What makes earth life sustaining

In particular, understanding the processes that can maintain or lead to the loss of habitability on a planet requires the use of multiple coupled models that can examine these processes in detail, especially at the boundaries where these processes intersect each other. By studying ways that biospheres interact with planetary environments, SEEC researchers are pioneering methods to detect life on other worlds.

Planetary habitability results from a complex network of interactions between the planet, its planetary system, and host star. In our quest to find life outside of our solar system, we look for planets that resemble Earth, the only planet that we know of that is habitable. Biodiversity provides a large number of goods and services that sustain our lives. At the Earth Summit in Rio de Janeiro, world leaders agreed on a comprehensive strategy for "sustainable development" -- meeting our needs while ensuring that we leave a healthy and viable world for future generations.

One of the key agreements adopted at Rio was the Convention on Biological Diversity. This pact among the vast majority of the world's governments sets out commitments for maintaining the world's ecological underpinnings as we go about the business of economic development. For instance, while liquid water might not currently persist on the surface of Mars or Venus, there may have been a time when it did. Life might have evolved on their surfaces in that time, and then either fled to safer locales on those planets, such as underground, or adapted to the environment when it became harsh, much as so-called extremophile organisms have on Earth, or both.

In addition, other solvents might host life. The most obvious source of energy is a planet or moon's host star, as is the case on Earth, where sunlight drives photosynthesis in plants. The nutrients created by photosynthesis in turn are what the bulk of life on Earth directly or indirectly relies on for fuel. Still, countless organisms on Earth subsist on other sources of energy as well, such as the chemicals from deep water vents.

There may be no shortage of energy sources for life to live off. Scientists have argued that habitable worlds need stars that can live at least several billion years, long enough for life to evolve, as was the case on Earth.

Some stars only live a few million years before dying. Still, "life might originate very fast, so age is not that important," astrobiologist Jim Kasting at Pennsylvania State University told OurAmazingPlanet. Coastal mangroves, a vital nursery habitat for countless species, are also vulnerable, with half already gone. Global atmospheric changes, such as ozone depletion and climate change, only add to the stress. A thinner ozone layer lets more ultraviolet-B radiation reach the Earth's surface where it damages living tissue.

Global warming is already changing habitats and the distribution of species. Scientists warn that even a one-degree increase in the average global temperature, if it comes rapidly, will push many species over the brink.

Our food production systems could also be seriously disrupted. The loss of biodiversity often reduces the productivity of ecosystems, thereby shrinking nature's basket of goods and services, from which we constantly draw. It destabilizes ecosystems, and weakens their ability to deal with natural disasters such as floods, droughts, and hurricanes, and with human-caused stresses, such as pollution and climate change.

Already, we are spending huge sums in response to flood and storm damage exacerbated by deforestation; such damage is expected to increase due to global warming. The reduction in biodiversity also hurts us in other ways.

Our cultural identity is deeply rooted in our biological environment. Plants and animals are symbols of our world, preserved in flags, sculptures, and other images that define us and our societies. We draw inspiration just from looking at nature's beauty and power. While loss of species has always occurred as a natural phenomenon, the pace of extinction has accelerated dramatically as a result of human activity.