The ninth biennial conference of the Surface Ocean – Lower Atmosphere Study (SOLAS), a global and multidisciplinary project aiming to understand the key biogeochemical-physical interactions and feedback between the ocean and atmosphere, hosted by the National Institute of Oceanography ended in Goa on Thursday.
HT caught up with co-chairs Christa Maradino of GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany, and William Miller, Department of Marine Sciences, University of Georgia, USA, to understand the science community’s latest understanding of the changing climate that is impacting the ocean and its interaction with the atmosphere. Edited excerpts:
HT: Today the ocean is the biggest recycler of atmospheric CO2, and the fear is that as temperatures rise, the ocean’s ability to absorb CO2 will reduce. Is this something the scientific community is seeing happening?
William Miller: This entire programme is about the relationship between the atmosphere and the ocean, that’s what we study. Heat exchange, CO2 exchange, ocean acidification, those are the processes that we study. It (the world’s oceans) has already absorbed so much of the anthropogenic CO2. The ocean is a resource. If that is changing in a marked way, then people’s relationships change in a marked way. There’s a synergy between the uses of the ocean, pressures on the ocean and changes in the ocean. They are not only in the ocean, but also reflected on land through people.
All these things affect physics and circulation, and the heat distribution and atmosphere exchange. It is all a big connected system and connected in a very different way in the Indian Ocean than it is in the South Atlantic or the South Pacific and the South Pacific.
HT: Speaking of the Indian Ocean, given the population it sustains, is it something the community is especially concerned about?
Christa Maradino: It has features that set it apart from the other ocean basins, like there’s a northern boundary, so it’s warming fast…more warming than some other ocean basins. It has some interesting features like the monsoon circulation, which brings a lot of polluted air to the oceans and when the monsoons switch, marine air makes it to the coast. So, the Indian Ocean is affecting atmosphere chemistry and cloud formation. What we also very acutely noticed is that the Indian Ocean is also very under-sampled. So, there’s a lot of missing data. There had been large campaigns that occurred in the Indian Ocean in the 1990s and even in the 2000s and you look for that data in the next decades and you see that there is not that much. The basin is so different, the equatorial upwelling is different, you can’t just make the same measurements in the Pacific or the Atlantic and say that these are the things that are going to happen in the Indian Ocean.
We need more understanding of the Indian Ocean, especially because it’s changing so differently and so much more quickly than the rest of the Oceans except for maybe the polar regions.
Miller: You cannot do any extensive survey of any place and then stop because the climate is changing and so you have to watch a long-term trend to understand how that’s happening. Short term datasets may not capture the long-term trend. So, it may be a place where it can vary, and it will vary. You need a long-term data set so that lack of sampling over recent decades is actually a big problem in our understanding of the changes that are happening in the Indian Ocean.
HT: Does the data indicate cause for alarm?
Maradino: There are these oxygen minimum zones that are here in the Arabian Sea. I wouldn’t say alarming, but there are phenomena, so understanding the upwelling that occurs and the formation of the oxygen minimum zone and how this changes the amount of oxygen that’s in the Arabian Sea, this is something that is closely looked at. The warming (of the ocean) and how it affects biogeochemistry is closely looked at.
HT: The community has expressed a need to elevate its focus from doing science of discovery to the science of solutions. What has prompted this?
Miller: We are still doing discovery science. That is the core of what we do. Because of understanding the process and the way these things work from a basic scientific way, you can’t project what will happen in the future. That’s still a big part of the next science plan.
We are elevating science for solutions to a higher priority, making sure that the problems that we address can be used in solutions that are coming. For example, CO2 removal into marine systems – marine carbon dioxide removal (MCDR). People are going to (try to) do this anyway. So, we are trying to provide the scientific background to make sure it’s done responsibly, because you need to know the effect of what you might do. We are studying the science that informs people how to do it. Or how not to do it.
HT: Has the science of MCDR (carbon sequestration) shown promise?
Miller: It will work to some capacity. If it is a long-term solution, it is hard to say because carbon is a very interesting thing in the ocean – plants take CO2 and then they die, and the CO2 goes back up. As you raise CO2 into the atmosphere, you’d like to think you could put more into the ocean and change that cycle in some way that you remove CO2, into the marine cycle. The ocean already has absorbed so much of the anthropogenic CO2. How to speed up those processes or enhance these processes – there’s different methods that are being tried.
We are not doing very well at stopping fossil fuels, so maybe we can do better by taking them out of the atmosphere. We didn’t invent it (MCDR technology), but we know about it as oceanographers and atmospheric scientists, and so we recognise it as our responsibility (to study it). There’s no other international programme that is focussed on this interface.
Maradino: There’s a lot of direction that if you want to meet this 1.5°C target, you can’t only reduce emissions. You have to make negative emissions. This is what people are saying. So, in order to make negative emissions, you have to do something like MCDR.
This idea of MCDR did not come from SOLAS at the outset. But there’s a lot of urgency among young people now that there’s a bigger revolt against business as usual and all this talk about the 1.5°C target not being able to be reached, which has prompted people to start coming up with things. And within the general scientific community, people have been trying to come up with ideas for quite some time. And this one directly relates to SOLAS, and we feel that it is our responsibility to do research on that.
HT: What will be the way going forward?
Maradino: We are looking at the future because of science. We want to get people’s ideas of what needs to be addressed in that science plan in the next 10 years of SOLAS science. We would also like to engage policy makers and governments.
We hope to make some interaction with the plastics treaty, it’s being negotiated right now, and we are trying to use our SOLAS and highlight that the atmospheric deposition and the atmospheric entry point of microplastics to the ocean is completely missing from the discussion.
