# Is global warming falsifiable? **URL:** \ **Category:** Great Debates\ **Created:** [May 6, 2014, 7:30am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786 "2014-05-06T07:30:04Z")\ **Posts on this page:** 20\ **Page:** 19
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 6:40pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/361 "2014-10-14T18:40:05Z")
> [@FXMastermind](#): > > > [@](#): > > > > No one but you is making any claim that recent mid-latitude winter temperatures are anything more than circulation perturbations. Judah Cohen certainly isn’t, despite your propensity for incorrectly citing him all over the place. > > That sort of smug claim is hilarious, it tells me the author hasn’t actually read the papers, something that is obvious when you actually do read. Here is what I said: > [@wolfpup](#): > > Indeed Cohen questions whether there is any systemic cause at all underlying recent mid-latitude winter trends, but if there are, he suggests three possible mechanisms for it: **changes in storm tracks, the effects of Arctic amplification on the polar jet stream, or the possible effects of Rossby waves in weakening the polar vortex.** You will of course immediately be able to cite where Cohen contradicts this, since you’ve read the papers. Or, if you can’t, I presume you will be happy to retract your remark and apologize. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 6:56pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/362 "2014-10-14T18:56:46Z")
> [@wolfpup](#): > > At no point does Cohen suggest that this invalidates the fundamental principles of AGW Once more. What do you mean when you say “the fundamental principles of AGW”. Please provide scientific evidence if you make something up. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 7:03pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/363 "2014-10-14T19:03:30Z")
[This link](https://www.google.com/search?q=%22the+fundamental+principles+of+AGW%22) should explain why it’s important for you to explain what you mean. Can you see why there is no way to even know what you are saying? > [@wolfpup](#): > > You are once again very confused – on several different levels. It is confusing when somebody uses strange terms, and will not define them. Or worse, just ignores the issue. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 7:20pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/364 "2014-10-14T19:20:02Z")
No, we’re not going to carry on and ignore your insult. I said that I read the latest Cohen paper, and I provided an accurate summary of its main points. I don’t appreciate your insulting implication that I am a liar who didn’t read it and doesn’t know what it says. Are you going to provide a cite for your claim [as I requested here](http://boards.straightdope.com/sdmb/showpost.php?p=17815059&postcount=361), or are you going to retract your remark? ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 7:35pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/365 "2014-10-14T19:35:03Z")
To belabor the point, which is pretty east to see. So unless we can know with certainty, with a scientific understanding, what is meant by “the fundamental principles of AGW”, it’s impossible to resolve this. And this is where the OP has nailed it. In science, a question like this, “what exactly do you mean by your statement?” is followed by a lengthy scientific explanation, with sources and documentation, if it’s scientific, this is easy to do. Anything else, and you know you are up against some woo woo or religious beliefs, something, but not science. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 7:40pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/366 "2014-10-14T19:40:55Z")
The fundamental issue isn’t _Cohen et al,_ which is why asking what the fundamentals of AGW are is so important. > [@FXMastermind](#): > > [http://seattletimes.com/html/localnews/2001910590\_northpole23m.html](http://seattletimes.com/html/localnews/2001910590_northpole23m.html) > In 2004 This is the circumpolar vortex we heard so much about in the last 7 months in the US. > > Warmer means stronger winds, a stronger vortex, something that will be important in a little while. > [http://www.washingtonpost.com/wp-dyn/content/article/2011/02/07/AR2011020703936.html](http://www.washingtonpost.com/wp-dyn/content/article/2011/02/07/AR2011020703936.html) > In 2011 Now, just 5 years later, after the first two shockingly cold winters, the warming suddenly might be causing it to be colder. > > At which point your thinking person might start to wonder. Warming is thought to cause the vortex to be stronger, making it warmer, because the the cold air is bottled up. But then one might wonder, how the exact opposite can be true? > Now warming causes the vortex to “break down”, letting the cold air out, making it colder. The key issue is about the theory of course. As I pointed out, using direct quotes from _Cohen et al_, theory does not predict colder winters, a point that is ignored over and over again. If it were 1999, and anyone was arguing global warming is going to cause more extreme cold, more snow, worse winters for large areas of the NH, they woul sound cray. But now we see time and time again, efforts to say the much colder winters are because of global warming. You can deny this all you want, it won’t change what has happened. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [October 14, 2014, 8:21pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/367 "2014-10-14T20:21:00Z")
