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‘Few people have made an ocean cruise’

Gert-Jan Reichart advocates the importance of oceans in CO2 storage

'This summer, Gert-Jan Reichart expects the first international treaty about open seas'. 'On land, we simply do not realise just how fast it is becoming much warmer'. '98 percent of all CO2 around our planet is dissolved in the oceans'. Quotes from NOS, Trouw, BNNVARA: in various Dutch media this year, the head of Ocean Systems at NWO institute NIOZ emphasised possibilities to tackle climate change using the oceans. He explains his passionate plea to the employees of NWO-I.

'In contrast to what people often think, forests produce just half of all oxygen on earth, and the other half is produced by organisms in the sea. There is still a lot we don't know about how the sea works, and that is because too few people have made an ocean cruise. Only then do you realise how overwhelmingly vast and extensive it is.'
The central theme in Gert-Jan Reichart's research is the natural cycle of carbon in the ocean. 'This makes the ocean mega important. For example, when we think about carbon in the atmosphere, we mainly consider planting trees to remove CO2 from the air. That idea has caught the general public's imagination – compensate for your flight by planting trees. However, 98 percent of the carbon dioxide is dissolved in seawater. And if you look at all the carbon that is available for life then 95 percent still circulates in the oceans and only 5 percent outside of these in the rainforests, tundras and soils. The carbon cycle has a complex and still partly unknown (bio) chemistry, which is hard to understand. Moreover, it is scarcely studied.'

If you examine the greenhouse effect, then it is clear that our seawater has absorbed the vast majority of all warming due to climate change. This is because seawater has a high "calorific value", which means it can absorb a lot of heat. Therefore the amount of heat energy absorbed by "system earth" as a consequence of the greenhouse effect is allocated as follows: 97 percent is absorbed by the oceans and just 3 percent by the atmosphere, the land surface and the melting ice caps. 'All of these figures and information are also stated in the reports of the IPPC (the climate panel of the United Nations) but have scarcely been picked up on by the general public.'

Mixing in the oceans
Does this heat storage role of the oceans provide opportunities to counteract the temperature rise? 'In the case of CO2 storage, it might. Seawater has already absorbed about 30 percent of the CO2 emitted by humans since 1850. However, if something changes in the ocean circulation, such as the Gulf Stream that brings warm surface water from the Gulf of Mexico to Europe, then the CO2 uptake could also decrease. The uptake effect of the Gulf Stream is enormous. So if the Gulf stream weakens, all of the measures you take to ensure that CO2 levels remain limited could become insignificant. Therefore we also monitor this at our department: what is the state of the Gulf Stream and is this subject to change?
The current models predict that there are "reasonable chances" that the Gulf Stream could weaken under the influence of the increasingly warm climate. 'If that is the case, then far stricter requirements need to be placed on CO2 emission. Then you can anticipate such changes. This large effect of the "mixing in the ocean" by the Gulf Stream also requires further research.'

Could the oceans be actively used to store excess CO2? 'Then we are talking about geo-engineering: deliberate large-scale intervention in the earth's natural systems to counteract climate change, especially global warming. It might be possible, but then you would need to have an excellent understanding of how the carbon cycle works. This uptake of CO2 proceeds via the process of rock weathering and the burial of organic material, and it takes hundreds of thousands of years. In the past –on the geological timescale of millions of years– the ocean was always the counterweight that stabilised the climate. That works as follows: in warmer periods caused by excess CO2 in the atmosphere, for example due to vulcanism, the rocks "weathered" faster. As a result of that, more CO2 bound to the minerals from those rocks, which subsequently dissolved in rainwater and was ultimately stored as chalk in the ocean. At present, however, global warming due to CO2 emissions is proceeding so fast that the natural weathering processes can no longer keep up with this. The deliberate acceleration of the weathering processes has therefore been seriously considered. One way of doing that would be to make use of rocks that weather faster than others, such as the frequently mentioned olivine.'

How can you answer those questions? 'We are now joining forces with other institutes such as the Royal Netherlands Meteorological Institute (KNMI) and the NWO institutes SRON and DIFFER to realise a national "flagship" CO2 research initiative. This builds further upon a Dutch Research Agenda proposal into the carbon cycle in the oceans. We want to bring together researchers from all disciplines in marine science with policymakers and industry to investigate the current and future role of biological, physical and chemical routes. And, of course, the ocean plays an essential role in that. Such a research agenda is particularly important for the Netherlands because in view of our location, we are very vulnerable to climate change and sea-level rise.'
'The idea is to acquire more insight into the "behaviour" of carbon (what is the flow rate, what is the quantity at specific locations in the atmosphere, what are concentration areas) on our planet so that we can describe this better. Carbon dioxide is currently measured at a limited number of locations on earth. For example, the KNMI makes use of satellite missions to monitor CO2. Now, our first priority is acquiring more knowledge. The collaboration is still in its infancy, but I am very pleased to be working with a group of experts on thinking about further research into the carbon cycle.'

Always surrounded by water
Gert-Jan Reichart lives in Utrecht, his wife works in Leiden and they have two young children. One day per week he works as Professor of Marine Geology at Utrecht University. 'Before I went to study geology, I worked in the harbours of Harlingen and Amsterdam. Working on a ship in the North Sea in winter proved too cold for me. For my work, I've been on a lot of expeditions, which included visiting the Arabian Sea. I found that fantastic! That is my passion: ocean and sea research and the climate puzzle. How the climate changes and how that used to happen in the past too has always fascinated me.'
'During the summer holiday, my wife wanted to go camping on Vlieland, but I was not interested in doing that because I am always surrounded by water at NIOZ on Texel. So now we are going to France where we can enjoy camping on the mainland!'

About NIOZ
Royal NIOZ, the Netherlands Institute for Sea Research, is the largest NWO institute and operates in collaboration with Utrecht University. The facilities are located on the Wadden Island Texel and in the town of Yerseke on the southern shore of the Oosterschelde. NIOZ also manages the Caribbean Netherlands Science Institute CNSI on St Eustatius for NWO and the Ministry of Education, Culture and Science. NIOZ also has three research vessels: the Pelagia, Navicula and Stern. Each of these has a specific working area, from the shallow waters of the Wadden Sea to the open oceans worldwide. The vessels are available for the entire national marine and maritime research community.

Newsletter Inside NWO-I, September 2019

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