CHAPTER 23 Summary

• Ecosystems are made up of the living and nonliving components of an environment, including the communities of organisms present and the physical and chemical environment with which they interact.
• Temperature is an important physical feature of any ecosystem and serves as a clock that cues many biological events, such as breeding, blooming, and hibernation.
• Biomes are large, geographically distinct ecosystems, defined by their characteristic plant life, which in turn is determined by temperature and levels of moisture.
• Climate change is a persistent pattern of change in Earth’s climate. Global warming is an increase in Earth’s average temperature over time.
• Climate change, and especially global warming, is having widespread effects on plant and animal life on the planet—altering seasonal life cycles, shifting ranges, and contributing to species loss by extinction.
• The greenhouse effect is a natural process by which heat radiated from Earth’s surface is absorbed by heat-trapping gases in the atmosphere, maintaining a global temperature that can support life. Rising levels of greenhouse gases have led to the enhanced greenhouse effect.
• Elements cycle through ecosystems. The carbon cycle is the movement of carbon atoms through living and nonliving components of the environment by the biotic processes of photosynthesis, cellular respiration, and decomposition, as well as by long-term geological processes.
• Global warming results from an increase in the amount of carbon dioxide and other greenhouse gases in the atmosphere; the warming that has occurred over the past half century is due largely to human activities, such as burning fossil fuels and deforestation.
• Global warming is leading to the melting of sea ice in the Arctic, which is diminishing habitat for the organisms that rely on sea ice and creating a positive feedback loop for increased warming. Melting glaciers and ice caps on land are leading to rising sea levels.
• Methane is a significant greenhouse gas whose levels have increased because of human activities, including raising cattle and farming rice in paddies.

• MORE TO EXPLORE

  • NASA Goddard Institute for Space Studies http://www.giss.nasa.gov/
  • National Snow and Ice Data Center http://nsidc.org/
  • NOAA, Earth System Research Laboratory, Trends in Atmospheric Carbon Dioxide (animation) http://www.esrl.noaa.gov/gmd/ccgg/trends/history.html
  • Ilya M. D. Maclean, I. M. D., and Wilson, R. J. (2011) Recent ecological responses to climate change support predictions of high extinction risk. Proceedings of the National Academy of Sciences 108:12337–12342.
  • Oreskes, N., and Conway, E. M. (2010) Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. New York: Bloomsbury Press.
  • Kolbert, E. (2006) Field Notes from a Catastrophe: Man, Nature, and Climate Change. New York: Bloomsbury Books.