For all the romanticised talk about Frost Fairs on a frozen Thames, Hubert Lamb and other historians also found that the Thames froze in 923 & 998.It froze for seven weeks in 1061 and was also completely frozen over during the severe winters of 1149/50, 1204/05, 1269/70 and 1281/82, 1309/10, 1407/08, 1409/10 (this time for 14 weeks), 1434/35, early 1506, 1513/14, 1516/17 and 1536/37. That’s throughout the entire Medieval Warm Period, however you wish to date its start and finish. Ice was reported on both the Bospherous and Nile in 829 and again in 1010/11.
If we’re looking at reduced sun spot activity causing cold periods then the correlation isn’t perfect. To take the Little Ice Age as an example: North eastern America’s coldest period of the past Millennium was the 19th century. Western Europe and China’s coldest period was in the 17th. In Tibet it was the 16th. In north-western America it was the 15th. In Western Greenland it was the 14th. Western North America had both its highest and lowest peaks of temperatures (of the 1000 – 1900 period) in the same century. The 15th. So not the perfect fall and rise in temperature that the program tries to paint and difficult to explain just using the cosmic rays hypothesis.
On Cosmic Rays and cloud formation: Different clouds formed at different altitudes have different properties. High altitude clouds reflect solar energy; low altitude clouds can help retain heat. Sorting out exactly what effect they have is going to be difficult, will take decades and * cough * climate models. All they can claim to have detected so far is a 3% difference between solar maximum and minimum. Wooo.
It’s also worth noting that the Danish Space centre isn’t the only centre with a hypothesis about cosmic rays; a pity the other, rival, hypothesis weren’t also given airtime.
We’re going to enter into a major solar minimum period in the next year or two so we’ll have a chance to see what effect it really has. Even so it’ll take decades to arrive at evidence as to their effect, one way or another. Those with longer memories know that sunspot/solar cycle theories have been proposed many times in the past, only to wither for lack of evidence.
As for Ice Ages and the observation that rises in CO2 follow rises in temperature; you really need to explain the causes of Ice Ages (Milankovitch cycles) to understand why and how they end. Of course tap isn’t turned to release CO2 into the atmosphere to initiate temperature rises. Just as it wasn’t turned off to lower temperatures as the ice age developed. As the Solar System and Earth move into new positions in the cycle the Earth begins to warm; this starts the release of CO2, this acts as both forcing and feedback thus increasing temperature rise. That’s why CO2 lags the temperature rise.
Water vapour and warming. Firstly the amount varies in the atmosphere (The amount of cloud cover varies for example.) Water vapour is a feedback, not a cause (forcing) of warming. The absolute (not relative) humidity of the atmosphere varies by place, time & altitude, but it’s a stable balance. Absolute humidity means the atmosphere can only hold an absolute ammount at any one time. It can’t therfore increase and raise temperatures on its own. It has to be preceeded by a temperature rise. Sorry guys, but it’s the laws of thermodynamics. Add more Water Vapour to the atmosphere and it won’t stay there, it quickly falls as rain/snow. No effect on temperature. The air’s capacity to hold vapour (absolute humidity) is limited but increases as the air warms, roughly doubling for each temperature increase of 10°C. CO2 increase = Forcing. Water Vapour + temperature increase = Feedback.
Those who try to deny that CO2 or methane, CH4, plays any part in climate are in danger of denying the basic known physics behind the role of the greenhouse effect. Find out about the interaction between triatomic gas molecules in the atmosphere and electromagnetic energy (Google it if you haven’t a textbook) before dismissing it out of hand. The greenhouse effect is based on solid physics, and it’s possible to demonstrate these properties in a lab.
