June 26, 2021

A One-Hundred Year Heat Wave Event Comes Into Focus

 Update at 1PM Sunday.  I will talk not only about the records but something else...the amazing temperature drop late Monday...one for the record books.

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As we get closer to the big heat event, powerful new forecasting tools are becoming available.  Tools that provide a higher resolution and more nuanced view of the extreme heatwave event that is about to happen.

One such tool is ultra-high resolution numerical weather prediction models.  My group at the University of Washington runs the highest-resolution operational weather prediction system in the region, with a grid spacing of 1.3 km.  High enough resolution to get many of the local water bodies approximately correct, as well as the impacts of our regional terrain features.

Let me show you the surface air temperatures predicted today through Monday...all shown at 5 PM. 

Today, Portland and the lower Columbia Basin surges above 100F and Seattle rises into the upper 90s. The kind of conditions we typically experience once or twice each summer.


Sunday afternoon is a much warmer story.  Portland is above 104-108 and the central Puget Sound away from the water is above 100F.


What about humidity?  Will the air be so moist that evaporation on your skin won't be effective?  The answer is no.   

Here is the predicted relative humidity at the same time (5 PM Sunday):  most of the region will have relative humidity below 30%.  Sweating or wetting your skin will provide substantial cooling.  Very good.


And then there is Monday, a day that will be the warmest in the past century for portions of western Washington.  

Just madness. If you are right on Puget Sound temperatures will be tolerable (80s), but go inland a few miles and temperatures will zoom above 104F.  Go inland a bit more,  temperatures will be above 110F.  I have provided a zoomed-in view for better viewing below.   I never expected to see such temperatures in my lifetime.

Eastside communities like Bellevue, Redmond, and Woodinville will be hit much harder than Seattle, Tacoma, and Everett.




Another powerful tool is high-resolution ensembles of many forecasts, which allow us to see the uncertainty in the forecasts.   

Here is the University of Washington high-resolution ensemble prediction for the temperature at Seattle Tacoma Airport, with the black line indicating the mean of all the forecasts (a good forecast in general).  Today (00/27) has the ensembles on the same page (the upper 90s).  More variations on Sunday, but nearly all above 100F (man about 104-105).  And on Monday the mean is around 110F, with a range of 100-115.   Yikes.


Now I have been somewhat fixated on high temperatures, but nighttime lows are also important because they greatly influence the quality of our sleep and ability to cool down our homes and apartments.  

The ensemble predictions above indicate a substantial increase in daily minimum temperatures, with temperatures on SundayNight/Monday morning only dropping to around 75F.

Wow...that is more than our typical highs this time of year (~72F).  It will be very hard to cool off before the super warm day on Monday.  We will be breaking major low-temperature records--the highest low temperature in history--at many stations.

The good news in all this?  Tuesday will be considerably cooler, but still way above normal.  More on that in my next blog.

When this is all over, I plan to do a detailed examination of this event in the context of global warming.  
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The New Edition of My Book:  The Weather of the Pacific Northwest Will be Available in August

The book includes new chapters on the meteorology of Northwest wildfires and the weather of British Columbia, and the rest of the book is greatly enhanced.  It is available for pre-order on Amazon.

57 comments:

  1. Thanks Cliff- in your post-mortem can you discuss the range of extremes we have seen this month relative to global warming. Several extremely wet (some of the highest June rainfall totals if I recall correctly) systems followed by all time record heat. Random variability or GW jiggling the swings?

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    1. It is not just here.
      https://www.nytimes.com/2021/07/17/world/europe/siberia-fires.html?action=click&module=Spotlight&pgtype=Homepage

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  2. Is this an isolated summer or what we need to get used to?

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    1. I was wondering that as well. Is this an isolated event or is this going to happen several times this summer

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    2. As the author points out 98% of this is a weather event, if you like, you can conclude that the last 2% is long term temperature variability, of which some part is attributable to being AGW.

      So no, this is NOT "the new normal". Just like the 107F in Portland in 1942 did not become the "the new normal".

      That is just unscientific misdirection from climate zealots with an agenda, like Gavin Schmitt, for example.

