bio 1m03 Questions and Answers

Short term carbon cycle Answer Photosynthesis to respiration Rates of respiration vs photosynthesis Answer Roughly equal Explain the seasonal variation in CO2 levels Answer Follows the seasonal activity of plants, plants become more active = less CO2 in the air. Plants die around winter seasons = more CO2 in the air. More pronounced in the Northern Hemisphere (where there are more plants) than the Southern Hemisphere. Equator remains largely unaffected, as climate is more constant there. Keeling curve Answer Daily record of global CO2 levels in the air that shows the rise and fall on a seasonal basis, and the overall increase on a yearly basis How did they figure out CO2 levels of the years before Keeling? Answer Drilled into ice (Law Dome)- trapped CO2 in the ice that could be measured What did scientists find after drilling into the Law Dome? Answer Before industrial revolution (before early 1800s) , atmospheric CO2 levels varied little over the years (270 ppm - 280 ppm) What did Hans Suess find? Answer Observed that the ratio of 13C:12C (less 13C) isotope in atmospheric CO2 has declined as the total amount of CO2 increased. This allows us to conclude that burning of fossil fuels by industrialized societies has been a principal source of CO2 buildup in the Earth's atmosphere (ratio of 13:12 C in organic matter formed by photosynthesis matches the ratio found in the atmosphere) What pattern was found in 14C? Answer 14C has also been decreasing. Modern organic matter has too much 14C compared to the atmospheric levels, meaning the source comes from burning ancient organic matter. How much CO2 do humans add to the atmosphere yearly Answer 40 billion metric tons Where does human added CO2 end up Answer Half in atmosphere, half in CO2 sinks (oceans, vegetations, forests, soils etc