Rising CO2 Emissions and Global Warming

India’s carbon dioxide emissions from fossil fuels are projected to increase by 4.6% in 2024. This rise is the highest among major economies. The Global Carbon Project reports that global fossil-based CO2 emissions will reach a record 37.4 billion tonnes. This trend suggests an important risk of global warming exceeding 1.5 degrees Celsius within six years.

About Greenhouse Gases

Greenhouse gases (GHGs) trap heat in the Earth’s atmosphere. They include carbon dioxide (CO2), methane (CH4), and water vapour. The Sun emits shortwave radiation, which warms the Earth’s surface. The surface then emits infrared radiation, which is absorbed by GHGs. This process creates the greenhouse effect, essential for maintaining life on Earth.

Role of Carbon Dioxide in Climate Change

CO2 is the primary driver of climate change. It is responsible for about 70% of global warming. The Intergovernmental Panel on Climate Change (IPCC) found that CO2 has the highest positive radiative forcing compared to other climate drivers. This means CO2 has the greatest warming effect on the planet.

Concentration Levels of Greenhouse Gases

The concentration of GHGs has risen since the Industrial Revolution. Before this period, levels were relatively stable. Human activities, particularly fossil fuel combustion, have increased CO2 levels by 50%. Currently, CO2 levels are 150% of pre-industrial values.

Longevity of Carbon Dioxide in the Atmosphere

CO2 remains in the atmosphere much longer than other GHGs. About 40% of emitted CO2 stays for 100 years. In contrast, methane has a much shorter lifespan, converting to CO2 within a decade. This long atmospheric presence of CO2 contributes to its warming effects.

Impact of Water Vapour

Water vapour is the most abundant GHG. However, it has a short atmospheric cycle of about 10 days. It does not accumulate like CO2. As temperatures rise, more water evaporates, leading to increased warming. This creates a feedback loop that exacerbates climate change.

Future Projections

With current emission trends, the situation is alarming. The increase in CO2 emissions and the potential for exceeding critical temperature thresholds highlight the urgent need for action. Reducing fossil fuel dependency and enhancing sustainable practices are crucial for mitigating climate change.

Questions for UPSC:

1. Critically analyse the role of carbon dioxide in anthropogenic climate change.
2. Explain the greenhouse effect and its significance for life on Earth.
3. What are the long-term impacts of increased carbon dioxide levels in the atmosphere? Discuss with examples.
4. What is the significance of water vapour in the climate system? How does it interact with other greenhouse gases?

Answer Hints:

1. Critically analyse the role of carbon dioxide in anthropogenic climate change.

1. CO2 is the primary greenhouse gas, responsible for about 70% of global warming.
2. Its concentration has increased by 50% since the Industrial Revolution, impacting climate systems.
3. CO2 has the highest positive radiative forcing compared to other climate drivers, leading to greater warming effects.
4. Unlike other GHGs, CO2 remains in the atmosphere for centuries, prolonging its impact on climate change.
5. Human activities, particularly fossil fuel combustion, are the main contributors to rising CO2 levels.

2. Explain the greenhouse effect and its significance for life on Earth.

1. The greenhouse effect is the process by which GHGs trap heat in the Earth’s atmosphere, maintaining a stable temperature.
2. This effect is essential for life, as it keeps the planet warm enough for liquid water and biological processes.
3. Sunlight is absorbed by the Earth’s surface and re-emitted as infrared radiation, which is then trapped by GHGs.
4. Without the greenhouse effect, Earth would be too cold to support most forms of life.
5. However, excessive GHG concentrations can enhance this effect, leading to global warming and climate instability.

3. What are the long-term impacts of increased carbon dioxide levels in the atmosphere? Discuss with examples.

1. Increased CO2 levels lead to higher global temperatures, resulting in climate change and extreme weather events.
2. Ocean acidification occurs as CO2 is absorbed by seawater, harming marine life and ecosystems.
3. Long-term warming can disrupt agricultural productivity, affecting food security worldwide.
4. Melting polar ice caps and glaciers contribute to rising sea levels, threatening coastal communities.
5. Increased CO2 levels can alter ecosystems and biodiversity, leading to species extinction and habitat loss.

4. What is the significance of water vapour in the climate system? How does it interact with other greenhouse gases?

1. Water vapour is the most abundant GHG and plays important role in the greenhouse effect by trapping heat.
2. It has a short atmospheric cycle, typically around 10 days, and does not accumulate like CO2.
3. As temperatures rise due to increased CO2, more water evaporates, enhancing the greenhouse effect in a feedback loop.
4. Water vapour amplifies the warming effects of other GHGs, such as CO2 and methane, by increasing heat retention.
5. Its interaction with other GHGs can lead to complex climate dynamics, influencing weather patterns and climate stability.