The Ocean's Conveyor Belt

Science · Ocean Life · ages 11-12

Name ______________________ Date ____________

Thermohaline circulation is powered mainly by wind.
Circle one: True False
What drives the ocean's global conveyor belt?
- Temperature and saltiness
- Wind blowing over the surface
- The pull of the moon
Which ocean circulation carries warm water from the tropics toward Europe?
- The Pacific trade winds
- The AMOC
- The polar jet stream
About what percent of the extra heat trapped by pollution has the ocean absorbed? Type the number, rounded to the nearest 10.
Answer: ______________
Sea ice forms near the Arctic and leaves extra salt in the water below it. What happens to that water next?
- It becomes lighter and rises
- It stays at the same depth
- It becomes denser and sinks
London and Winnipeg sit at similar latitudes, but London's winters are far milder. What part does the ocean play in that difference?
- Mild Atlantic air reaches London, warmed in part by heat the AMOC carries north
- Winnipeg receives more sunlight hours overall
- Winnipeg sits much closer to the North Pole
Cold water sinks near Greenland, travels far away, warms at the surface, and eventually flows back. Why does this loop matter for the whole planet?
- It only affects fish and other ocean animals
- It happens too slowly to matter for climate
- It moves heat between the tropics and the poles, shaping climate across many regions
A friend says: 'A weaker AMOC cannot affect warming in western Europe.' Why is this mistaken?
- AMOC has no real effect on European climate
- A weaker AMOC carries less heat north, partly offsetting the warming that would otherwise occur in western Europe
- A weaker AMOC would only affect ocean animals, not climate

Answer key

For grown-ups. Fold this page away before handing over the rest.

The Ocean's Conveyor Belt W1-mt_Mp_CpVK6e--s1

False · Wind drives surface currents, but this deep circulation is powered by temperature and salinity differences instead.
Temperature and saltiness · Temperature and salt differences change how dense water is, and dense water sinks. That sinking drives the deep circulation.
The AMOC · AMOC moves warm water north through the Atlantic, then sends cold, dense water back south at depth.
90 · Oceans have absorbed more than 90 percent of the extra heat, acting like a giant heat sponge for the planet.
It becomes denser and sinks · Colder, saltier water is denser, so it sinks and starts the deep part of the conveyor belt.
Mild Atlantic air reaches London, warmed in part by heat the AMOC carries north · Winds bring mild Atlantic air to London. AMOC heat transport contributes to that ocean warmth. Winnipeg is far inland, away from the same maritime influence.
It moves heat between the tropics and the poles, shaping climate across many regions · This slow-moving loop redistributes heat around the globe, which is why it can shift the climate of whole regions like Northern Europe.
A weaker AMOC carries less heat north, partly offsetting the warming that would otherwise occur in western Europe · Less heat carried north can partly offset greenhouse warming. Under projected gradual weakening, western Europe is still expected to warm overall.