Monday, March 19, 2012

Is This Global Warming?

Boston experienced its warmest winter ever and the past couple of weeks have been way warmer than usual. By this Thursday we are supposed to hit a record-shattering 86 F, weather that belongs in July or August. My students, my neighbors, and it seems everyone is asking "is this global warming?"

Miniature Tulips

The short answer would have to be "no." If you check out today's New York Times weather map you will see a simple explanation for this weather. On one side of the continent the jet stream has dipped way south, providing the West with unusual coolness and rain, even into Phoenix. Meanwhile, the pattern of the jet stream in the midwest and east coast is experiencing the "flipside" of the circulation coin, traveling far to our north.

Growing Storm on the Prairie

So, simply put, the flow dynamics of the jet stream, while unusual, are immediately responsible for this weather.

Another part of the story...in Boston we boast that the month of March lasts here for ninety days. What do we mean by that? Again the simple answer is that the Atlantic Ocean, a huge body of water that takes relatively long to warm up in the spring, is right at our front door. Ocean breezes come inland through June, taking even the warmest days down into the 50s. Why isn't that happening now? Simply because the southwesterly flow of air, which is linked to the flow of the Jet Stream, is strong enough to keep an onshore breeze from occurring. The result? We stay warm.

The Great Boston Smokeout

A third part of the story is explained by our weather last week. A "back door cold front" bathed the city in cool ocean air carried on a breeze from the northeast. This wasn't a nor'easter because there was no precipitation involved with it. It was simply part of the dynamic of an air current circulating around a high pressure area to our north and east. The weather last week was more like San Francisco than Boston, consistently cool, oceany, and never warming up even in full sunlight.

Structure and Function

So, it all these patterns point to a "no" for global warming, why do scientists insist that the phenomenon is real?

For an answer to this question all you have to do is go to the superb "Earth Observatory" sponsored by NASA. All kinds of interactive maps will show you that there have been long-term warming trends, not necessarily on land, not necessarily in the temperate zones where most people would notice it, but in the Arctic Ocean and waters adjacent to it.

Scientists have demonstrated without question that the planet is warming by using simple methods of observation. That doesn't mean we notice it on a day to day basis. Certainly if we compare last winter's notable cold and abundant precipitation with this year's winter, we see a big difference. But that is not the evidence for global warming.

Metermaid's Dilemma

Tiger in the Snow

Snow Slide

Global warming and global climate change are planet-wide phenomena that are measured not day to day, but over decades, and not in a single locality like Boston, but all over the Earth, including our oceans.

Wake

Enjoy the nice weather but think hard about how your own activities can calm the trend to global warming. Walk, ride a bike, or take public transportation instead of driving. Turn down the heat and skip the AC. Eat less meat. Try to travel less by air.

69 comments:

  1. I would have totally blamed this weather on global warming if it weren't for this article. Fascinating. Thanks!

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  2. I think this is the reason why many people find global warming to be a joke. One week we have warm temperatures and everyone assumes global warming, then the next its freezing again, and it seems as though those who preached about this warming lose their credibility. Global warming is most certainly not a joke, and I think it is important that people understand that we are not going to suddenly see the effects of global warming, but regardless, we must accept it as a valid issue, and do what we can to prevent the problem from worsening.

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    1. Good point. I think we need to look at the "bigger picture," for example the data on the NASA site.

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  3. I couldn't help but think Global Warming was the culprit until I read this. It's interesting to put it in perspective. While we are experiencing incredible summer-like weather in March, at home in California over break I was cold! It was in the low 50's and rainy! I guess that would be an argument against Global Warming. No matter the cause, I definitely am grateful, seeing as last winter Boston had snow on April 1st! Clearly, we cannot count Global Warming out, but it is something we must understand is not happening over night.

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    1. Sorry you experienced that cold weather back home! We understand now that global phenomena like climate change are not necessarily observable in the short term (one season to the next).

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  4. I figured it was not global warming considering it was a steady incline of temperatures from last week. None of the weather is really extreme, but rather surprising, and the snow-less winter has happened multiple times in the New England area. However, it is very surprising to see weather like this so soon in the year especially temperature in the 80s where it belongs in the summer. It is important to understand that global warming is a problem though. Just because we are having nice weather it doesn't mean that the things we are doing to the Earth is not affecting the world. Plus global warming does not have to affect weather directly it could be that the water level in the Atlantic is rising, so different consequences result from global warming.

