Scientists want to use giant PARACHUTES to stop the Gulf Stream collapsing – in controversial geoengineering experiment to combat global warming

Daily Mail​

2 days ago

As climate change disrupts the planet, experts are worried that a key ocean current called the Atlantic Meridional Overturning Circulation (AMOC) may collapse.
This current is responsible for driving the Gulf Stream and bringing warm water from the tropics northwards to keep Europe temperate.
Now, scientists have proposed a radical solution to save these vital systems and prevent Europe from slipping into a new Ice Age.
Researchers say tugboats could tow huge underwater parachutes around the ocean to manually power the current.
Each parachute would be the size of half a football field and would feature a 12-metre hole in the centre to allow ocean life to pass through.
Just 30 to 50 shipping tankers, drones, fishing boats, or wind kites operating 365 days a year could be enough to power the entire Atlantic Meridional Overturning Circulation (AMOC).
Professor Stuart Haszeldine, of the University of Edinburgh, and David Sevier, founder of water treatment Strengite, presented the idea at the Arctic Repair conference in Cambridge this week.
Professor Haszeldine told MailOnline: 'We think that this is a remedy well worth trying - because we want to keep the flows of ocean current similar to what we know works well just now.'
The AMOC is the largest ocean current in the world and runs from south to north through the Atlantic Ocean.
As warm water travels northwards from the tropics, it hits the sea ice around Greenland and the Nordic countries, cooling and becoming much saltier.
As the water cools, it becomes denser, sinking rapidly towards the bottom of the ocean where it flows back southwards before once again warming and rising to the surface.
This process of 'deep water formation' is the engine for a vast global conveyor belt which pumps heat and water all around the Atlantic Ocean.
However, climate change is now melting the northern sea ice and warming the ocean, sparking fears that the engine driving this current could soon stall.
The effects of an AMOC collapse would be devastating, leaving European countries 5-20°C (9-36°F) colder and drastically weakening the Gulf Stream.
Professor Haszeldine says: 'Our proposition is made in the realisation that there is a real risk that the AMOC current could decrease and falter in the next 20 or 50 years.'
If it does begin to falter, these scientists suggest that existing technology could be adapted to keep the current moving.
What is the AMOC?
The Gulf Stream is a small part of a much wider system of currents, officially called the Atlantic Meridional Overturning Circulation or AMOC.
Described as 'the conveyor belt of the ocean', it transports warm water near the ocean's surface northwards - from the tropics to the northern hemisphere.
When the warm water reaches the North Atlantic (Europe and the UK, and the US east coast), it releases the heat and then freezes. As this ice forms, salt is left behind in the ocean water.
Due to the large amount of salt in the water, it becomes denser, sinks, and is carried southwards – back towards the tropics – in the depths below.
Eventually, the water gets pulled back up towards the surface and warms up in a process called upwelling, completing the cycle.
Scientists think AMOC brings enough warmth to the northern hemisphere that without it, large parts of Europe could enter a deep freeze.
'The key point is to use surface shipping, which can tow a specially designed sea anchor behind the shipping, at a controlled depth,' says Professor Haszeldine.
Parachutes, similar to current sea anchors used to hold ships in place, would be towed in the direction of the existing AMOC flow.
The ships would only need to move just faster than the AMOC itself moves, no more than 2.5 miles per hour (4 kmph) - or about walking speed.
Although the AMOC moves vast quantities of heat around the globe, Professor Haszeldine says its overall kinetic energy is relatively small.
By selecting areas where the AMOC current is shallow enough to reach with a parachute and concentrated enough for the ships to make an impact, only a handful of ships will be needed.
These ships will need to be in motion 24 hours a day, 365 days a year, on rotating shifts.
However, Professor Haszeldine says this would be 'a small amount of kinetic movement' to produce a large impact on moving heat.
Their research estimates that the required energy would be no more than that produced by a small offshore wind farm each year.
If biodiesel is used, this would produce approximately 2.6 million tonnes of CO2 per year, which the researchers say is a 'very low' impact compared to the benefits.
However, the proposal has been met with scepticism by leading AMOC researchers.
Dr René van Westen, of Utrecht University, told MailOnline: 'The AMOC carries 17 million cubic meters of water per second - for reference, one million cubic meters of water per second is equivalent to the globally combined river discharge.
'I can't imagine that one can displace that amount of water with parachutes.'
Even if parachutes could be effective, Dr van Westen says that they would only strengthen the upper wind-blown portion of the AMOC current.
This section extends between 100 and 500 metres beneath the surface but only affects a small part of the ocean current's overall movement.
Deeper currents are primarily driven by the sinking of colder water due to density differences across the Atlantic Ocean.
It is this part of the current which is most at risk of collapsing due to climate change's impact on the Arctic.
Dr van Westen says: 'The sinking is a crucial part of the AMOC, and you do not change this with the surface winds.
Likewise, Professor Meric Srokosz, of the National Oceanography Centre in Southampton, told MailOnline: 'The physics just doesn't work.'
Professor Srokosz says: 'In rather simplistic terms, think about pushing water along with your hand in the bath, it won't sink but rather flow round the sides of your hand.
'Even if you could move the water along, you still need to make it sink.'
ATLANTIC OCEAN CIRCULATION PLAYS A KEY ROLE IN REGULATING THE GLOBAL CLIMATE
When it comes to regulating global climate, the circulation of the Atlantic Ocean plays a key role.
This is due to a constantly moving system of deep-water circulation often referred to as the Global Ocean Conveyor Belt which sends warm, salty Gulf Stream water to the North Atlantic where it releases heat to the atmosphere and warms Western Europe.
The cooler water then sinks to great depths and travels all the way to Antarctica and eventually circulates back up to the Gulf Stream.
This motion is fuelled by thermohaline currents – a combination of temperature and salt.
It takes thousands of years for water to complete a continuous journey around the world.
Researchers believe that as the North Atlantic began to warm near the end of the Little Ice Age, freshwater disrupted the system, called the Atlantic Meridional Overturning Circulation (AMOC).
Arctic sea ice, and ice sheets and glaciers surrounding the Arctic began to melt, forming a huge natural tap of fresh water that gushed into the North Atlantic.
This huge influx of freshwater diluted the surface seawater, making it lighter and less able to sink deep, slowing down the AMOC system.