... very very interesting... please keep posting stuff like this... scientific points like this are so much more valuable that much of the opinion expressed on this forum... you'll get less posts than the opinion threads... its easy to have an opposite opinion... but you post will be read and are useful... thanks
[QUOTE] Water vapour and warming. Firstly the amount varies in the atmosphere (The amount of cloud cover varies for example.) Water vapour is a feedback, not a cause (forcing) of warming. The absolute (not relative) humidity of the atmosphere varies by place, time & altitude, but it’s a stable balance. Absolute humidity means the atmosphere can only hold an absolute ammount at any one time. It can’t therfore increase and raise temperatures on its own. It has to be preceeded by a temperature rise. Sorry guys, but it’s the laws of thermodynamics. Add more Water Vapour to the atmosphere and it won’t stay there, it quickly falls as rain/snow. No effect on temperature. The air’s capacity to hold vapour (absolute humidity) is limited but increases as the air warms, roughly doubling for each temperature increase of 10°C. CO2 increase = Forcing. Water Vapour + temperature increase = Feedback. QUOTE]
If all the water vapour was removed from the atmosphere never to return, would temperature stay the same?
I had gained the impression from other web sites that water vapour absorbs certain thermal radiation frequencies and does contribute to warming.
If all the water vapour was removed from the atmosphere never to return, would temperature stay the same?
I had gained the impression from other web sites that water vapour absorbs certain thermal radiation frequencies and does contribute to warming.
Yes it would probably cool down a lot. Your second statement is also true.
The thing is that were all water removed from the atmosphere, it would probably all be replaced within a few months from evaporation from the sea.
ie. it does keep us warm. But on average it never increases, never decreases and can't be affected by man. Therefore it doesn't, on its own, cause change in climate. (The qualifier is that if temperatures rose, for whatever reason, by, say 1C, then water vapour would increase slightly which would cause an additional small amount of warming).
Does that mean, even if there were no CO2 in the atmosphere and all other things being equal, that water vapour alone could make the earth go on getting warmer and warmer for ever? As you said, a rise in temperature causes more water vapour, which causes warming, which causes more water vapour, which causes more warming, ad infinitum.
What would limit the temperature rise?
I know the question is rather theoretical as there obviously are other greenhouse gases and other factors. But I am trying to get a clearer picture of the role water vapour plays.
No it's not a runaway effect thankfully. The extra water vapour is not significant enough as it has a steadily diminishing effect.
(To illustrate imagine you double CO2 and it causes a 1.5C rise. This increases the water vapour which produces a rise of 1/3 of the original. ie a 0.5C rise. This increases the water vapour again, but produces another 1/3 of 0.5C rise - only 0.16C then 0.05 then 0.02...ie. you eventually get to a rise of about 2.25C. It's a bit more complicated than that.)
‘I had gained the impression from other web sites that water vapour absorbs certain thermal radiation frequencies and does contribute to warming.’ Steve M
Water vapour is a greenhouse gas so it does play a role in temperature, but the amount of WV in the atmosphere cannot increase without there first being an increase in temperature. That’s a key point in the global warming debate. Only after the atmosphere increases in temperature can the total amount of WV increase.
We get thunderstorms, for example, in hot weather because warmer air holds more water vapour and warm air rises, the vapour condenses when it meets colder air higher in the atmosphere and so on: More below: http://www.weatherquestions.com/What_causes_thunderstorms.htm
Since WV is a greenhouse gas, it should increase warming as a warmer atmosphere can support more WV. It [WV] is therefore not a primary cause of warming, but a contributing feedback.
For the same reason some of the driest places on earth are also the coldest. Much of Antarctica is technically as desert! Because of its cold atmosphere little precipitation falls in many areas and most moisture is locked up as ice. There are some valleys in mountains where it’s thought that no precipitation has fallen for two million years. http://www.flex.net/~lonestar/coldest.htm
If all the water vapour was removed from the atmosphere never to return, would temperature stay the same? Steve M
Yes, probably a very cold one. It’s thought that during the last Ice Age the few humans were confined to certain areas of the planet, not just because of the cold but because much of the fresh water was frozen as well. A cold atmosphere also meant little precipitation. It was a cold drought essentially. Because temperatures dropped the atmosphere couldn’t hold much water and water on the surface froze.
I have seen some figures for an estimated temperature for Earth without a greenhouse effect and its a chilly –19°C (2°F) because all the solar energy just radiates back to space. There probably are other estimates, but they’ll all be cold.
