Stronger west winds blow ill wind for climate change

July 09, 2018

Stronger westerly winds in the Southern Ocean could be the cause of a sudden rise in atmospheric CO2 and temperatures in a period of less than 100 years about 16,000 years ago, according to a study published in Nature Communications.

The westerly winds during that event strengthened as they contracted closer to Antarctica, leading to a domino effect that caused an outgassing of carbon dioxide from the Southern Ocean into the atmosphere.

This contraction and strengthening of the winds is very similar to what we are already seeing today as a result of human caused climate change.

"During this earlier period, known as Heinrich stadial 1, atmospheric CO2 increased by a total of ~40ppm, Antarctic surface atmospheric temperatures increased by around 5°C and Southern Ocean temperatures increased by 3°C," said lead author Dr Laurie Menviel, a Scientia Fellow with the University of New South Wales (Sydney).

"With this in mind, the contraction and strengthening of westerly winds today could have significant implications for atmospheric CO2 concentrations and our future climate."

Scientists know changes in atmospheric carbon dioxide have profound impacts on our climate system. This is why researchers are so interested in Heinrich events, where rapid increases in atmospheric carbon dioxide occur over a very short period of time.

Heinrich event 1, which occurred about 16,000 years ago, is a favorite to study because alterations in ocean currents, temperature, ice and sea levels are clearly captured in an array of geological measures. This allows theories to be tested against these changes.

Until now, many of the propositions put forward for the carbon dioxide spike struggled to explain its timing, rapidity and magnitude.

But when the researchers used climate models to replicate an increase in the strength of westerly winds as they contracted towards the Antarctic, the elements began to align. The stronger winds caused a domino effect that not only reproduced the increase in atmospheric carbon dioxide but also other changes seen during Heinrich 1.

The stronger winds had a direct impact on the ocean circulation, increasing the formation of bottom water along the Antarctic coast and enhancing the transport of carbon rich waters from the deep Pacific Ocean to the surface of the Southern Ocean. As a result, about 100Gt of carbon dioxide was emitted into the atmosphere by the Southern Ocean.

Today, observations suggest westerly winds are again contracting southwards and getting stronger in response to the warming of our planet.

"The carbon exchange in particular between the Southern Ocean and the atmosphere matter deeply for our climate. It is estimated the Southern Ocean absorbs around 25% of our atmospheric carbon emissions and that ~43% of that carbon is taken up by the Ocean south of 30S," said Dr Menviel.

"With westerly winds already contracting towards Antarctica, it's important to know if this event is an analogue for what we may see in our own future.

"For this reason, it is vital to bring more observational networks into the Southern Ocean to monitor these changes. We need a clear warning if we are approaching a point in our climate system where we may see a spike in atmospheric carbon dioxide and the rapid temperature rise that inevitably follows."
-end-
Paper: Menviel L., Spence P., Yu J.,Chamberlain M. A., Matear R. J., Meissner K. J., England M. H. Southern Hemisphere westerlies as a driver of the early deglacial atmospheric CO2 rise. Nature Communications. DOI: 10.1038/s41467-018-04876-4

University of New South Wales

Related Antarctica Articles from Brightsurf:

Ice loss likely to continue in Antarctica
A new international study led by Monash University climate scientists has revealed that ice loss in Antarctica persisted for many centuries after it was initiated and is expected to continue.

Antarctica: cracks in the ice
In recent years, the Pine Island Glacier and the Thwaites Glacier on West-Antarctica have been undergoing rapid changes, with potentially major consequences for rising sea levels.

Equatorial winds ripple down to Antarctica
A CIRES-led team has uncovered a critical connection between winds at Earth's equator and atmospheric waves 6,000 miles away at the South Pole.

Antarctica more widely impacted by humans than previously thought
Using a data set of 2.7 million human activity records, the team showed just how extensive human use of Antarctica has been over the last 200 years

Antarctica more widely impacted than previously thought
Researchers at Australia's Monash University, using a data set of 2.7 million human activity records, have shown just how extensive human use of Antarctica has been over the last 200 years.

Predicting non-native invasions in Antarctica
A new study identifies the non-native species most likely to invade the Antarctic Peninsula region over the next decade.

Persistent drizzle at sub-zero temps in Antarctica
When the temperature drops below freezing, snow and ice are expected to follow.

Human 'footprint' on Antarctica measured for first time
The full extent of the human 'footprint' on Antarctica has been revealed for the first time by new IMAS-led research which used satellite images to measure stations, huts, runways, waste sites and tourist camps at 158 locations.

Iguana-sized dinosaur cousin discovered in Antarctica
Scientists have discovered the fossils of an iguana-sized reptile, which they named 'Antarctic king,' that lived at the South Pole 250 million years ago (it used to be warmer).

Scientists drill to record depths in West Antarctica
A team of scientists and engineers has for the first time successfully drilled over two kilometres through the ice sheet in West Antarctica using hot water.

Read More: Antarctica News and Antarctica Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.