Increased Sun Spot, Solar Activity proves Gloabal warming is caused by Sun,Not humans

[konradv]

That's true. So why do you keep ignoring them? Please note it wasn't the deniers who came up with "sensitive CO2".

Keep ignoring what? You maybe, but the REAL science, never. What does "sensitive CO2" have to do with anything? How about explaining something once in a while? Insults and C&Ps just don't cut it all the time.

You ignore chemistry and physics.

It's probably no coincidence that the AGW cult and the 9/11 "Troof" movement share a lot of members.

Quit avoiding the issue, Dave. What are you afraid of? What's the "sensitive CO2" comment all about. Please, let us know or we'll just have to assume it's a throwaway phrase to cover up their lack of knowledge. "the AGW cult and the 9/11 "Troof" movement share a lot of members" You mean like the ex-military and right wing nutcases? You dissed Obama for that, but apparently it doesn't bother you to use the same logic.

 

[CrusaderFrank]

Water Vapor Confirmed as Major Player in Climate Change11.17.08

The AGW cult ignores water vapor because there is no way to regulate and tax human production of it.

The goal is not to "save the planet". The goal is greater control over individual lives.

No one ignores water vapor. That's just another denier LIE. Continue to raise GHGs and temps will eventually rise, a simple application of the Laws of Chemistry and Physics, causing more water vapor to enter the atmosphere, causing temps to rise. It's part of EVERY calculation and computer model out there. So, apparently, not only do the deniers not trust the models, they don't even believe they exist!!! Any wonder they can only get traction on a political basis? They either misrepresent or ignore the science, a stance guaranteed to get them laughed off any scientific stage! Here's a clue for you politico-deniers, the Laws of Chemistry and Physics aren't up for a vote.

Water vapor is a GHG, but EnviroMarxists would have a hard time calling for the end of hot showers to save the planet

 

[IanC]

American Institute of Physics.

Basic Radiation Calculations

Most experts stuck by the old objection to the greenhouse theory of climate change — in the parts of the spectrum where infrared absorption took place, the CO2 plus the water vapor that were already in the atmosphere sufficed to block all the radiation that could be blocked. In this "saturated" condition, raising the level of the gas could not change anything. But this argument was falling into doubt. The discovery of quantum mechanics in the 1920s had opened the way to an accurate theory for the details of how absorption took place, developed by Walter Elsasser during the Second World War. Precise laboratory measurements studies during the war and after confirmed a new outlook. In the frigid and rarified upper atmosphere where the crucial infrared absorption takes place, the nature of the absorption is different from what scientists had assumed from the old sea-level measurements.

Take a single molecule of CO2 or H2O. It will absorb light only in a set of specific wavelengths, which show up as thin dark lines in a spectrum. In a gas at sea-level temperature and pressure, the countless molecules colliding with one another at different velocities each absorb at slightly different wavelengths, so the lines are broadened considerably. With the primitive infrared instruments available earlier in the 20th century, scientists saw the absorption smeared out into wide bands. And they had no theory to suggest anything else.

A modern spectrograph shows a set of peaks and valleys superimposed on each band, even at sea-level pressure. In cold air at low pressure, each band resolves into a cluster of sharply defined lines, like a picket fence. There are gaps between the H2O lines where radiation can get through unless blocked by CO2 lines. That showed up clearly in data compiled for the U.S. Air Force, drawing the attention of researchers to the details of the absorption, especially at high altitudes. Moreover, researchers working for the Air Force had become acutely aware of how very dry the air gets at upper altitudes—indeed the stratosphere has scarcely any water vapor at all. By contrast, CO2 is fairly well mixed all through the atmosphere, so as you look higher it becomes relatively more significant.(9a)

You do realize this means that GHGs are screens rather than blankets then? That there are more ways for radiation to pass through? By the time you get very high most of the radiation has been converted to frequencies that CO2 is oblivious to.

 

[konradv]

The AGW cult ignores water vapor because there is no way to regulate and tax human production of it.

The goal is not to "save the planet". The goal is greater control over individual lives.

No one ignores water vapor. That's just another denier LIE. Continue to raise GHGs and temps will eventually rise, a simple application of the Laws of Chemistry and Physics, causing more water vapor to enter the atmosphere, causing temps to rise. It's part of EVERY calculation and computer model out there. So, apparently, not only do the deniers not trust the models, they don't even believe they exist!!! Any wonder they can only get traction on a political basis? They either misrepresent or ignore the science, a stance guaranteed to get them laughed off any scientific stage! Here's a clue for you politico-deniers, the Laws of Chemistry and Physics aren't up for a vote.