‘You said, a rise in temperature causes more water vapour, which causes warming, which causes more water vapour, which causes more warming, ad infinitum. What would limit the temperature rise?’ Mike RR.
Hi Shefftim Your argument regarding water vapour is simply wrong. It would be valid only if the atmosphere were saturated over its full depth but it is not. It is therefore entirely possible to increase the total water vapour in the atmosphere without increasing the temperature. The 'balance' that determines the amount of water vapour in the atmosphere is extremely complex as it involves all the factors that affect the evaporation rate at the surface (plant cover, roughness length ground-air temperature differential etc, etc), the vertical transport processes that carry the water vapour away from the surface, and all the factors that affect the precipitation processes from cloud (cloud condensation nucleus spectrum, cloudbase updraft speeds, entrainment processes into the clouds, the presence of the ice phase in the cloud, coalescence, etc, etc. All the reasons, in fact, why the IPCC cite clouds and aerosol as the main area of uncertainty.
Thanks Shefftim. Had a look at http://www.nsc.org/EHC/climate/ccucla6.htm and it answers several questions. It says "Water vapor is responsible for about two-thirds of the natural greenhouse effect."
And goes on to say "Most models suggest (and most climate scientists think) that manmade global warming will crank up the whole hydrological cycle: more evaporation, more water vapor, more precipitation. The warming-induced increase in humidity will be enough to further increase warming – what is called a "positive feedback," magnifying the direct warming effect of CO2".
But also "Clouds currently are believed to have a small net cooling effect. The effect they will have in the future is uncertain. The interactions among water vapor, clouds, aerosols, and radiation are far more complex than we have room to hint at here. The computer models generally used to simulate climate are not yet very helpful in understanding clouds, because clouds are much smaller than the finest detail the models can represent." Which does make one wonder how accurate some of the AGW predictions are.
For the record I'm neither an AGW believer nor a sceptic (that’s sceptic with a c – please let's not have it spelt with a k) – I'm a "trying to understand it all".
But also "Clouds currently are believed to have a small net cooling effect. The effect they will have in the future is uncertain. The interactions among water vapor, clouds, aerosols, and radiation are far more complex than we have room to hint at here. The computer models generally used to simulate climate are not yet very helpful in understanding clouds, because clouds are much smaller than the finest detail the models can represent." Which does make one wonder how accurate some of the AGW predictions are.
I think Cloud man has a point about needing to understand clouds better. But as yet, no mechanisms or observations are giving sufficient evidence of an effect that could cause GW. Meanwhile, there is a very good greenhouse gas theory on the table whose models, though imperfect, have predicted the last 20 years' warming, and other features of the climate as well.
You might find following link that follows the history of climate science interesting.
Cloudman: I’ll maintain my assertion that the overall amount of water vapour in the atmosphere is dependent on temperature in support on the point I made above. i.e. “Since WV is a greenhouse gas, it should increase warming as a warmer atmosphere can support more WV. It [WV] is therefore not a cause of warming, but a contributing feedback.”
‘The amount of water vapour that can be maintained in the air at saturation changes depending on the air temperature. Because energy is required to allow water molecules to escape liquid form to become a gas (evaporation) the cooler the air temperature, the lesser the energy available for evaporation to occur. Conversely, the warmer the air, the more the energy available for evaporation and, hence, the more water molecules able to evaporate into the air. The warmer the air, the larger the number of water vapour molecules can be mixed into the air before saturation occurs. The cooler the air, the smaller the number of water vapour molecules can be mixed into the air before saturation occurs.’ From: http://earthstorm.ocs.ou.edu/materials/ref_watervapor.php
(This is also why humidity occurs at night after a hot day, the air temperature has dropped.)
I mentioned the laws of thermodynamics before. Heat is energy. If you increase the temperature, you are increasing the average energy of the particles present. That means that more of them are likely to have enough energy to escape (evaporate) from the surface of the liquid.
