Please follow the following link and pdf attachment for the answer.

http://www.ucsusa.org/global_warming/science_and_impacts/science/global-warming-faq.html

Please check this link also for the said query.

http://phys.org/news/2014-07-vapor-global-amplifier.html

please check this pdf file

Thanks all

I tried hard to understand  this topic and I put so much time on that, BUT in my opinion there are so many doubt and unknown thing about this topic

and

unfortunately there is a competition between  policy and science or maybe scientist are not really free to say their statements.....

please look at the attachment file....

The main reason is the increased concentration of CO2 supplemented with N2O and CH4 - all 3 caused by human activities.

These gasses absorbe infrared radiation and thus decreases the loss of heat from the lower atmosphere from the pre-industrial steady state.

http://www.ucsusa.org/assets/images/gw/global-climate-drivers.PNG

I am not going to attempt an answer of my own but I ere refer you to a very nice explanation by Ray Weymann that looks at the issue quite broadly:

https://vimeo.com/34692993

Dear colleagues,

You can search for long-lived climate pollutants (LLCPs), i.e. CO2 and short-lived climate pollutants (SLCPs), i.e. black carbon (BC).

All the best

@Ken, "My figure": Natural variations such as solar radiation are included. They are just small compared to the effect of gasses absorbing infrared rays. 

Dear Henrik 

As you know the absorption range of CO2 is about 15 micrometer and CO2 is not sensitive to other EM waves.

@Nasibollah Doustimotlagh: I am not sure if there was a point to your comment, but at least there are two other absorption peaks (2.7 µm and 4.3 µm). They are quite important as it is just in the middle of an area there water doesn't absorb.

The life is a cycle and every think is with in this cycle .....  Plants undergo continuous depletions which are the main sink for CO2 and dust accumulation in air.  CO2 is a bipolar gas molecules tend to detain the heat irradiated from long wave irradiation commencing from red 660 micron, Dust particles also participate in heat accumulation through intercepting with solar light. CO2 and dust substantially increased lately, owing to cities expansions on the account of agricultural area, chopping trees, fires and fuel composition. CO2 homeostasis between air and water, particularly seas is over saturated. Therefore, global warms occurred which facilitate drought, strong storms and high wind speed.        

 The values of infrared (IR) radiations that come from Earth are limited and are no infinity 

 Greenhouse gasses just absorbed special spectral of electromagnetic waves. So because of the limited values of electromagnetic waves that come from Earth and limitation of absorption of greenhouse gasses, the greenhouse effect of greenhouse gasses should be limited. In other words, after absorbing of all the IR waves that come from Earth by greenhouse gasses in the atmosphere, there are no IR waves to cause greenhouse effect.  It means that “two things that cause greenhouse effect are greenhouse gasses and IR waves in absorption spectrum of these gasses, so if in spite of lack of IR waves, greenhouse gasses increase, then the absence of the greenhouse effect is natural.

@Nasibollah Doustimotlagh: I cannot see the point in your statements. Could you read a text book chapter on the greenhouse effect or just the Wikipedia articles.

If the greenhouse effect didn't exist Earth would be very cold at night. 

https://en.wikipedia.org/wiki/Greenhouse_gas

https://en.wikipedia.org/wiki/Greenhouse_effect

@Henrik Rasmus Andersen:

The point in my statement is that the greenhouse effect of CO2 is limited.....who said that there is no greenhouse effect??? I believe in greenhouse effect BUT I said that greenhouse effect is limited and it is not infinity...... you can see the attachment file for more information

@Henrik Rasmus Andersen:

could you tell me, what is the mechanism or physics of heating via greenhouse effect??

2 factors we need for heating: 1) GHGs 2) IR waves

On CO2: CO2 currently contributes most to the greenhouse effect following the effect of water and clouds (See table in linked Wiki article). This cannot be termed a limited contribution.

