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Global weirding is a term used to describe how, with global warming, we will see more extreme weather events:

Avoid the term “global warming.” I prefer the term “global weirding,” because that is what actually happens as global temperatures rise and the climate changes. The weather gets weird. The hots are expected to get hotter, the wets wetter, the dries drier and the most violent storms more numerous.

The fact that it has snowed like crazy in Washington — while it has rained at the Winter Olympics in Canada, while Australia is having a record 13-year drought — is right in line with what every major study on climate change predicts: The weather will get weird; some areas will get more precipitation than ever; others will become drier than ever.

I have a decent understanding of physics but don't know much about weather and climate. I think I understand a few things about global weirding:

  • Warmer waters mean typhoons can form more often, so in locations where extreme weather is also caused by typhoons they will see this more often

  • Warmer air can transport more water and since steam pressure rises greater than linear with temperature, the same temp. swing around a high mean means that more water can precipitate.

  • I often here a statement to the effect that more energy in a weather system means it has more extreme 'swings' in its behaviour. I find this rather opaque and unconvincing.

Here's what I don't understand: Does 'extreme heat wave' in this context mean

  • In 2100, we'll see more extreme heat events relative to 2015 mean temperatures or

  • In 2100 we'll see more extreme heat events relative to 2100 mean temperatures

I think it means the latter, but given that today's heat waves can cost lives and damage crops, I think it would be relevant to point out that we will see more of this so the first definition has some merit. So I want to be clear about the terminology.

But my main question is, will we see more extreme temperature swings and what are the main mechanisms driving this?

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  • $\begingroup$ My understanding is the extreme heat waves would be relative to 2015 temperatures. Without anthropogenic warming, due to increases in greenhouse gases, it would be fair to assume temps in 2100 & 3100 would be similar to temps now. $\endgroup$ – Fred Nov 9 '15 at 13:59
  • $\begingroup$ @fred I don't understand your comment. Gloal weirding is a consequence of global warming, the term is used because supposedly the weather won't be the same, but warmer. $\endgroup$ – mart Nov 9 '15 at 14:10
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First things first. Global "Weirding" is very difficult to quantify. That doesn't mean it's not happening, but it's inexact. The idea came from climate models, which produced a lot of unexpected variations as opposed to more smooth and consistent warming and weather patterns are so complicated that there's still a lot of unknowns in this area.

Warmer waters mean typhoons can form more often, so in locations where extreme weather is also caused by typhoons they will see this more often

Typhoons/Hurricanes are formed not just by warm water but by warm air and wind direction. If the wind is too strong, the hurricane doesn't form, it needs to build and as it builds, begin to spin. That's a dummies explanation, more details here

Warmer water can make hurricanes grow larger (unclear if it makes the wind blow faster too, it might). One of the fun little jokes made about global warming is that in the IPCC's 4th assessment report (4AR) they predicted fewer hurricanes and in the 5th (5AR) they predicted more, though both were stated with some uncertainty and in the 4AR they predicted fewer with a chance of larger so those predictions aren't nearly as contradictory as this cartoon writers tries to make it sound.

https://pbs.twimg.com/media/B2ev-UdIYAA7KAM.jpg:large

I personally trust 5AR over 4AR cause it's had 7 more years of research behind it, but whatever ends up being true, predicting hurricanes is complicated. Short article on the debate of cause of the apparent recent increase here

Warmer air can transport more water and since steam pressure rises greater than linear with temperature, the same temp. swing around a high mean means that more water can precipitate.

I'm not sure about stream pressure, though warmer air can hold significantly more water vapor, so that I agree with.

Every 1 ° warmer, the atmosphere can hold in saturation about 6% more water. So warmer air can hold quite significantly more water and as a result, lead to larger rain storms, though it's not just air temperature, but temperature variation as the warm air rises, etc. But more precipitation per storm is a very likely consequence of man made climate change. Source.

Also, while the Earth has warmed less than 1 ° C so far, most of the surface temperature over land has warmed over 1 ° C (1.53 ° C on average - see here) and it's the rainfall over land that affects us. This means that the atmosphere over the land can hold as much as 10% more water on average than it did at pre-climate change levels. Now, the temperature increase is lower in the upper atmosphere, so it's not really 10%. but we've seen a few percent increase in how much water our atmosphere can store over land over just the last few decades and that's expected to continue to increase.

Water evaporation and atmospheric water-vapor replenishment is trickier and depends on a few factors, river flow rate is based on rainfall and snow-melt upstream, wind speed and plant transpiration are also important. Some people say CO2 is plant food but it's not that simple. Plants need to take in oxygen to capture CO2 which they use to grow. Sunlight and soil neutralists are the actually the "food" for plants, CO2 is what they use to grow and with higher levels of CO2 in the air, they need to take in less atmosphere to get what they need and as a result, they lose less water, so less water is returned to the atmosphere from forests and trees, as CO2 increases.

So, in a nutshell, the global warmed atmosphere on average can hold more water, it can also take more time for the atmosphere "fill up again" after a rainfall or after passing over high mountains and dropping a lot of water-vapor. That's why you get more floods and more droughts. That much is simple physics.

If snow melt is high, that can lead to greater river flow and more flooding, and snow tends to fall in greater amounts with more water-vapor in the air. There's a number of factors.

