The biosphere

All life on Earth exists in the small space on the surface of our planet known as the biosphere. Planet Earth is the only place in our solar system that can sustain life - as we know it.

The biosphere extends from the deepest ocean trenches, about 8 km below the Earth’s surface to approximately 12 km above. Life on Earth is not evenly distributed; the poles have limited life, whilst the tropical rainforests are incredibly diverse.

Scientists estimate that there are between 2 and 100 million species in the biosphere, the best estimate is approximately 10 million. So far science has recorded 1.4 million. More than half of recorded species are classified as insects, 30% are classified as micro-organisms, while the remaining 20% include all other vertebrates (including human beings), invertebrates, flowering and non-flowering plants, fungi, algae, etc.

Only a fraction of the total species which currently live on this planet have been found, identified and described, but all species form part of a complex interacting and interdependent system. Even a minor disruption to any part of that system can produce dramatic consequences for the maintenance of the biosphere on which all life on Earth depends.

'The absolutely best case scenario - which in my opinion is unrealistic - with the minimum expected climate change... we end up with an estimate of nine percent [of all species] facing extinction… The midrange estimate is that 24 percent of plants and animals will be committed to extinction by 2050… We’re not talking about the occasional extinction – we’re talking about 1.25 million species. It’s a massive number.'
Professor Chris D. Thomas, ecologist

A recent assessment report by the Intergovernmental Panel on Climate Change concluded that approximately 20-30% of plant and animal species assessed are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5 to 2.5 degrees.

Humans have a responsibility to care for Planet Earth, to save other species from extinction, to preserve threatened ecosystems, and to reduce and try to reverse the harm that human activity has caused.

There are about 6 billion people on Planet Earth. It is estimated that the population of the planet will probably reach 9 billion by 2050, with most of the growth in developing countries. If everyone in the world used the same amount of resources as people in Scotland we would need three Planet Earths to provide these resources and manage all our waste. It’s up to us to work towards a fairer, more sustainable future.

By 2020 more than 80% of the Earth’s population will live in developing countries and they will all need food, energy and work; all of which have implications for the future of climate change.

The consumption of scarce resources is in itself contributing to global warming. Oil, gas, coal and even uranium will eventually run out. The first two may already have reached their maximum production levels with no new fields to be found. We need to reduce our consumption of the Earth’s resources to a sustainable level, end our reliance on fossil fuels, and cut emissions of associated greenhouse gases.

Photo credit: Image courtesy NASA Johnson Space CenterGateway to Astronaut Photography of Earth

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