Correct Option: C. Global Warming
Detailed Explanation:
- Understanding Sea Level Rise:
-
Sea level rise refers to the increase in the average level of the world's oceans. This phenomenon is primarily caused by two main factors: thermal expansion of seawater as it warms and the addition of water from melting ice sheets and glaciers.
-
Role of Global Warming:
- Global Warming Defined: Global warming is the long-term increase in Earth's average surface temperature due to human activities, primarily the burning of fossil fuels, which increases concentrations of greenhouse gases in the atmosphere.
- Thermal Expansion: As global temperatures rise, ocean water warms and expands. This thermal expansion contributes significantly to rising sea levels.
-
Melting Ice: Global warming leads to the melting of polar ice caps and glaciers. The Greenland and Antarctic ice sheets are particularly significant contributors to sea level rise. As these ice masses melt, they release freshwater into the oceans, further increasing sea levels.
-
Evidence Supporting Global Warming as the Cause:
- Scientific studies and climate models consistently show a correlation between rising global temperatures and rising sea levels. The Intergovernmental Panel on Climate Change (IPCC) reports provide extensive data on this relationship, indicating that the rate of sea level rise has accelerated in recent decades due to increased global temperatures.
Why Other Options Are Incorrect:
- A. Excessive Rainfall:
-
While excessive rainfall can lead to localized flooding and temporary increases in water levels in certain areas, it does not contribute to a global rise in sea levels. Rainfall is part of the hydrological cycle and does not add to the overall volume of the oceans.
-
B. Excavation of Sand from Ocean Beds:
-
Excavating sand from ocean beds can have localized effects on coastal erosion and sediment distribution, but it does not significantly impact global sea levels. The volume of sand removed is negligible compared to the vast volume of water in the oceans.
-
D. Man-Induced Erosion Along Sea Coasts:
- Coastal erosion can lead to the loss of land and may affect local sea levels in specific areas, but it does not contribute to a global rise in sea levels. Erosion is a natural process that can be exacerbated by human activities, but it does not add water to the oceans.
Summary of Key Points:
- Global warming is the primary driver of rising sea levels due to thermal expansion and melting ice.
- Excessive rainfall, sand excavation, and coastal erosion do not contribute significantly to global sea level rise.
- Understanding the causes of sea level rise is crucial for addressing climate change and its impacts on coastal communities.
Revision Summary:
- Sea level rise is primarily caused by global warming.
- Thermal expansion and melting ice sheets are key contributors.
- Localized factors like rainfall and erosion do not affect global sea levels.
- Scientific consensus supports the link between rising temperatures and sea level rise.