WEBVTT 00:00:09.388 --> 00:00:13.432 The ocean conveyor belt and the Gulf Stream. 00:00:13.432 --> 00:00:16.921 Ocean currents have a direct influence on our lives. 00:00:16.921 --> 00:00:21.863 They determine our weather, our climate, and much more. 00:00:21.863 --> 00:00:24.251 The ocean currents and wind systems 00:00:24.251 --> 00:00:26.511 transport heat from the equator to the poles 00:00:26.511 --> 00:00:30.385 and operate like a large engine for the global climate. 00:00:30.385 --> 00:00:33.522 In the oceans, there are numerous currents. 00:00:33.522 --> 00:00:37.942 The so-called ocean conveyor belt is very important for our climate. 00:00:37.942 --> 00:00:40.947 This term describes a combination of currents 00:00:40.947 --> 00:00:45.726 that result in four of the five global oceans exchanging water with each other. 00:00:45.726 --> 00:00:49.762 They form a worldwide circulation system. 00:00:49.762 --> 00:00:53.087 The conveyor belt is also called the thermohaline circulation, 00:00:53.087 --> 00:00:55.679 with “thermo” referring to the temperature, 00:00:55.679 --> 00:00:57.730 and “haline” to the salt content of the water. 00:00:59.729 --> 00:01:02.277 Both determine the density of the water. 00:01:02.809 --> 00:01:05.538 While the masses of water may be moved in part by wind, 00:01:05.538 --> 00:01:08.765 primarily the different densities of the global oceans are 00:01:08.765 --> 00:01:10.284 responsible for their movement. 00:01:11.347 --> 00:01:16.615 Warm water has a lower density and rises while cold water sinks. 00:01:16.907 --> 00:01:20.303 The water’s density also increases with a higher salt content. 00:01:20.702 --> 00:01:23.933 At the equator the heat from the sun is especially strong, 00:01:23.933 --> 00:01:27.662 resulting in a lot of evaporation and thus a rise in the water’s salt content. 00:01:29.762 --> 00:01:31.951 That is where the Gulf Stream begins. 00:01:32.794 --> 00:01:36.075 The Gulf Stream is very important for the European climate. 00:01:37.524 --> 00:01:42.419 Its length of 10,000 km makes it one of the largest and fastest currents on Earth, 00:01:42.419 --> 00:01:44.407 and it’s very warm. 00:01:44.874 --> 00:01:50.490 At roughly 2 m/s it brings up to 100,000,000 m³ of water per second 00:01:52.247 --> 00:01:53.098 towards Europe. 00:01:53.098 --> 00:01:53.348 A constantly blowing wind, the southeast trade wind, 00:01:57.549 --> 00:02:00.474 drives warm surface water to the northwest, into the 00:02:00.474 --> 00:02:02.892 Gulf of Mexico, where it heats up to 30 °C. 00:02:05.234 --> 00:02:07.286 The turning of the Earth and the west winds then direct 00:02:07.286 --> 00:02:09.937 the Gulf Stream towards Europe and split it up. 00:02:11.242 --> 00:02:13.633 One part flows south, another east to the Canary Current, 00:02:13.633 --> 00:02:19.073 and a third part flows north where it releases a lot of heat 00:02:19.073 --> 00:02:21.496 into the atmosphere as the North Atlantic Current. 00:02:23.026 --> 00:02:25.191 The water becomes colder there. 00:02:25.191 --> 00:02:28.473 Its salt content and density rise on the account of evaporation 00:02:28.473 --> 00:02:32.363 and it drops down between Greenland, Norway, and Iceland. 00:02:33.636 --> 00:02:37.078 There we also find the largest waterfall on Earth. 00:02:37.078 --> 00:02:44.696 The so-called Chimneys, roughly 15-km-wide pillars with water falling up to 4,000 m. 00:02:44.696 --> 00:02:50.215 17,000,000 m³ of water per second, or roughly 15 times more water than 00:02:50.215 --> 00:02:52.504 is carried by all the rivers in the world. 00:02:53.736 --> 00:02:57.254 This creates a strong maelstrom, which constantly pulls in new water 00:02:57.254 --> 00:03:00.113 and is the reason that the Gulf Stream moves towards Europe. 00:03:01.208 --> 00:03:04.567 Countless species use the Gulf Stream as a means of transport on their trips 00:03:04.567 --> 00:03:06.491 from the Caribbean to northern areas. 00:03:07.443 --> 00:03:09.074 But it doesn’t just bring us animals; 00:03:09.074 --> 00:03:12.042 an enormous quantity of warm air also comes with it. 00:03:12.433 --> 00:03:15.482 In order to produce the same heat that it brings to the shores of Europe, 00:03:15.482 --> 00:03:18.116 we would need 1,000,000 nuclear power plants. 00:03:19.036 --> 00:03:21.698 That’s why we also call the Gulf Stream a heat pump. 00:03:21.991 --> 00:03:24.523 Without it, the temperature would be significantly colder here, 00:03:24.523 --> 00:03:27.283 at least five to ten degrees. 00:03:27.283 --> 00:03:30.177 Instead of lush fields, we would have long winters and sparse ice-covered 00:03:30.177 --> 00:03:31.840 landscapes in Europe. 00:03:32.324 --> 00:03:36.346 In the last few years, scientists and pundits in the media have repeatedly 00:03:36.346 --> 00:03:40.704 expressed the fear that the Gulf Stream could come to a standstill 00:03:41.395 --> 00:03:41.918 due to climate change. 00:03:42.674 --> 00:03:45.428 Because if the polar caps actually melt, the salt content in the water 00:03:45.428 --> 00:03:47.622 off Greenland would fall, as would its density. 00:03:49.377 --> 00:03:51.705 The North Atlantic Current would no longer be heavy enough, 00:03:51.705 --> 00:03:54.062 and so it woundn’t sink as usual. 00:03:56.082 --> 00:04:00.201 In the worst case, that would bring the Gulf Stream, our heat pump, to a stop. 00:04:01.980 --> 00:04:04.947 Some climate experts also assume that climate change could 00:04:04.947 --> 00:04:06.433 compensate for this effect. 00:04:07.366 --> 00:04:10.693 We know that it can be normal for the climate to change 00:04:10.693 --> 00:04:13.954 by looking at the development of the Earth over the last few million years. 00:04:15.184 --> 00:04:17.506 There are ice ages and warm periods. 00:04:17.506 --> 00:04:22.061 In the last ice age, a gigantic flood of melting water crippled 00:04:22.061 --> 00:04:26.274 the heat-bringing North Atlantic Current, covering the northern hemisphere in ice. 00:04:28.338 --> 00:04:32.427 Scientists have different views on the impact that climate change will have 00:04:32.427 --> 00:04:36.474 on the global ocean conveyor belt, but one thing is clear: 00:04:36.474 --> 00:04:40.202 when the climate changes, then the complex system of ocean currents and winds, 00:04:40.202 --> 00:04:43.384 which has remained fairly stable since the last ice age, 00:04:43.384 --> 00:04:46.114 will change in ways that we don’t yet understand.