Fact 1: Carbon dioxide concentrations in the air have increased over the last decade dramatically.

Fact 2: Carbon dioxide is formed by burning carbon.

Given the two facts above, answer the question "Burning carbon concentrations have what?" with the following options: 
- Greenhouse gases
 - Chemical energy
 - reduced significantly
 - increased dramatically
 - Plant growth is reduced
 - heat energy
 - shrunk
 - declined spectacularly


 

    increased dramatically     