The first mission involving the autonomous submarine vehicle Autosub Long Range (better known as ‘Boaty McBoatface’) has for the first time shed light on a key process linking increasing Antarctic winds to rising sea temperatures
University of Southampton
The first mission involving the autonomous submarine vehicle Autosub Long Range (better known as “Boaty McBoatface”) has for the first time shed light on a key process linking increasing Antarctic winds to rising sea temperatures. Data collected from the expedition, published today in the scientific journal PNAS, will help climate scientists build more accurate predictions of the effects of climate change on rising sea levels.
The research, which took place in April 2017, studied the changing temperatures at the bottom of the Southern Ocean.
During the three day mission, Boaty travelled 180 kilometres through mountainous underwater valleys measuring the temperature, saltiness and turbulence of the water at the bottom of the ocean. Using an echo sounder to navigate, Boaty successfully completed the perilous route, reaching depths of up to 4000 metres, to re-unite with the rest of the project team at the programmed rendezvous location where the sub was recovered and measurements collected along its route were downloaded.
In recent decades, winds blowing over the Southern Ocean have been getting stronger due to the hole in the ozone layer above Antarctica and increasing greenhouse gases. The data collected by Boaty, along with other ocean measurements collected from research vessel RRS James Clark Ross, have revealed a mechanism that enables these winds to increase turbulence deep in the Southern Ocean, causing warm water at mid depths to mix with cold, dense water in the abyss.
The resulting warming of the water on the sea bed is a significant contributor to rising sea levels. However, the mechanism uncovered by Boaty is not built into current models for predicting the impact of increasing global temperatures on our oceans.
Boaty’s mission was part of a joint project involving the University of Southampton, the National Oceanography Centre, the British Antarctic Survey, Woods Hole Oceanographic Institution and Princeton University.
Professor Alberto Naveira Garabato from the University of Southampton who led the project said: ‘Our study is an important step in understanding how the climate change happening in the remote and inhospitable Antarctic waters will impact the warming of the oceans as a whole and future sea level rise’
Dr. Eleanor Frajka-Williams of the National Oceanography Centre said: “The data from Boaty McBoatface gave us a completely new way of looking at the deep ocean–the path taken by Boaty created a spatial view of the turbulence near the seafloor.”
Dr. Povl Abrahamsen of the British Antarctic Survey said: ‘This study is a great example of how exciting new technology such as the unmanned submarine “Boaty McBoatface” can be used along with ship-based measurements and cutting-edge ocean models to discover and explain previously unknown processes affecting heat transport within the ocean.’
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This was an expensive project. If the correct conclusions are not reached, guess what happens to any further funding. And bad results would be devastating to the morale of the team. And underlying funding from the local government could be jeopardized. And the team spent thousands of person hours defining the proper data analysis processes (and expectations).
Confirmation bias is a fire with many fuels…and that’s why confrontational science (using the scientific method) is absolutely essential to establishing the best agreements about the truth.
Introducing one sided politics makes coming to any agreement nearly impossible…and the more complex the subject the more impossible. And Climate is an order of magnitude more complex than rocket science.
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On another point, could not underwater volcanism create some turbulence and mixing? …only need ~a degrees of warming.
Oh, so Boaty Boatface has made this run once a year for ten years? No you say. Like in many such pronouncements now days what does one transect mean in the scheme of things, not much. If we have never been there before, never made such measurements before how do we know the relevance of the data collected? I spent a good deal of my life on the sea. One thing was clearly evident, the ocean is a very, very dynamic system. We ran transects collecting all sorts of data across the Gulf of Mexico back in the early 1970s. The idea was to get a benchmark for comparing future data from the Gulf.
