The Curiosity rover is currently trundling its way across the surface of Mars in a quest to understand if Mars was ever able to support life and perhaps even detect evidence of past life. We’ve come a long way from fearing an attack from a hostile Martian civilisation. The Earth is at no risk from Martian rockets, heat rays or tripods. Mars, like our other nearest Solar System neighbour Venus, is a barren world devoid of any life. Why is the Earth the way it is and not more like Mars or Venus?
Prior to joining the Institute for Complex Systems Simulation at the University of Southampton I thought about this question rather a lot. It was a central part of my previous job as a member of the Helmholtz Alliance funded Planetary Evolution & Life project that I worked on at the Max Planck Institute for Biogeochemistry in Jena.
But my interest in this question predates my time in Germany.
It’s seems clear that the emergence and evolution of life has profoundly affected the Earth. So part of the answer to why the Earth is the way it is will involve an appreciation of the effects of life. We are reminded by this every time we take a breath. 21% of the Earth’s atmosphere is composed of oxygen. This very reactive element is at such high concentrations because of photosynthetic life: trees, algae etc. In that respect we, and other oxygen breathing eukaryote life forms, are connected to carbon dioxide breathing autotrophic life forms.
The more we look at the Earth, the more we see these connections. An atom of carbon can be recycled many times in many different organisms during its voyage around the biosphere. Biogeochemistry is very much the study of natural recycling processes. I’m not a chemist. Or a biologist. Or geologist. But fortunately for me, I do know some very good ones. I tend to be interested in the connections in a more abstract sense. The Earth system is a very complicated or complex highly connected system. How did these connections emerge, how are they maintained, how stable are they and how may they change in the future? What are they systemic properties of the Earth system? I thought about these questions during my doctorate at the University of Sussex by exploring a conceptual model of a biosphere called Daisyworld.
As well as some rather rarified academic interests in this area, there are a range of real world issues that urgently need to be addressed. The fact of the matter is that we are currently undertaking a number of global scale experiments on the Earth system. Here are two important examples:
- What happens to the Earth’s climate if we increase the amount of carbon dioxide in the Earth’s atmosphere to levels unprecedented in the previous 800,000 years?
- What happens to ecosystem and biosphere functioning if we reduce the number of species by hunting and habitat change so much that we are in the middle of what some argue to be one of the more significant mass extinction events in the history of life on Earth?
I think it’s fair to say that we don’t exactly know the answer to these and similar questions. Given the potential consequences then this is worrying. Not for the Earth (if it could worry about anything). It will continue to turn. Nor the biosphere. Life will continue in some form irrespective of what we do. It’s not even particular worrying for adults alive right now (no more than the other things that we continually worry about).
But it is a worry for future generations. And it may even be a worry for young people today because the impacts of our experiments may start to be felt in their lifetimes. So the question that guides my research is:
Why is the Earth system the way it is and how are we affecting it?
If you have any answers or insights, then do please get in touch.