This summer I'll be heading to Europe for about a month and a half. Don't worry I'll still be trying to make videos the whole time, but I've never been and I'm very excited about it Anyway when thinking about what clothes and stuff I'll be bringing I figured I'll just bring my typical summer clothes as summers in Europe are fairly comparable to those I've experienced my whole life living in New York. The only thing is, that's sort of strange. I mean, if we look at a map of the world (any ol' map will do), and we lay some lines of latitude on it, we'll have, well, a pretty standard map still. but the assumption made with these latitude lines is that the further away from the equator you get, the colder it gets as well, makes sense, right? So if we look at the general latitude I live at now, and then follow that line all the way to Europe, we'll find that I live roughly at the same latitudes as central Spain and Italy actually very close to the latitude of Madrid, but also close to Barcelona or Rome in Italy all of which are on average both warmer and drier than New York despite being at the same or even higher latitudes. to find a place more similar to the climate of New York (maybe a city like London), will need to move over 12,000 kilometers north. if we look at London's latitude then and see where that corresponds to in America, we'll find in northern Canada mostly Quebec, which is on average much colder than where I am in New York. Now if what we said about latitudes is true, and it gets colder the higher you go (which it is.) How can it be that Europe, on average, is much warmer than its american latitudinal counterparts? Well, maybe we should take a look at a map again. Except this time, Let's look at one that shows average temperature across the world. If we look at Europe, we'll see it's mostly this mustard color, which represents an average temperature of about 10 to 12 degrees Celsius Looking for the same temperature in America, we'll find the same color range from right around Virginia to the bottom of New York. Ok Yes, this is what I was saying before.. But, if we go back to Europe and then move only latitudinally, from Europe west to America, we again find northern Canada and now we can really see the temperature difference between these two places. Here the map is mostly this cyan light blue color, which represents an average of around 0 degrees Celsius. Pretty cold. And a whole 10 to 12 degrees colder on average than neighboring Europe despite being at this same exact latitude So that proves it. Latitude isn't the only thing that influences climate. But then this still leaves the question: if not latitude, then what causes this difference in climate? To figure this one out, we're going to need to look between Europe and America at the Atlantic Ocean. Turning the map to ocean temperature mode, if we look back to New York, we'll find this very thin line of greenish blue surrounded by larger zones of different water temperatures. Moving over to Europe though we can see this greenish blue layer expands greatly and essentially covers all of Western Europe. What this means is that the ocean temperature surrounding most of Europe is on average about the same temperature as the ocean water much further south by New York. If the ocean temperatures are the same in these two places, that explains why they have such a similar climates. (man, it's really lucky that I'm from New York or I would have had no idea how to begin this video.) So, these warmer ocean temperatures around Europe are the cause of the continents higher than average temperatures, but that still leaves the question: Why are these European waters warmer? To answer THIS, we're going to need to learn about the Gulf Stream. You see, prevailing winds in the area move from the southwest to the northeast. These are called the westerlies, and essentially take air from around the Gulf of Mexico and Caribbean and blows it up towards Western Europe. This creates a very similar ocean current where warm surface water from the Gulf of Mexico and Caribbean move along the coast of America, ending somewhere generally between Iceland and Norway. As this warm water travels up, its heat is dissipated to the surrounding areas, i.e. Europe, making it warmer than it should be. But, the title of this video isn't why Europe is warmer than it should be, which means we're only just getting started. You see, this process of water cycling in the Atlantic is part of a larger water circulation system called thermohaline circulation. While winds are pretty good at moving surface water, anything below the surface isn't so easy. So, for this ocean circulation to function, other forces need to drive it. That's where the thermohaline comes into play, as the two main movers of deep ocean water are temperature and salinity. Let me explain. Being relatively close to the equator, temperatures around the Gulf of Mexico and the Caribbean are hot nearly year-round These hot temperatures caused the ocean water here to evaporate much faster than they would further north. As the water evaporates, it leaves the salt in the water behind, and therefore the remaining water becomes highly concentrated in salt. Now, having more salt in your water does two things: first, it makes it taste horrible, and second, it makes the water more dense. This dense water doesn't sink however, because it's warm, which works to counterbalance the high salinity, making it more or less of regular density here. But, as it travels up the American coast towards Europe, as I said, it loses its heat to the surrounding land; itself becoming colder. The colder the water becomes the more dense it becomes as well But also another thing begins to happen here too. Some of this water travels far enough north to become Arctic sea ice. When this happens, the water forms into ice crystals and leaves its salt behind, making the water surrounding the ice even saltier, and therefore even more dense. Finally, this cold extremely salty water is too dense to remain near the surface. Now, the Gulf Stream moves around 100 million cubic meters of water per second, and all that water has to go somewhere. What ends up happening is all that water sinks. The water sinks down about 4 kilometers and what can only be described as the greatest waterfall anywhere on earth. Well actually, several of the world's greatest waterfalls, as the waters fall in what are called chimneys that can reach 15 kilometers wide. This amounts to each one of these chimneys moving up to 17 million cubic meters of water per second down to the ocean floor, which comes out to about 15 times more water than what's transported by all the rivers in the world combined. This down pouring of water does two things: near the surface this falling water creates a maelstrom, which pulls in more water from the surroundings, and, it also transports water into the deep ocean, where it begins to travel back south, taking as long as 1,500 years to return to the surface. This specific process of sinking water in the North Atlantic is called Atlantic Meridional Overturning Circulation But, because that's a mouthful, I'll just say AMOC from here on out. With both of these things happening, (the Maelstrom and moving south), the AMOC can be maintained indefinitely As long as the two conditions necessary to drive the process (temperature and salinity), aren't messed with on a global scale. But oh wait! We ARE messing with the ocean temperature and salinity on a global scale so we all