2. Which is not one of the theories on global warming:
the Sun is the cause humans are responsible caused by erratic weather

3. Burning fossil fuels may contribute to global warming because:
they don't dissipate they contain PCBs carbon is trapped in atmosphere

4. Every year fossil fuels emit ___ tons of carbon:
6,000,000,000 16,000,000,000 26,000,000,000

5. Carbon dioxide content in the atmosphere has increased 13% because of:
decaying plants factory output oxygen & carbon interaction

6. One theory says 55% of the greenhouse pollutants in the form of carbon dioxide comes from:
biomass burning fossil fuels factory output

7. Our atmosphere allows which 3 gasses through to the Earth's surface:
water vapor, carbon dioxide, methane water vapor, carbon dioxide, helium water vapor, carbon monoxide, methane

8. The greenhouse effect is:
a man-made process an environmental process a natural process