Rachel Mills

Rachel Mills

Provost, University of Sussex, former member of Exploring our Oceans team, passionate about ocean literacy and sustainability



Location University of Sussex


  • Hi @AlexanderLiu -we created it in 2014 and have run it 18 times to date - it has progressed hugely during this time and we are planning the next update right now! A great team effort over several years.

  • Thank you @GillMcKenzie - enjoy the rest of the course & good luck

  • You are right @ClaireG - this pandemic has created a huge amount of waste in so many areas - can we learn from any best practice out there?

  • What a fantastic pledge @JerryWatkins - your wide reading round the subject will serve you well - good luck & keep in touch

  • Mr White pre-dates me (BSc Soton class of ‘88) but welcome back - great to have you onboard

  • Thanks to all our learners for your great interactions, questions and answers, for your passion and commitment and for your pledges for the planet - do come back again and spread the word

  • Great final thoughts @PeteB and thx for your contributions over the last 4 weeks - it’s been great having you on board

  • Welcome @IvanaMatlovičova we are drawing the direct facilitation to a close soon but lots of learners still joining to help answer questions and great links in the chat section for you to follow up on

  • Great insights @annitariddle thank you

  • No not really @RichardDennehy - some technical aspects to the arguments but laid out well here: https://brill.com/view/book/edcoll/9789004391567/BP000020.xml

  • Disturbing and inspiring we hope :)

  • Absolutely! @KarenJ @PeteB sampling is biased and behaviours are different in different areas

  • fantastic idea @GordonG

  • Thanks all, I think this is the direction of travel for all external links and we will have to rethink how to use them in future runs - they add huge value, they are completely optional but we need to make sure we use accessible material - the team will be on the case

  • I don't think the story is anywhere near the end yet @NigelThomas, and yes some of our material dates from earlier runs, other links are to recent articles - it is always good to understand the context of the publication/webpage and there is huge value in older literature.

  • What Steve Roberts says is that (1) some scientists think that there is enough copper to supply societal needs for a long period and (2) others think that these are over estimates and will not meet future demands in a meanginful way - he is expressing the range of thinking that exists in the community, that you will pick up in a lot of the debate around this...

  • Thank you @MichaelHowie

  • Great ideas @RachelMyers - let’s spread the words wide across our networks

  • Great to hear about your talk programme - hopefully you can weave in some of our oceans material

  • Good question @LenaBulmer - this very much depends on where it is dumped - if it is pumped in liquid form into subseafloor reservoirs and monitored carefully then this is a credible solution to CO2 disposal

  • Fantastic list of actions @MichaelHowie - really inspirational

  • Do you have the link to hand @DaanVanWijk? Always keen to share news items

  • We will get right onto this in Week 4 @JerryWatkins

  • Nicely put @TomDussman

  • That makes it all so worthwhile @AndreaStables

  • Welcome to our final week - I know many of you are catching up or will be reviewing this material later but please do share your thoughts and questions and discoveries here - this week we address some tough questions about how we live responsibly on our planet.

  • Great provocation @JerryWatkins - this is the key issue for week 4 - how do we balance our societal needs in the most sustainable way?

  • Great to see you all enjoying this week's material - there is so much still to learn about our oceans! Looking forward to our discussions next week in our final week of the course.

  • Thanks @PeteB - yet again you have spotted our broken links that worked 3 weeks ago when we did our checks! I've updated the first and changed the link to the latter which should help.

    See you for week 4

  • Absolutely - so if we look at an element such as nitrogen in the ocean, we can see human impact in the amount of nitrate in the upper ocean - a lot of this gets there via the atmosphere but a non insignificant amount via rivers

  • Welcome @JuneAtkinson yes please to sharing your knowledge and opinions - it is this conversation that makes each run different and interesting, enjoy......

  • Welcome @AliceVigor hope you and your baby enjoy the course :)

  • reallly good questions @UteLang - sharing a BBC article on marine viruses as a starting point: https://www.bbc.co.uk/news/science-environment-48066332

  • Not at all - we would need a star to recycle that! Pressure and heat do great things to molten rock but not nuclear reactions unless special circumstances

  • @ClaireG agree it's rather pricey - if he sells lots they reduce the price.....

  • Love it when we have educators on this course as it spreads ocean literacy really far and wide. The reason why we use the calculations, knowing that some learners really hate them and get more confused, not less, is that for some people it is the best way to understand the issues presented. All of your questions would be great for high school students to have...