know, or at least we all should know, that human activity is causing the atmospheric composition to change, with the end result being the warming of the earth, which has two effects on this circuit well actually, it has a lot of effects, but we'll be concerned with two: first warmer air temperatures at higher latitudes means the waters up here become warmer too and therefore less dense. This means the water in the AMOC doesn't sink as readily in those chimneys. Then the second, and perhaps more important of the two effects is that warmer temperatures means melting ice, as large amounts of ice from the Arctic Ocean and Greenland melt, that floods surrounding areas with high quantities of fresh water lowering the overall salinity of the ocean water in this area. With lower salinity the water is again less dense, which means again it's less likely to sink. or basically, the whole system depends on waters here being cold and salty, while climate change is making them warm and.. well.. there's not really a single word to mean less salty, so I'll just say unsalty. Overall, these two changing conditions should, in theory, weaken the circulation system with the worst case scenario being a complete shutdown. Now, there is some disagreement within the scientific community as to whether a slowing of the circulation has actually been observed in recent years. some data from NASA suggested despite global changes in climate, this circulation has actually been speeding up slightly since 1993. Meanwhile, a study published in 2015 reversed this, claiming circulation has slowed down between 15 to 20 percent over the last 200 years. So, there is still some division in the scientific community as to whether this slowdown is happening. Though our most recent data suggest that this hypothesis is drifting dangerously close to becoming a theory, and because it's a lot better to think about the future and prepare for potential disasters instead of ignoring all the signs pointing towards them, NOW we need to ask what would happen if climate change, in fact, does lead to a slowing down or even a breakdown of this thermohaline circulation. Well, for starters, it would mean no more giant waterfalls, no more warm water flowing north, and no more free utilities for Europe. But perhaps worse than what wouldn't be happening is what would begin to happen. First, the heat produced around the equator would be retained here, making this area warmer than it is. now. This could potentially cause greater droughts, more powerful storms, and throwing all sorts of weather systems out of whack that would mean any agriculture here would be vulnerable to decreased production as local weather pattern shifted and crop fields could become subject to desertification The second impact of this would be almost to the opposite Without the system bringing warm water and air up north, The higher latitudes would be allowed to get much colder than they are now. Now, the extent to which both of these changes would occur and by how many degrees temperature change would actually be expected is near impossible to predict with current models. So, to get any more specific than this we'll need to look into Earth's past. Luckily, similar changes in the thermohaline circulation system have been recorded. And, samples from ice cores taken in Greenland revealed the entire thermohaline circulation system has shut down before. As the enormous glaciers of the last ice age receded, this released a tremendous amount of fresh water back into the ocean. This had the exact expected results, making the ocean water in the north Atlantic too fresh and therefore not dense enough to sink and the whole AMOC shut off This was followed by a 7 degrees Celsius drop in temperatures around Greenland over the span of just a few decades, which is incredibly fast on a geological timescale. It was only after these melt waters ceased, that the circulation could slowly begin to restart. Even more recently however, between the years 1300 to 1850 C.E. an event known as the Little Ice Age occurred. This was a time when average global temperatures decreased by about one degree Celsius. Immediately preceding this event was a period called the Medieval Warm Period, which reached its peak around 1100 C.E. This was a time when average global temperatures and especially those over Europe were much warmer than previous eras. By around 1200 C.E., this warm period came to an end, and the average global temperature steadily declined until a minimum was reached by around 1600 C.E. This pattern of warming followed by a sudden drop in temperature can be seen as analogous to our current situation in which we are throwing the earth into a period of increased warmth with the potential for a sudden and more extreme reversal of such a trend. The worrisome part for us, is that the heating we've caused to the planet has been to a far greater magnitude than the medieval warming period. And so, if the two events are seen as analogs, this could mean the resulting cold spike from global warming could be far greater in magnitude than that of the Little Ice Age, possibly resulting in a medium ice age or even a large ice age. Though probably not an extra-large or a double extra-large ice age, but the changes would certainly be noticeable over a single human lifespan. Moreover, evidence has been found that this swing from medieval warm to little ice age was in fact related to changes in ocean circulation showing the Gulf Stream to have weakened during this time of the Little Ice Age. Whether or not one of these was the cause of the other is still up for debate, though, and not all data is aligned neatly for a single conclusion. Essentially, studying the past climate is hard and all sorts of things can cause fluctuations, but that doesn't mean we can't at the very least try to understand the future by looking at the past. All that can really be said at this point, is that evidence exists which points towards a possible cooling of the polar regions as global temperatures continue to rise and the destabilizing of the ocean circulatory system in the past has been associated with ice age events. And, if that's the case, our world would become one of.. well.. fire and ice, where average temperatures around the equator exceeds our current levels, while those around the poles drop far below what we're accustomed to. Either way, if we can't reverse this trend of circulation breakdown that's been observed for the past 40 years, at least Europe can expect to decrease to temperatures as less heat is brought up to the continent and the climate here will likely become more similar to that of northern Canada; cold, snowy, bad for crops, and overall less pleasant. (No offense to any northern Canadians though.) while countries in and around the equator could expect higher temperatures potentially causing droughts and lower crop yields as well. Yeah, happy stuff. Anyway, if you want to keep learning about this I put a couple links/sources in the description. If you want to help videos like these to be made, well.. you might want to check out my patreon like all these people did, and consider becoming a patron. It really helps this channel out, which if you think about it helps you out by giving you more videos. If not, though, that's ok, but maybe at the very least subscribe if you want to keep seeing videos like this. I've really started to dislike making these outros. So let's keep things fast. I'll be back soon with another one...? Thanks <3.
