9.5 Global Climate Change

Heating and Cooling Climate Cycles

The Earth has naturally experienced large-scale climate shifts over time. Scientists are able to track past climate by studying CO2 concentrations in ice cores. In very cold places, snowfall compacts and becomes ice.  Bubbles in the ice are small samples of the atmosphere that existed when the snow originally fell—meaning they can be analyzed to determine the levels of gases, such as carbon dioxide and methane, and pollutants in the atmosphere at the time the ice formed. 

Some places in Antarctica have ice that is 500,000 years old. These ice samples can tell scientists about historic atmospheric CO2 concentrations. Periods of high CO2 concentration translate to a warmer climate.

The Earth naturally disperses heat from the equator towards the poles via atmospheric and oceanic circulation.  These currents circulate warm water and air to the poles and cool water and air back toward the equator. Climate change may disrupt these patterns, causing a large impact on global climates. Scientists have been able to create computer models to predict future global temperatures based on little, moderate, or high growth of CO2 emissions—estimating a temperature increase of 1.8 Degrees Celsius by 2,100. 

The Poles and Positive Feedback Loops

Effects of climate change include rising temperatures, melting permafrost and sea ice, rising sea levels, and displacement of coastal populations.

As the poles warm, the ice and snow will melt. Consequently, less solar radiation is reflected by white surfaces back into space. Once more solar radiation is absorbed in polar regions, the poles will warm even faster. This process creates a positive feedback loop for warming. 

Moreover, snow and ice melt results in the loss of habitat for creatures like seals, walruses, and polar bears.  The thawing of polar areas also leads to the decomposition of large quantities of previously frozen biomass. This decomposition releases methane and further adds to the increased rate of climate change. 

In addition, the melting of vast areas of ice will increase the amount of water in the ocean, causing flooding in low-lying coastal areas worldwide. Marine ecosystems are affected by changes in sea level. While flooded continental shelves create new habitats, deeper communities may be pushed outside the photic zone (sunlight layer) of seawater. 

Image Courtesy of Wikimedia

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