The first law of Thermodynamics states that you cannot create or destroy energy. Energy can change from one form to another, like electricity converting into heat, or heat converting into light, or water converting into vapour. Increase in temperature = increase in available energy. The stronger the forces that are keeping the molecules together in a liquid or solid state, the more energy that must be input to evaporate them. (It takes about 600 calories of heat energy to change 1 gram of liquid water into a gas form.) Warmer air can also hold more water vapour than colder air because colder air is denser. Heat causes molecules to agitate faster; these cause a parcel of air molecules to expand and so it can hold more vapour. http://www.atmosphere.mpg.de/enid/254.html http://www.coleparmer.com/techinfo/print.asp?htmlfile=D...int_Humid.htm&ID=108
Greenhouse gasses and their roles; H20, CO2, CH4 etc. Not all Greenhouse Gasses are the same; they interact with different wavelengths of infrared (their absorption bands) in different ways.
Water vapour absorbs infrared at 0.6 Microns, 0.72 Microns, 0.82 Microns, 0.94 Microns, 1.10 Microns, 1.38 Microns, 1.87 Microns, 2.70 Microns, 3.20 Microns, and 6.30 Microns. Carbon dioxide absorbs infrared radiation at wavelengths of 2.69 micrometers (Microns) & 2.76 Microns, 4.25 Microns, 14 Microns, and 15 Microns. Methane absorbs infrared at 3.4 Microns, 7.4 Microns, 7.58 Microns, and 7.87 Microns. Carbon monoxide absorbs infrared at 2.3 Microns, and 4.7 Microns. Nitrous oxide absorbs infrared at 7.83 Microns, 16.98 Microns, and 44.9 Microns. Ozone absorbs infrared at 9.0 Microns, 9.6 Microns, and 14.2 Microns.
For example, the 8-18 micron band is where water vapour is a weak absorber of infrared radiation and where the Earth's thermal radiation is greatest. Part of this "window" (12.5-18 micron) is largely blocked by carbon dioxide absorption, even at the low levels originally existing in the atmosphere. The remainder of the "window" coincides with the absorption proclivities of the other radiative gases: methane, tropospheric ozone, CFCs and nitrous oxide. It also appears that increased levels of carbon dioxide will increase the capture of heat in its absorption band to some extent.
Of greater concern is the release of Methane into the atmosphere as the atmosphere warms, as there is greater room in the absorptions bands for them to be blocked by rising levels of CH4. (CH4 = a simple molecule consisting of one carbon atom bonded to four hydrogen atoms. Part of the carbon family if you like.) In cool periods Methane is stored as a Clathrate (also known as a hydtrate), a chemical compound that consist of a ‘cage’ of molecules (usually water) that can trap a gas. (Methane Clathrate’s chemical formula is : CH4.6H2O)
Methane Clathrate’s are very stable at high pressure and low temperature. This is why a vast amount are locked up in frozen Tundra within the arctic circle and in ocean sediments. And why they can be released when the temperature rises. A warmer atmosphere helps release the methane from the Clathrate. eg as frozen permafrost thaws. Which is why it’s not just polar bears we should be concerned about as the Arctic and sub Polar Regions warm.
I agree clouds are complex and need to be understood more. They can play a part in both warming and cooling by at least two methods. This is also one reason I’m prepared to be open minded about, but yet am wholly unconvinced by, the cosmic rays hypothesis. Even Danes say they have only detected a 3% difference between solar maximum and minimum periods. The warming and cooling effects of the clouds could even cancel each other out.
Mike RR. I agree about sceptic. Skeptic is how the Americans spell it.
Always be open minded; I go with what makes most sense at that time. If someone can explain gravity better than Newton and his successors so far have, most scientists would go along with the new thinking. This is a good way of looking at it; science as a process for extending understanding, not as unalterable truth. From: http://www.ncrel.org/sdrs/areas/issues/content/cntareas/science/sc4imagi.htm
It’s why I think terms like Hoax and Swindle are counter productive, inaccurate and ultimately dishonest. It’s political propaganda, but not an argument. Just as if all contrarians were labelled ‘Liars’ wouldn’t be accurate, as I have no doubt they honestly do believe they know a better explanation.