Water vapor is a GHG, but EnviroMarxists would have a hard time calling for the end of hot showers to save the planet

It's easier than you posting something sensible, apparently. I guess I have to spell it out for you. Higher CO2, higher temp. Higher temp, more water vapor. If you use logic, it's obvious that you'd need to lower CO2. Not showering wouldn't help at all. Wikipedia has a good article on Logic. You should read it some time.

 

[daveman]

That was performed by John Tyndal in 1858.

No, he proved CO2 is a greenhouse gas. He didn't prove AGW.

Amen, brother.

Old Rocks can't tell the difference between 200PPM and 990,000PPM.

Oh, if ONLY evil Americans would stop driving SUVs! Gaea is weeping!

 

[daveman]

Keep ignoring what? You maybe, but the REAL science, never. What does "sensitive CO2" have to do with anything? How about explaining something once in a while? Insults and C&Ps just don't cut it all the time.

You ignore chemistry and physics.

It's probably no coincidence that the AGW cult and the 9/11 "Troof" movement share a lot of members.

Quit avoiding the issue, Dave. What are you afraid of? What's the "sensitive CO2" comment all about. Please, let us know or we'll just have to assume it's a throwaway phrase to cover up their lack of knowledge. "the AGW cult and the 9/11 "Troof" movement share a lot of members" You mean like the ex-military and right wing nutcases? You dissed Obama for that, but apparently it doesn't bother you to use the same logic.

I calls 'em likes I sees 'em. Deal with it.

 

[westwall]

So, all the skeptics were telling us that the climate was cooling, there was no warming after 1998. Where are these people now?

No, I do not state that every event is related to global warming. However, when you get enough events, the totality does indicate a change.

For a number of years, the people that have been studying the climate, have been warning us that it is the food supply in a world of about 7 billion people that is in danger. Depending on the source of information, 20% to 33% of the Russian grain crop is gone. Pakistan's bread basket is devastated. And there are many smaller areas where the crops have been ruined by floods or heat, from Iowa and Mississippi to China.

And then there is the little matter of about 40% of the oceans phytoplankton gone missing. Nothing to worry about, just the base of the ocean's food chain, and the largest single source for converting CO2 into O2 and food.

Here's one:

BBC: Do you agree that from 1995 to the present there has been no statistically-significant global warming

Phil Jones: Yes

BBC News - Q&A: Professor Phil Jones

I've lost track of how many times you posted this lie and I've nailed you on this lie only for you to post this lie again. If you were even remotely honest you would have put an ellipses after the yes.

The complete answer was:
"Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods."

Statistically insignificant. Like most alarmist arguments.

 

[westwall]

Water Vapor Confirmed as Major Player in Climate Change11.17.08

The AGW cult ignores water vapor because there is no way to regulate and tax human production of it.

The goal is not to "save the planet". The goal is greater control over individual lives.

No one ignores water vapor. That's just another denier LIE. Continue to raise GHGs and temps will eventually rise, a simple application of the Laws of Chemistry and Physics, causing more water vapor to enter the atmosphere, causing temps to rise. It's part of EVERY calculation and computer model out there. So, apparently, not only do the deniers not trust the models, they don't even believe they exist!!! Any wonder they can only get traction on a political basis? They either misrepresent or ignore the science, a stance guaranteed to get them laughed off any scientific stage! Here's a clue for you politico-deniers, the Laws of Chemistry and Physics aren't up for a vote.

konrad, COME ON DOWN TO WESTWALLS BITCHSLAPALOOZA! No one ignores it huh?

I present you with this then, it is from the US EPA....I take it you've heard of them?. The relevant sentence is at the bottom...highlighted in blue so you can find it easier.

Care to esplain this Looocy?






Concentrations of Greenhouse Gases

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enlarge

Exhibit 2-52


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Exhibit 2-53


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Exhibit 2-54


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Exhibit 2-55
Notice: Updated June 2010 with most recent data points.

Q: What are the trends in greenhouse gas emissions and concentrations?

The above question pertains to all 'Greenhouse Gases' Indicators, however, the information on these pages (overview, graphics, references and metadata) relates specifically to "Atmospheric Concentrations of Greenhouse Gases". Use the right side drop list to view the other related indicators on this question.

