Home » How Blue Whales help regulate climate by stirring and fertilising the ocean

How Blue Whales help regulate climate by stirring and fertilising the ocean

by simon

How Blue Whales help regulate climate is by stirring and fertilising the ocean. In Indonesia’s Banda Sea, just north of Australia, they contribute to cold layer mixing and significantly contribute to cooling the planet. Acting like the pump on a fridge, this process moderates global weather. Australia happens to be on the hot-side of the process, so when the intensity of the feeding event in 2019 increased, due to a longer-than-normal monsoon season, it increased the effect of Australia’s bushfires.

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Each year when the Central Asian plateau warms and air rushes up the sides of Mount Everest, the winds that are sucked in over the Banda Sea from the south east, drive upwellings that attract Blue Whales to feed on an abundance of plankton. In late 2019, Blue Whales had a prolonged feeding season and were in particularly large numbers in the shadow of Banda Neira’s main volcano. It was also a bumper year for Hammerhead Sharks.

The port city of Banda Neira. The wealth of Europe was built on the islands’ spices and the harbour-front hotel used to host global royalty and celebrity elites.
The Banda Sea is a large basin where warm water flows in from the tropical Pacific to the north and empties into the Indian Ocean to the southwest.

Climate, Whales and the Indian Ocean Dipole

In any normal southeast monsoon season, the Banda Sea surface cools by about three degrees, compared to other times of year but it only takes a fluctuation of about 1.2ºC to trigger the Indian Ocean Dipole (IOD), a climate phenomenon that drives Australia’s weather systems and agriculture. 2019 was one of the most persistent IODs recorded and the southeast monsoon winds continued weeks longer than normal.

The prolonged monsoon winds meant the whales could feed more actively, thus reducing world temperatures, by pumping harder. Animals are Earth’s cooling pumps and if they break down completely, we have an even bigger climate problem.

We don’t appreciate that marine vertebrates are responsible for up to a third of ocean mixing, equivalent to all tides and wind combined. The top 150m layer of the Banda Sea is warm water from the Pacific and flows in one direction, while below it, is cooler water flowing in the opposite direction, emanating from the deep. Whales, sharks and fish, swim up and down through the boundary layer, stirring the cool and warm water, driving the system like a massive refrigeration pump.

Blue Whales regulate climate in the Banda Sea by mixing layers.
One of dozens of Blue Whales that were feeding around Banda Neira during the 2019 southeast monsoon. These animals complete an annual migration around Australia as far as Tasmania, a return migration of about 14,000 km.
Blue Whales regulate climate in the Banda Sea by mixing layers.
We think Blues are diving to about 300m to feed on copepods. The most efficient way to get there is straight down, so the whales mostly throw their tail-flukes up high when descending.

The unusually strong winds meant an abundance of plankton, so Blue Whales and other animals went into over-drive, feeding longer and more persistently, forcing even greater mixing and cooling. The whales also lift nutrients to the surface where sulfides oxydise with ammonia from seabirds and fish droppings, creating cloud seeds. This way, seabird colonies influence rainfall on a continental scale. The cloud albedo effect also reflects the Sun’s heat and further cools the ocean.

Concept diagram of Blue Whales feeding in the Banda Sea. Blue Whales regulate climate by mixing cold and warm water layers. Drawing by Simon Mustoe.
Concept diagram of Blue Whales feeding in the Banda Sea. Blue Whales regulate climate by mixing cold and warm water layers. Drawing by Simon Mustoe.

Why are bushfires worse when the climate cools?

Cooler conditions means drier air and combined with southeast winds and the hot Australian desert, makes for little or no rainfall. In 2019, this led catastrophic bushfires.

Mount Solitary on fire with apocalyptic smoke plumes billowing up into the air and settling into the valley as well. Viewed from Wentworth Falls. Lovleah iStock photo ID:1058698942
A positive Indian Ocean Dipole reduces change of rainfall in Australia. Image, Commonwealth of Australia.

Blue Whales regulate climate because they are a significant component in ocean cooling. It’s not just about Blue Whales though. The Banda Sea has a staggering density and diversity of wildlife. Just as significant are the sharks, turtles, fish and seabirds. They all hold up their pillar of the food pyramid and are doing their part to keep these life support planetary systems under control.

Ironically, this does mean that the whales and other marine life, contributed to the bushfires and destruction of huge areas of farmland and forest across southeast Australia in 2019. Animals are part of climate-ecosystem-coupled process and feeding is a mechanism to lock free energy safely away from the atmosphere and oceans (because animals that can feed and evolve successfully must, by definition, be able to stabilise their environment).

But this makes the strongest case for the conservation of Blue Whales and all wildlife, when you realise the story in full. Banda’s Blue Whales are a portent of what happens when we allow wildlife populations to decline. Biodiversity collapse means ecosystems become hotter and more unpredictable, which debilitates farming and fisheries. The oceans aren’t habitable – our world isn’t habitable, without marine animals to regulate climate.

Why must we conserve animals such as whales to regulate our climate

At the back of your fridge, the pipes that flow around the coolant can get very hot. If you remove the processes that circulate the coolant, your compressor can overheat and cause a kitchen fire. You don’t disable the pump to fix the problem, you replace it, so your fridge doesn’t get damaged.

In 2019, Blue Whales were responding to an enormous influx of free energy which was the consequence of global heating. The kitchen that was threatening to burn, was Australia’s backyard. The prolonged monsoon winds meant the whales could feed more actively, thus reducing world temperatures, by pumping harder. Animals are Earth’s cooling pumps and if they break down completely, we have an even bigger climate problem.

Unfortunately, bushfires in 2019 were a by-product of a climate that has changed due to the loss of animals already. In the last few hundred years, there has been a massive 96% decline in the movement of marine vertebrates around the world. In the Banda Sea alone, most vertebrate populations have been reduced by 90% in the last 50 years.

Animals were moderating Earth’s heat engine well before we started burning fossil fuels so if we have any chance of avoiding catastrophic events in future, even if we reach our 2050 carbon-reduction targets, we are going to need to not only conserve, but rebuild animal populations too.

As for Australia, we happen to live on the wrong side of the cooling system … the side that gets hot when the pumps are working overtime. This means we have a lot more to lose than other nations.

The take-home message is that our nation’s future food security and climate stability will depend on regrowing populations of animals, including Blue Whales, in future. 

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