Climate Change and Cloud Cover Decline

In 2023, global mean temperatures surged to nearly 1.5 degrees Celsius above pre-industrial levels. This rise is influenced by a notable decline in low-altitude cloud cover. Research indicates that low-altitude clouds, essential for cooling the planet by reflecting sunlight, have decreased by 1.5 per cent compared to average levels. This trend continues a decade-long reduction of 1.27 per cent. The loss of these clouds has led to a measurable decline in planetary albedo, which is the fraction of solar radiation reflected back into space.

About Planetary Albedo

Planetary albedo is critical for regulating Earth’s temperature. It measures how much solar energy is reflected versus absorbed. A decrease in albedo means more heat is retained, contributing to rising temperatures. Approximately 15 per cent of the albedo decline is attributed to the loss of Arctic snow and sea ice, which are vital for reflecting sunlight.

Impact of Low-Altitude Clouds

Low-altitude clouds play role in cooling the Earth. Their decline has been particularly pronounced over northern mid-latitudes and tropical oceans, especially in the Atlantic. This loss is alarming as it correlates with a substantial increase in global temperatures. The eastern North Atlantic has seen drop in low-altitude clouds, contributing to unusual temperature records.

Factors Contributing to Temperature Rise

The research identifies several factors contributing to the temperature surge. The El Niño phenomenon, long-term greenhouse gas emissions, and increased solar activity are primary drivers. Additionally, volcanic eruptions and reduced aerosol particles in the atmosphere may play a role. However, there remains a 0.2 degrees Celsius increase without a clear cause.

Aerosols and Cloud Formation

Aerosols are tiny particles that influence climate and weather. They are crucial for cloud formation and can reflect sunlight. Stricter regulations on marine fuel have led to lower aerosol concentrations, potentially explaining the decline in cloud cover. This reduction may also be linked to natural fluctuations in weather patterns and ocean feedbacks.

Future Implications

The research warns that if the decline in albedo is primarily due to interactions between global warming and low clouds, future warming could become more intense. This marks the urgent need for climate action to mitigate these effects.

Questions for UPSC:

1. Examine the role of low-altitude clouds in regulating Earth’s temperature.
2. Critically discuss the implications of declining planetary albedo on global warming.
3. Analyse the factors contributing to the rise in global temperatures in 2023.
4. Point out the relationship between aerosols and cloud formation in the context of climate change.

Answer Hints:

1. Examine the role of low-altitude clouds in regulating Earth’s temperature.

1. Low-altitude clouds reflect sunlight, helping to cool the Earth.
2. The decline in these clouds has contributed to a measurable drop in planetary albedo.
3. They play important role in maintaining the Earth’s energy balance.
4. Loss of low-altitude clouds correlates with increased global temperatures, especially in the Atlantic.
5. Continued decline may lead to more intense warming in the future.

2. Critically discuss the implications of declining planetary albedo on global warming.

1. A decrease in planetary albedo means more solar energy is absorbed, raising temperatures.
2. Approximately 15% of the albedo decline is due to loss of Arctic ice and snow.
3. Lower albedo can create a feedback loop, accelerating global warming.
4. Research indicates 2023 saw the lowest albedo levels since at least 1940.
5. Future climate scenarios suggest that continued decline in albedo could exacerbate warming trends.

3. Analyse the factors contributing to the rise in global temperatures in 2023.

1. El Niño phenomenon impacts global temperature fluctuations.
2. Long-term anthropogenic greenhouse gas emissions are primary contributors.
3. Increased solar activity and volcanic eruptions also play roles in temperature rise.
4. There remains an unexplained 0.2 degrees Celsius increase attributed to other factors.
5. Declining low-altitude cloud cover is a critical factor in the temperature surge.

4. Point out the relationship between aerosols and cloud formation in the context of climate change.

1. Aerosols are essential for cloud formation and can influence climate and weather patterns.
2. Stricter regulations on marine fuel have led to reduced aerosol concentrations.
3. Lower aerosol levels may contribute to the decline of low-altitude clouds.
4. Aerosols can reflect sunlight, impacting the Earth’s energy balance.
5. The interplay between aerosols and clouds is crucial in understanding climate change dynamics.