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    1. Right. There are lots of potential consequences of global warming. At the beginning of the semester we talked about the importance of predicting. With the data scientists are collecting, we are better able to predict the outcomes of global warming.

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  5. I think it is interesting how the jet stream is able to "flip" in a year and give a certain part of the country such extreme climate changes. Though many people think that this warm weather is an effect of global warming, it is also nice to think that this isn't all happening in a year and there might be another cause for the warmer temperatures.

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    1. Yes the jet stream often "flips" as you say and the result is unusual weather. This is one of the short-term weather patterns and not overall climate. (-:

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  6. I think it is very important for students to realize that climate change does not happen overnight, and in fact it is the little things adding up (like turning down our AC while a window is open...) that contribute to global warming. Thanks for the insightful information!

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    1. You're welcome! Thanks for your note!

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  7. I have always heard people blaming mild winters on global warming so it was great to hear your reasoning behind why a mild winter doesn't necessarily mean that.

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    1. Great. Now you have an argument you can use too! (-:

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  8. I agree with most of the posts above on that I also assumed that a mild winter and an earlier start to summer was due to global warming! Hearing about the weather in the West Coast being colder for the past few days than it has been here on the East Coast made me wonder how quickly global warming was affecting us. After reading your observations, I understood how this is not due to global warming, and was kind of shocked! But I'm glad I now have a better understanding of why we have this sudden warm weather (which is beautiful and no ones complaining). Although like you said this is just a short term weather pattern and not our overall climate, we should enjoy it while it lasts!

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    1. I totally agree. Let's enjoy this great weather. We do need to look at our patterns of consumption, travel, energy use, etc. in order to make decisions about how we can ameliorate global warming.

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  9. I was in northern California for Spring break and joked that the weather on the east and west coast had switched, now I know that that's actually what's happening! Very interesting and relevant post.

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  10. I also thought that the warm temperatures we have been experiencing were due to global warming. Last winter we had so much snow and the cold weather lasted so long that I assumed that the dramatic change this year did with global warming. It is interesting to know that the weather has a different cause behind it, which is the the jet stream on the west has gone more south so we are experiencing the "flipside" of that. I do think it is still important for us to keep global warming in mind and to do things that could will not add to the global warming already happening.

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    1. Thanks fir your note. Yes, there is plenty of evidence that the mean temperature of the planet is going up, as we studied using maps from NASA.

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  11. I really thought last year's harsh winter compared to this year's mild one had everything to do with global warming. It's extremely surprising and fascinating to find that it has very little to do with it! Maybe the reason why most of us are not panicked by global warming is because of how it gradually creeps up on us. We notice it over decades, not seasons, and this is alarming.

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    1. I think once we see sea levels rising (due in part to melting of the Greenland ice cap) it won't seem so gradual.

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  12. I honestly just assumed it was global warming that was causing this crazy weather. The difference between this winter and last year's is miraculous, therefore I was convinced that global warming was the problem. It's so interesting to learn that this awesome weather has nothing to do with it. I do not think the general public will begin to seriously worry about global warming until it hits them on an everyday basis. For example, if global warming began to effect the normal weather people would become much more worried and involved.

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    1. So Kevin do you think that the evidence on the NASA site is not persuasive?

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  13. I thought it was really interesting how the flow of the jet stream can affect the warm weather we have been having. Initially, I thought it definitely had to do with global warming. Its interesting though how we as humans don't think twice about the warm weather and just enjoy it instead of thinking how strange this is and what it means for our planet.

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    1. Well the anomalies in the jet stream don't affect things in the long run...they are part of daily weather patterns rather than climate.

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  14. With the high temperatures of this past school year I would absolutely have thought it was global warming. Although I did realize that this sort of thing takes time to measure and can not be proven in just one year. There has always been so much hype about global warming and what it might do to our planet. Most of the outcomes seem frightening to say the least. I feel more people need to be more aware of what to do to prevent it- like the things you mentioned at the end of this essay. If more people can see how doing things like that actually have an impact (and a big one) then maybe they will start doing more.

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    1. I was surprised to see how much carbon dioxide I added to the environment by flying. It absolutely outweighed all my conservation efforts, including never ever using a car, barely ever eating meat, never using AC, keeping my house cold in winter, etc.