The 3-day mission was in April 2017. It seems odd that it has taken over two years to produce this paper. Maybe they did other more important analyses first. No matter…
No actual temperatures are given (not that I can find) so it is difficult to check the findings of the paper. From Wikipedia: Deep ocean water makes up about 90% of the volume of the oceans. Deep ocean water has a very uniform temperature, around 0-3 °C (https://en.wikipedia.org/wiki/Deep_ocean_water). The first part of any warming of that water will reduce its volume, not increase it. Water that is drawn down to warm it presumably comes from where temperature is well above 4 deg C, and that water when cooled by the mixing will reduce in volume too. So the mixing they claim to have found will lower sea levels not raise them. It is mathematically possible for there to be no net effect, but not for there to be higher sea levels.
Others have made similar comments, so apologies for any duplication.
I’ve looked at the graph posted by Nicholas McGinley, and if I’m reading it correctly then my above comment is incorrect. Salt water at 0-3 deg C does expand with increasing temperature. But the rate of expansion is slightly less per degree than for warmer water, so the final conclusion is still correct – the end result is a (slightly) decreased sea level.
charles the moderator / 10 hours ago June 17, 2019:
new insight into warming ocean abyss –
The first mission involving the autonomous submarine vehicle Autosub Long Range.
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What’s that handy for. Maybe punch in nails.
Or spread the door.
The boat did a 112 mile journey. Antarctica is how big? From Wikipedia “The circumference of the Antarctic Circle is roughly 16,000 kilometres (9,900 mi). The area south of the Circle is about 20,000,000 km2 (7,700,000 sq mi) and covers roughly 4% of Earth’s surface. Most of the continent of Antarctica is within the Antarctic Circle.
Antarctic Circle – Wikipedia
112 miles aint even worth Giraffe Poop
We should name the next manned spaceship “Rocky McRocketface”. That would be awesome.
Any documentation for the paper’s assertion that Southern winds are increasing due to ozone depletion and CO2 increases? Come on, data cowboys!
This is what drives me crazy – a hypothesis stated as a closed fact – without challenge – and then base other suppositions on this alleged fact.
“In recent decades, winds blowing over the Southern Ocean have been getting stronger due to the hole in the ozone layer above Antarctica and increasing greenhouse gases.”
And here I was told by the same folks all those CFC restrictions was closing that hole?
All this gathered and proved after a 180 KM trip. What part of the ocean surface is 180km? Seems a small sampling, methinks.
There are some major differences between the North and South Poles: The former is covered by ocean whereas the latter is a continent some 5,000 ft above ocean level. Secondly, Antarctica is home to Mt Erebus, an active strato-volcano that for decades has been belching gasses such as carbon dioxide, hydrochloric acid, hydrofluoric acid and sulfur dioxide. It was only relatively recently that the discovery of 90 or so new (ice-covered) volcanoes was announced.
Their dewy-eyed faith in the major insights they expect to glean about currents and turbulence in the vast 8 million square km southern ocean from a brief 3-day, 180 km excursion is heartwarming. Would that we all could have such simplistic, child-like faith. Like in the Tooth Fairy and Santa Claus.
Just another PNAS article – getting the GOB peer-review lite treatment.
-Others above made similar comments to my thoughts on this:
1. They’ve never used Boaty McB to do anything like this data measurment before. Now they have new data they’ve never jad before, and now things have apparently “changed” and credited all the way to trace gas increase…. wow! Assumptions on top of assumptions to make that conclusion.
Talk about taking a little data in one small area for the first time ever and extrapolating to get the whole elephant, and then telling us how the elephant has changed due to a trace gas change.
Super Wow!
Again, where are the studies showing ozone and CO2 impacts on Southern Ocean wind patterns?
“In recent decades significant trends in the summertime atmospheric circulation over the Southern Ocean (SO) have been observed. The extratropical jet has shifted poleward and intensified (Thompson et al. 2011; Swart and Fyfe 2012; Hande et al. 2012), consistent with a more positive southern annular mode (SAM). These trends are outside the range of natural variability found in coupled climate models (Thomas et al. 2015) and have been largely attributed to the impact of stratospheric ozone depletion (Polvani et al. 2011; Gerber and Son 2014). At the same time, an increase in Southern Hemisphere sea ice cover has been observed (Comiso and Nishio 2008; Parkinson and Cavalieri 2012), most prominent in the fall and in contrast to the large decrease seen in the Arctic.
