Are we and Earth coupled?

We and Earth are part of a single system. We affect nature, and nature affects us, in endless cycles.

Coupled. Joined together. Linked.

That’s what scientists believe we are, with Earth. Scientists sometimes call us and Earth a coupled human-Earth system, or a coupled human-natural system. Dr. Robert B. Waide, executive director of the Long Term Ecological Research Network Office and member of EarthSky’s Global Science Advisory Council – explained this concept to Jorge Salazar in a recent EarthSky interview.

In his interview, Waide used the language of science when he spoke of ecosystem services, which is a phrase that describes aspects of nature upon which we humans depend: air, water, plants, metals, sunshine, essentially everything tangible. But even the concept of ecosystem services doesn’t go deeply enough for most people. The words don’t convey the depth of our bond with Earth. It’s not just that nature provides services for us, upon which we depend. It’s also that, in acquiring those services – by the simple fact of our living on this planet – we humans in turn affect nature powerfully. Dr. Waide spoke to Salazar about scientists’ emerging understanding of the deeply-interwoven interactions between human and natural systems. He said:

We can no longer understand either natural or human systems by themselves. They’re deeply interwoven, and they each have long-term dynamics which influence the operation of those systems. So, in fact, humans behave in certain ways that effect the function and the structure of the ecosystems around them, and therefore effect the ecosystem services that come back to humans from those ecosystems.

It isn’t just that we live on Earth. It’s that we and Earth are joined together. Examples of our bond with Earth are all around us, and always have been. That’s what Jared Diamond was getting at in his book Collapse, which described societies that failed due to deforestation, fertility losses in soil, overhunting, overfishing, water management problems, or that most integral of issues, human population growth.

Here’s an illustration. In 2005, when Hurricane Katrina initiated a tragic illustration of a coupled human-environment system along the Gulf Coast. What began as a natural event, a hurricane, became a human disaster as levees broke and New Orleans flooded. Afterwards, contaminated water from the city had to be pumped back into the Mississippi River and Lake Pontchartrain, as environmental experts warned of devastating effects to surrounding wetlands. The secondary damage caused by polluted flood waters then impacted humans again, economically. And so the human and natural impacts cycled back and forth, dependent on each other: coupled.

Or here’s another illustration, in Texas, closer to home for me. The magnificent Big Bend National Park provided an ecosystem service to ranchers in the 1800s, who grazed their cattle on the vast fields of tobosa grass there. In other words, nature was affecting humans, providing a service. But in only decades beautiful Big Bend was overgrazed, and ocotillos and prickly pear replaced the grass. Humans had affected nature. Today, though, many people now find the desert landscape in Big Bend restful and enchanting, and the area has become a sanctuary to the hundreds of thousands of people each year who view the park from scenic overlooks or hike on designated trails. Nature is affecting humans again, providing new ecosystem services (spiritual rejuvenation and recreation).

And so it goes, with nature affecting us, and us affecting nature, back and forth. The examples I just gave are big ones, but you can find little ones as close as your suburban backyard. That’s because, no matter where you are on Earth, you and Earth are part of a single system. This is what many scientists today are trying to parse and analyze. In fact, the study of the human-Earth system is a priority area for the National Science Foundation via its Biocomplexity in the Environment program. A fall 2008 deadline has just passed for scientists to submit proposals to study the dynamics of coupled natural and human systems. Looking at the 2008 awards in this area, you get a glimpse of just how minute and detailed those scientific studies have to be, in order for scientists to make progress in understanding our connection to Earth.

My guess is that, as this century progresses, the understanding that humans and Earth are linked will become better known. It might become as powerful and ubiquitous in human culture as Albert Einstein’s revelation early in the 20th century that space and time are linked. Today’s astrophysicists will correct you if you speak of space and time separately. Astrophysicists have coined a new word – spacetime – which has become familiar to many people. In a way that’s similar, will many people come to understand that we don’t just live on Earth? Will we and our children come to recognize that, in the deepest possible sense, we and Earth are one thing?

Here in late 2008, with few people on Earth recognizing the vital link between us and the planet, we do harmful things to Earth that might ultimately harm ourselves. Will people come to see themselves as coupledjoinedlinked to Earth? Consider that this recognition could lead to a more harmonious, more beautiful and safer place to live if an older and wiser human species learns to take care of Earth, much as older people learn through necessity to take care of their own bodies.

Deborah Byrd