Approach:

1. Introduction: Define the heat budget of the Earth, mentioning how energy is absorbed and radiated by the Earth’s system. Provide recent data or facts from recognized sources regarding the changing heat budget due to global warming.
2. Body:
   1. Heat Budget Explanation: Detail the components of the heat budget and how the balance is maintained.
   2. Impact of Global Warming: Discuss how global warming is disturbing this balance.
   3. Strategies: Explain policies and actions by India and globally to tackle the impact.
3. Conclusion: Summarise the importance of maintaining the heat budget.

Ans. According to the World Meteorological Organization (WMO), The heat budget refers to the balance between the incoming solar radiation absorbed by the Earth and the outgoing terrestrial radiation emitted back into space.

NASA’s 2021 report indicated that the Earth’s energy imbalance doubled over the last 14 years, primarily due to increased greenhouse gases.

Heat Budget of the Earth

1. Solar Radiation (Insolation): The Sun emits solar radiation, with around 30% being reflected back by clouds, ice, and Earth’s surface. This incoming energy is essential for the Earth’s weather and climate systems.
2. Absorption by Atmosphere and Surface: About 70% of solar radiation is absorbed by the atmosphere, oceans, and land, warming the Earth’s surface. The absorbed heat is critical for sustaining life and driving various atmospheric processes.
3. Terrestrial Radiation (Longwave Radiation): The Earth’s surface emits longwave radiation back into space. This process balances the incoming solar energy, maintaining the Earth’s average temperature at around 15°C.
4. Greenhouse Effect: Certain gases like CO2, methane, and water vapor trap some of the outgoing radiation, creating the natural greenhouse effect, which is essential for maintaining temperatures conducive to life.
5. Heat Transfer Mechanisms: Heat is transferred within the Earth system through conduction, convection, and radiation. The movement of warm air and ocean currents also helps distribute heat across the globe.

Impact of Global Warming on the Heat Budget

1. Increased Greenhouse Gases: The rapid increase in greenhouse gases, particularly CO2 (concentration at 417 ppm as of 2023), traps more outgoing radiation. This leads to an enhanced greenhouse effect, causing global warming.
2. Reduction in Albedo: Melting ice caps and glaciers reduce the Earth’s albedo (reflectivity). As less sunlight is reflected and more is absorbed, the heat budget is further disturbed, leading to rising global temperatures.
3. Increased Ocean Heat Content: Oceans absorb around 90% of the excess heat generated by global warming. As a result, sea surface temperatures rise, affecting marine ecosystems and contributing to more intense tropical cyclones.
4. Amplified Heat Waves: The imbalance in the heat budget has led to more frequent and severe heat waves. For example, the 2023 heatwave across Europe and South Asia was attributed to global warming intensifying the Earth’s heat imbalance.
5. Changes in Radiative Forcing: Radiative forcing, the change in energy balance caused by human activities, has increased due to elevated CO2 levels, aerosol emissions, and land-use changes. This disrupts the natural heat budget of the planet.
6. Feedback Loops: Positive feedback loops, like the increased release of methane from thawing permafrost, further disrupt the heat budget. These loops lead to accelerated warming and more significant energy imbalances.

Strategies to Address the Changing Heat Budget

1. Global Climate Agreements: The Paris Agreement (2015) set a target to limit global temperature rise to 1.5°C above pre-industrial levels. Nations are committed to reducing greenhouse gas emissions through Nationally Determined Contributions (NDCs).
2. Renewable Energy Transition: Countries, including India, are shifting to renewable energy sources like solar and wind to reduce their carbon footprint. India’s National Solar Mission aims for 450 GW of renewable energy by 2030, mitigating the impact on the heat budget.
3. Carbon Pricing and Emission Trading: The concept of carbon pricing and emission trading systems is gaining traction worldwide, including in Europe and parts of India, to limit greenhouse gas emissions and restore the heat budget balance.
4. Reforestation and Afforestation: Programs like India’s Green India Mission promote large-scale afforestation and reforestation efforts, which help in carbon sequestration and maintaining the Earth’s energy balance by absorbing more CO2.

Conclusion

The challenge of climate change is fundamentally a challenge of managing the planet’s heat balance. Addressing this requires concerted global efforts in reducing emissions, adopting sustainable energy practices, and reinforcing natural carbon sinks. Restoring the heat budget is essential for maintaining climate stability and protecting ecosystems for future generations.