A: Everywhere. Basically, any place that we would consider habitable for us, we find microbes. And in places that we would consider too extreme for multicellular life, we also find microbes. They are really the champions of colonizing every possible livable space on the planet.
Q: And what do microbes have to do with climate change?
A: Many microbes in the ocean photosynthesize just like plants. They are responsible for generating half of the oxygen in our atmosphere. At the same time, they are also pulling carbon dioxide from the atmosphere into the ocean and turning it into biomass. So they play a huge role as a sink for carbon dioxide, for example.
Q: Methane is another important greenhouse gas. What about that?
A: Methane is largely cycled by microbes. We study one particular process in which two microorganisms collaborate to do this really challenging chemistry of oxidizing methane with sulfate. And they do this very effectively. We don't know the numbers exactly, but the upper estimates are 80% of the methane in ocean sediments is consumed by this team of microorganisms before it reaches the atmosphere.
Q: So, if these microbes weren't working together, a lot more methane would be getting into the atmosphere?
A: That's right. We're concerned that there's a lot of discussion about things like deep-sea mining of natural resources. We know so little about these deep-sea habitats. If we start destroying them, this may perturb the system and make these important biological filters less effective.
Q: Have microbes been overlooked in how we think about climate science?
It depends on who you ask. Some scientists are acutely aware of the importance of microbes. But we need to get the word out to everybody else that this is really critical.
This is not just in the deep ocean, where I do most of my work, but in every single habitat. Microorganisms are basically determining how much greenhouse gases are emitted from these ecosystems, either as sources or as consumers of those gases.