But it’s been cold and wet here, how is that possible?
There are several layers to that question; the explicit question of how it is possible, and the implicit assumption that it should not be happening. There is a third part that almost never comes up, the question of whether it actually has been cool and wet.
In looking at the question of cold in a warming world I will just quickly summarize what is well covered elsewhere and refer you to some resources. Then we can move on to aspects of the issue that I have not seen generally discussed for the average reader. Particularly I want to talk about the actual mechanics of how you get record cold temperatures in a hot world.
We all know that many climate change Deniers have a habit of seizing upon any “record cold day” or unseasonal cold spell as being evidence that climate change is not happening:
Dissecting the Denialosphere
and at least some media are only too happy to help perpetuate climate ignorance:
and the Media-ocrity
- Media enable denier spin 1: A (sort of) cold January doesn’t mean climate stopped warming
- Fox Trumpets Global Warming Denier Conference: ‘We Should Be Worried About Global Cooling’
- Nutty Fox (Gop) Mouthpieces Claim Cold Weather Snaps Mean Global Warming Is Not Real
- The Australian’s War on Science 32
The standard correct answers note that regardless of whether the climate trend is warming, cooling, or stable, you will still get short term fluctuations in weather. This means you get ups and downs from day to day, and from year to year.
In a warming trend that means every new record year will be followed by a number of cooler years before a new record is set.
Numerous factors will cause these fluctuations in temperature. Some examples are natural cycles like solar sunspots and ocean circulation, and semi-random events such as massive volcano eruptions.
Here is a collection of resources that address the issue. They differ in emphasis, tone, and amount of information presented. Please use and share the one(s) that are most appropriate to the people you talk to.
For the general reader:
Fable: “It’s cold in my yard today, so there’s no Climate Change”
- ‘It’s cold today in Wagga Wagga’—Weather and climate are different
- The Planet Gets Cooler in ’08. Say What?
- What A Record Cold Winter Means for Global Warming
- Why Global Warming Can Mean Harsher Winter Weather
- Cool Spells Normal in Warming World
- Hot or Not? Making Sense of Climate Variability
- Has global warming really stopped?
- It’s cold. Does that debunk global warming?
- Why a cold winter doesn’t mean climate change is behind us
- Is Climate Warming or Cooling?
- “Global Cooling” myth gets fried
A little more technical – (Weather vs Climate)
- Definition of Climate: Average versus Accumulation:
- El Nino, Global Warming, and Anomalous U.S. Winter Warmth
- Global trends and ENSO
- More ice, flat temperatures – what does it all mean?
- NOAA says “El Niño arrives; Expected to Persist through Winter 2009-10″
- Western Sizzlin’
- Last Year and This Year:
- Cold in a Warm World:
- The folly of extrapolating from short term trends
Now for the fun stuff.
First question, “Is it even happening?” After hearing many people talk about how unusually cool it was, Nate Silver of Minnesota astutely thought to check whether it actually was unusually cool.
Indeed, it’s been pretty cool in Minneapolis for the past couple of days; the temperature hasn’t hit 70 since midday Thursday. But has it been an unusually cool summer? No, not really. Since summer began on June 21st, high temperatures there have been above average 15 times and below average 13 times. The average high temperature there since summer began this year has been 82.4 degrees. The average historic high temperature over the same period is … 82.4 degrees. It’s been a completely typical summer in Minneapolis.
Tired of all of the Denier “it’s cold today” and armed with this knowledge, Nate has issued the following open challenge:
For each day that the high temperature in your hometown is at least 1 degree Fahrenheit above average, as listed by Weather Underground, you owe me $25. For each day that it is at least 1 degree Fahrenheit below average, I owe you $25.
I wish him all the best and I am going to follow this, but as has been noted about Deniers here before, they’ll bet your life, but not their money!
Fine, but sometimes it really is cooler, even record cold, how is THAT possible if the world is warming? Notwithstanding the truth about this years global record (top), the fact is some places really have been cool and wet.
A not very satisfying correct answer is that the heat is somewhere else. Let’s see if we can turn that into a more satisfying answer.
One of the problems is the “Mind prison” of expectations.
Everyone understands that even a house can have a particular room that is colder than the rest, even one part of a room can be detectably colder. It all depends on uneven warming and air movements.
Our expectation is not because we have never experienced uneven warming and temperature, even in small spaces. So why is it so surprising that we experience the same in a large, planet sized space? In that sense the Earth is a huge and very old house; sturdy, but with a lot of idiosyncrasies.
To understand how this cold occurs we really need to understand that what we are dealing with is “climate change”, a term that the science community has been using since 1975 (before anyone pops up with ‘that’ Denier chestnut). Whether the trend is warming or cooling we would still be experiencing significant disruption of our weather systems, and that means unpredictable and unusual weather. A more detailed (and useful) discussion can be found at Imprecision of the Phrase “Global Warming”
In Climate Deniers literally are “Flat Earthers” I talked about some of the macro factors that give us variation in our weather patterns, and how climate change causes them to shift. Let’s look at that in more detail and at a slightly finer scale.