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  15. Thank you for this piece! I had no idea that the warm weather we are experiencing is due to the flow dynamics of the jet stream. Just out of curiosity, what causes the change in the flow dynamics of the jet stream? As far as global warming is concerned, I think we all can say it is a serious issue that needs to be better addressed and more attention should be given to global warming. It is scary to think that global warming exists and I think we all need to take measures to combat it. I personally will try my hardest to conserve less electricity.

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    1. You're welcome.

      The reasons for changes in the jet stream are complex. But partly they have to do with "bulges" of cold air that form in the arctic. This season the cold air "bulged" southward over Europe and Asia, causing the jet stream to flow north of us. This is not the only reason but a major one.

      As far as conservation I was shocked to see how much carbon dioxide is added to the atmosphere by flying. One flight to the west coast totally outweighed all my conservation efforts all year including only riding a bike and never taking a car, keeping my house super cool, never ever using AC, hardly ever eating meat, etc. So it points to the fact that just by living "normal" lifestyles we are really adding a lot to global warming.

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  16. This is very interesting. My roomate was actually blaming the recent high temperatures on global warming and I probably would have too if I had not read this. So it's interesting to know that other factors come into play. Nevertheless, I think that global warming is a serious matter and that people really need to start paying attention to how they contribute to it.

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    1. You can show this piece to your roommate and see if it makes sense to her as a person who I assume is not taking a science course.

      I think in your country most people are not contributing significantly to global warming because they just don't use the resources we do here. But a single airplane trip home definitely adds an enormous amt of carbon dioxide to the atmosphere.

      My very limited plane travel totally outweighs all the conservation I do---no AC, no car, cold house in winter, barely ever eating meat. So, just by living "normal" North American lifestyles we ad a huge amount of carbon dioxide to the environment.

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  17. Thank you for sharing this! I found this really helpful because I thought the weather changes were 100% due to global warming. I'm from Florida, so last year's winter was horrible for me and I was not prepared for this winter to be so warm, especially not as warm as it has been this week.

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    1. You are welcome. Have people in Florida been trying to lower carbon emissions by 1) using solar power and 2) cutting down on the amount of AC used?

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  18. I hope the jet stream stays shifted like this and comes at the same time next year too.

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  19. This is cool, but I don't understand what makes the jet stream change? If the wind affects the jet stream then how is the wind affeted? I became a vegeterian after hearing so much information about animal rights from Humanities and about how cows and other live stock are producing too much methane. I want worms to help the enviornment. Where do I get these worms?

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    1. Hi Mandy. The jet stream is based on a number of factors like the rotation of the Earth and temperature differences between various parts of the globe. It is kind of like the ocean conveyer belt but it is a lot more changeable and it takes a much shorter time to circle the globe (days instead of years). One of the things that affects it are "bulges" of cold air that head south from the North Pole. They are called "Arctic Outbreaks." This year, the cold air bulged southward into Europe and Asia causing very cold temps there and relatively warm temps here in North America.

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  20. It's funny that you sent us this article now, because over break, we in Palo Alto had an unusual amount of rain, and the "unusual coolness" you write about. Someone said to me back home, "I heard this rain is all coming from Alaska!" and I didn't quite understand what she meant... but now I see the influence of the jetstream across the continent.

    I personally think that whenever we comment about this weather and attribute it to global warming, especially in a somewhat flippant or joking manner, it all seemingly lessens the magnitude of the issue. If discussions about global warming take place in a scientifically inaccurate fashion, doesn't that give "ammo" to the politicians/activists/skeptics in general who already firmly believe that we have no idea what we're talking about and that global warming is bogus?

    -Gunita Singh

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    1. So we need to understand that global warming is a long-term phenomenon that is observable in ways that are different from how weather is observable. For example, anomalous sea temps in the arctic over decades.

      The NASA website provides incontrovertible evidence of global warming and we only need to look at some of those maps to refute skeptics, etc.

      For me, teaching science is about helping students interpret the real world around them. Of course this is open to interpretation and creative thinking but there are certain bottom-line facts that speak for themselves. Global climate change is one of them.

      The rain was coming from Alaska in a way!

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  21. Like so many of my classmates, I also believed that global warming was to blame for the unusually high temperatures. However, I'm happy to hear that the cause for the warm weather was the shifting of the jet stream- good to know!

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    1. The jet stream shift is temporary but global warming is increasing. The only thing is that this is not a sign of it.

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  22. I think that experiencing severe changes in weather, and knowing that Boston weather is notorious for changing almost overnight, prevents us from seeing the bigger picture of climate change. It makes it feel as though it isn't really happening when we as individuals only observe it in such a small window of time. But we have to remember that, as you mentioned, looking at the larger trends across the globe over hundreds of years can tell us more than a single week in one specific city.