Introduction
What the Data Show
Limitations
Introduction
The Earth’s temperature depends mainly on the amount of energy received from the sun, the portion reflected back into space, and the extent to which the atmosphere retains heat. Natural forces (e.g., volcanoes and changes in the Earth’s orbit) and human activities (e.g., emissions of so-called “greenhouse gases ” [GHGs] and land use change) affect the amount of energy held in the Earth-atmosphere system and therefore affect the Earth’s climate. Human activities in all countries have altered the chemical composition of the atmosphere by the emissions and accumulation in the atmosphere of GHGs. The primary gases that retain heat in the atmosphere are water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and certain manufactured gases such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and sulfur hexafluoride (SF6).

Once emitted, gases remain in the atmosphere for varying amounts of time. Very “short-lived” compounds, such as particulate matter (PM), remain airborne on average for only hours or days. CH4 also has a relatively short average lifetime, though much longer than PM, remaining in the atmosphere for roughly 12 years. The half-life of CO2 emissions is roughly 100 years (5 to 200 years: IPCC, 2001), but about a quarter of emissions today will still be in the atmosphere after hundreds of years and about one-tenth for hundreds of thousands of years (Archer and Ganopolski, 2005; Archer et al., 1998). Finally, many of the synthetic gases such as halocarbons (or gases that contain the halogens chlorine, fluorine, bromine, or iodine) are extremely long-lived, remaining in the atmosphere for hundreds or even tens of thousands of years. When emissions—from the U.S. (the U.S. Greenhouse Gas Emissions indicator) as well as other countries—remain in the atmosphere over long periods, they accumulate and are measured as atmospheric concentrations. U.S. GHG emissions from 1890 to 2000 are estimated to have contributed about one-fifth of the increase in global GHG concentrations (den Elzen et al., 2005).

This indicator shows trends in the accumulation of the following principal GHGs in the atmosphere: CO2, CH4, N2O, and selected halocarbons. Recent data are from global networks that monitor the concentrations of these gases in the atmosphere. Older historical data come from measurements of gases in the air trapped in ice cores at the time the ice was formed. Because the gases shown in this indicator remain in the atmosphere for long periods, they are well-mixed, so that measurements at individual locations are globally representative. This indicator summarizes GHG concentration measurements reported in a collection of studies published in the peer-reviewed literature. In order to provide the most extensive temporal coverage, this indicator aggregates comparable, high-quality data from individual studies that each focused on different time frames. None of the data in this indicator are based on modeled concentrations.

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What The Data Show
Exhibits 2-52 through 2-54 show the evolution of concentrations of three principal GHGs in the atmosphere over three intervals: geological time (hundreds of thousands of years), the past 12,000 years, and recent decades. The exhibits represent data sets covering a wide range of latitudes, showing some latitudinal differences in concentrations but also showing a high level of consistency—indicating that the gases are well-mixed and that the sampling can be considered spatially representative. The graphs show patterns of large cycles of concentrations over geological time, and they also depict increases in concentrations in the industrial era (post-1780) that exceed concentrations over the past hundreds of thousands of years.

The concentration of CO2, the most important anthropogenic GHG, has varied considerably over geological time (Exhibit 2-52). Over the past 650,000 years, CO2 concentrations have generally cycled over several-thousand-year periods from highs around 285-300 parts per million (ppm) to lows around 180-185 ppm. From at least 900 A.D. to 1800 A.D., CO2 concentrations stayed relatively constant at about 270-290 ppm (panel B). Over the past 150 years, annual average CO2 concentrations increased steadily from approximately 270-290 ppm in pre-industrial times to 387 ppm in 2009, a 38 percent increase (panels B and C). Almost all of this increase is due to human activities (IPCC, 2007), and the concentrations measured currently are the highest observed over the entire period of record.

