Climate change and Terrestrial Environments

Global Warming

• Simply put, global warming is the planet heating up.
• It is caused by the injection of greenhouse gases into the atmosphere.
• Greenhouse gases trap heat and prevent it from escaping into space, radiating it back to earth’s surface.

Primary effects of global warming

• Reduction in polar icecaps
  • As the Greenhouse Effect continues, the earth’s temperature will increase, and the icecaps will begin to melt.
  • Given that the icecaps in Antarctica alone represent a water volume equivalent to sea levels of 73.2 meters, this is not an insignificant occurrence.
  • The earth’s albedo will also be reduced, increasing the Greenhouse Effect as more energy is absorbed and radiated back.
• Sea level rise
  • As the earth warms up, oceanic temperatures will increase, and the oceans will begin to expand.
  • Water from the melting icecaps will be added to oceanic volume, raising sea levels substantially.
  • Sea levels are rising now
• Depletion of snowpack and glaciers
  • Glacial lakes and streams will become swollen with meltwater as the glaciers and snowpacks of the world melt.
  • Increased runoff and an earlier spring peak discharge will occur (and already are occuring) in meltwater-fed streams and rivers.

Secondary effects of global warming

• Increased Precipitation
  • Water from icecaps, glaciers, and snowmelt will enter the hydrologic cycle through evaporation/sublimation.
  • The excess water in the cycle will be purged through heavier than normal precipitation, including large amounts of rain.
• Inundation of low-lying coastal and island areas.
  • With the rise in global sea levels, all coasts will be affected in some manner.
  • Low-lying areas, i.e. the Maldives islands (2-3 meters above sea levels) are at extreme risk of total inundation.
  • Continental areas such as river deltas also are at risk. For example the Mississippi River delta loses 100 square kilometers per year, yet sinks in elevation only a centimeter annually.
• Availability of meltwater will decrease over time.
  • Initially melting snowpack and glaciers will increase meltwater supplies, but this is only a temporary phenomenon.
  • In time, meltwater availability will decrease to an extent such that more than one-sixth of the world’s population will be affected.

Impact on Terrestrial Habitats

• Heavy precipitation
  • Heavy precipitation will lead to damage to crops, soil erosion, and an inability to grow anything due to water-logged soil.
  • Low-lying areas will subject to flash floods, and plants such as oaks which do not prosper in a water-rich environment will become stressed.
  • Flooding near rivers will become more common, temporarily eliminating habitats for both humans and animals. Plant life in the area will be replaced with growth capable of surviving inundation.
• Flooding and groundwater contamination
  • As sea levels rise, the high tide mark will rise with them. Low-lying coastal areas will be subject to periodic or permanent inundation, rendering them useless to all non-marine plant and animal life.
  • The vernal pools of California, to use an example, will have their annual flood duration disrupted and possibly contaminated by saltwater infiltration, resulting in a potentially serious disruption of their fragile ecosystems.
  • As ocean levels rise, oceanwater will mix with ground water, contaminating it with salt and harming localized plant life. Especially at risk are the coastal Mangrove groves of the world, and wetlands environments.
  • Rivers and estuaries will also be contaminated, driving freshwater fish and aquatic plants further inland or eradicating them altogether.
• Water stress
  • By mid-century annual river runoff and water availability are predicted to decrease by 10-30% in dry regions at mid-latitudes and the dry tropics.
  • Frequency of droughts will increase, stressing local plant and animal life.
  • Already in the Sahelian region of Africa, warmer and drier conditions have led to a reduced length of growing season with detrimental effects on crops and plant life in general.

Conclusion

• Global warming will result in increased precipitation, sea level rise, and water stress.
• Coastal, low-lying, and river-related habitats will suffer as a result of flooding and saltwater intrusion.
• Plants and animals unable to adapt or flee to new habitats will be extremely stressed and may become endangered or extinct.