> [@FXMastermind](#): > > As I pointed out, using direct quotes from _Cohen et al_, theory does not predict colder winters, a point that is ignored over and over again. It is not ignored at all. The rebuttal of your “point” has been explained to you over and over again, and you keep failing to understand it. To wit: 1. Just because your cherrypicked subset of data corresponding to “colder winters” is not directly predicted as a specific consequence of AGW theory does not mean that the theory of AGW, or any part of it, is wrong. _It may be that these data don’t even have any systemic cause whatsoever, but just reflect unpredictable circulation perturbations._ 2. There is nothing even in your cherrypicked subset of data that actually **contradicts** any part of the theory of AGW. > [@FXMastermind](#): > > If it were 1999, and anyone was arguing global warming is going to cause more extreme cold, more snow, worse winters for large areas of the NH, they woul sound cray. Only to people like you who _naively assume that a valid “falsifiable” climate theory must be totally deterministic_ and predict every possible outcome as a specific consequence of one or more of its model features. In fact, **guess who _was_ pointing out way back in 1999 that global warming might impact wintertime extratropical Northern Hemisphere climate variability, which is what sometimes leads to “more extreme cold, more snow, worse winters for large areas of the NH”?** Why, **none other than Judah Cohen himself!** (Cohen and D. Entekhabi, 1999: Eurasian snow cover variability and Northern Hemisphere climate predictability. _Geophys. Res. Lett._, 26, 345-348) Did serious scientists back in 1999 think that Cohen and Entekhabi sounded “cray” for suggesting such an idea? On the contrary, they published the suggestion in a peer-reviewed research journal. So much for your ill-informed contention. To sum up, **FXMastermind** , _your naive idea of constantly consistent predictability of all possible observed phenomena simply is not the way that the science of dynamical systems (such as climate) works._ Some dynamical-systems phenomena are _intrinsically_ unpredictable, while the prediction of others may be theoretically attainable but very difficult to achieve in practice. Still other phenomena may be initially difficult to predict but become more predictable with minor modifications to the models. _These facts do not automatically invalidate scientific theories about dynamical systems._ ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 8:40pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/368 "2014-10-14T20:40:32Z")
No, the issue is Cohen. You made it the issue. I want you to either support what you said or retract it. It’s not complicated. Once again: I said that Cohen “suggests three possible mechanisms for recent mid-latitude winter trends: changes in storm tracks, the effects of Arctic amplification on the polar jet stream, or the possible effects of Rossby waves in weakening the polar vortex.” These are circulation system effects. Your statement “that sort of smug claim is hilarious, it tells me the author hasn’t actually read the papers, something that is obvious when you actually do read.” Again, please cite why it tells you that I am a liar and haven’t read the papers, and why it’s so “obvious” to you that Cohen is saying something else. What is he saying that contradicts me? And where is he saying it? Provide the cite. Why would you want to miss an opportunity to prove me wrong? ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 14, 2014, 8:56pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/369 "2014-10-14T20:56:11Z")
> [@FXMastermind](#): > > To belabor the point, which is pretty east to see. > > So unless we can know with certainty, with a scientific understanding, what is meant by “the fundamental principles of AGW”, it’s impossible to resolve this. > > And this is where the OP has nailed it. In science, a question like this, “what exactly do you mean by your statement?” is followed by a lengthy scientific explanation, with sources and documentation, if it’s scientific, this is easy to do. > > Anything else, and you know you are up against some woo woo or religious beliefs, something, but not science. Again, deal with posts #2 and #4, or just admit that you had no idea that this is science that can indeed be falsified. And you are confusing the true failure of past efforts at falsification with the idea that it can not be falsified, that is silly. The fact that is that theories that got into their modern form by Plass remained the best explanation for the observed current warming increase. That is one big reason that has convinced most scientists about the problem we are facing. As for your really silly falsification effort here no one has taken it seriously in the organizations that collect the data that is abused by you. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 9:04pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/370 "2014-10-14T21:04:53Z")
