Complete the summary with the words from the text.

Global warming happens because we burn ... which produce . ... These will o ... ur world by up to three degrees C, which means big . ... Mountain glaciers and the
a ... re fa ... st! Parts of the world in are ... as may comp ... letely in 100 years. Many animals are also in great , lik ... e the polar bear, which may
. Ext ... reme weather such as hurricanes and will ... also become more frequent.