1. Global warming refers to the gradual rise in the overall .............. of the atmosphere of the Earth.

temperature

water

air

clouds

2. ............... are also responsible for global warming.

water

volcanic eruptions

food

plants

3. these eruptions release tons of .............. which contributes to global warming.

dust

oxygen

carbon dioxide

sand

4. ............. is also one big issue responsible for global warming.

oxygen

methane

sand

dust

5. China has taken the lead in global-warming pollution, producing about ............. percent of all CO2 emissions.

28

50

36

14

6. we produce a whopping ............. percent of all global CO2 emissions as much as the European Union and India.

12

16

25

30