> [@Kimstu](#): > > It is not ignored at all. The rebuttal of your “point” has been explained to you over and over again, and you keep failing to understand it. To wit: > > 1. Just because your cherrypicked subset of data corresponding to “colder winters” is not directly predicted as a specific consequence of AGW theory does not mean that the theory of AGW, or any part of it, is wrong. _It may be that these data don’t even have any systemic cause whatsoever, but just reflect unpredictable circulation perturbations._ > > 2. There is nothing even in your cherrypicked subset of data that actually **contradicts** any part of the theory of AGW. > Only to people like you who _naively assume that a valid “falsifiable” climate theory must be totally deterministic_ and predict every possible outcome as a specific consequence of one or more of its model features. > > In fact, **guess who _was_ pointing out way back in 1999 that global warming might impact wintertime extratropical Northern Hemisphere climate variability, which is what sometimes leads to “more extreme cold, more snow, worse winters for large areas of the NH”?** > > Why, **none other than Judah Cohen himself!** (Cohen and D. Entekhabi, 1999: Eurasian snow cover variability and Northern Hemisphere climate predictability. _Geophys. Res. Lett._, 26, 345-348) > > Did serious scientists back in 1999 think that Cohen and Entekhabi sounded “cray” for suggesting such an idea? On the contrary, they published the suggestion in a peer-reviewed research journal. So much for your ill-informed contention. > To sum up, **FXMastermind** , _your naive idea of constantly consistent predictability of all possible observed phenomena simply is not the way that the science of dynamical systems (such as climate) works._ > > Some dynamical-systems phenomena are _intrinsically_ unpredictable, while the prediction of others may be theoretically attainable but very difficult to achieve in practice. Still other phenomena may be initially difficult to predict but become more predictable with minor modifications to the models. _These facts do not automatically invalidate scientific theories about dynamical systems._ All very good points, **Kimstu**. Another point I’d make is that the most fundamental climate drivers are defined in terms of energy balance principles, because what changes the earth’s thermal energy balance is more fundamentally important than the temporal factors like circulation systems that just move heat around. Circulation systems are important to understand because they’re the determinants of regional climates and weather extremes, but they’re fundamentally driven by changes in the energy balance. **FX** has yet to grasp the basic idea that global warming theory at its most fundamental is an energy balance theory, and circulation system changes are its second-order consequence whose magnitude and extent is determined by the strength of the underlying forcings. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 9:24pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/371 "2014-10-14T21:24:28Z")
> [@Kimstu](#): > > In fact, \*\*guess who _was_ pointing out way back in 1999 that global warming might impact wintertime extratropical Northern Hemisphere climate variability, which is what sometimes leads to “more extreme cold, more snow, worse winters for large areas of the NH”? Now why would you make that up? [Here’s the full paper](http://www.agu.org/pubs/sample_articles/cr/2002GL016341/2002GL016341.pdf), and anyone can read it, it’s about how snow cover might be forcing the interannual variability, it says nothing about predicting colder winters, much less from changes in greenhouse forcings (AGW theory) And once again, you and wolfpup avoid answering direct questions about the topic at hand, the theory of global warming. Why is that? Do you think a red herring will really stop the debate? ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 9:27pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/372 "2014-10-14T21:27:38Z")
> [@Kimstu](#): > > 1. Just because your cherrypicked subset of data corresponding to “colder winters” is not directly predicted as a specific consequence of AGW theory does not mean that the theory of AGW, or any part of it, is wrong. There you go again, you keep using a term, but you refuse to define it, explain what you mean, or provide a single source to support you definition. But then, you didn’t provide any definition. So you want to keep debating a topic, but you don’t know what the subject of the topic means. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 10:03pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/373 "2014-10-14T22:03:50Z")
