every ton of wood product (building, furniture, etc.) that is still in service today is approximately 0.5 tons of sequestered carbon which came from capturing approximately 1.3 tons of CO2 from the atmosphere.
When wood products are demolished they can be converted to biochar instead of being burned or instead of being allowed to rot. In this way the carbon never returns to the atmosphere.
It would be interesting to compare how many tons of wood products are in service today compared with how many tons of equivalent carbon has been extracted as hydrocarbon fuels over the past 150 years.
Regard, Ron Zylla
Radix Innovation Corp.
Have you ever worked with distillation columns? Can you model their heat transfer properties as just a single plate? Of course not. And you can't presume that since we have enough CO2 to be completely "opaque" as a single radiating body, that no further heat can be trapped by increased CO2 concentrations.
The atmosphere must be modelled as a large stack of layers interacting with each other. Heat transfer is primarily convective at the lowest altitudes. Radiation properties becomes a more important heat transfer component as you increase altitude. When you model the atmosphere as if it were 100 or 1000 theoretical plates, no single plate is opaque because of CO2, each is just a little more efficient at retaining heat.
The amount of energy absorbed by CO2 can be calculated using line-by-line radiative transfer codes. These results have been experimentally confirmed by satellite and surface measurements. Please see Climate Change Facts: Humans Are Forcing the Climate | Weather Underground
Also, Galileo was the father of scientific consensus. The opposition he faced was not scientific consensus, so his story does not lend credence to the notion that the current scientific consensus around climate change is politically motivated.
This paragraph appeared in Mr. Braccili's last last post:
"Water vapor is a greenhouse gas. The difference between water vapor and CO2 is that water vapor does not build up in the atmosphere. It has a very efficient removal process called rain. Since it can't build up in the atmosphere it's effect on the continuing rise of the Internal Energy of The Earth is non-existent. That leaves the ability of clouds to reflect solar radiation. This has a cooling effect and won't cause the Internal Energy of the Earth to rise. Clouds are not a plausible explanation for what we are seeing."
The global warming scenario from CO2 is founded on the idea that the slight warming from increasing CO2 levels increases water evaporation such that the humidity does in fact increase and contribute further to the "forcing" of temperature rise that can supposedly get out of control as in excessive positive feedback. The global warming models are founded on this compounded positive feedback being real. If it is not, then the whole concept of runaway global warming falls apart. I would like to know what is the negative feedback that keeps water from undergoing its own thermal runaway without "help" from CO2? It must be pretty effective and if so why do we think a little push from CO2 will make any difference? I have stated before in other posts that CO2 is purely a dependent variable and its levels are "system response outputs". CO2 cannot independently drive climate or temperature change. It is certainly an actor. If our activities like burning fossil fuels add to atmospheric CO2, we did that not CO2 itself. The climate system has to have robust mechanisms to control actors like CO2 for there to have been life sustained in some form or other for billions of years. We don't yet know very well the details of how these operate over time.
We have no idea how in some geologic eras the CO2 levels rose to thousands of ppm and later dropped to below 200 ppm often out of step with temperature. If I am tasked to design a system to control the earth's temperature, I would not tweak a dependent variable!? A recent Science Digest flyout showed work using ZnSe windows in a vacuum to radiate out in the 8-13 micron atmospheric window that could maintain 40 C lower temperature than ambient in a cloudless sky. I want to control insolation and outgoing radiation. CO2 is a nuisance just noise in the control architecture.
The stakes are high. Here in Maryland our legislature has passed a bill to attain 25% renewables in our electricity generation mix by 2022. My Current BG&E bill shows we are at 4%. So we have to add that much each year for the next 5 years to meet the goal. Some estimates are $12.5 billion for 6 million people so per capita it is about $2000 or $400/yr. The bill assumes that this will be primarily wind and solar. There isn't really enough windy real estate to install the number of wind turbines to make a dent. So we will have to buy from other states or fail the mandate. Solar of course for sure only works in the daytime so some kind of back up must be retained that likely will still burn fossil fuels. Several colleagues and myself are advocating changing from an RPS (renewable portfolio standard) that does not include nuclear power to a CES (Clean Energy Standard) that recognizes nuclear as a near zero carbon emitter. If we did that, MD would be over 25% already due to Calvert Cliffs nuclear plant. We are getting some traction with legislators. What are you doing in your state? BTW, MD passed another bill that commits to 50% renewable energy for all sectors by 2030 with a eventual goal of ~90% by 2050! These are not engineerable goals at this point in time in my view.
You or others who question climate science have still not answered my original question. The internal energy of the Earth is rising and has been for years. As night follows day, so will the temperature of the earth. The only way the excess energy gets off the planet is by radiating it into space. If the "greenhouse' effect is not the cause, then what is?
