Introduction to the Earth system

Question 1

What is the Earth System?

Answer 1

The Earth System is the atmosphere, biosphere, lithosphere, cryosphere and hydrosphere treated as one entity: a functioning system at the surface of the planet with linkages comprising energy and matter.

Question 2

Why is the Earth System dynamic?

Answer 2

The different spheres are ever-changing as a result of external energies (eg. sunlight, geothermal) and internal transformations (eg. rock weathering – and increasingly by humans).

Question 3

Earth System - Gaia

Answer 3

The idea of a the earth as a functioning system was an element in James Lovelock’s Gaia hypothesis (1970s).
It was at first rejected but gradually taken up as global environmental issues (like climate change) have become as important as local and regional ones.

Question 4

What does the Gaia hypothesis suggest?

Answer 4

There is a planetary, homeostatic control of the concentration of molecular oxygen in the atmosphere.

If the atmospheric concentration of oxygen was ~25% instead of ~21%, then large scale fires would be more common and severely damaging to Earth’s ecosystems and species.

Question 5

As humans have increasingly interacted with the earth, the study of earth system science becomes more relevant to human futures.

Answer 5

Human activities over the millennia have modified many parts of the earth system and may now be affecting the earth system as a whole - through atmospheric emissions, for example carbon dioxide (CO2) and methane (CH4), affecting global climate.

Earth’s major systems are now changing more rapidly than at any time in the last half million years (at least)
Many of these changes are pushing the planet into hitherto uncharted territory – it has never been here before