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    3. Except it is a worldwide phenomenon. Cliff may know local weather, but he is no climatologist.
      https://www.nytimes.com/2021/07/17/world/europe/siberia-fires.html?action=click&module=Spotlight&pgtype=Homepage

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  3. Can't wait for the new book!

    One thing that I noticed: The barometric pressure isn't as high as I imagined. I remember getting a reading mid winter 2014 (Dec 30) over 1040 hPa on my weather station. I'm reading about 1015 now.

    Is it the position and size of the high pressure that is important and less the pressure reading?

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  4. I grew up in South Texas, but this is absolutely bonkers. In my hometown, it is currently cooler than it is here. I've seen you mention before that global warming plays a very small part in heat waves like this because you say there's only a one to two degree temperature increase where we are. I'm curious as to what the ocean temperature raising has to do with systems like this forming. Interested to hear what you have to say after all this is over. Thanks for the update.

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  5. "Any extreme event can have both ultimate and proximate causes. The proximate cause could be a frontal system, a jet stream meander, a hurricane etc. which are not unique. But this all takes place within the climatology, which as we know, is changing.
    Cliff Mass' claim is based on a naive accounting of the proximate and ultimate causes. He takes the weather-related anomaly (large) and compares it to climatological anomaly (smaller) and concludes that the climate change fraction gets smaller if the weather anomaly grows.

    But this leads to a logical paradox. Take a situation where climate change now means that we can experience an extreme that could effectively never* happen under the previous climate [how near we are to this point is not relevant for the argument].

    *a v. low probability
    Mass would claim that this situation has less of climate change attribution than a more common event, even though it would never have happened without climate change. That is absurd.

    Instead it is much more coherent (and practical) to judge attribution based on thresholds. What is likelihood of exceeding, say, 105°F under the previous climate (P) and the new situation (N)? The fractional attribution to climate change is then (N-P)/N.

    So if P=0 (the extreme was never going to happen before), the attribution to climate change is 100%. If the odds of an event have doubled, then climate change is 50% responsible etc. This is far more intuitive and more closely aligned with impacts which are often threshold-based" - Gavin Schmidt, Climatologist and head of NASA's Goddard institute

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    1. Gavin….your approach is not rigorous and logically inconsistent. Specifically, your use of thresholds is problematic. Keep in mind that all thresholds are arbitrary. But let me show you why your approach does not work.

      Consider a situation in which you set a threshold of 35F above normal. Natural variability produces an anomaly of 34.9F. Global warming produces an additional warming of .1 degree, so your threshold is reached. In your world, you would ascribe the event (reaching the threshold) to global warming. Does not make sense.

      The only reasonable and rigorous approach is to consider the anomaly from climatology and to ask: what portion of the anomaly is natural variability and what portion is from anthropogenic forcing/ This avoids the non-rigorous threshold approach.

      And clearly, nearly all of this heat wave is due to natural variability. Global warming has warmed the maximum in the Northwest 1-2F. Let’s say 2F. The predicted anomaly is roughly 35F. There is no evidence of any non-linearities or feedbacks connected with GW that is revving this particular event up. So the bottom line is that roughly 33/35 or approximately 94% of this event is due to natural variability, 6% from GW.

      This is a good example of the golden rule of climate attribution: the greater the anomaly from climatology, the greater the proportion is from natural variability. I am sure you agree this makes a lot of sense.

      Consistent with my analysis is the fact the there is no trend in the number of records in max temperature for Washington State, something you would expect if GW was significant. Eventually, as GW increases I would expect a trend for more high temp records…. Give me a call if you want to discuss or need further clarifications…cliff

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    2. I'd still like to see a list of all major cold, rain, heat, etc records broken in the past 10 or so years. It seems like we are inching toward more extremes in most categories.

      It also seems like we are breaking these records in higher numbers than ever before. I.E. How many high temp/warm and rain records have we broken in the past 5 years vs the 5 years before that...and the 5 years before that? Are we seeing an increase in record breaking weather events?