I could guess that you want to discuss that the absorption of heat by CO2 is already substantial at the wavelengths there CO2 absorbs strongly and therefore the greenhouse effect increase with adding more CO2 is likely less than linear. I do not disagree this is possible but I don't want to try. I also claim that it doesn't change that the main reason for global warming is the increase in the atmospheric concentration of CO2, CH4 and N2O caused by human activities.

I will not explain you how greenhouse gasses works as this is textbook material and you can easily get the overview from the Wiki article I linked.

Regarding the paper/manuscript you attached to your comment. It lacks a source and it appears not to be peer reviewed from a recognised journal.

https://en.wikipedia.org/wiki/Greenhouse_gas

CO2: I am sure that if one can understand the mechanism, physics and chemistry of greenhouse effect, he will be convinced that the reason of global warming is not CO2. 

Then you disagree with me and most of the researchers in the climate field about the effect of CO2. I think that most people that work with climate have understood the greenhouse effect and it appears that the role of CO2 is reasonably well agreed on.

I think you should write a paper about your disagreement with most other and once it is peer reviewed I look forward to reading it.

I think I get it and I just disagree: CO2 increase has contributed to the global warming.  

Ken: that's easy to answer, you can see it in increasing ocean acidity and rising sea levels. What is causing that?

Kenneth It seems I always miss the point. It must be very frustrating. I think we forgot to isotope label the oil and coal as we burned it the last 100 y.

Would you take as proof that humans have burned more than the equivalent amount of oil and coal and +99 % of scientists believe that the reaction of organic carbon with oxygen at high temperatures yield CO2 and some energy?

Henrik: in fact isotopic analysis shows, both in ice cores and tree rings, that ratios changed in the past century or so, which can only be due to fossil fuel burning.

http://www.realclimate.org/index.php/archives/2004/12/how-do-we-know-that-recent-cosub2sub-increases-are-due-to-human-activities-updated/

Fine. I hope you don't change your mind about this.

The subject is not if global warming occurs or if it might not be harmfull. (Denmark looks forward to more space once we get rid of the ice we are storing on Greenland).

More CO2 means more energy is retained in the atmosphere therefore it contributes to global warming. It was textbook stuff already 20 years ago that CO2 already absorbs most IR radiation at and around its peak absorptions wavelengths and therefore adding CO2 doesn't increase the greenhouse effect linearly to the concentration increase. As this is well known it is considered in the evaluations of the gasses relative importance which we can see in the relatively higher impact per molecule of N2O and CH4.

This is a very interesting discussion and I am reluctant to join in but it seems to me it might be helpful to draw back a bit and gain perspective. At the moment there is no smoking gun. The evidence of human-induced climate change (aka "global warming") is circumstantial but accumulative. The standard symptoms currently being bantied about include the retreat of mountain glaciers, the continuing disappearance of artic sea ice, the increasing annual global average temperature, etc. No single one of these is sufficient "proof" of an effect of specifically human-induced climate change only when taken together do they constitute an internally consistent argument as long, however, as no bias is introduced by leaving out evidence to the contrary. "Global warming" may be just a passing fad but is it not prudent to perform a cost-benefit analysis of the possible impacts if as Pogo said "We have met the enemy and he is us"

Dr. Towe: Thank you for the compilation, which to my mind, reinforces that we need always to step back to maintain a proper perspective and avoid jumping to conclusions based on questionable evidence. Let's rephrase the question: What, if any, global effects might we expect by the burning of fossil fuels before and during the Industrial Revolution? Well, there always have been forrest and other fires of natural origin and now we add the fires of human origin (plus, of course autombile exhaust etc.) and ask does this make a difference? If so, is the difference "signifcant" - that is can we show that there is an impact beyond the natural variability in the non-human component. If so we have a case, if no we stll have a premise. 

The general problem is bigger than the icebergs. See all the glaciers around the world.Ex: the glacer U/psala in the Andes. Is nea 5km upwards from 1930 to now

I have seen  the glacier  in 1972 and 2002. It was near 1 km less ice and the front is not more lineal, but curved towards one side. More data in my Conference paper ( now in a book): Cambio Ambiental y Climático Global.