> [@FXMastermind](#): > > Now why would you make that up? > > [Here’s the full paper](http://www.agu.org/pubs/sample_articles/cr/2002GL016341/2002GL016341.pdf), and anyone can read it, it’s about how snow cover might be forcing the interannual variability, it says nothing about predicting colder winters, much less from changes in greenhouse forcings (AGW theory) Too bad that’s not the paper he was referring to. The actual paper is from 1999 [J. Cohen and D. Entekhabi, GRL: February, 1999], and concludes thus: > [@](#): > > A more expansive Siberian high results in higher pressures across northern Siberia, northern North America, the high latitude North Atlantic and Northern Europe, and displaces the Icelandic low south and west. With more frequent intrusions of the Siberian high into eastern North America and Western Europe, colder surface temperatures are observed [Hurtell,1995]. More equatorward Arctic air in the North Atlantic sector forces the latitudinal temperature gradient and, thus, the tropospheric Atlantic jet, south. With a more southerly jet, the Atlantic storm track is shifted south, bringing drier conditions to Northern Europe and wetter conditions to Southern Europe and the Mediterranean. In conclusion, we put forth that cooling associated with early-season Eurasian snow cover and the Siberian high are dominant forces in the climate variability of the NH. That’s OK, you can apologize for accusing **Kimstu** of “making things up” at the same time that you [apologize to me for being a liar](http://boards.straightdope.com/sdmb/showpost.php?p=17815509&postcount=368). I’m still waiting, and now we’re both waiting: please cite why Cohen’s latest paper that I talked about tells you that I am a liar and that haven’t read it, and why it’s so “obvious” to you that Cohen is saying something else. What is he saying that contradicts me? And where is he saying it? Provide the cite. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 14, 2014, 10:16pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/374 "2014-10-14T22:16:00Z")
Argh! Just want to be clear that that previous linked phrase should have read “…and apologize to me for _implying that I am a liar_”! I’m not making the accusation, I’m reflecting one that was made about me, and phrased it badly. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [October 14, 2014, 10:20pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/375 "2014-10-14T22:20:52Z")
> [@FXMastermind](#): > > [Here’s the full paper](http://www.agu.org/pubs/sample_articles/cr/2002GL016341/2002GL016341.pdf), and anyone can read it, it’s about how snow cover might be forcing the interannual variability, it says nothing about predicting colder winters, much less from changes in greenhouse forcings (AGW theory) For pity’s sake, **FXMastermind** , you can’t even manage to link to the correct research article, even when I provide you with its complete bibliographic citation. The link you’ve got there is a 2003 paper by Saito and Cohen, **not** the 1999 paper of Cohen and Entekhabi that I was talking about. (ETA: As **wolfpup** pointed out above.) (If you had actually read the paper you linked to, you might have noticed that it cites the paper I was talking about in its references section. Seeing a paper cited in the references of another paper should tip you off that they’re two different publications.) No clearer illustration could be desired of the fact that for the most part _you simply do not know what you are talking about_ when it comes to climate science research. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 10:29pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/376 "2014-10-14T22:29:03Z")
> [@wolfpup](#): > > Argh! Just want to be clear that that previous linked phrase should have read “…and apologize to me for _implying that I am a liar_”! I’m not making the accusation, I’m reflecting one that was made about me, and phrased it badly. Well imagine how I feel! I meant to link to the paper ([here is the correct link](http://onlinelibrary.wiley.com/doi/10.1029/1998GL900321/pdf)) and linked to the wrong one. The horror, the horror. My point still stands. They did not predict colder NH winters, much less due to greenhouse forcing. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 10:31pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/377 "2014-10-14T22:31:02Z")
> [@wolfpup](#): > > Too bad that’s not the paper he was referring to. The actual paper is from 1999 [J. Cohen and D. Entekhabi, GRL: February, 1999], and concludes thus: It’s very unscientific to quote a source and not link to it. Sure I had the wrong link in my buffer and made a mistake, but I provided two sources, rather than trying to tell you what they say, you can read them yourself. It’s petty to not provide a source. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 10:36pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/378 "2014-10-14T22:36:38Z")
