Global Warming Explained and Acidification of Oceans
Global Warming
The Earth's climate is different from what it was only 20,000 years ago when ice sheets covered much of the Northern Hemisphere. Since the industrial revolution humans have been dumping exhaust from burning fossil fuels into the atmosphere, thereby significantly increasing the amount of carbon dioxide (CO2) in the atmosphere. This “extra” CO2 increases the natural capacity of the atmosphere to trap radiant heat near the Earth's surface. This trapping is called the greenhouse effect that works in the following manner. Solar energy reaching the Earth's surface warms the lower atmosphere. Gases such as water vapor and CO2 trap a large fraction of this heat near the Earth's surface. The natural greenhouse effect, not aided by human emissions, is responsible for keeping our planet at a livable temperature—around 33C on average at the surface. The concentration of greenhouse gases in the atmosphere determines how much heat is trapped. Even seemingly small human-induced addition of greenhouse gases have already resulted in the average global temperature increasing around 0.8oC in the last 100 years. Without technology that allows us to switch off our fossil-fuel lifestyle yet maintain or improve our typical life style that we have today, within the next century the global average temperature could continue to warm by 1C if we are quite lucky, 6C if we are unlucky or up to 12oC or more if we are very unlucky. This could result in ecologically significant changes, which are why climatic considerations are fundamental in the discussion of possible ecological consequences of wildlife.
Acidification of Oceans
Besides increasing the average global temperature, the added CO2 in the atmosphere is discernibly changing the pH balance of the oceans. The CO2 concentration is greater in the atmosphere than in the oceans, meaning that at the air-water boundary CO2 is diffusing into the water. The carbonic acid that forms in the water has already discernibly changed the oceans pH from 8.0 - 8.3 (before the industrial revolution) to 7.9 – 8.2. If we do not change away from how we currently use fossil fuels, The Royal Society of the United Kingdom has estimated by 2100 the pH range could be 7.5 – 7.8. Coral reefs and other structure built by animals using calcium carbonate (e.g., shells) will not only be difficult to build, but those that are built will dissolve. Obviously this will be detrimental to marine organisms, but we will also be affected because ocean fisheries will most likely be negatively affected and reefs that protect the shores during large storms could be so weaken or eroded to be of little use. Scientist in The Royal Society warn that even if we curtailed our CO2emissions in 2010, the pH change already evident in the oceans will take tens of thousands of years to return to pre-industrial levels. What we are doing today will truly impact the lives of people over 500 generations from now.
Further Resources
Intergovernmental Panel on Climate Change (IPCC). 2001. Climate Change 2001: Impacts, Adaptations, and Vulnerability. Cambridge University Press, NY.
The Royal Society. 2005. Ocean acidification due to increased atmospheric carbon dioxide. Policy document 12/05.