For The First Time, Scientists Prove Human Activity Is The Top Cause Of Warming Antarctic Waters

National Observer - Kelsey Litwin

Researchers take part in a 2006 sampling expedition around Antarctica on the SA Agulhas. Photo courtesy of Neil Swart 

Neil Swart had barely begun his master’s degree at the University of Cape Town when he embarked on a three-month voyage to the South Pole.While aboard a ship meant to resupply South Africa’s research facilities in Antarctica, enduring rocky waters and waves reaching 10 metres tall, Swart deployed instruments to record the Antarctic Ocean’s temperature.

"We have to get to zero emissions at some point in the future if we were to stabilize the climate,” said Environment Canada scientist @Neil_C_Swart #climateaction #climatechange #oceans

At the time, Swart thought of himself as a volunteer helping further “someone else’s science.” He didn’t expect that 13 years later, the data he collected would allow him and a team of researchers to identify human activity as the number one cause of rising water temperatures in the Antarctic Ocean, also known as the Southern Ocean.
“It’s kind of nice to see it come full circle,” Swart, now a researcher with Environment and Climate Change Canada, told National Observer in an interview.
Along with other scientists from the department, and the Scripps Institution of Oceanography in California, Swart found that changes seen in Southern Ocean temperature are directly tied to ozone depletion and human-induced greenhouse gas emissions, as opposed to regular temperature variations or responses to natural climate changes, such as volcanic eruptions or changes in the sun.
Their findings were published in the scientific journal Nature Geoscience on Monday.

Researchers on the SA agulhas (left to right) Mike Funke, Sebastian Swart, Natalie Burls and Neil Swart hold an "Argo float," which Swart says is an instrument that dives 2,000 metres down while measuring ocean temperature and salinity. Photo courtesy of Neil Swart on Facebook

Serious consequences for the ocean
While the connection between human-made greenhouse gas emissions and rising global ocean temperatures has long been understood, this is the first time it has been proven specifically for the waters that surround Antarctica, explained Swart.
Since industrialization, the ocean has absorbed nearly 40 per cent of human-made greenhouse gas emissions. The Southern Ocean, according to Swart, is responsible for absorbing the majority of those emissions.
“The Southern Ocean is the single most important region globally taking up the heat associated with global warming,” he said. As a result, it plays a huge role in mitigating the effects of climate change.
“If it weren’t providing these services, so to speak, we would be experiencing far more CO2 increases in the atmosphere. So understanding changes in this region is really critical.”
The consequences of human-induced warming in that region are not minor, he added.
"By driving an intense warming of these southern waters, we’re increasingly destabilizing the Antarctic ice sheet,” he said. That contributes to well-documented increases in sea level, affecting coastal populations, he explained, and “the warmer ocean water becomes, the less effective it becomes at absorbing CO2.”

IMAGE
Link: Human Causes Only Plausible Source of Warming in Southern Ocean

Swart explained that as the ocean’s ability to absorb climate-warming carbon dioxide decreases, global temperatures stand to increase, all of which could lead to greater weather extremes, such as more heat waves and changes in or stronger precipitation events.
To attribute the rise in ocean water temperature in the region to human activity, Swart and his team used simulations based off historical data and recent observations. By removing contributing factors from their simulation, the researchers were able to pinpoint the the cause as being man-made greenhouse gas emissions and ozone depletion.
Fossil fuel production and consumption are some of the greatest emitters of greenhouse gases. In 2015, 26 per cent of Canada’s greenhouse gas emissions came from the oil and gas industry.
In a 2012, Swart and Andrew Weaver – then a climate scientist, now an MLA in British Columbia and head of the province’s Green Party — published a controversial article in the journal Nature Climate Change. The pair suggested coal was a bigger threat to climate change than oilsands, while stressing that there was a need to move toward non-greenhouse gas emitting sources of energy and avoiding new fossil fuel infrastructure. After their research was used by pro-oilsands advocates to justify calls for expansion, the two scientists later reiterated that all fossil fuel use needs to be regulated to reduce global warming.

An Antarctic Ocean ice shelf is captured during a 2006 sampling expedition and resupply mission, during which Neil Swart and his colleagues collected the data that was eventually published in the Nature Geoscience report on Sept 24, 2018. Photo courtesy of Neil Swart

‘Zero emissions’ only way to stabilize climate
“It is very clear that to limit warming to any given (global temperature) target…there’s a finite amount of CO2 emissions that we’re allowed to make, kind of like a budget we’re allowed to spend,” said Swart.
“If we go above that, we will exceed that target threshold. We have to get to zero emissions at some point in the future if we were to stabilize the climate.”
While it’s a lofty goal, Swart said ozone depletion is a good example of a climate problem tackled by policy. The Montreal Protocol, which took effect in 1989, helped eliminate the production of chlorofluorcarbons, a chemical that contributed the depletion of the ozone layer and was once commonly found in refrigerators and aerosol sprays. In the decades since, there has been significant decrease in ozone depletion.
Last November, an amendment was added to the protocol to reduce production of hydrofluorocarbons, which are used similarly to chlorofluorcarbons. Titled the Kigali Amendment, it will come into effect on Jan. 1, 2019.
“As a result, the consequences of (ozone depletion) are not going to be as severe as they would have been if we hadn’t taken action,” said Swart.
“I think that provides a good model for the case with CO2 – that we also have to take some kind of similar action which ultimately deals with the problem.”

IMAGE
Link: Recent Southern Ocean warming and freshening driven by greenhouse gas emissions and ozone depletion

The Pan-Canadian Framework on Clean Growth and Climate Change is one of the federal government’s attempts to take such action. The strategy, which was introduced in December 2016, is meant to significantly reduce Canada’s greenhouse gas emissions by 2030. It intends to do so, in part, through a carbon tax scheme, which Ontario, Saskatchewan and Alberta have all opposed.
Canada has also committed to the Paris Agreement, along with 194 other countries in December 2015. Though not legally binding, in doing so, Canada also pledged to take action to limit a global temperature increase of 2 degrees this century.

Links

• Antarctic ice could melt rapidly, adding three feet to sea level rise by 2100, study warns
• What’s Causing Antarctica’s Ocean To Heat Up? New Study Points To 2 Human Sources
• NASA launches Satellite To Precisely Track How Earth's Ice Is Melting
• At This Rate, Earth Risks Sea Level Rise Of 20 To 30 Feet, Historical Analysis Shows
• Planet At Risk Of Heading Towards “Hothouse Earth” State
• New Antarctica Map Is Like ‘Putting On Glasses For The First Time And Seeing 20/20’
• Domino-Effect Of Climate Events Could Push Earth Into A ‘Hothouse’ State
• Earth At Risk Of 'Hothouse Climate' Where Efforts To Reduce Emissions Will Have No Impact, Study Finds
• How Scientists Tracked Antarctica's Stunning Ice Loss
• Antarctica Has Lost 3 Trillion Tonnes Of Ice In 25 Years. Time Is Running Out For The Frozen Continent