How can you call CO2 a "dependent" variable? In our current situation we are the ones causing the change in CO2 concentration in the atmosphere. We are the ones that dump CO2 into the atmosphere faster than it can be removed. That doesn't sound like a "dependent" variable to me.
A great smoke and mirrors argument that climate deniers use is that the "models" don't match reality, therefore, climate science has got it all wrong. Let's say I build a model of a tank with a valve to predict how fast the tank drains. My model predicts the tank will drain in x minutes. I open the valve and nothing comes out. Does that mean that the science behind draining the tank has got it all wrong? No, it means I missed something. Like the valve being clogged.
It is true that a rising Earth temperature will cause the atmosphere to hold more water. Water is a greenhouse gas and that will contribute to climate change, but CO2 is the culprit. It is the "independent" variable in the current situation.
Water vapor is a greenhouse gas. The vast majority of water on the planet is on the surface, either as ice or water. So its concentrations only change as a function of average temperature. Increasing the earth's surface temperature from 50 F to 70 F approximately doubles the surface concentration of water vapor at a given relative humidity. This will increase the greenhouse effect of water vapor. But water has an interesting property. As it approaches saturation humidity at any given temperature it becomes opaque to visible light (clouds). Clouds reflect solar radiation (a majority of it in visible and near-visible wavelengths) back into space. So while water vapor can slow the migration of heat from the surface of the earth, it offsets that greenhouse effect by reducing the solar radiation that actually makes it to the earths surface. We feel this every day when a cloud passes in front of the sun.
Carbon dioxide is a greenhouse gas Unlike water, there is no saturation carbon dioxide concentration under normal earth temperatures. Carbon dioxide is transparent to the majority of solar radiation as it passes through the atmosphere. Carbon dioxide, however, preferentially absorbs the radiation re-emitted by the warmed earth. Some of this absorbed energy is ultimately emitted back towards the ground, hence an energy accumulation in the atmosphere (and also the earth's land and water, adjusting the equilibrium with the warmed atmosphere). Before the industrial revolution, the carbon on the surface of the planet was in a rough equilibrium, in the active biomass, the ocean's carbonates, and the equilibrium carbon dioxide in the atmosphere. But much of the carbon on the planet had been fixed, or locked, both physically and chemically, in fossil fuels. The last few centuries have seen mankind's enormous strides in accessing and utilizing fossil fuels. This has reintroduced an ever-increasing amount of carbon, as carbon dioxide, into the atmosphere. [Note: for those who claim the effects of fossil fuel utilization should have shown up sooner, go look at the ever increasing fossil fuel utilization as a function of year.] This released carbon has overwhelmed, at least in the short term, the earth's mechanisms for fixing that carbon back into a non-greenhouse alternative.
And it doesn't take much of a change in the greenhouse equilibrium to impact the earth. A previous thread contained a graph showing the earth's increased latent heat over the last 40 years. Unfortunately that was the thread that was mysteriously deleted off the AICHE discussion forum a few weeks ago. The increase in latent heat was huge by many metrics; it was orders of magnitude higher than the energy contained in all the known fossil fuel reserves on the entire earth.
But the amount was minimal relative to the amount of solar energy that reaches the earth's surface. In fact, over the 40 year (14,620 day) period represented by the graph, the increase in the earth's latent heat represented a net absorption of an additional 14 or 15 days worth of solar energy. Maybe it was all the greenhouse result of carbon dioxide. Maybe it was the greenhouse result of both carbon dioxide and water vapor. We know it wasn't changes in solar energy. We know it wasn't just the heat from combustion of fossil fuels. We know it wasn't any of the other proposed suspects (non-greenhouse contributors can not have contributed even 10% of the total latent heat increases).
For everyone out there that likes to bash "deniers", I have two questions for you.
1. Do you agree that the earth experienced ice ages in the past before man or at least before modern man?
2. How did the earth warm back up after the ice ages?
Hi, Mr. Polk. I thought we already talked about the effect of solar insolation on climate change, but maybe that happened on the thread that was deleted. Earth tends to cool every 100,000 years or so due to small changes in its orbit around the Sun. Large meteorites, volcanoes, and the concentration of greenhouse gases are also thought to have played a role in climate change in Earth's past.
Climate change scientists include solar effects in their models. The warming that we are experiencing in recent years cannot be explained by solar-related effects. In fact, the sun has shown a slight cooling trend over the last 30 years, while Earth's temperature has increased (see https://www.wunderground.com/climate/facts/sun_is_not_to_blame.asp).