This was done at a gallop on Sunday night; forgive me (for any typos etc. as well) but I have a busy week ahead, so may not get back here for a while. Thank you for a much better debate than we often get on this issue.
While the saturation vapour density is indeed a strong function of temperature it is entirely wrong to assert that it is the only factor and in so doing overlook the very real possibility that changes in other factors that affect the evaporation process (such as vegetation) and precipitation processes (such as CCN) are not also critical in determining the degree to which water vapour acts as a greenhouse gas. Those that assert that water vapour is only a feedback process are ignoring the possibility of changes in these other factors (accidentally, or deliberately by human activity or otherwise)
Regret to say because it's all interesting and intellectually stimulating but vapor's classification, or any other of the seemingly scientific minutiae diversions offered by the deluded new Messiah Gore and his blind followers only confuse the issue. The key to the whole saga of global warming is this.
We humans contribute only a small percentage to the total release of CO2. If we were to drop dead, the 6bn plus of humans (and disregarding the carbon dioxide that our dead bodies would discharge), then the overall annual total of CO2 would drop by just 4%. The best, and most reader friendly explanation of the CO2 conundrum could be found in Bill Bryson's book 'A short history of nearly everything', page 328 paperback edition, Black Swan 2004. And since you ask, no Bill Bryson isn't a scientist, and hasn't digged himself into the problem, but he has talked to others who did. Mr. Bryson has no axe to grind (no tax implications, or budget approval committees for research projects), and he hasn't been challenged on this figure when the book was published 3 years ago. Indeed, he was complimented. Other sources differ, but not substantially. You will not find any of this in any of the stuff published by the followers of the new 21st century religion. If you pin any of the followers of the new creed down the two answers they give are variations on two themes; it's either that 'we cannot stop a volcano belching', or, 'all other sources of CO2 haven't increased as much as did human discharge'. Big deal.
On clouds/vapour and global dimming: I was initially surprised that the impact of aircraft vapour trails did not feature in the GGWS programme. After all, (if I understood last year's Horizon programme correctly) you'd expect doubters to say that there is no point us decreasing air travel as a plane's vapour trail apparently reflects more solar heat than is kept in the earth's atmosphere by the CO2 released by the burn of the aircraft engines.
Am I right in thinking the reason this was not mentioned in the GGWS was because if you accept global dimming it makes recent temperature rises seem far more worrying and thus strengthens the global warmers' case? I guess this is the same reason it is not mentioned by the likes of Ryan Air?
Surely though, whether man-made CO2 is causing global warming or not, we should keep planes flying as they are helping to cool the planet which is, we are all agreed, heating up for one reason or another?
as a plane's vapour trail apparently reflects more solar heat than is kept in the earth's atmosphere by the CO2 released by the burn of the aircraft engines.
I have not seen this claimed elsewhere - I very much doubt that it is true.
Cloudman - you can get the full transcript from the bbc site, but the below is the key bit of the Horizon programme as it relates to vapour trails or contrails as they are known. It suggests that contrails are continually reflecting huge amounts of solar energy and that we would notice a sudden jump in surface temp if all planes were grounded tomorrow as happened in the US after Sept 11. Given the proportion of CO2 which is man-made, and the proportion of man-made CO2 which is released by planes, it seems to me that, on balance they had better stay flying about up there.
DR DAVID TRAVIS: As we began to look at the climate data and the evidence began to grow I got more and more excited. The actual results were much larger than I expected. So here we see for the 3 days preceding September 11th a slightly negative value of temperature range with lots of contrails as normal. Then we have this sudden spike right here of the 3 day period. This reflects lack of clouds, lack of contrails, warmer days cooler nights, exactly what we expected but even larger than what we expected. So what this indicates is that during this 3 day period we had a sudden drop in Global Dimming contributed from airplanes.
NARRATOR: During the grounding the temperature range jumped by over a degree Celsius. Travis had never seen anything like it before.
