Ocean Currents and Global Heat
Explain thermohaline circulation (the global conveyor belt) as driven by temperature and salinity differences that cause dense water to sink; describe how the Atlantic Meridional Overturning Circulation (AMOC) transfers heat from the tropics toward Europe; explain that oceans absorb more than 90% of excess heat and ~25% of CO2 from human emissions; explore what would happen to Northern European climates if circulation weakened
The lesson
You already know ocean currents move heat around the planet. Some of the biggest currents aren't pushed by wind at all. They're powered by the water itself, through something called thermohaline circulation: a deep, slow loop scientists nickname the ocean conveyor belt.
Near the Arctic, seawater gets very cold, and when sea ice forms, it leaves extra salt behind in the water below. That water is now cold and salty, which makes it denser than the water around it, so it sinks straight down. As it sinks, warmer water from the south flows in to take its place at the surface.
Emma lives in London, UK. Her cousin lives in Winnipeg, Canada, at nearly the same distance from the equator. Yet Emma's winters are far milder. The reason is a current called the Atlantic Meridional Overturning Circulation, or AMOC. It carries warm water from the tropics up past the UK before that water cools, sinks, and heads back south.
Scientists watch AMOC closely because it could weaken as the planet warms. If it did, less warm water would reach Northern Europe, and winters there could turn colder, even while the rest of the world keeps heating up.
Cold, salty water sinks and drags a global current called the conveyor belt, and that current is why places like the UK stay milder than you'd expect for their latitude.
Watch it
Where it sits
Learn first
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.