Dead Zones

• Dead zones refer to places in the ocean with low levels of oxygen. Increased levels of CO2 in the ocean produce these zones. About one-third of the carbon dioxide produced by humans burning fossil fuels ends up in the oceans. More acidic oceans result from this increased CO2. It becomes more difficult for marine animals to take oxygen out of the ocean water to breathe as a result of the higher levels of CO2. This double effect of higher CO2 and lower oxygen means marine life is less likely to find food, reproduce and continue with their way of life.
  
  

Loss of Pasture

• Rising CO2 levels and the corresponding rise in temperatures mean less grass for grazing by animals. In addition to reducing the quantity of pasture land, the rising levels impact the quality of the remaining land. High CO2 levels affect plant nitrogen and protein content, making the soil unable to sustain the plants animals need for food.
  
  

Crop Yields

• Expect diminished crop yields with rising levels of CO2. Plants convert CO2 to sugars through photosynthesis, so plant productivity may rise but any gains may be offset by rising temperatures, which lower productivity according to the United States Global Change Research Program. Other problems for crop yields include weeds and insects, both of whom thrive during periods of high CO2.
  
  

Loss of Habitat

• Rising levels of CO2 impact animal habitats. An example is the big horn sheep of the Sierra Nevada. This animal thrives in a hostile cold mountain environment. That habitat is now threatened by rising temperatures, loss or precipitation and less snow. Its vegetation is not suitable for warmer temperatures and the big horn sheep find their home vanishing. They are not designed for a warm climate and may not survive.