      And if so....why? And is this number of record breaking events increasing in rapidly increasing in frequency based on historic data (for example: If we get 10 record breaking events in the last 1 year, but only had 8 the year before that, and 6 the year before that...), are we seeing trending data like that?

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    3. Gavin Schmidt has made a career out of obfuscating climate science. He can always contrive some model that explains global warming, and often the models are so convoluted that they are hard to falsify, which gives Gavin the false perception of being the sole expert.

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    4. Tempest in a tea cup. I know everyone is worried about climate change. But just try to fathom just how long this blue globe has been circling the sun. It is quite a long time. In my opinion we are just getting started. We have much to learn but we should not panic.

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    5. Cliff, it looks like that probability BS from Gav was just a quotation, not Gav himself posting here, but thanks for showing what a crock of concocted lies it is.

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    6. "the golden rule of climate attribution: the greater the anomaly from climatology, the greater the proportion is from natural variability. I am sure you agree this makes a lot of sense."

      I don't agree that it makes any sense. I agree that natural variability is likely a much bigger factor than climatology in the past few days' temperatures, but I don't see how your statement follows at all. What am I missing?

      "there is no trend in the number of records in max temperature for Washington State, something you would expect if GW was significant"

      Not necessarily. As you know, records cover only a relatively short period, rarely more than 100-150 years. So if the climate were not changing at all, statistically you would expect the number of record-setting days to decline each year as the number of data points to beat (in either direction) increased. This decline would be significant between, say, the 1950s when you and I were born, and today, when there are about twice as many data points to beat. So if we continue to break records at a constant rate, that suggests that climate is indeed changing. My understanding is that we're actually breaking heat records at an increasing rate -- the past 7 years have been the 7 hottest for the overall planet in history -- but there are many types of records and I have not studied this in detail.

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  6. Already broke 100 at SeaTac.

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  7. Hi Cliff, what are your thought about how our mountains such as Mt Rainier will respond during this extreme event? With temperatures at the summit > freezing (50+ degrees) for several days combined with intense solar radiation is it possible that there is another glacial outburst event? The southern glaciers such as the South Tahoma/Nisqually have historically released large volumes of ice in previous years that have severely damaged park infrastructure. I was observing the South Tahoma recently and noted that it was much more crevassed than usual and there isnt much of it left.

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    1. Seconded. @NWSSeattle warns of melting snowpack causing glacier instability (i.e., crevasses opening, snow bridges failing)and difficult stream crossings.

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  8. Just a question: could you please unpack the science behind your statement that the more extreme the weather event, the less it stems from global heating due to climate change? This is intriguing.

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    1. I wonder how global heating or cooling affects temperature extremes. Is 2 degrees change in average temp directly proportional to 2 degrees change in max or min? Or does 2 degrees up in average equate to 4 degrees up, and 2 degrees cooling equate to 4 degrees extreme low or something like that?
      Is the earth's yearly temperature variation bigger when it is at it's hottest, or during an ice age?

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    2. You are asking whether overall changes affect daily max, min, or both. I wonder about that, too. I would add a related question: Do overall changes affect hotter than average days, cooler than average days, or both? For example, does a 2 degree average increase typically mean that all days (max, min, or both, as per your question) are hotter, or are heat waves >2 degrees hotter while cold waves are similar to before? Or are heat waves about the same while cold waves are >2 degrees hotter? Or something else?

      I imagine the answer might vary by place and season.

      We tend to notice high temperatures during heat waves most clearly, and we've seen data suggesting those are increasing in many places. But I'm curious how the science of climate change relates to these possible alternatives.

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  9. Maybe the Seattle Times isn't so far off the mark when they refer to this as a heat dome. Darn hot on both sides of the Cascades, and already hotter than predicted for today.

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  10. UW Atmospheric sciences rooftop just registered 99F, putting it above all except the highest two models. "Upper 90s" indeed.

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    1. And those humidities in the 30s? I’m seeing 40% in Seattle, 48%-52% on the eastside. BIG difference.

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  11. Oops, make that 100F at UW Atmospheric Sciences rooftop.

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  12. Can confirm: it's hot right now -_-

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  13. It is not the temperature that will "kill" us. It is the humidity.