Ken: Good Heavens, such a long tortuous cherry-picked piece on icebergs.

A graph shows the situation much more clearly.

Animals, particularly sheep and cattle, produce large amounts of methane. Some fertilisers also release nitrous oxide, which is another greenhouse gas.

It is difficult for me to discern in this stimulating discussion who is promoting a position and who is playing "devil's advocate". But with regard to human-induced wildfires that is another human-induced production of CO2 in the atmosphere but, of course, after the fire there is regrowth that becomes a a sink for CO2 but maybe not as a big a sink as the original mature forrest. So now we have a differential effect that could be positive or negative wrt atmospheric CO2 - negative if in fact forrest regrowth consumes more CO2 than the original mature forrest. The details are niggling and I maintain that getting lost in them is to lose sight of the forrest for the trees. "Global warming" requires a "global" point of view.

And I spelled "forest"  with two r's. One should not comment on RG before one has their morning coffee!

Oh Ken why drag up Danish documents from the 1920s, it's just more cherry picking. You seem to be deliberately ignoring the main body of evidence.

Kenneth: Your comment 3 days ago about Copenhagen temperature in the 1930es compared to the current. Did you pick a single cherry around 1935 to support that conclusion?

Can we stay on the subject which I believe is the reason for global warming. Not if there might be locations there heating isn't statistically proven or if it might be harmless.

http://www.dmi.dk/index.php?eID=tx_cms_showpic&file=uploads%2Fpics%2Ft_dk_k_1873_2015_eng.PNG&md5=6e524c2b9ad85aebd5330b7c514f308118295d39¶meters%5B0%5D=YTo0OntzOjU6IndpZHRoIjtzOjQ6IjgwMG0iO3M6NjoiaGVpZ2h0IjtzOjQ6IjYw¶meters%5B1%5D=MG0iO3M6NzoiYm9keVRhZyI7czo0MToiPGJvZHkgc3R5bGU9Im1hcmdpbjowOyBi¶meters%5B2%5D=YWNrZ3JvdW5kOiNmZmY7Ij4iO3M6NDoid3JhcCI7czozNzoiPGEgaHJlZj0iamF2¶meters%5B3%5D=YXNjcmlwdDpjbG9zZSgpOyI%2BIHwgPC9hPiI7fQ%3D%3D

No cherry? You compare a 10 year period with a 30 year period. The latter you label current but it ended 15 year ago. Would you take a look at my graph and tell us if you claim we could compare to the last 30 year (1985-2015) and get your conclusion.

Corrections is not an issue here. We have the same weather stations with real thermometers for the entire period.

There are no corrections. We measure 2m above surface in a standardised box that holds the thermometer! So can you explain your method choice and not jump to other issues. So you don't forget: Your method was to compare a 10 year to a 30 year period and omit the latest 15 years from current.

Central Copenhagen is several degrees above the surrounding landscapes temperature on calm days both winter and summer and that is why the graph I gave was for all of the European part of Denmark (not Greenland). The graph shows most of the increase is in the latest 20 years so where is the "pause"?

If somebody told you a fairytale about El Nino you should be old enough to know that there are people that like to get mentioned in the press to boost their funding.

Kenneth. So you don't forget. The issue to answer is the first few lines of my comment about the comparison of the temperature in the 1930es to the last 30 years.

Kenneth. To continue the criticism of the cherry picking. Two days ago the subject was the arctic sea ice and your hand picked reports on sea ice from the 1920es. You demanded to see "Arctic sea ice volume for the first 50 years of the 20th century?" Yesterday Peter Baker gave a graph that shows ice cower in the Arctic continuously since 1870. The graph clearly show there was no decrease in ice amounts in the 1920 so it would again appear that the effect is created by picking single data points. 

http://www.climatechange2013.org/images/figures/WGI_AR5_Fig4-3.jpg

Long time since I checked what was going on re. Global Warming. The first thing I did was to read Ashkan's comment: The current radiative forcing levels are clearly outside of the natural cycle range.  This statement woke me up. How can you be sure that radiative forcing is outside natural bounds? Furthermore, what do you know about radiative forcings?

