Global Warming and Natural Disturbances

Global warming refers to the long-term heating of Earth’s climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. This warming trend has significant impacts on the planet, leading to various natural disturbances.

Analyzing Disturbances Related to Global Warming

Let's examine each disturbance listed and determine its connection to global warming:

• A. Coral bleaching: This occurs when corals expel the algae (zooxanthellae) living in their tissues, causing them to turn completely white. Rising sea temperatures, a direct consequence of global warming, are a primary driver of coral bleaching events globally.
• B. Rising sea levels: Global warming causes sea levels to rise primarily through two mechanisms: thermal expansion of seawater as it warms and the melting of glaciers and ice sheets, which adds water to the oceans.
• C. Shifts in species distribution: As temperatures change and climate patterns are altered due to global warming, many plant and animal species are forced to move to new areas that are more suitable for their survival. This leads to shifts in their geographical distribution.
• D. Lowering of sea levels: Global warming generally causes sea levels to rise, not fall. While regional fluctuations can occur due to other factors, a general lowering of sea levels is not a characteristic disturbance caused by global warming on a global scale.
• E. Increase in glacial sheets: Global warming causes glaciers and ice sheets to melt at an accelerated rate, leading to a decrease in their size and volume, not an increase. An increase in glacial sheets would typically be associated with cooling periods.

Identifying the Correct Combination

Based on the analysis, the natural disturbances directly attributable to global warming from the given list are:

• Coral bleaching (A)
• Rising sea levels (B)
• Shifts in species distribution (C)

Disturbances D (Lowering of sea levels) and E (Increase in glacial sheets) are not typical or direct consequences of global warming; in fact, the opposite effects (rising sea levels and melting glaciers) are observed.

Therefore, the combination of disturbances that can be attributed to global warming is A, B, and C.