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    1. You make an excellent point. How do you think we can get your idea across to people, since by nature humans are kind of short-sighted?

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  23. I think that it is really interesting to note that jet streams are the causes of this recent warm weather. Although jet streams are discussed on weather segments, I feel that it is pretty natural for people to blame global warming for the unusual shifts in weather. In regards to the weather, I personally find myself thinking that experiences of warm weather during cold months are due to the phenomena of global warming. However, it is important to keep in mind of other aspects of weather that directly influences temperature. Likewise, it’s essential for people to note that global warming should be a total consideration of weather changes happening over the decades and worldwide. A random change of weather in one particular place for a limited period of time shouldn’t force us to think that global warming is truly at the forefront.

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    1. Well global warming is in the "forefront" if you consider long-term climate change and other dangers like rising sea levels (caused by ice melting at the poles and from glaciers elsewhere). It's also important to keep in mind that the great ocean conveyer belt can be altered because of decreased salinity in northern latitudes (because of so much melting ice). All of these factors are threatening the long-term sustainability of our ecosystems.

      So just because this warm spell is not an indication of global warming that doesn't mean that global warming is not real. (-:

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  24. I find this every interesting because even for myself I questioned the unusually warm weather we had in Massachusetts over the break and into this week. I know it is because of different warm and cold fronts that have been shifting, however I am still skeptical. How do we really know that this isn't just another sign that the environment is headed in a bad direction? I guess my understanding of global warming is still a little fuzzy.

    -Christina Fleury

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    1. Thanks for your note. At the beginning of the semester we studied some maps published by NASA that show a warming trend in the Northern Ocean. That warming trend happens to be the most significant long-range sign of global warming. And it provides rock-hard evidence that warming is occurring at the global level. However, we can't attribute this warm spring to global warming. Why not? One reason is that previous years in the 1920s and 1940s were much warmer in Boston. This was before much global warming had occurred.

      Boston (like most temperate, terrestrial environments) is changeable in regard to weather. So we can't take short-term phenomena at this small geographical perspective to explain global changes in climate.

      One thing you are right about---scientists predict that anomalous weather changes will become more frequent and more severe as the climate changes. So we can expect more heavy rain, more frequent drought, and more major changes in temperature as the climate continues to change.

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  25. This is so interesting that it's not global warming. It makes me wonder if this drastic weather change will effect the summer and even next winter?

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    1. That's an interesting question. The National Weather Service issues long-range forecasts that might be address your concern.

      http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/t.gif

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  26. You claim that this is merely a weather event so therefore can't be global warming. But as you say climate is measured over decades. It is the aggregate of weather over long periods of time. More warm events more often means that our globe is warmer. Climate is nothing more than the aggregate of weather. You cannot say that this warm weather is caused by global warming but instead you should say that this event adds to proof that the globe is warming. We are stuck in a reverse mindset of cause effect.

    Also, you should pay close attention to the arctic. A larger number of days without ice cover means that high pressure systems will develop (sea absorbs sun ice reflects) and alter jet streams across the northern hemisphere. I suggest reading Dr. Jeff Masters at the weather underground. He is one of the few people who elucidates the connection between weather and climate.

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    1. Thanks for your note. Your point on ice cover is super important and I teach exactly what you refer to. All of these things contribute to global warming/climate change. And of course, climate changes as a result of aggregate weather patterns over long periods of time.

      One of the things I've been stressing with my students is that we have to look deeper at scientific evidence in order to understand global warming. If someone claims that the warm weather in Boston this week = global warming it is just as logical to say that the cool weather in the West "disproves" global warming.

      That's why I focused so much this semester on discussing anomalous trends in the Northern Ocean. But it took this unusually hot weather to bring on a "teachable moment."

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  27. This was a very interesting article. Like many others, I would too jump to conclusion that the warm weather we are experiencing in Boston is due to global warming. However, after reading this it opened my eyes to what may be really occurring and how global warming is a long term phenomenon rather than a short and sudden change in weather like we are experiencing.
    Brittany Sebade

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  28. I assumed it as global warming too, but another professor in CGS told me that it's freezing in eastern Europe and those countries are getting a lot of snow. I was just really confused when I heard that, but this makes a lot more sense now.