Several studies have investigated a possible link between these atmospheric and ocean–sea ice trends. The sea surface temperature (SST) pattern associated with interannual variability in the SAM is a dipole in the meridional direction, a feature driven largely by horizontal Ekman transport (as well as vertical Ekman pumping in summer; Purich et al. 2016), and is consistent across observations and climate models (Watterson 2000; Hall and Visbeck 2002; Sen Gupta and England 2006; Ciasto and Thompson 2008). For the positive phase of the SAM, this pattern gives a warming in SST at about 40°S and cooling south of about 50°S, leading to an overall increase in SO sea ice cover (Lefebvre et al. 2004; Lefebvre and Goosse 2008; Purich et al. 2016). Following these results, Goosse et al. (2009) argued that the ozone-driven trend toward a more positive SAM is the main driver of the observed SO sea ice expansion. However, this contradicts the results of many coupled climate model studies that have found a warming of the SO and a reduction in sea ice extent associated with stratospheric ozone depletion (Sigmond and Fyfe 2010; Bitz and Polvani 2012; Smith et al. 2012; Sigmond and Fyfe 2014; Previdi et al. 2014; Solomon et al. 2015a).
Ferreira et al. (2015, hereafter F15) attempted to reconcile these opposing views by proposing that the response of the SO to stratospheric ozone depletion has two time scales: a fast and slow response. They found the fast response to be similar to the interannual SAM–SST correlation, driven by horizontal Ekman transport, and leading to an increase in sea ice cover. On the other hand, the slow response was shown to be driven by upwelling of warm water from below the mixed layer, leading to a reduction in sea ice cover, consistent with coupled climate modeling studies. F15 computed the transient ocean response to a step function in ozone depletion in two coupled climate models: the MITgcm and CCSM3.5. These two simulations had very different configurations, with the MITgcm using an idealized geometry (Double Drake) and without an explicit representation of ozone, while CCSM3.5 is a more comprehensive coupled model with explicit ozone, realistic geometry, and more sophisticated radiation and cloud schemes. While F15 showed both models to give a two-time-scale response, there were also significant differences between the simulations. The initial cooling period was about 20 yr in the MITgcm but just 5 yr in CCSM3.5. Furthermore, the magnitude of the cooling was around 3 times greater in the MITgcm than CCSM3.5.”
Polvani, L. M., D. W. Waugh, G. J. P. Correa, and S.-W. Son, 2011: Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. J. Climate, 24, 795–812, doi:https://doi.org/10.1175/2010JCLI3772.1. Link, Google Scholar
Gerber, E. P., and S.-W. Son, 2014: Quantifying the summertime response of the austral jet stream and Hadley cell to stratospheric ozone and greenhouse gases. J. Climate, 27, 5538–5559, doi:https://doi.org/10.1175/JCLI-D-13-00539.1. Link, Google Scholar
Goosse, H., W. Lefebvre, A. de Montety, E. Crespin, and A. H. Orsi, 2009: Consistent past half-century trends in the atmosphere, the sea ice and the ocean at high southern latitudes. Climate Dyn., 33, 999–1016, doi:https://doi.org/10.1007/s00382-008-0500-9. Crossref, Google Scholar
Ferreira, D., J. Marshall, C. M. Bitz, S. Solomon, and R. A. Plumb, 2015: Antarctic Ocean and sea ice response to ozone depletion: A two-time-scale problem. J. Climate, 28, 1206–1226, doi:https://doi.org/10.1175/JCLI-D-14-00313.1. Link, Google Scholar
Dueling UN IPCC climate models give conflicting results. And a real screamer: We don’t see it when we run (tuned) models with only natural forcing.
A couple of decades of data (out of 60-80 year cycles) leading to some guesses as to an ozone depletion cause. Let’s give it a few more decades before drawing firm conclusions about what drives any SAM changes.
No mention of CO2 causing any of this.