While many prescriptions exist for what ails Mother Earth, there’s also one major problem: we know precious little about our planetary home. MIT ecologist Penny Chisholm cites an example from her own area of expertise — life forms that exist near the ocean surface. “In any given sample of seawater,” she notes, “we’ll know virtually nothing about 99 percent of the microbes you’ll find there.”
Why should we care? Well, one of the things we do know is that these microscopic entities are helping ensure that our world stays livable. Thanks to a complex interplay among plant-like microbes, animal-like microbes, and higher life forms, for example, some of the carbon dioxide that routinely enters the ocean’s surface waters from the atmosphere ends up far down below. And it may stay there for centuries — something for which we can all be grateful.
If the CO2 stored in the deep oceans equilibrated with Earth’s atmosphere, notes Chisholm, “atmospheric CO2 levels would be at least double, and maybe triple, their current levels.” And we’d be dealing with an environment drastically hotter than anything threatened by the current atmospheric buildups of CO2 and other so-called greenhouse gases.
So there’s ample reason to explore what makes individual types of microbes tick. But also critical is knowing how the different microbe species fit into a larger picture. “The basic point,” says Chisholm, “is that it isn’t just some individual types of organisms that cause carbon to be stored in the deep oceans. It’s the whole microbial food web — what’s referred to as the ‘biological pump.’ If we change the distribution and dominance patterns of the organisms involved in the pump’s machinery, we don’t know how it would work.”
Exploring not only that kind of phenomenon but many aspects of our planet is the goal of MIT’s Earth System Initiative (ESI). Led by Chisholm and geologist Kip Hodges, this enterprise is enlisting faculty and students from civil and environmental engineering, and earth, atmospheric, and planetary sciences — ESI’s lead departments — and from other science and engineering areas in studies of Earth.
The researchers aren’t seeking to explain the planet in all its mind-numbing complexity. (Just for starters, it’s estimated that somewhere between one million and 200 million species exist on Earth, most so far undiscovered.) Instead, they’re looking for patterns within that complexity which might help us predict how our world will respond to changing conditions.
To accomplish that, ESI members are doing things like probing the links between the evolution of Earth’s living organisms and non-living structures, and analyzing real-time satellite views of our planet as it changes.
The hope, says Chisholm, is that eventually we’ll understand a lot about how our planetary home functions. That means, for example, having a reasonable chance of predicting how specified changes in the proportions of different sea-borne microbes might affect CO2 levels in the atmosphere.
The initiative is not only raising such questions, it’s also teaching students to tackle them. ESI’s flagship educational offering is Terrascope, a special freshman program focused on Earth system science and engineering. At the heart of Terrascope is the already-successful “Mission” seminar series, led by Hodges. The first in the series, Mission 2004, let teams of freshmen create detailed plans for a manned exploration of Mars. Mission 2005, meanwhile, focused on designing a safe deep-ocean observatory.
The goal of Mission 2006 — the first linked with Terrascope — was to create a hypothetical plan for using the resources of the Amazon River basin while safeguarding its fragile ecology. Having explored issues like how to cut the pollution of the Amazon and protect the rain forest, the students made their final presentations to a panel of outside experts in December.
“I was especially impressed with how they fielded questions,” notes Chisholm, a co-director of Terrascope. “Their answers showed they’d truly immersed themselves in the topic. I kept thinking, ‘Are these really freshmen?'” For the Mission 2006 students involved in Terrascope, the Amazon studies are continuing this semester under Rafael Bras of the civil and environmental engineering faculty. A March trip to Brazil is in the offing.
For Chisholm, meanwhile, the new emphasis on our planet, at MIT and elsewhere, is welcome. A specialist in the microbes called plankton, she’s explored the wonders of oceanic life close-up. One of her early achievements at MIT, in fact, was to discover what may be the most abundant oxygen-producing organism on Earth.
This ocean denizen, dubbed Prochlorococcus, is almost unimaginably tiny. (If you cut a snippet of human hair so it was exactly as long as it was wide, it would still be 10 times the size of this microbe. )She last year convinced the Department of Energy it was vital to map the microbe’s genes — a prelude to exploring how different strains interact with other microbes, and with the broader environment. Such studies, in turn, can help us understand how these tiny entities ultimately help support other forms of life on Earth, including human life. “We need to recognize that we’re now in charge of this planet,” notes Chisholm, “and we want to be able to put our fingers on its pulse and say, ‘This is what we need to do.'”