DR DAVID TRAVIS: This was the largest temperature swing of this magnitude in the last thirty years.
Cloudman: You post above is confusing, so I’ll break it into pieces.
Cloudman: ‘While the saturation vapour density’
ME: This means relative humidity. If you did mean relative humidity then this is the ratio between how much water vapour exists in the air, and how much water vapour can exist in the air given the temperature of the air. It is usually expressed as a percentage. 100% humidity means the air has as much water vapour as it can have. There are lots of pages if you Google for relative humidity. Here’s two: http://www.usatoday.com/weather/wrelhum.htm http://www.bbc.co.uk/weather/features/understanding/humidity.shtml
ME: You meant the absolute humidity (probably)
Cloudman: ‘is indeed a strong function of temperature’
ME: I’m afraid it’s wholly dependent upon the atmosphere’s temperature. To refer back the Ice Age example I used above. Due to the cold there was very little WV in the atmosphere, only AFTER the temperature rose was the amount of WV able to rise as well.
Here’s the generally accepted definition: Absolute Humidity: Measurement of atmospheric humidity. Absolute humidity is the mass of water vapour in a given volume of air (this measurement is not influenced by the mass of the air). Normally expressed in grams of water vapour per cubic meter of atmosphere AT A SPECIFIC TEMPERATURE. http://www.physicalgeography.net/physgeoglos/a.html
Cloudman: ‘ that changes in other factors that affect the evaporation process’
ME: Your talking about the known hydrological cycle (see links in post above and also the para. near end of this post.). BUT the total amount of water vapour the atmosphere can hold is dependent on the temperature of the atmosphere. See above.
Cloudman: ‘(such as vegetation) and precipitation processes (such as CCN) are not also critical in determining the degree to which water vapour acts as a greenhouse gas.’ The concentration of water vapour in the atmosphere depends only on the temperature. It is not dependent on the amount of water available.
ME: The degree by which water vapour acts as a GHG is down to its molecular structure, how it interacts with infrared and has nothing at all to do vegetation etc. Cloud condensation nuclei (CNN) simply speed up the process of forming raindrops. They’re (cnn) aerosols (particulate matter) and not WV. It’s a separate issue, prob. best left to a separate discussion.
Cloudman: ‘Those that assert that water vapour is only a feedback process are ignoring the possibility of changes in these other factors (accidentally, or deliberately by human activity or otherwise).’
ME: A point at which I agree with you in that that human activity can increase or decrease the amount of WV available to be released into the atmosphere. More water evaporates from irrigated fields for example. Deforestation reduces the amount of transpiration and so on. BUT the overall amount of WV the atmosphere can hold is dictated by it’s temperature. Everyone on planet earth could participate in a stream day where we released as much steam as possible (kettles etc) into the atmosphere. It would very quickly condense and fall back to earth. The concentration of water vapour in the atmosphere depends only on the temperature. It is not dependent on the amount of water available.
Orfeus: Amount of CO2 released by humans: Well Water Vapour in the atmosphere fluctuates between 2– 4%, Carbon Dioxide (CO2) accounts for only 0.0001%. Yet they help keep Earth habitable. So a small disruption in the carbon cycle could make a big difference. Carbon Cycle: http://www.physicalgeography.net/fundamentals/9r.html http://earthobservatory.nasa.gov/Library/CarbonCycle/ http://library.thinkquest.org/11226/why.htm Nature used to cycle this and keep the amount in balance, now it doesn’t (CO2 concentrations are rising) because we are a new player in the cycle. It creates an atmospheric imbalance. Big deal? We’ll find out one way or another.
(such as vegetation) and precipitation processes (such as CCN) are not also critical in determining the degree to which water vapour acts as a greenhouse gas.’
This is just not true. Perhaps you should bear in mind that, for the purposes of global warming, "substantial" amounts to an effect of the order 1 Watt/sq. m - a very small shift in the greenhouse effect of water vapour.