So far I have not seen any proper explanation on how solar induced warming actually functions via radiative processes. A continuous debate has been going about whether radiative forcing can increase the temperature of a surface (land or water) if the radiation is emitted from a cooler surface???

We do know that the Sun heats Earth's surface. The near surface air warms up through conduction and convection and above all as latent heat from water evaporated  from the sea/ocean surfaces by the Sun. Condensation of water vapour at higher altitudes increases the air temperature and amplifies convection.

I would also like to question the validity of the high role given the Milankovitch cycles as inducing ice ages, etc.

The debate on Copenhagen's average T between Ken and Henrik is really off the topic when discussing  global warming. Local temperatyre variations are prone to so many variables that they have no relevance in the current issue. In fact all discussion on averages are of interest only when discussing very local climates (e.g. urban climate).

I should also add that ice extent in the Arctic is also dependent on a variety of factors. the problem today is that the majority of especially young climatologists are in a hurry to publish headline science for the benefit of media instead of really producing sound science based on scrutiny of data and facts.

Kenneth - No answer. You just move on to other discussions.

So perhaps the sea ice wasn't almost gone from the Arctic Seas in the 1920'es and Copenhagen/Denmark wasn't much hotter than currently in the 1930'es if you cannot pick in the data. 

I am on the perphery of this discussion but permit me to offer a "naive scientist's" view of the issue:

Dwight, thanks for your simplified downscaling of a very complex issue. When asked, my answer to the causes of current slight global warming is just the result of natural variability, but alas, I agree with Kenneth that there are far too many of us spoiling the environment and off course we are emitting CO2, but so what. People tend to forget that water vapour is a much more potent greenhouse gas. Furthermore H2O is a very interesting compound, because its workings in nature are very complex (thermodynamic phase changes) and especially regarding the atmosphere.

Now to your graph, what does it show? The alleged near surface global average temperature from 1850 to almost the present.

Does the graph show - increasing global heat content - absolutely NOT. It is just an average numerical value calculated from a very heterogeneous huge mass of individual thermometer readings. The data covers over a century and a half and should mimic our globe's real temperature including land and oceans. I wonder how reliable this data could be?

Because of the highly irregular data, meteorologists had to resort to very questionable methods to manipulate (cohere) the temperature readings. In my view the data does not allow the conclusions made by the IPCC.

In reality I find that the Roman Warm period, the poor weather during the Dark Ages followed by the Medieval Warm period, and again deteriorating climate during the Little Ice Age, etc. are sufficient to cast a shadow on the so-called manmade warming of today. As long as nobody can produce reliable views on what has driven our climates through the past centuries and millennia, I find the IPCC to be a very questionable source of views on future events.

These rather eccentric views will have to do for now, because I am due for surgery coming morning, but I will return in a very near future.

There were other similar waves of hot climate. The last was 600 000 years ago.

The difference is that it takes 1000 years to get the maximun anthe decrease to "normal". The problem is that similar amount we have got in 90-100 years.. See my note on glaciers. In 1930 Father D`Agostini, the Patagonia mountains take a  lot of snapshots (very nice indeed). the comparison with actual state of glaciers is relevant.

In my city the last frost in winter was in the 60`s (2 days). We "feel" the change along the last 60 years. 

Kenneth, with a new right knee joint life feels good again thanks to modern painkillers.

Luis, I don't understand what your point is. You are talking about winter - do you mean austral winter or global winter (Dec, Jan, Feb.)? Is Your city Ushuaia? I have had the impression that South America and also Patagonia has experienced the same temperature fluctuations as Europe, that is the cold Dark Ages, Warm Medieval Period, the Little Ice Age, and finally the present warming spell; in other words the natural millennial cycles.