CH4 concentrations also cycled widely over the past 650,000 years, but peaks remained below 800 parts per billion (ppb) until after 1800 A.D. (Exhibit 2-53). Concentrations slightly increased between 1000 A.D. and 1730 A.D. (panel B). It then took approximately 175 years (c. 1905) to add 200 ppb to atmospheric CH4 concentrations, approximately 40 years (c. 1945) to add the next 200 ppb, approximately 20 years (c. 1965) to add the next 200 ppb, and approximately 10 years (c. 1975) to add the next 200 ppb (panel B). In 2008, the annual average CH4 concentrations at the two stations with available data were 1,741 ppb and 1,800 ppb, respectively (panel C), and current levels far exceed the natural range surmised from the ice core samples. The rates at which CH4 concentrations increased began to slow by the late 1970s, with approximately 300 ppb added to atmospheric concentrations between 1978 and 2008 (panels B and C). Overall, global CH4 concentrations have more than doubled in the past 150 years. The most recent data show a significant difference in CH4 concentrations across latitudes—a pattern of peak concentrations in the most northern latitudes decreasing toward the southern latitudes, suggesting net sources of CH4 in northern latitudes. Yet, despite the latitudinal differences in concentrations, the pattern over the past two centuries shows a common trend in all locations.

N2O concentrations (Exhibit 2-54) vacillated widely through geological time, with ice sample measurements ranging from as low as 180 ppb to above 280 ppb. Despite considerable inter-decadal variability, N2O stayed mostly below 280 ppb from 1756 A.D. until the 1920s (panel B), at which point levels began to rise rapidly to approximately 323 ppb in 2009 (panels B and C), the highest level recorded over the more than 100,000 years of data available.

Concentrations of the halocarbons were essentially zero a few decades ago, but have increased rapidly as they were incorporated into industrial products and processes (Exhibit 2-55). Concentrations of hydrochlorofluorocarbons HCFC-141b and HCFC-142b increased through 2006, but are expected to gradually stabilize over this decade as they are phased out in industrialized countries as part of the Montreal Protocol on Substances That Deplete the Ozone Layer. The concentration of HFC-23, which is a byproduct of HCFC-22 production, increased more than five-fold between 1978 and 2006. Halocarbons that are not controlled by the Montreal Protocol (because they do not contribute to stratospheric ozone losses) mostly continued to increase because of their widespread use as substitutes for the Montreal Protocol gases.

Top of Page

Limitations
Water vapor is not tracked in this indicator, as it is generally accepted that human activities have not increased the concentration of water vapor in the atmosphere.


Some radiatively important atmospheric constituents that are substantially affected by human activities (such as tropospheric ozone, black carbon, aerosols, and sulfates) are not included in this indicator because of their spatial and temporal variability and the inadequacy of available data to characterize long-term averages or trends.


Concentration data are not available for all the halogenated compounds that are potentially important GHGs. For instance, global concentration data are not sufficient yet to track trends in concentrations of SF6 and PFCs.


Ice core measurements are not taken in real time, which introduces some error into the date of the sample. Dating accuracy for the ice cores ranged up to +20 years (often less), depending on the method used and the time period of the sample. Diffusion of gases from the samples, which would tend to reduce the measured values, might also add a small amount of uncertainty. More information on the accuracy of measurements of ice samples and other measurement methods can be found at CDIAC Global Change Data and Information Products - By Subject.

Atmospheric Concentrations of Greenhouse Gases | Report on the Environment Database | US EPA

 

[Dr Grump]

Scientists say global warming is undeniable

''We are very confident that human-induced global warming is a real phenomenon.''

A former academy president, Kurt Lambeck, said the report was aimed at clarifying often contradictory comments from non-scientific ''instant experts''.

The report refutes many of the claims made by climate change sceptics, such as that the globe has been cooling since 1998, the sun is mainly to blame for recent warming, recent warming is part of natural variability, and volcanoes emit more carbon dioxide than human activities.

Gee, who to believe?? Scientists who study this stuff or wannabe 'experts' on blogs and messageboards....hhhmmm....

 

[westwall]

Scientists say global warming is undeniable

''We are very confident that human-induced global warming is a real phenomenon.''

A former academy president, Kurt Lambeck, said the report was aimed at clarifying often contradictory comments from non-scientific ''instant experts''.

The report refutes many of the claims made by climate change sceptics, such as that the globe has been cooling since 1998, the sun is mainly to blame for recent warming, recent warming is part of natural variability, and volcanoes emit more carbon dioxide than human activities.

Gee, who to believe?? Scientists who study this stuff or wannabe 'experts' on blogs and messageboards....hhhmmm....

Care to post the actual study so we can all have a good laugh.

 

[Old Rocks]

The actual studies have been posted here many times, Walleyes. Just one, for you to have a laugh at, seeing as how you know so much more than all the people at the USGS.

Which produces more CO2, volcanic or human activity?

Gas studies at volcanoes worldwide have helped volcanologists tally up a global volcanic CO2 budget in the same way that nations around the globe have cooperated to determine how much CO2 is released by human activity through the burning of fossil fuels. Our studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually.