  • Reading the new issue of the Challenger Society’s ‘Ocean Challenge’ and think many of you would appreciate the articles on seamount mapping and William Scoresby - download the whole issue here:


  • Not at all @GillianShannon - that’s much more complex when you can see them clearly, nor really understand what they do, so we use the DNA to help us

  • @PeteB great to hear

  • Welcome all to week 3, we are now moving onto thinking about life in the different parts of our ocean - lots of exciting new environments to think about and do keep posting your thoughts and questions here.

  • Perhaps this new book by my colleague Bob Marsh would be of interest: https://www.waterstones.com/book/ocean-currents/robert-marsh/erik-van-sebille/9780128160596

  • and presumably hydrogen would be even more intense! But not at all advisable ;)

  • Hydrothermal vents are hugely dynamic environments, if you watch the videos of billowing black smoke you can see that there isn't a sharp static boundary, rather a murky transition zone where on one side in the vent fluid it is extraordinarily hot, on the other side we have near freezing background seawater. On one side we have acidic, oxygen depleted, metal...

  • Great question Lee - all isotopes of Helium are chemically equivalent but the mass difference between 3-He and 4-He is huge so there will be a differential effect in terms of pitch with the lighter 3-He being even more intense an effect. Has anyone else thought about this at all?

  • Thanks for pointing out that the links went to the previous run of the course - I've updated the links above so the links go to both the current run AND the previous run because as you say @JerryWatkins, there are few economics-oriented posts at the start of most of our runs.

  • Loving the padlet pictures and thoughts - some really inspirational stuff on there for a drizzly Saturday morning - thank you all

  • Great questions @JanineKelley that we can all have a go at answering - the oceans were salty pretty early in their history and lots of debate about what and when out there but certainly before most life evolved,

    Ocean that is saltiest at the surface is the Atlantic: https://earthobservatory.nasa.gov/images/78250/a-measure-of-salt

  • Some, in fact most, restricted basins are linked to the oceans which is why they don’t get supersaturated with salt, some aren’t as per your examples

  • Hi @MomChattopadhyay - don’t worry if you skip these bits - different learners need information in different ways and that’s what makes education and learning exciting - take the main points and move on to the next section

  • Great infographic @MichaelHowie

  • Very true @PeteB and the heating of the subducting slab means these sediments get cooked and form molten rock and gases that escape back out in island arc volcanoes near areas of subduction - this whole cycle takes millions of years

  • Not shelved yet - lots of interest in geoengineering solutions for removal of carbon as part of a mix of approaches but lots of differing views on pros and cons - here’s a great article discussing these ideas:

  • Great questions - do any of our learners have ideas on answers here?

  • Great question @JoyceJ - can we think of ways this question might be answered?

  • We’ve clearly got an issue with Thinglink access this run for some reason - apologies - will have another go at fixing

  • well spotted @PeteB - sometimes we use language to be clear and are not quite as technically accurate in doing so - please bear with us

  • really good question @GillianShannon - we need lithium as you know for batteries and we need lots of it - seawater is a real potential source of this element for society

  • See my answer to your other question - to get pure sodium chloride needs a step or two in addition to simple evaporation

  • A roughh separation can be achieved by scraping off the salts as they form - the first to precipitate out is calcium carbonate (chalk) and this doesn’t taste great. Next is calcium sulphate, again not tasty but has other uses. Scrape these away (or filter off) and the next salt to precipitate out is mostly sodium chloride - the minor impurities give colour and...

  • Great questions @JanineKelley and only time for partial answers (but perhaps other learners want to elucidate)

    Size of ocean seamounts depends on intensity of melting and magma supply and in real hot spots above upwelling mantle they are huge and break the sea surface to form volcanic islands - these mountains are made from sea floor rocks (basalt), whereas...

  • We will cover tides in the next steps.

    Yes ocean depth in part is controlled by ocean volcanoes - the hot magma is buoyant and pushes the sea floor up - as the mew crust cools, spreads away from the source it sinks to form deep ocean basins

  • No licences for exploitation have been issued yet, just exploration.

    We come back to this in detail in week 4 so do join us then to find out more

  • @GordonG if you email me directly at Rachel.mills@soton.ac.uk and I'll put you two in touch

  • The ARGO floats last 3-6 years in operation before corroding and falling to the sea floor: https://argo.ucsd.edu/about/argos-environmental-impact/

    Interesting to think about balance of impact on environment versus benefits for environmental research and understanding - what do our learners think?

  • I think you mean the 'thermocline' which separates the upper warm parts of the lit surface ocean from the deeper colder and darker ocean. The depth of this invisible barrier depends on the season, how windy it is, and where you are in the ocean. It is a density barrier that stops the warm surface waters mixing with the cold deeper waters - this characteristic...

