Choose the correct option

1. Carbon dioxide is dangerous because it [traps|catches] heat in the Earth's atmosphere.
2. Arctic polar bears are in [danger|threat] of losing their natural habitat.
3. Global warming is causing the Earth to [heat|rise up].
4. Power plants burn fossil [gases|fuels] like coal to create energy.
5. Dangerous gases like carbon dioxide [surround|hold] the planet.
6. The ice [sheets|blankets] that cover Greenland and Antarctica are melting rapidly.
7. Scientists believe that global warming may be the cause of [hard|extreme] weather-related natural disasters such as floods.