We've Disrupted the All-Important ‘Ocean Conveyor Belt’

Video Description

Experts are terrified this climate 'tipping element' could devastate humanity. Watch the full conversation: https://tdc.video/programs/how-earths-climate-system-is-changing Dr. Jennifer A. Francis: https://www.jenniferafrancis.com/ https://www.woodwellclimate.org/staff/jennifer-francis/ Check out my new member-video website: https://tdc.video/catalog Video by Bryce Plank Subscribe to TDC: https://www.youtube.com/TheDailyConversation/ Full Transcript: (Bryce) Global weather patterns are regulated by ocean currents, but warming water is causing those currents to change. This is one of a handful of earth system tipping elements that climate experts fear could set off incomprehensible devastation. (Dr. Francis) I'm sure most people have heard about the ocean conveyor belt which is basically the system of ocean currents that flow all around the world's oceans. There are two places really that that push that current to flow. One of them is in the North Atlantic. And the idea here is that when fall and winter come along the ocean surface waters get cold and they freeze. And when they freeze, they eject the salt out of the water. And that heavy, salty, cold water that comes out of that freezing process is very heavy relative to the other water in the area, and so it sinks really rapidly. And it creates this downward flow of water which then basically turns south and starts heading towards the southern Atlantic and meets up with other currents along the way. And another area where this happens is off the coast of Antarctica, where also you get some very cold air temperatures and ocean water freezing. So the concern is that in the area around Greenland, the water has been becoming fresher partly because of the water that's being melted from the Greenland ice sheet. (Medley) "Over the past few days we've seen a significant amount of, actually, liquid water on the surface that have both accumulated in small ponds, and probably approaching the size of lakes especially near the edge of the ice sheet. An interesting thing is that the melt season actually in Greenland started pretty much end of April, beginning of May--which, in the grand scheme of things, is very close to a month earlier than average. My name is Brooke Medley. I'm the deputy project scientist for Operation Ice Bridge. Last April and May, we were actually flying in Greenland out of Kangerlussuaq on the NASA P-3. This was somewhat of a unique year where we expected to be going early enough where we would see the typical dry snow conditions. But, rather, we were met with a much different scenario where we saw all these spectacular blue ponds of beautiful liquid water just pooling on top of the surface. The ice sheet is actually experiencing almost an additional month of melt because it started so early here. Part of it is actually driven by the fact that it's very warm right now, but also that there was not a lot of snowfall last winter. And so what that means is when the snow does melt it very quickly exposes darker ice, which can then melt even faster. Just a significant increase in the total amount of water that we just see in general over the course of 2019. There was so much melt that it actually ended up being the second largest meltwater production year for the Greenland ice sheet since 1980. It's actually quite simple: the longer your melt season that means you can just have more time to accumulate more melt, and the only place for this water to go is into the oceans." (Dr. Francis) Also, there's more fresh water flowing from rivers into the Arctic ocean. That fresher water then comes out into the North Atlantic in that passage between Europe and Greenland there. And so we're finding this area of fresher than normal water just south of Greenland and the reason it's looking colder than average there is because when that fresh water is sitting there it floats because fresh water is lighter than the salt water. It sits on top and it prevents that freezing process and that creation of that very salty, dense water from happening, it slows it down anyway. (Bryce) You can see that on the map--that's the most contrasting, rapidly contrasting color area. (Dr. Francis) Exactly. (Bryce) It's very clear. (Dr. Francis) Yes it is. And it even has a name. It's called the 'Cold Blob.' (Bryce) The cold blob? (Dr. Francis) Yes, it's a very technical term. (Bryce) Because it just sits. (Dr. Francis) Yeah, it's been there for several years and it's a very interesting area. A lot of people are studying it because not only does it have this effect on the ocean circulation, but it also is causing weather patterns to change in the North Atlantic and in Europe. Because whenever you change temperature patterns in the ocean or on land you affect winds. And when you affect winds, you affect weather.