Which of the following is not a major positive feedback mechanism in which the activity of humans to increase global climate temperatures leads to an even further increase?

Options

A. Global warming causes increased rainfall, plant growth and photosynthesis
B. Global warming causes increased CO, release from biomass decomposition
C. Tropical deforestation causes warming and drying so that remaining forests begin to decline
D. Global warming causes snow to melt in polar regions and therefore increases global albedo

Answer

To solve the question of which option is not a major positive feedback mechanism related to human activities increasing global climate temperatures, we can follow these steps:

### Step 1: Understand Positive Feedback Mechanisms
Positive feedback mechanisms are processes that amplify or increase the effects of a change. In the context of climate change, this means that as temperatures rise due to human activities (like greenhouse gas emissions), certain processes can further increase temperatures.

### Step 2: Identify the Given Options
We need to look at the options provided in the question (not listed in the transcript) and evaluate each one to determine if it is a positive feedback mechanism.

### Step 3: Analyze Each Option
- **Option A:** If it states that global warming causes increased rainfall, this would not be a positive feedback mechanism because increased rainfall could lead to more plant growth and photosynthesis, which are generally beneficial and do not contribute to further warming.

- **Option B:** If it states that global warming causes increased carbon monoxide release from mass decomposition, this is a positive feedback mechanism because it indicates that warming leads to more decomposition, which releases more greenhouse gases.

- **Option C:** If it states that global warming causes deforestation, this is also a positive feedback mechanism because deforestation leads to higher CO2 levels, which further warms the planet.

- **Option D:** If it states that global warming causes snow to melt in polar regions, this is a positive feedback mechanism as melting ice reduces the albedo effect, leading to more heat absorption and further warming.

### Step 4: Determine the Correct Answer
Based on the analysis, the option that does not represent a major positive feedback mechanism is likely the one that indicates increased rainfall leading to more plant growth and photosynthesis, as this does not contribute to further warming.

### Conclusion
The correct answer to the question is the option that states global warming causes increased rainfall, which leads to more plant growth and photosynthesis.

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