Expanding on the newest herring, red or otherwise, in the early 1950s arctic stations were proposed as a way of predicting winter storms, since it was believed they originated in certain areas, where no weather data at all was being recorded. Funding and the harsh conditions were both obstacles to research and synoptic meteorology at the time. Same for the far northern oceans, where almost no data was ever gathered. When you see some 100 year record of most arctic areas, you can be sure it’s not actual data, just computer guessing. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [October 14, 2014, 11:00pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/379 "2014-10-14T23:00:01Z")
> [@FXMastermind](#): > > It’s very unscientific to quote a source and not link to it. […] > > It’s petty to not provide a source. There’s nothing “unscientific” or “petty” about giving a correct bibliographic citation and letting the reader look up the original text of the source on their own, if they want to. That’s exactly what most scientific research publications do when referring to sources, and that’s what I did in my post. Admittedly, it makes online discussion easier when all the sources discussed are right at hand, so thank you for the link to the 1999 paper that I was talking about. And what I said about that paper was perfectly true. It does suggest that global warming might impact wintertime extratropical Northern Hemisphere climate variability, because it proposes climate-linked Eurasian snow cover as a driver of winter variability. And one of the results of increased winter variability is that a spate of cold winters in particular regions is less surprising. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 14, 2014, 11:15pm UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/380 "2014-10-14T23:15:33Z")
Returning to the eternal dispute once more. > [@FXMastermind](#): > > > [@wolfpup](#): > > > > At elevated levels of CO2 and temperature, many feedbacks are intensified – in particular, those feedbacks associated with albedo changes from reduced polar ice cover > > There’s that key prediction/assumption from the enhanced greenhouse effect theory once more. It is assumed that increasing CO2 will lead to increased warming at the poles, which will lead to less ice and snow, which will lead to increased warming, which will lead to less ice and snow, leading to more warming. > > This is supposed to show up the most in winter, and is a sign of greenhouse gas increase causing warming. It’s a key assumption of the theory. It’s why NH winter warming is so important for the theory, and this feedback is a key mechanism of why the enhanced greenhouse effect is supposed to lead to drastic warming. > [@Kimstu](#): > > And one of the results of increased winter variability is that a spate of cold winters in particular regions is less surprising. But that is not what _Cohen et al 2014_ is theorizing about. Recall the earlier scientific musings. [Greenhouse Gas Influence on Northern Hemisphere Winter Climate Trends](http://www.giss.nasa.gov/research/briefs/shindell_04/) By Drew Shindell, Gavin Schmidt and Ron Miller — May 1999 > [@](#): > > Global surface temperature has risen during the past century, but it is still uncertain whether warming in particular regions can be directly attributed to human activities. The largest warming has occurred over Northern Hemisphere land masses during winter, where temperatures have risen by several degrees during the 20th century. (In comparison, the global, annual average temperature has increased by only half a degree). These dramatic local changes are related to recent changes in atmospheric wind patterns. Hence, it is more likely that they arise from a redistribution of heat around the globe, rather than purely from an enhanced “greenhouse effect”, whereby heat is trapped near Earth’s surface by pollutants such as CO2. **The question is whether these recent changes in the winds are merely part of a long term cycle or whether they are linked to the increasing greenhouse effect**. This was during the period [where winters were warming](http://data.giss.nasa.gov/cgi-bin/gistemp/nmaps.cgi?sat=4&sst=3&type=trends&mean_gen=1203&year1=1980&year2=1998&base1=1951&base2=1980&radius=250&pol=rob), and it was global warming as the cause. Which brings us to the essence again. If winters had continued the trend, and were mild, with less snow, it would be because of global warming. Nobody would argue against this. It’s what the theory predicted, and the models all predict warming winters for the NH. If the winters were still warm, it would be global warming. But since it’s so obvious that it can no longer be denied, now global warming is being put forth as the cause of colder winters. _Cohen et al_ was brought up for two reasons. The first was to show that there is a cooling trend, something denied like cray at first. The second was to show that there is a theory, and it does not predict colder winters, nor explain them. [Previous page](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786.md?page=18) [Next page](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786.md?page=20)