Naked Science Forum

Life Sciences => Marine Science => Topic started by: katieHaylor on 15/08/2018 12:42:30

Title: What would happen if we didn't have ocean currents?
Post by: katieHaylor on 15/08/2018 12:42:30
Alejandra asks:

What happens if the oceanic currents stop?

What do you think?
Title: Re: What would happen if we didn't have ocean currents?
Post by: chris on 15/08/2018 23:17:52
Why should they stop? The drivers of ocean circulation are usually thermal: heat from equatorial reasons leads to less dense water that flows pole-ward; at the poles, colder, denser water sinks and upwells towards the equator to displace the less dense warmer water towards the poles.

This is a gross simplification, but essentially ocean currents are thermal conveyors that distribute heat around the planet. As long as there is a thermal gradient then they will flow.
Title: Re: What would happen if we didn't have ocean currents?
Post by: Colin2B on 16/08/2018 08:40:16
I was thinking along similar lines Chris; what would stop the currents, because thatís what we would notice first.
Even if the poles melted so no ice cap, you would still expect a thermal gradient between equator and poles, so we would still get a circulation albeit reduced.
Title: Re: What would happen if we didn't have ocean currents?
Post by: evan_au on 16/08/2018 11:45:29
Quote from: Alejandra
What happens if the oceanic currents stop?
I agree that some ocean currents will continue wherever there is a temperature difference.

However, there is another factor of great interest to the UK which is currently opposing ocean currents in the Atlantic ocean: salinity (saltiness).

Warm water is less dense than cold water (at least down to 4C).
But fresh water is less dense than salty water, and there is a fair amount of fresh water melting off Greenland at present, and mixing with surface waters. This opposes the tendency for water to sink at the poles.

It is the Gulf stream that gives a significant temperature boost to the UK - and the UK's legendary foggy/cloudy weather.

If the Gulf Stream stopped (or diverted elsewhere), the UK and northern Europe would approach temperatures seen at similar latitudes in Canada and Russia.
If the Gulf Stream stopped or slowed significantly, that would leave a patch of warmer water near the Gulf of Mexico which would spawn more hurricanes.
See: https://en.wikipedia.org/wiki/Shutdown_of_thermohaline_circulation

The results of ocean currents are not very conclusive, because this has not been well-studied (at least in non-classified publications). However, there is now a fleet of economical deep-ocean "gliders" that are exploring ocean currents, measuring temperature and salinity at various depths, and reporting the results back over satellite. So we may find out more in the near future.
See: https://en.wikipedia.org/wiki/Underwater_glider
Title: Re: What would happen if we didn't have ocean currents?
Post by: Colin2B on 16/08/2018 12:29:09
It is the Gulf stream that gives a significant temperature boost to the UK - and the UK's legendary foggy/cloudy weather.

If the Gulf Stream stopped (or diverted elsewhere), the UK and northern Europe would approach temperatures seen at similar latitudes in Canada and Russia.
There is a degree of debate about how much the gulf stream influences UK climate. It certainly influences the W Coasts of Ireland and Scotland but overall the effect of being surrounded by a large heat sink in the form of the sea is thought to be a greater influence. This contrasts with central continental climates like Canada and Russia.
Not that Iíd be keen for the gulf stream to go however!

Also, we are less foggy than people think. Although compared to Australia......  :)