IRA FLATOW: This is Science Friday. I’m Ira Flatow. Despite what you may have been told, this really isn’t our planet. All the plants and animals on earth are relatively new additions. The planet really belongs to the microbes. There are more microbes on Earth than anything else. But despite living basically everywhere and playing a role in many of the processes that affect the climate, the connection between microbes and the climate isn’t talked about that much. And that, my next guest says, needs to change. 

David Mark Welch is director at the Division of Research at the Marine Biological Laboratory in Woods Hole. And he’s one of the co-authors of a consensus statement about the importance of microbes in the climate equation. It was published this week in the journal Nature Reviews Microbiology. He joins me from WCAI in Woods Hole. Welcome to Science Friday. 

DAVID MARK WELCH: Thank you, Ira. 

IRA FLATOW: So you have people signing on to this consensus document. Why do we need this sort of warning statement? 

DAVID MARK WELCH: Well, as you said in your intro, we really have not appreciated the role that microbes play in the world and particularly the role that microbes are going to be playing with a changing climate. So we need to become more aware of that, both on the level of policymakers, scientists, and just individuals. 

IRA FLATOW: So make me a little bit more aware right now. Let’s talk about some of the ways. First, how do microbes affect the climate? 

DAVID MARK WELCH: Sure, well, you know as you said, there are tremendous number of microbes in the world– about 90% of all of the weight– the mass of everything in the ocean are microbes. Microbes are everywhere, and they’re carrying out all of the major sort of biophysical processes that create the atmosphere. Essentially, all of the oxygen that we are able to breathe is here because of microbes originally. 

Microbes both release carbon dioxide into the atmosphere and they absorb carbon dioxide. Microbes are responsible for absorbing about 50% of all of the carbon dioxide in the atmosphere. They create methane, and they eat methane. They create nitrous oxide, and they eat nitrous oxide. Those are both additional harmful greenhouse gases in addition to carbon dioxide. 

So microbes are playing a critical role in determining what the climate is like. And as we force the climate into new directions, those microbes are going to react to that forcing. And we really don’t have any idea what they’re going to do. 

IRA FLATOW: So when we talk about methane– cows producing methane or rice paddies making greenhouse gases– that’s not those objects that are doing it. It’s the microbes that live with them that are doing it. 

DAVID MARK WELCH: Exactly. And that’s part of why we need to have a greater understanding at the individual and policy level of what’s going on there. We talk about cattle producing methane. As you say, cows don’t produce the methane. It’s microbes inside the cows that are producing the methane. And there may be ways, therefore, of altering the amount of methane that those communities produce– the same with nitrous oxide and methane that are both produced in rice paddies and other sorts of agricultural areas. There may be ways that we can modify what the microbes are doing in order to mitigate the changes of climate. 

IRA FLATOW: Are we talking about breeding or modifying microbes that would suck in more CO2 than give off greenhouse gases? 

DAVID MARK WELCH: It wouldn’t even necessarily need to be breeding individual microbes. And this is one of the things that I hope comes through in the article is we’re not so much talking about individual microbes as microbial communities. So if you pick up a little bit of soil or a little bit of seawater, there are millions of microbes in that drop of seawater. But more importantly, there are many, many different species of microbes. And they’re all interacting in different ways. 

So there are these microbes that produce nitrous oxide and other microbes that eat nitrous oxide. Can we help the microorganisms that are eating the nitrous oxide? Can we help the ones that are eating the methane to shift that balance in a more beneficial direction? 

IRA FLATOW: Tell us exactly what this consensus document is calling for. 

DAVID MARK WELCH: It’s primarily calling for a greater awareness of microbes in the environment, the role that they play in changing the climate, and the role that climate change will play in changing those microbial populations. It’s really written at a Scientific American sort of level. It is an open-access article, and I would encourage people to download it and take a look at it. There call-out boxes that define certain terms that people might not be familiar with– just an attempt to educate themselves about microbes in the environment. 

IRA FLATOW: You know we love to talk about the microbiome here, and we usually focus on our bodies. But you’re saying there are so many different microbiomes living in the soil, living in the ocean, living in our bodies that we don’t talk about enough. 

DAVID MARK WELCH: Exactly, exactly, I think that we have learned– and certainly your show has brought this up many times about the importance of microbes in the human microbiome. I think we still make the mistake of thinking that there are a few bacteria out there and most of them are bad. That’s why we wash our hands and clean our surfaces. If we clean the surfaces, we’ll get rid of the microbes. Now we think there are some good microbes. And we worry about the balance of good and bad in our own stomach. 

That same sort of dynamic is happening all over the planet. There are these complex microbial communities. And small changes to those communities can end up having very large effects on things like the production of methane, carbon dioxide, or nitrous oxide. 

IRA FLATOW: Yeah, because we have all been taught that microbes– that they are all bad things. But some of them are very useful to us. 

DAVID MARK WELCH: Really, most of them– I mean there are a small number of disease causing bacteria and viruses and a tremendously huge number, probably millions, of different species of bacteria alone. And that’s not including all the other sorts of microbes– the archaea, the protist, small fungi. 

IRA FLATOW: So where do you go with this document? What’s going to happen to it? How many signers are you looking for? 

DAVID MARK WELCH: Well, this is one of a number of papers that will be coming out around this scientist’s warning to humanity concept of pointing out the different sorts of changes that will be coming about because of climate change and the things that we need to do to address them. We hope that this leads to a greater appreciation of microbes in the environment, both on the part of policymakers, scientists, and individuals. 

IRA FLATOW: I’d like to thank you for taking time to be with us today, David. 

DAVID MARK WELCH: Sure, thank you very much, Ira. This is a fantastic show you do. 

IRA FLATOW: Thank you very much. 

DAVID MARK WELCH: Very important work. 

IRA FLATOW: Thank you. David Mark Welch is director of the Division of Research at the Marine Biological Laboratory in Woods Hole and talking about this very interesting paper he’s put out.

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