Originally posted by Shefftim: For all the romanticised talk about Frost Fairs on a frozen Thames, Hubert Lamb and other historians also found that the Thames froze in 923 & 998.It froze for seven weeks in 1061 and was also completely frozen over during the severe winters of 1149/50, 1204/05, 1269/70 and 1281/82, 1309/10, 1407/08, 1409/10 (this time for 14 weeks), 1434/35, early 1506, 1513/14, 1516/17 and 1536/37. That’s throughout the entire Medieval Warm Period, however you wish to date its start and finish. Ice was reported on both the Bospherous and Nile in 829 and again in 1010/11.
If we’re looking at reduced sun spot activity causing cold periods then the correlation isn’t perfect. To take the Little Ice Age as an example: North eastern America’s coldest period of the past Millennium was the 19th century. Western Europe and China’s coldest period was in the 17th. In Tibet it was the 16th. In north-western America it was the 15th. In Western Greenland it was the 14th. Western North America had both its highest and lowest peaks of temperatures (of the 1000 – 1900 period) in the same century. The 15th. So not the perfect fall and rise in temperature that the program tries to paint and difficult to explain just using the cosmic rays hypothesis.
On Cosmic Rays and cloud formation: Different clouds formed at different altitudes have different properties. High altitude clouds reflect solar energy; low altitude clouds can help retain heat. Sorting out exactly what effect they have is going to be difficult, will take decades and * cough * climate models. All they can claim to have detected so far is a 3% difference between solar maximum and minimum. Wooo.
It’s also worth noting that the Danish Space centre isn’t the only centre with a hypothesis about cosmic rays; a pity the other, rival, hypothesis weren’t also given airtime.
We’re going to enter into a major solar minimum period in the next year or two so we’ll have a chance to see what effect it really has. Even so it’ll take decades to arrive at evidence as to their effect, one way or another. Those with longer memories know that sunspot/solar cycle theories have been proposed many times in the past, only to wither for lack of evidence.
As for Ice Ages and the observation that rises in CO2 follow rises in temperature; you really need to explain the causes of Ice Ages (Milankovitch cycles) to understand why and how they end. Of course tap isn’t turned to release CO2 into the atmosphere to initiate temperature rises. Just as it wasn’t turned off to lower temperatures as the ice age developed. As the Solar System and Earth move into new positions in the cycle the Earth begins to warm; this starts the release of CO2, this acts as both forcing and feedback thus increasing temperature rise. That’s why CO2 lags the temperature rise.
Water vapour and warming. Firstly the amount varies in the atmosphere (The amount of cloud cover varies for example.) Water vapour is a feedback, not a cause (forcing) of warming. The absolute (not relative) humidity of the atmosphere varies by place, time & altitude, but it’s a stable balance. Absolute humidity means the atmosphere can only hold an absolute ammount at any one time. It can’t therfore increase and raise temperatures on its own. It has to be preceeded by a temperature rise. Sorry guys, but it’s the laws of thermodynamics. Add more Water Vapour to the atmosphere and it won’t stay there, it quickly falls as rain/snow. No effect on temperature. The air’s capacity to hold vapour (absolute humidity) is limited but increases as the air warms, roughly doubling for each temperature increase of 10°C. CO2 increase = Forcing. Water Vapour + temperature increase = Feedback.
Those who try to deny that CO2 or methane, CH4, plays any part in climate are in danger of denying the basic known physics behind the role of the greenhouse effect. Find out about the interaction between triatomic gas molecules in the atmosphere and electromagnetic energy (Google it if you haven’t a textbook) before dismissing it out of hand. The greenhouse effect is based on solid physics, and it’s possible to demonstrate these properties in a lab.
Yes yes your point is?
All you are pointing out is climate variability. The Roman warm period, dark ages cooling, medieval warm period and little ice are fact. Thet were not uniformly cool or warm however.
As for clouds and solar rays, well we can't model them so 3% may have a large effect. Do you know? Come on you may get a Npbel prize lol.
If you had a Scientific background you would undertand that the greenhouse effect for CO2 is not linear. About all of the forcing effect for CO2 has been used up now. Good job we have an alternative theory to fall back on.