This seems like a huge amount of CO2, but a visit to the U.S. Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) website (Carbon Dioxide Information Analysis Center) helps anyone armed with a handheld calculator and a high school chemistry text put the volcanic CO2 tally into perspective. Because while 200 million tonnes of CO2 is large, the global fossil fuel CO2 emissions for 2003 tipped the scales at 26.8 billion tonnes. Thus, not only does volcanic CO2 not dwarf that of human activity, it actually comprises less than 1 percent of that value.

 

[daveman]

Scientists say global warming is undeniable

''We are very confident that human-induced global warming is a real phenomenon.''

A former academy president, Kurt Lambeck, said the report was aimed at clarifying often contradictory comments from non-scientific ''instant experts''.

The report refutes many of the claims made by climate change sceptics, such as that the globe has been cooling since 1998, the sun is mainly to blame for recent warming, recent warming is part of natural variability, and volcanoes emit more carbon dioxide than human activities.

Gee, who to believe?? Scientists who study this stuff or wannabe 'experts' on blogs and messageboards....hhhmmm....

A more pertinent question is, "Who believes it? Wannabe 'experts' on blogs and messageboards, or the men and women who shape policy and legislation?"

It doesn't matter if you armchair climatologists believe it. You're insignificant. What matters is if politicians believe it. They're the people who can ruin the entire economy (worse than they already have) for some leftist horseshit that doesn't have the science to back it up.

 

[konradv]

Water vapor is not tracked in this indicator, as it is generally accepted that human activities have not increased the concentration of water vapor in the atmosphere.

Are we talking consensus here?!?! I thought that was a bad word! If it gets hotter, there WILL BE more water vapor in the atmosphere. That's simple physics. The fact that it's not tracked makes it a tough thing to hang your hat on. I thought you were opposed to data being ignored. It's a red herring anyway, since it's the other ADDED GHGs since the advent of the Industrial Revolution which would drive temps up. The rise in water vapor is a consequence of that. Therefore, the reason it isn't tracked like GHGs is because, it's a result not a cause of AGW and it's good scientific practice to measure root causes instead of results, if you can.

 

[CrusaderFrank]

No one ignores water vapor. That's just another denier LIE. Continue to raise GHGs and temps will eventually rise, a simple application of the Laws of Chemistry and Physics, causing more water vapor to enter the atmosphere, causing temps to rise. It's part of EVERY calculation and computer model out there. So, apparently, not only do the deniers not trust the models, they don't even believe they exist!!! Any wonder they can only get traction on a political basis? They either misrepresent or ignore the science, a stance guaranteed to get them laughed off any scientific stage! Here's a clue for you politico-deniers, the Laws of Chemistry and Physics aren't up for a vote.

Water vapor is a GHG, but EnviroMarxists would have a hard time calling for the end of hot showers to save the planet

It's easier than you posting something sensible, apparently. I guess I have to spell it out for you. Higher CO2, higher temp. Higher temp, more water vapor. If you use logic, it's obvious that you'd need to lower CO2. Not showering wouldn't help at all. Wikipedia has a good article on Logic. You should read it some time.

Show me ONE TIME IN A LABORATORY how this happens!

One time: 200PPM causes a Temp Increase

 

[CrusaderFrank]

U.S. Department of Energy's Carbon Dioxide Information Analysis Center

When I Googled "U.S. Department of Energy's Water Vaspor Information Analysis Center" I got lemons.

Odd, no?

 

[daveman]

U.S. Department of Energy's Carbon Dioxide Information Analysis Center

When I Googled "U.S. Department of Energy's Water Vaspor Information Analysis Center" I and got lemons.

Odd, no?

Ummm...

Carbon Dioxide Information Analysis Center

 

[westwall]

Water vapor is not tracked in this indicator, as it is generally accepted that human activities have not increased the concentration of water vapor in the atmosphere.

Are we talking consensus here?!?! I thought that was a bad word! If it gets hotter, there WILL BE more water vapor in the atmosphere. That's simple physics. The fact that it's not tracked makes it a tough thing to hang your hat on. I thought you were opposed to data being ignored. It's a red herring anyway, since it's the other ADDED GHGs since the advent of the Industrial Revolution which would drive temps up. The rise in water vapor is a consequence of that. Therefore, the reason it isn't tracked like GHGs is because, it's a result not a cause of AGW and it's good scientific practice to measure root causes instead of results, if you can.