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    1. 8:30am this morning it was 75f and about 70% humidity in auburn. Right now at 7:24pm it's 97f and 31% humidity. Quite a drop in humidity throughout the day (was actually in the mid 20% humidity just an hour ago...it's rising a bit again).

      I'm curious what the cause is for the change and what will occur tomorrow/monday. From the blog it seems like we should have a low humidity the next 48 hours at least.

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    2. You are pointing out why they don’t use relative humidity in general and talk about dew point. What you are seeing is the temperature moving away from the dew point as it rises and since the warmer air could hold more moisture the relative humidity drops. As the temps cool and approach the dew point the relative humidity rises.

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    3. Scott,

      I recommend that you follow Ventusky, this website has a superb range of weather tools.
      The only possible issue is the the URL time stamp for Ventusky is UTC/GTM so I have tried to account for the -7 hours difference for your local time in Auburn.
      26Jun21 15:00UTC https://www.ventusky.com/?p=47.14;-122.90;6&l=humidity&t=20210626/1500
      27Jun21 03:00UTC https://www.ventusky.com/?p=47.14;-122.90;6&l=humidity&t=20210627/0300

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  14. RH is an important metric for moisture, but if you want to talk health and safety (and cooling efficiency) - wetbulb temperature is a fair mor appropriate number as it relates to evaprotive cooling potential. I understand its not as well understood by the public and it doesnt have as easy a definition as RH

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  15. I measured humidity in the upper 60% range here in Kingston not far from the water. There is a tradeoff between heat and humidity depending upon how close to the water one is it seems. Currently its around 76F according to the Skunk Bay Webcam and the humidity there is 64%. It was 85% before sunrise.

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  16. Great stuff, and a big thanks for the clarity of your information.

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  17. You conclude, "The good news in all this? Tuesday will be considerably cooler, but still way above normal". But that is not true everywhere...east of the Cascades the NWS forecast predicts temperatures will be warmer Tuesday, and stay at 110 or higher through the end of the week. East of the Cascades, Monday is just the beginning of this insanity.

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  18. You've said in an earlier blog that only about two degrees of this heat wave is human caused. What is causing the other eight degrees? I don't ever remember it getting over 100 in the last forty years.

    Also, the last time the earth experienced the amount of warming that is projected now, most of life went extinct.

    If, as you say, the most dramatic effects of GW are 100 years away, what difference does it make?

    It's still very bad.

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    Replies
    1. Seattle hit 102 in 2009. Olympia had 104 in 1981. What caused that?

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  19. Cliff, this is interesting stuff and I much appreciate your fair minded approach to all this.

    What would be interesting is to see how well these computer predictions shape up against recorded temperatures in a few days when this hot spell has passed. I assume as part of the work you are doing on the forecasts you are doing some retrospective accuracy assessments. It is always hard to do this since once the date is past weather forecasts disappear and never seem to be accessible to the public for validation or assessment of reliability.

    Please come back on Tuesday and tell us how it went. It already looks like the OMG event on Monday is fading and Sunday (today) may be the hottest day in this event.

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  20. "When this is all over, I plan to do a detailed examination of this event in the context of global warming."

    I hope that you mention that the origin of this airmass is from northern Canada and that this is a Ferrel Cell meridional airflow weather pattern event.

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    1. Cliff, maybe in a future blog you could go over Hadley, Ferrell, and Polar Cells and how they influence global convection currents. Would love to hear your explanation! Bests.

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    2. Maybe even a major widespread lowland Ferrel Cell meridional airflow weather pattern event.

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  21. The most recent ecmwf and gfs ensemble runs don't even agree for Sunday, 12hr out. The European is considerably cooler, being only in the 90s, whereas the gfs is well above 100. Both have above 100 for Monday.

    Yesterday the gfs won. 8(

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  22. Great blog, but would you please consider elaborating, perhaps in a future post, WHY we had such high dew points/humidity? I know with thermal troughs, the air sinks and then heats/dries in the process. I was expecting humidity to be 20-25% yesterday.

