Earth’s Energy Budget- Concerns over Imbalance
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Recently, the WMO released the State of the Global Climate 2022 report. The report has raised concerns about imbalance in the planet’s energy budget.
What is the Energy Budget?
- Energy budget refers to the balance between the incoming and outgoing radiant energy, to and from the earth.
- Earth’s energy sources:
- Solar radiation- most of the energy comes from this source
- Earth’s internal heat
- Tidal energy
- 30% of the solar radiation reaching the earth is reflected back into the space by the aerosols, clouds and other reflective surfaces like ice sheets, etc.
- The greenhouse gases, like methane and carbon dioxide, let the solar radiation enter the earth’s atmosphere, but block the radiation emitted by the earth from escaping into space.
- This energy trapping is responsible for maintaining the near surface temperature of 15°C. In the absence of these gases, the temperature would be -19°C.
Imbalance in the Energy Budget:
- When the difference between the incoming energy and outgoing energy is non-zero, then Earth Energy Imbalance is said to exist.
- According to a recent report from the WMO (World Meteorological Organization), the earth’s climate system has been imbalanced for the past decades.
- The 2022 global mean temperature was 1.15°C above the average temperature level of the pre-industrial period (1850-1900).
- The past 8 years (2015-22) have been the warmest years on record. Note that instrumental temperature record-keeping started 173 years ago.
- This has happened despite the triple dip La Niña phenomenon.
- This imbalance has been caused by high concentration of GHGs in the atmosphere, resulting from unsustainable anthropogenic activities.
- The earth has been accumulating excess heat since 1971. This excess energy, trapped by the higher levels of GHGs, is getting accumulated in different components of the planet’s climate system, resulting in global warming.
- 89% of the heat is stored in the oceans- especially in the upper 0-700 m of the oceans.
- 6% of the heat is being stored by the landmasses.
- 4% of the heat is melting the cryosphere- composed of glaciers, sea ice and ice sheets.
- 1% is with the atmosphere.
- Apart from storing the heat, the oceans are also acting as an important carbon sink. Hence, they play an especially crucial role in regulating the global climate.
Why is this of concern?
- According to the IPCC Synthesis Report, 3.3 to 3.6 billion people are highly vulnerable to global warming.
- Negatively affects physical and mental health of the people. Eg: apart from loss of lives, it can also cause trauma and climate anxiety.
- This is especially true in case of people living in the coastal areas, given the rising sea levels.
- Contribution to sea level rise in 2005-19 period:
- Ocean thermal expansion- 55%
- Melting of land ice- 36%
- Contribution to sea level rise in 2005-19 period:
- It is feared that the oceans would become less efficient in capturing the carbon dioxide from the atmosphere, especially given the increase in ocean temperatures. Note that cold water dissolves more carbon dioxide than warm water.
- 2022 saw ocean heat content breaking records.
- Also in 2022, 58% of the ocean surface experienced minimum 1 marine heatwave. This has resulted in negative consequences like coral bleaching.
- Since mid-March 2023, the mean ocean surface temperature has been the highest since the start of the satellite era.
What is the way ahead?
- The earth energy imbalance and the consequent climate change could threaten the stability of the society and even, the very survival of human beings. However, the subject still doesn’t receive the attention it deserves.
- The in-principle solution to arrest this imbalance is reducing GHG emissions from anthropogenic sources to zero. Several states have already set their net zero targets.
- Individual-level action is also necessary. Eg: reducing our individual carbon footprints by:
- Using an active mode of transport- like walking or cycling
- Reducing consumption of meat and dairy products
- Reducing food wastage
- Improving energy efficiency of homes, etc.
Conclusion:
The WMO’s observation about a persisting earth energy imbalance is only the latest in a growing list of evidence-backed warnings about how poorly we have been stewarding the planet and its delicately balanced climate system. The situation calls for urgent science-backed action at the levels- international, national and individual.
Practice Question for Mains:
What is earth energy budget? How has it been imbalanced by GHG emissions? (250 words)
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