Dear all

please look at these important webs:

http://www.petitionproject.org/index.php

http://www.petitionproject.org/gw_article/GWReview_OISM150.pdf

Are you agree with "global warming petition project ( http://www.petitionproject.org/purpose_of_petition.php ) "? 

I think it is more reasonable than IPCC..... how do you think?

http://www.petitionproject.org/signers_by_last_name.php?run=all

Boris:

My city is around Buenos Aires. . I refer to the visible changes in climate in  the last 70 years. Respect to the icbergs. The presence more to the south depends on the size of the iceberg, the greater, arerives more to the souith and perhaps because the climate change makes greater sized ruptures of the Groenland ice.

To the effect of water vapour: look at th old grahic of water vapour pressure vs. temperature.  It has a retroeffect. . Higher temp.- higher pressure.-higher quantityu of water vapour-highet temperature-higher climate change.. But the origin is in the concentration of CO2 un air ( an antropic cause)

It seems the denial people have most time for RG discussions.

Claiming a conspiracy to alter the large data series and picking single events to claim that the climate is not changing.

We should not forget that the vast majority of people who work with climate and environment are convinced that humans are close to changing the climate and it is not generally good for humanity.

http://www.aaas.org/sites/default/files/06282016.pdf

Henrik

i agree with you! This global-warming/human-induced climate-change issue continues on and on without meaningful resolution. People are suspicious of science and even when the aim is to help, science and scientists emerge as evil and evil-doers, respectively. Pick up any advanced text on quantum mechanics and open to any page and look at all those mathematical symbols - clearly it must the heirglyphics of some evil spirit! People resent the "I know more than you" attitude that pervades so many scientists and prevents them from communicating with the "common folk". "Here's a broom, go sweep the floor!" "Me, sweep the floor? I've got a PhD!" "Oh. I'm sorry - I forgot! Here let me show you how!"

About sea level rise:   In the River Plate mouth it has been of 20 cm in the last 80 years

That gives us higher level in the coastal plains . Some one needs more data?

Kenneth, please I want to be clear on your point of view. It seems clear to me that there is strong evidence that at this moment a phenomenon of "globar warming" is taking place. It also seems clear to me that the abundance of greenhouse gases is increasing. These are two observational data sets. The theory of the greenhouse effect, I gelieve also is well-established. So do we not expect that increasing greenhouse gas abundance will be accompanied by increasing temperature?The problem, as I see it, is jumping to the unsubstantiated albeit plausible conclusion that the increasing greenhouse gas abundance is human induced. I fully agree that cherry-picking isolated events, such Sandy, is not evidence of anything but that hurricanes happen!

I don't want to be obnoxious but you didn't answer my question: Setting aside any speculation of cause, do you think, with the data/evidence at hand, the globe is passing through a warming phase of magnitude that exceeds that expected to be produced by "natural climate variation"?

Global warming could also be due to solar flares, beyond the control of anyone on earth - it is more of global warning for mankind to get together and cool down the differences.

deforestation & raising of co2 & cfc

Solar flares.......? The measure of solar irradiance since 1980 show no changes.

Manmade  cfc

Fits well. Before 1920 there was also no signs of global warming.

CFC began in the 40s..Nobody kows then,  that they may have an effect in the air . 

"The 1920s and 1930s were among the warmest years on record. " Kenneth, timeline problem again. Did the 1920s and 1930s occur after 1920?

Perhaps the heat in those decades was something you read in a more than 50 years old newspaper clip that you refuse to give the source for!

https://www.ncdc.noaa.gov/cag/time-series/global/globe/land_ocean/ytd/12/1880-2017

Kenneth, you started out with 1920. The method to make CFCs was only introduced around 1928 and used commercially after WWII so no CFC in the atmosphere back then as well as it isn't true that "The 1920s and 1930s were among the warmest years on record".

Notice how the graph shows every year the latest 30 years have been hotter than every year in the 1920s and 1930s.