Here is a map of the air masses that largely determine the weather for North America (from Geography 101, University of Wisconsin). These air masses are created by the air circulation patterns discussed in the previous post (above).
Continental Arctic (cA)- very cold; very dry
Continental Polar (cP) – cold & dry
Maritime Tropical (mT) – warm & moist
Maritime Polar (mP) – cool & moist
One of the reasons weather patterns get severely disrupted is that the warming of the Earth is uneven with the greatest warming at the poles (Polar Amplification and What exactly is polar amplification and why does it matter?).
As a purely hypothetical exercise, let’s take some of those air masses and warm them up, say 2C to 3C (warming tends to be greater over land). This naturally causes disruption of how the different air masses interact with one another, so there is some slight shifting in exactly which areas of the continent are dominated by which air masses.
Continuing our hypothetical exercise, let’s suppose that the shifting pushes the continental polar air mass in the middle north somewhat further south and a bit more east. At the same time, the eastern maritime Polar air mass also extends a little more south and east.
In this hypothetical example everything is warmer than it had been, but the result is that the regions described as A and B are having their weather more heavily influenced by a different air mass than they had been historically.
As a consequence, even though the continental Polar air mass is warmer than it had been before, the people in area A are experiencing weather that is cooler than they had historically.
Generally cooler, and undoubtedly they would be experiencing many new record cold days. Equally, the people in area B would be experiencing wetter weather than they had historically, which would undoubtedly include record snowfalls.
I cannot emphasize enough that this is a grossly over-simplified, purely hypothetical example, but hopefully it makes it clearer how it is possible to warm everything up, and still have some places that actually are cooler, and experiencing record cold periods and/or record snow falls.
Now imagine the consequences as we shake, rattle and roll all of the Earth’s air masses:
That’s because it takes an unbelievable amount of heat energy to warm up billions of tonnes of water even a single degree, say from 6C to 7C. When that volume of water cools 1C it releases that heat energy, which partially explains why ice shelves are so vulnerable to warming from below.
Of course if climate change causes disruption of ocean currents such that your region’s weather becomes heavily influenced by that “warmer” 7C current when it hadn’t been before … well, you’ll probably spend a lot of time sloshing through cold rain muttering “Global warming? … bullshit!”
Of course climate change is affecting ocean currents, and will undoubtedly disrupt them much more as it continues.
Which is another piece of the puzzle as to how it is possible to warm the planet as a whole, while still having some areas apparently unifluenced, or even become colder, at least in the short term. This variation is just another consequence of the variation discussed in the Flat Earth discussion.
Note here how a Denier attempts to spin geographic variation of weather, A Warming Hole in the U.S. as Warming of planet occurring only in certain geography.
Two other things to note about reports of “record temperatures”:
First, many of them are not necessarily that meaningful. A “record” just means that we have recorded an extreme that has never been recorded before. We have a lot of data from 130 yrs of record keeping, but I doubt we are even close to having recorded every “normal” extreme for every geographic location.
Further, our 130 year long data base is vast enough to be highly meaningful scientifically, but it does not mean that we have 130 years of temperature records for absolutely every location where we now record temperatures. Some of the “records” being reported by the media are in fact for places that have quite short and scientifically meaningless temperature records.
So if Wakawak’s previous record cold for July 20th was 20C, and this year it drops to 19C for whatever reason, we have a new “record cold.” Given tens of thousands of locations, in any given week chances are good that somewhere is going to experience “record” something. Such a minor difference on such a small scale is meaningless, but you can bet Fox News? and the Denialosphere will report it as though it had dropped -40C across half the continent.
One of the other sources of new “records” is an artifact of being a calendar rather than season based society. This is relevant because the climate disruption is also manifesting as a shift in the seasons: Summer peak, winter low temperatures now arrive 2 days earlier. As a consequence the “seasonal days” occurs 2 days earlier, which across continents is going to be enough to create new “records” here and there even if absolutely nothing else changes.
So what does a lot unusual cold periods, record snow falls, and record cold days tell us? If there is enough of them over a period of years it could be an indicator of climate change, but you still have to look at the global temperature trend over a period of at least 30 years to get a sense of just how the climate is changing.
And as long as the trend looks like this:
I don’t care how often Fox News? tells me that the good people of Wakawak had to wear a sweater yesterday, the planet is definitely warming.
Temperature records from a suburb north of Los Angeles indicate that periods of three consecutive days when the temperature exceeds 90 degrees Fahrenheit (events commonly referred to as “heat waves”) are more common now than they were 100 years ago. Earth Gauge
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Denier “Challenge” aka Deathwatch Update: Day 264 … still no evidence.
North America from Freemap
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