Water Vapor is THE DOMINANT GREENHOUSE GAS. Climatologists though don't know enough about it so they ignore it. Look at any climate prediction model and water vapor is not included as a variable.

What I find amusing is the scientific method requires the creation of a hypothesis, the demonstration of said hypothesis through experimentation and the presentation of results to the scientific community to determine if those results can be reproduced by anybody.

The climatologists computer models are the hypothesis. They can not predict what will happen in a month much less ten years. They can not reproduce what we know has happened in the past.


Below is Gavin Schmidts revelation about the climate model problems (once again highlighted in blue) and this from one of the lead alrmists.

The only consensus is they havn't a clue how the climate works. That is a fact. All the rest is the waving of hands to confuse you.

THE PHYSICS THAT WE KNOW

[GAVIN SCHMIDT:] The key environmental question facing us now (and for at least the next century) is to what extent are the changes we are making to the atmosphere, to the oceans, to the composition of the air, going to impact sea levels, temperature, and rainfall and hydrological resources?

Societies make decisions based on certain expectations for their climates. How far away from the shore should we build? How do we design our agriculture? What kind of air conditioning system do we put in a building? All of these decisions depend on the expectations we have for the summer temperature, or the intensity of the ocean surge during a Northeasterly storm. Our expectations in such matters have been built over hundreds of years of experience. But things have changed.

How do we come up with new expectations when our models are no longer valid? We need new information on which to base decisions being made now that will affect how we deal with the climate in 10, 20, 30, 50 years time because we are now building infrastructure for with these kinds of timeframes.

We have to ask questions about what expectations we may have for the future based on the physics that we presently know, on processes we can measure, and that resonate with our ability to understand the current climate. Among the questions we need to ask are: Why are there seasonal cycles? Why are there storms? What controls the frequency of such events over a winter, over a longer period? What controls the frequency of, say, El Nino events in the tropical Pacific that impacts on rainfall in California or in Peru or in Indonesia?

We have decided, as a scientific endeavor, to extrapolate as much as we can from our knowledge of the individual processes that we can measure: evaporation from the ocean, the formation of a cloud, rainfall coming from a cloud, changes in wind patterns as a function of the pressure field, changes in the jet stream. What we have tried to do is encapsulate those small-scale processes, put them together, and see if we can predict the emerging properties of that fundamental complex system.

This is very ambitious because there is a lot of complexity, a lot of structure in the climate that is not a priori predictable from any small scale process. The wet and dry seasons in the tropics come about because of the combination of the seasonal cycle of the orbit around the earth, changes in evaporation, changes in moist convection (the process that creates the big cumulus towers and thunderstorms), water vapor transports because of the moist convection, because of the Hadley Cell that gets set up as a function of all those things. It is a very complex environment.

We have been quite successful at building these models on the basis of small-scale processes to produce large-scale simulation of the emerging properties of the climate system. We understand why we have a seasonal cycle; we understand why we have storms in the mid-latitudes; we understand what controls the ebb and flow of the seasonal sea ice distribution in the Arctic. We have good estimates in this regard.

But we don't have perfect estimates. Instead, there are about twenty groups around the world that have reported on such processes, which ones are important, which ones are not. Each group has produced a separate digital world, a digital climate, and they each differ as a whole and in terms of their levels of sensitivity. For example, if I change an element in one of the models, each of the other models reacts in a slightly different manner.

In some respects they all act in very similar ways — for instance, when you put in more carbon dioxide, which is a greenhouse gas, it increases the opacity of the atmosphere and it warms up the surface. That is a universal feature of these models and it is universal because it is based on very fundamental physics that you don't need a climate model to work out. But when it comes to aspects that are slightly more relevant — I mean, nobody lives in the global mean atmosphere, nobody makes the global mean temperature an important part of his expectations — things change. When it comes to something like rainfall in the American Southwest or rainfall in the Sahel or the monsoon system in India, it turns out that the assumptions we make in building the models (the slightly different decisions about what is important and what isn't important) have an important effect on the sensitivity of very complex elements of the climate.

Some models strongly suggest that the American Southwest will dry in a warming world; some models suggest that the Sahel will dry in a warming world. But other models suggest the opposite. Let's imagine that the models have an equal pedigree in terms of the scientists who have worked on them and in terms of the papers that have been published — it's not quite the case but it's a good working assumption. With these two models, you have two estimates — one says the area will get wetter and one says it will get drier. What do you do? Is there anything you can say at all? It is a really difficult question.