  • I agree @LeeScott - optimising food source vs death by scalding

  • Welcome to week 2 - we change focus this week and get into some details - some of you will want to skip the calculations, some of you will love them - both approaches are great and we will support you along the way

  • Fantastic summary @PeteB - thanks for this and yes, we are ‘ball parking’ our estimates and ignoring the smaller contributions

  • @LeeScott the shrimp get well cooked in 400degrees water like anything organic but they do hang out remarkably close to these high temperatures in the warm waters on very steep temperature gradients on the chimney walls and in the turbulent mixing zones

    More details here if you fancy reading some studies on Atlantic...

  • Great to have you onboard @EmilyS - we are passionate about ocean literacy and getting into classrooms is one key way to make this happen - do share your learnings and spread the word

  • Yes individual vents clog up over time as the minerals build up and up - the hot venting fluid then is channelled through alternative cracks to form new vents. On longer (tens of thousand years and more) timescales the hot magma driving the system cools and the vents become dormant

  • Great to have S330 alums here, we learn new things all the time

  • Good question - increasingly acidic oceans will dissolve the calcium carbonate deposits on the sea floor and these make up a significant component of the sediments in the shallower parts of the ocean basins

  • We can only speculate on the rationale but a pragmatic captain will use prevailing winds, knows when they are due back in the UK and choice of ports is often geopolitical - there must be many other reasons for the choice of route too

  • great question @HelenB - what we are learning is that we can't look at individual elements without looking at how they interact with each other and they do this in surprising ways that needs to be considered simultaneously to understand the whole.

  • There are some great resources on the Smithsonian Museums website and they explain this here: https://ocean.si.edu/ocean-life/fish/bioluminescence

  • Love this thread! The temperature gradients are incredibly steep so the shrimp are bathing in warm rather than scalding waters and if you watch the videos you can see them clustering in this zone and not getting cooked. The background seawater temperatures are near freezing.

  • thanks @JanineKelley - I'll replace with some of the NOAA links until fixed

  • @LeeScott I agree stunning illustrations and I have copies here on my wall in my study at home where I've been working for months. I do think they might have been finalised for publication over the many years post expedition where these books were finalised.

  • Glad all the additional information and links are providing the learning you want - do share any more you come across

  • Facilitated forums are key to learning - and the discussions are what make each run different. Great to have you all on board and please do keep up the discussions.

  • Hi @HelenB - we have updated the Thinglink and tested here with no problems - can you let us know if you can access and if not what the error message is please. Regarding calculations, these are not essential at all but certainly help learners understand the processes and interactions in different ways. Do ask questions here and we will help

  • Link to our blog now fixed :)

  • All fixed now @EdoardoDaffonchio hope you enjoy it

  • Thx @EdoardoDaffonchio - we have an internal problem with this server and have requested a fix - will let you know when it’s complete

  • Great to hear you want to learn more about the workings of the earth - we don’t cover much on plate tectonics here but here is a list of moocs to try out next: https://www.mooc-list.com/tags/plate-tectonics

  • Thanks for sharing this interesting link @JerryWatkins

  • Life inhabits the extreme environments in all parts of the planet and we constantly find more examples. While some microbes don’t breathe oxygen they do rely on the chemical reactions driven by the fact we have oxygen in the atmosphere so indirectly rely on these chemical gradients

  • Hi @GillianShannon - we will be facilitating week 2 fully from 4th July but in the meantime do post any specific questions you have here and we will pick them up then

  • Thanks for sharing @MarthaGil-Montero - there are so many different lived experiences out there

  • Thank you @EdoardoDaffonchio - your words are very impactful and make it clear what the ocean means to you

  • Thanks again @PeteB - I've refreshed the link to the great set of resources provided by the RAMM

  • Alcohol is a great preservative, as is formaldehyde - plus the detailed and beautiful drawings capture organisms before preservation

  • Here's the link to the open access article: https://www.frontiersin.org/articles/10.3389/fmars.2019.00340/full

  • Hi @JerryWatkins - it is probably too early to tell but there is certainly significant funding being made available through the Blue Planet Fund but we need to see how this lands over the next months and years: https://www.gov.uk/government/publications/blue-planet-fund/blue-planet-fund

  • Apologies that our blog link above isn't working right now - working on fixing this link today

  • Thanks @PeteB - these links seem to be broken and I've removed the text until I can work out why the links freeze. Will reupload when fixed

  • Welcome to the course, great to have you all on board for this run whether you are new learners or returners. The discussions are what make this course so interesting and different each time so please do post your thoughts, your questions and let’s explore the ocean together