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  23. AA.... the answer is clear. Warm air can pick up more moisture and the air trajectories have been over relatively warm, moist land. Thus, higher dew points. But NOTHING compared to back east...cliff

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  24. Cliff: the NWS has(as of 3:35 this morning) pushed their transition day back to WEDNESDAY (6/30), with Tuesday now forecast @109F!!! Will this event become “Son-of-Smoke-Forecast II”!!!!????

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    1. Where are you seeing that?

      Tuesday - Sunny, with a high near 90. South southwest wind around 9 mph.

      https://forecast.weather.gov/MapClick.php?CityName=Seattle&state=WA&site=SEW&textField1=47.6218&textField2=-122.35&e=1#.YNimX04TF0s

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    2. I just reloaded the page and NWS had switched back to Monday 109F & Tuesday 90F....the original gave me horrible flashbacks to “Smoke-a-pa-looza” when the poor meteorologists had to keep re-jiggling their forecasts of when the smoke would ultimately depart the Seattle Metro area!!

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    3. I'm also seeing the forecast for Tuesday to be high 80s/low 90s. Still hot, but so much nicer than in the 100s!

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  25. Here's my question: is this heat wave so anomalous that we should conclude that it cannot simply be explained in the context of historical meteorology for this region? If the temperature tops 110 on Monday that would seem to be so far outside any conditions previously recorded that it raises some red flags.

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    1. The heat wave is an intersection of several low probability meteorological events. I think we overuse the word "anomaly." An anomaly is an occurrence that is an outlier or unexpected. This heat wave is no more unexpected than the individual meteorological events that produced it. Low probability does not mean anomalous.

      If all four of your best friends made lasagna on the exact same night (without any communication between them), is that an anomaly, or just a low probability event? Correct, that is a low probability event.

      If one of those friends made used lettuce instead of lasagna noodles to make their dish, is that a low probability event or an anomaly? Correct, it is an anomaly.

      So back to this heat wave. Yes, it's a record setter. But who said that the Earth's climate can't set records?

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    2. Totally disagree: "Anomalous: deviating from what is standard, normal, or expected." By definition this is an anomalous weather event.

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    3. No. This heat wave is expected with low probability. Heat waves happen.

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    4. Even the NWS forecaster agrees. The forecast wording from 320 AM includes: "Anomalously strong ridging combined with east winds in the lower
      levels will continue to work in tandem to provide historically hot
      temperatures over W WA"

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    5. Sure, and I am making the claim that the word is overused.

      Did the forecaster mean "unexpected strong ridging..."? I don't think so.

      The expectation that there are never heat waves is nonsense.

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  26. Thank you, Cliff, for educating us on this subject. I feel as though it does your profession proud. And I hope that you're able to instill your clarity into the students you teach.

    On a lighter note, I was thinking: Typically (at least historically) we'd all be joking about "June Gloom" right now and awaiting the sun and warmth's return after the rain on the 4th of July fireworks displays. So what do we call this event: June Doom? I'm "sweltering in place" in my a/c-less apartment.

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  27. SeaTac has matched the 06/27 record of 92F with the 10:53 observation.

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  28. Spokane's all time record of 108 was set in... 1881. Not 1928, not 1961 as a recent article falsely stated.

    It was 108 in BOTH July and August.

    Sources:
    https://wiki2.org/en/Spokane,_Washington

    The false claim: https://inlandnorthwestweather.blogspot.com/2021/

    There are probably better sources on 1881 weather. But I gave my sources.

    The PERCEPTION of heat wave behavior among contemporary Americans is very broken. The urgency in which global warming advocates are looking to demonstrate their belief system is unscientific, because the data says that these heat waves have came before the rise in industrial CO2. It's all zealotry and little objective thinking and an unwillingness to completely access the available data.

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    1. Two volcanic events had far-reaching effects in the 1800s.

      The explosion of Mt. Tambora in 1815 caused the famed 1816 "year without a summer" in Europe and North America. Tens of thousands of people (and likely more) died of famine. The explosion of Krakatoa in 1883 caused a series of exceptionally cold and fatal winters in North America, especially around the Great Lakes and in the West.

      The AGW proponents rely on historical ignorance.

      Delete

Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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