That strange 5 feet of snow event on Buffalo in 2014 happened when cold air blew over warm great lakes and the temperature difference caused the wind to draw a lot of water off the lakes. Which, as it blew inland a mile or two, it quickly turned to snow and not the houses on the lake, but the houses a mile away from the lake got covered in snow. The lake effect isn't unique to climate change. It happened in the 1940s and 1970s, but warm lakes and a cold blast of air are the 2 drivers. 2014 was perfect for that with the polar vortex and the warm temperature colliding. It was (I think) the largest lake effect Buffalo has on record.

Cool video here,

I often hear a statement to the effect that more energy in a weather system means it has more extreme 'swings' in its behaviour. I find this rather opaque and unconvincing.

I think I agree with you here. More "energy" is at best, vague, and it explains nothing.

Water vapor condensation is one way that air temperature can rapidly change. Condensation/cloud formation releases heat so more water vapor can play a role in faster temperature change, but I'm not sure how big a factor that is.

Changes in ocean currents, perhaps caused by salinization changes and glacier melt can have significant effects. Europe's moderate winters relative to high latitude are in large part caused by the gulf-stream and the gulf-stream may be slowing, article here. There's still some uncertainty on the extent of this effect, but there appears to be a connection.

The Polar Vortex may also be growing as a result of climate change, based on some complicated models. Despite the earth being warmer, harsh winters in some northern locations are still possible based on weather patterns. Key point from article here:

As strange as it sounds, Kim believes the intense cold air outbreaks in recent winters across Europe, Asia, and North America are, in his words, “a side effect of global warming.”

In 2100, we'll see more extreme heat events relative to 2015 mean temperatures or

In 2100 we'll see more extreme heat events relative to 2100 mean temperatures

This is a tough one.

First point is that there really is no 2015 mean in terms of temperature. We can generate a global average temperature for 2015, but local temperature fluctuates too much to have a 2015 standard. Temperature variation vs a standard is generally measured against a baseline over a few decades. For example, see chart below. (I couldn't get it to embed), but it compares 2014 local temperature to a baseline of 30 years, 1981-2010.

https://www.ncdc.noaa.gov/sotc/service/global/map-blended-mntp/201401.gif

If your question is rewritten as, will 2015, 2016, 2017, 2018, 2019, etc, compared to a 1981-2010 baseline have fewer extremes and look less "weird" than 2100, 2101, 2102, 2103, 2104, etc compared to a 2066-2095 baseline, then that's an interesting question but very hard to answer. Individual years will be hit or miss, but on average, …hard to say.

As ice melt increases and as oceans continue to store heat and slowly grow warmer the weird weather variation could increase, but as CO2 levels begin to perhaps at some point, stop rising and reach a leveling off, we might see a decrease in "weirdness" compared to previous years, though the planet would still be warmer, but the rate of change might drop, so the best answer I can give you is that it could go either way.

The IPCC models suggest a gradual increase in the rate of warming for surface temperatures between now and 2100, as well as an expected increase in sea level rise but that corresponds to a steady increase in CO2. The future CO2 growth rate could be a factor.

Guesses aside, when the experts say that weather will continue to get stranger, they are talking about compared to a consistent baseline, not a moving baseline cause that's a safer prediction, so your first sentence is the prediction that's usually put forth, but your 2nd sentence has a ballparkish 50% chance of being true too.

At some point the degree of weirdness has to level off simply because nothing builds indefinitely and for now global "weirding" appears to be gradually increasing, though as far as I know, precise measurements don't really exist. It's too hard to quantify.

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    $\begingroup$ All else even, warmer water does allow an increase of wind speed in fully-realized hurricanes, increasing storm MPI (maximum potential intensity). $\endgroup$ – JeopardyTempest Mar 11 '17 at 9:30
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    $\begingroup$ And the pronouncements over topics like hurricanes and tornadoes shows some of the trouble of reducing into sweeping statements. I was at the 2005 Hurricane Conference in which a session had very heated debate. To consider such a matter closed, even now, would be dishonest. (We've actually seen a slight decrease in ACE in recent years, but any change so far has really likely been very minor and tough to extract from other mechanisms.) Likewise, tornado count is up, but the majority of that is due to increased spotting/radar/surveying. So again, tough to mathematically note a trend either way. $\endgroup$ – JeopardyTempest Mar 11 '17 at 9:33
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But it's very hard to compare a world where every 'weird' event gets rapidly broadcast to one even 20/30 years ago where communications were not as extensive and comprehensive.

More water vapour increases albedo surely, therefore more tsi radiated back to space.

If these weirding theories are correct, why have there been no cat 5 hurricanes landfall the eastern America's since Katrina?

CO2 effects are inversely exponential and we've already 'eaten the worst bit' if you like

If you feel the oceans are warming, please cite the paper which supports thus aurgument.

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    $\begingroup$ Water vapor doesn't increase albedo. Clouds do, but water vapor traps thermal energy, similar to CO2. The water vapor effect is quite complicated cause you have to calculate cloud formation. There have been 4 Atlantic Cat-5 Hurricanes since Katrina, see here: en.wikipedia.org/wiki/List_of_Category_5_Atlantic_hurricanes and CO2 heat trapping may be inversely exponential, but you're ignoring feedback mechanisms. Saying we've "eaten the worst bit" is ignorant. Climate is more than just a logarithmic estimate. Also, there are numerous links available on the warming oceans. $\endgroup$ – userLTK Nov 12 '15 at 3:26

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