Ocean plastics researcher Olga Mironenko is blogging from a research vessel somewhere in the North Pacific. Read the whole series starting here.

Following my favorite principle, carpe diem (“seize the day”), I decided to interview a few scientists here on board about what they do, why they do it, and what sustainability means to them.  The parts in [brackets and italics] are my scientific two cents to explain certain points.

Let’s start with James Girton, the chief scientist of our cruise and a principal oceanographer at the Applied Physics Lab of the University of Washington’s School of Oceanography.

What are the big open questions in current-day oceanography?

Well, there’s the mixing question, for example — how much the deep ocean is mixing, and where this is occurring.

Why study mixing at all? What’s important about it?

It’s important to understand how much the ocean is transferring heat around, and how much heat it stores, but also atmospheric gases — of which CO2 is the big one, given the present-day issue of climate change. Studying ocean mixing gives you information on how quickly you get CO2 into the deep ocean.

We know that there are two carbon pumps in the ocean: biological and physical. The biological pump is the phytoplankton absorbing carbon during photosynthesis. The physical pump is CO2 being dissolved in seawater and then stored there [as carbonic acid or bicarbonate depending on the acidity of seawater]. So looking into ocean mixing means understanding more about what’s happening to, say, CO2 in seawater.

And of course, you also learn about nutrient pathways — that is, nitrate, phosphate and silicate in the case of silicon-based organisms. You see, the abundant marine life in the upper layers of the water column takes all of these nutrients out rather quickly, so mixing from below is how the stock is replenished.

What are your other research interests, apart from ocean mixing?

Arctic and Antarctic ice. It’s interesting to see how much heat the ocean is bringing there, and what share of that heat is anthropogenic as opposed to natural.

A lot of people say that they don’t believe in anthropogenically-driven climate change. What do you think about that kind of statement?

Well, you can’t really say that anymore. All the work done since the beginning of the 20th century has shown that the effect our activity has had on the climate is big enough to cause the changes that have been observed. The underlying principle of global warming is quite simple: Ff you have a layer in the atmosphere that lets shortwave solar radiation in and traps the long-wave radiation on its way out, you inevitably get a warmer surface. On Venus this has happened to an extreme – we know Venus [which has a very thick, predominantly CO2 atmosphere] to be a very hot place. In fact, it is hotter than it should be given its distance from the sun. In contrast, Mars [where the atmosphere is also CO2 but very thin] is, by the same logic, colder than it should be.  CO2 is just part of this overall “greenhouse effect” (which also includes water vapor and other gases), but it is the main one that we are changing.

In fact, the most convincing evidence about anthropogenic climate change comes from computer models that reproduce the global average temperature over the last century by combining the input of each natural and anthropogenic factor—including CO2 from fossil fuels, aerosols from large volcanic eruptions, and solar variability. There are multiple models that do this fairly well, as described in the IPCC reports, which have continued to be refined since the connection between models and temperature observations became firm in the late 1990s. These models are built using various approaches and so there are differences among them, but the point is that without anthropogenic CO2 the models all predict a substantially cooler global temperature.

No one would argue with the atmospheric CO2 record [406.42ppm, registered at Mauna Loa Observatory, Hawaii, February, 2017] showing a dramatic increase over the last 100 years, most of which is due to fossil fuel burning.

What issues do you think the ocean is facing, as a global ecosystem?

Climate change and ocean acidification would be the first ones, followed by ice melting and sea level rise, as consequences of climate change. Sea level rise is probably the most pressing issue for the upcoming century.

Does this knowledge affect the everyday choices you and your family make?

Well, like most people in Seattle I could say that I am trying to do something, but maybe not enough. I try not to take more airplane flights than necessary, but at the same time I realize I don’t cut flying as much as I might be able to. But there are many events a scientist has to attend.

How indispensable is it for a scientist to fly to all these conferences and events?

There are more and more scientists who start not showing up at meetings for this reason [laughing]. If it’s a small-scale event one could always do teleconference. While large, biannual conferences and meetings cannot be done remotely.

I once saw an ocean acidification presentation at the California Academy of Sciences Museum in San Francisco and the presenter emphasized the benefit of being vegetarian for our climate. Meat production brings about deforestation, which in its turn both decreases the amount of carbon that could potentially be taken up and stored by trees and releases more carbon when the trees are burned. I did not go completely vegetarian after that but I try to eat less meat than I normally would.

Because of climate change solely, or is it more of a health concern?

Carbon is my number one reason.

Is there anything else that you and your family do to reduce your carbon footprint?

My wife and I go for more fuel-efficient cars. We also choose to live in a fairly dense area close to work, instead of moving to a greener suburb.

I would be in favor of tax increases, introducing a carbon tax in particular. Gas is also way too cheap now in the United States, and it shouldn’t be that cheap. Price increases would discourage people from driving too much. Personally I am prepared to pay more, but I realize that this is not an option for everyone, since cars and long commutes are still cheaper than finding housing in dense parts of the city. I also am very much in favor of improving public transit and discouraging suburban development (sprawl).