Question

Which of the following is responsible for the anthropogenic climate change phenomenon?

• A. Volcanic eruption
• B. Variation in earth’s orbital characteristics or Milankovitch cycles
• C. Variation in solar output
• D. Effect of green house gases

Hint:

Always look for the word "anthropogenic," which means human-induced.
This immediately points to the burning of fossil fuels and the resulting accumulation of greenhouse gases in the atmosphere.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Climate change is driven by both natural processes and human activities.
"Anthropogenic" refers specifically to environmental changes or influences that originate from human activities.
To identify the primary driver of anthropogenic climate change, we must separate human-caused factors from natural geological or astronomical variations.

Step 2: Detailed Explanation:
Let us analyze the given options to distinguish between natural and human-caused factors:
- Volcanic eruption: This is a natural geological process.
Volcanoes release particulate matter, sulfur dioxide, and some carbon dioxide into the atmosphere, which can cause temporary, short-term changes in local and global climates. This is not an anthropogenic cause.
- Milankovitch cycles: These are natural variations in the Earth's orbital eccentricity, axial tilt (obliquity), and precession over tens of thousands of years.
These cycles alter the seasonal and latitudinal distribution of solar energy reaching the Earth, driving long-term climate cycles like ice ages. This is not an anthropogenic cause.
- Variation in solar output: This refers to natural changes in the sun's energy emission, such as those associated with sunspot cycles.
While these affect the Earth's energy balance over long periods, they are entirely natural.
- Effect of greenhouse gases (GHGs): The industrial revolution led to a dramatic increase in human activities, including fossil fuel combustion, deforestation, intensive agriculture, and industrial production.
These activities have released massive quantities of greenhouse gases—such as carbon dioxide (\( \text{CO}_2 \)), methane (\( \text{CH}_4 \)), and nitrous oxide (\( \text{N}_2\text{O} \))—into the atmosphere.
These gases trap outgoing longwave infrared radiation, warming the lower atmosphere.
This enhanced greenhouse effect is the primary driver of rapid global warming and associated climate change since the mid-20th century.

Step 3: Final Answer:
The factor responsible for anthropogenic climate change is the enhanced greenhouse effect caused by greenhouse gases.