Permafrost puzzle

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Across
  1. 2. water when it's cold and hard
  2. 4. When ice gets warm it's ____
  3. 5. is a natural greenhouse gas also released when you fart
  4. 7. something that causes an explosion
  5. 8. is the gas you breathe out.
  6. 10. is a build-up of ice underneath the ground.
  7. 11. A person who researches and experiments with scientific things
Down
  1. 1. the world is getting warmer and is a worldwide problem
  2. 3. is a hole caused by a methane bomb
  3. 6. Is a lake that is in Alaska and produces a wild amount of methane.
  4. 9. is the biggest country in the world