There are a couple of other issues that come up. It turns out that the average of these twenty models is a better model than any one of the twenty models. It better predicts the seasonal cycle of rainfall; it better predicts surface air temperatures; it better predicts cloudiness. This is odd because these aren't random models. You can't rely on the central limit theorem to demonstrate that their average must be the best predictor, because these are not twenty random samples of all possible climate models.

Rather, they have been tuned and they have been calibrated and they have been worked on for many years in trying to get the right answer. In the same way that you can't make an average arithmetic be more accurate than the correct arithmetic, it is not obvious that the average climate model should be better than all of the other climate models. For example, if I wanted to know what 2+2 was and I picked a set of random numbers, averaging all those random numbers is unlikely to give me four.

Yet in the case of climate models, this is kind of what you get. You take all the climate models, which give you numbers between three and five, and you get a result that is very close to four. Obviously, it's not pure mathematics. It's physics, it's approximations, it involves empirical estimates.. But it's very odd that the average of all the models is better than any one individual model.

Does that mean that the average of all the models' predictions is better than the prediction of any individual model? This doesn't follow, because it may be that all of the models contain errors, which for today's climate average out when you bring them together. Who is to say what controls their sensitivity since we know that in each model the sensitivity is being controlled by slightly different elements?

You need to have some kind of evaluation. I don't like to use the word validation because it implies a kind of binary true-false set up. But you need tests of the model's sensitivity compared to something in the real world that can confirm that model has the right sensitivity. This is very difficult.

For instance, let's imagine that the models I want to pay attention to are the ones that get the best seasonal cycle of rainfall. I rank the models, give them a score, and take the top 10 scoring models for that metric. Then somebody else says, no, I think it's more important that they get the annual mean right or they get the inter-annual variability (the variability from one year to another). Well, I can do that same ranking. It turns out that if I do the ranking for three different metrics — there is nothing that says that one metric is better than the other — I end up with ten completely different rankings.

Not only are the rankings uncorrelated to one another, but depending on the metric, the projections, the estimates that you get going into the future turn out to be uncorrelated to the score, as well. I get the same spread if I take the top ten models over here as I had for the whole set. There will still be some positive ones and there will still be some negative ones when, for instance, I look at projected rainfall in the American Southwest.

This is a real problem. How do you deal with these models in an intelligent way? Which information from the observational record, either over the 20th century or longer, can you use to test whether the models have any skill in their predictions? This is what I spent all of my time on: trying to find ways to constrain the models to improve the Bayesian subjective probability that they are telling you anything of use. It's not that we have been working in a complete vacuum for the last 30 years — these models are relatively mature and people have been thinking about these issues ever since the beginning.

There are lots of examples in the current climate with which you can demonstrate that the models have skill. Say, the response to the eruption of Mount Pinatubo in 1991 in the Philippines. The volcano released a huge amount of sulfur dioxide and sulfate aerosols into the atmosphere, which spread around the stratosphere and stayed for about two to three years. These aerosols are reflective; they are white.

So the sun gets reflected out. These aerosols acted as a kind of sunshade over the planet that caused the planet to cool. Our group (though this is before my time), before this cooling happened, did the calculations with their model, and predicted that the cooling would reach a maximum of about half a degree in about two years time. Lo and behold, such a thing happened.

If you go back, and we had lots of information about what happened over that period — what happened to radiation at the top of the atmosphere, what happened to the winds that changes the function of the temperature gradients in the lower stratosphere, what happened to water vapor — we can see whether the models got the right answer for the right reason, and for the most part they did. So that was a good real prediction in real time that could be tested in a short amount of time.

The problem with climate prediction and projections going out to 2030 and 2050 is that we don't anticipate that they can be tested in the way you can test a weather forecast. It takes about 20 years to evaluate because there is so much unforced variability in the system — the chaotic component of the climate system — that is not predictable beyond two weeks, even theoretically. This is something we can't really get a handle on. We can only look at the climate problem once we have had a long enough time for that chaotic noise to be washed out, so that we can see that there is a full signal that is significantly larger than the inter-annual or the inter-decadal variability. This is a real problem because society wants answers from us and won't wait 20 years.


Edge: THE PHYSICS THAT WE KNOW: A Conversation With Gavin Schmidt