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  29. I've always thought that this weather was due to global warming. But thanks to this article I now know the truth. Definitely a relief.

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  30. I assumed this increase in temperature was related to global warming too! That information about the jet-stream causing unusually cold weather in the west is very interesting. This article was very informative!

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  31. Although it's not global warming, I definitely think this wacky weather is really interesting and obviously worrisome. Thinking back to last year, i think that we had a huge amount of snow after decent weather the week before, it makes me wonder if the same thing can happen this year? Can the weather change from one extreme like 80 degree weather and go back to 40? I remember hearing on the news, a reporter posed the question of whether this is an indication that Boston's climate has changed? I personally dont agree with it because I feel like only a few instances isnt enough support to make such an assumption.

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  32. It really is weird to me how our planet works. I am not from the north so coming to Boston last year and experiencing the blisteringly cold winter was incredibly difficult. So when this year came around I was dreading another experience like that but now it seems hotter outside than it is back home. I'm glad to hear that it is not directly related to global warming, but it is worrying to me that weather patterns can change so drastically so quickly.

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  33. Professor, if you had not introduced this blog to the class I would have continued to blame this change in weather on global warming! So interesting! I love the winter and wish we had a bit more of it this year though!

    -Cibelle Levi

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  34. Sorry for such late comment but I believe that the constant unstable increase and decreased of temperature in Boston throughout this week is quite interesting. Ranging from the extreme warm temperature around mid 70s to low 80s, it is definitely quite relieving to hear that it is not a cause of global warming. If Jet streams are the main cause for the increase of climate temperatures, will it do any harm in the long run? This is what I am do not know and concern about....
    -Lena Wang

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  35. This was a very interesting article because I had no idea that this had to do with the jet stream rather than global warming. It really opened my eyes to realize how little I know about global warming and I am excited to stump people when trying to blame this on global warming. It is a very relieving fact that this isn't a more serious issue like global warming.

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  36. I find it interesting that although the majority of uninformed people would generally assume that the cause of this unusual weather is global warming, the actual reason is something unrelated to that matter. Although this particular weather change is not connected to global warming, I agree that this is a serious environmental issue that everyone should veer their attention toward. People tend to forget about the severe long-term impact that our way of living has on the earth and need to start being more aware of the importance of preventing future environmental harm.

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  37. It's funny that everyone blames unusual weather on global warming! I guess that it is good that the warm weather was caused by the flow of a jet stream, and not global warming! Regardless, I really enjoyed the nice weather that we experienced! What was the cause for the unusually warm winter we experienced this year?!

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  38. I have been blaming global warming this entire winter for the weather being so nice, well, actually thanking it. Thinking back to last winter in Boston where it felt like it snowed almost everyday and having lived in Boston my entire life, I never would have thought there could be a “winter” that had temperatures in the high 80s and I would be outside tanning. While I like this weather, I do miss winter a little bit. I am happy to know that global warming is not completely at fault for the warm trend, but everyone really needs to pay attention to what effect their activities can have on the environment.

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  39. Knowing global warming isn't the direct cause of this warmth phenomenon makes me extremely happy. It's great to know global warming isn't happening as quickly as people make it seem. However, I can't help but wonder if the unusual shift in the flow dynamics of the jet stream is a result of what humans are putting into the atmosphere.

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  40. It is extremely surprising to find out that global warming is not to blame, because it is now such a commonly accepted cause. It's interesting that so many people can accept the theory of global warming as true, when jet streams are actually to blame. This article makes me wonder what else is as misunderstood as this theory.

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  41. Wow! Global warning isn't to blame? I have been raised to curse the folks who don't recycle (and obviously I still think everyone should recycle and take care of the earth), but this makes me question everything I know, or think I know. It does make sense, though, that jet streams are the cause of the warm winter. I still believe that global warming is a serious issue, but now I will stop and think before I blame everything on the phenomenon. This is a very interesting blog that should make everyone stop and think about the causes of climate change.

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  42. It's surprising to discover that global warming may not be to blame. Based on what I know, I can not accurately say weather or jet streams are to blame or if global warming is to blame, but I will most definitely have to do more research to come to my own personal conclusion.

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  43. Last year my rhetoric professor gave us an article about the minority of scientists who don't believe in global warming (or at least don't fully agree). The article explained how these scientists were ostracized by their peers and how science was experiencing a 'tyranny of the majority' moment. Although I do believe in global warming, this article has convinced me that there are more factors involved in the global crisis then we like to think.

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