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This is a topic spun off from parts of the Arctic Sea Ice thread. As the title suggests, this topic is about discussing the hypothetical effects that different climate changes would exert. It doesn't have to be global warming - the effects of global cooling, increased rainfall, decreased rainfall, or a change in any other climatic variable can be discussed. Aside from the broad regional effects, such as moving climate zones, the nuts-and-bolts of what individual cities would average (temps, rain, snow) can be discussed. You can also discuss the effects of a hypothetical climate change on just one site, such as 2010's heavy snows becoming normal in Philadelphia. One region or continent can also be discussed, such as a particular extreme weather pattern (1977, 2012) becoming normal over North America.
The presentation of hypothetical climate averages and maps is encouraged. Keeping an open mind is strongly encouraged. This topic is not for discussing what you think or know will happen in the future, such as global warming or lack thereof, nor is it for debating climate change. It is purely hypothetical. In this thread questions should be framed in terms of "What if?" or "What would happen under this scenario?". Posing hypothetical questions and being curious about what would happen says nothing about your beliefs about what is happening in the real-world, and should be a fun exercise for any climate enthusiast.
The Gulf Stream being diluted/stopped etc by melting sea ice might well mean our winters in NW Europe become drier and colder without the Atlantic weather coming in (or at least us being more prone to unusually severe spells from the continent), only for the jet to dive south every summer opening the door to band after band of rain - basically what's happened the past five or so years becoming the norm. Also prolonged warm/settled spells becoming more common in spring/autumn.
This thread kinda died, maybe these ideas would help revive it. All I think plausible ideas suggested by climatologists.
1) What would the climate of the North Atlantic (both NW Europe and eastern North America) be like if Greenland had no ice sheet? It seems to have an effect on the NAO and the Jet Stream. At times, it creates a block of high pressure affecting circulation patterns (perhaps the track of Hurricane Sandy). It's a rather realistic idea, since there are ideas that the reason Greenland has an ice sheet is because it has an ice sheet. It's a relic of the ice age. Since the ice sheet is 1-2 miles high and reflecting sunlight, the air above the ice sheet is much colder than it would be otherwise and the ice sheet remains. But with a current day climate and no ice sheet, Greenland might be too warm to grow an ice sheet.
2) Around 50 million years ago, geologists found the earth was incredibly warm (rather disputed, not too sure, but this thread is about hypothetical effects). The tropics were hotter than today and the poles much, much hotter, maybe with a mean of up to 20°C. Climate models are unable to reproduce such a small temperature difference between poles and tropics. One possibility suggested is a different cloud pattern. If the tropics had more low lying stratus clouds reflecting sunlight, they wouldn't heat up as much. High altitude wispy cirrus clouds have the reverse effect: they absorb outgoing radiation but let sunlight through. So perhaps the poles had lots of cirrus clouds and much less stratus clouds than today? The increase in low lying stratus clouds for the tropics are predicted by computer models, change in polar cloudiness not, but a change in the polar cloud cover would allow the poles to warm up. When talking of climate change, temperature changes are frequently mentioned, precipitation changes are sometimes mentioned and cloudiness changes rarely. Maybe talking about climate change from a cloudiness change perspective could be interesting.
3) Most drastically — a runaway greenhouse effect. Water vapor is a greenhouse gas and traps outgoing radiation that lets the earth cool. If the amount of water vapor increases enough, the lower atmosphere (troposphere) becomes nearly opaque to outgoing radiation, and increasing the surface temperature has little to no effect on outgoing radiation. If that happens, past a certain temperature the earth will be unable to get rid of incoming heat from the sun, and will just keep heating up. And the oceans boil off. Not really sure, but the threshold to make the atmosphere opaque and set off a runaway greenhouse is supposed to be an average dewpoint of 30-40°C, maybe a bit higher. So the hypothetical super-hot climates people post may not be possible on a water world.
I didn't know that the climate models couldn't come up with a plausible temperature gradient for the early Eocene epoch... I wonder what is the smallest possible temperature gradient given the current configuration of continents is possible between equator and pole and the average annual temperature of the planet roughly what it is now.. what factors could be tweeked to make the gradient smaller if the temperature of the planet was roughly the same?
I wonder what is the smallest possible temperature gradient given the current configuration of continents is possible between equator and pole and the average annual temperature of the planet roughly what it is now.. what factors could be tweeked to make the gradient smaller if the temperature of the planet was roughly the same?
No clue what the smallest possible temperature gradient could be but I can guess what some factors that would change the gradient. The earth's tropics to pole gradient is much lower than would be expected by just considering the incoming solar radiation; heat transport (by both the atmosphere and ocean) from the tropics to the poles makes it smaller. Not as sure about the atmospheric heat transport, isolating the poles geographically should minimize the oceanic heat transport. The current Arctic Ocean setup seems ideal. Ditto with Antarctica. Having a continent surrounded by an ocean with a current wrapping around the continent rather than coming from lower latitudes helps keep things cold. Ice sheets reflecting sunlight and with higher elevation should also keep the poles colder. Year around sea ice could have a similar but weaker affect on the Arctic.
For atmospheric heat transport, maybe a geography consistent high pressure creating a blocking pattern prevent lower latitude air would increase the lower the heat transport.
It would've been interesting if North Africa shifted north into the Mediterranean and "touched" southern Europe and Turkey.
Cairo would've probably seen snow. And the northern edges would've been wet Mediterranean climates rather than semi arid/desert.
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