Global systems

7. single-celled organisms, some of which are crucial to the recycling of nitrogen through the atmosphere and living and dead things
8. all living things on the Earth
9. the variety of ecosystems and organisms found on Earth
11. all the water on the Earth
12. the outermost rocky layer of the Earth consisting of the mantle and the crust
13. the circular patterns shown by the ocean currents in the major ocean basins

1. chemical compound consisting of one carbon and two oxygen atoms that is a major greenhouse gas
2. fuels that contain carbon which comes from the remains of plants and animals that died and were preserved millions of years ago
3. the conditions of the air in the atmosphere on Earth, at any one time and place
4. weather conditions at a particular place over a long period of time
5. the layers of gases that surround the Earth
6. the process by which carbon on Earth is cycled through living and dead things, and through the soil, water and atmosphere
10. chemical compound consisting of one carbon and four hydrogen atoms that is a potent greenhouse gas