Editorial 2: Rising CO₂ Levels
Context:
The atmospheric concentration of carbon dioxide (CO₂), the most significant anthropogenic greenhouse gas, has witnessed an unprecedented rise between 2023 and 2024, marking the sharpest annual increase since systematic measurements began in 1957. This trend underscores both the persistence of human-induced emissions and the weakening efficiency of natural carbon sinks in regulating atmospheric carbon.
CO₂ and Its Role in Climate Change:
- CO₂ is the principal greenhouse gas contributing to global warming and climate change.
- Although it is less potent per molecule than methane (CH₄) or nitrous oxide (N₂O), it remains in the atmosphere for hundreds to thousands of years, creating a cumulative warming effect.
- CO₂ currently accounts for over 66% of the total Radiative forcing driving global temperature rise since the pre-industrial era.
- The pre-industrial CO₂ concentration stood at around 278 ppm, meaning today’s levels represent an increase of nearly 152%.
- The year 2024 also became the warmest year on record, with global average temperatures rising 1.55°C above pre-industrial levels, breaching the critical 1.5°C threshold set under the Paris Agreement (2015).
- Persistent crossing of this limit poses irreversible threats such as polar ice melt, sea-level rise, and ecosystem collapse.
Sources:
- The increase in CO₂ arises from both anthropogenic sources and natural feedback mechanisms. The principal human-induced sources include:
- Burning of fossil fuels for energy and transportation,
- Deforestation and land-use change,
- Industrial processes such as cement production.
Carbon cycle:
- CO₂ is also part of a natural carbon cycle, exchanged among the atmosphere, oceans, and terrestrial ecosystems.
- Typically, around half of the CO₂ emitted by human activities is absorbed by natural sinks, forests and oceans, through photosynthesis and dissolution in seawater.
- The remaining half accumulates in the atmosphere, amplifying the greenhouse effect.
- In 2024, WMO data indicated that natural sinks weakened, absorbing a smaller share of emitted CO₂. Oceanic absorption declined due to reduced solubility of CO₂ in warmer waters, while heat waves and droughts reduced terrestrial uptake.
- Additionally, forest fires and land degradation released vast quantities of carbon, further exacerbating atmospheric concentrations.
- These feedback loops highlight how global warming itself weakens Earth’s ability to regulate CO₂, creating a vicious cycle.
Other Greenhouse gases:
- While CO₂ remains the dominant greenhouse gas, methane (CH₄) and nitrous oxide (N₂O) also contribute substantially.
- In 2024, CH₄ levels rose to 1,542 parts per billion (ppb) and N₂O to 338 ppb.
- CH₄ is 25 times more potent than CO₂ in trapping heat but has a shorter atmospheric lifespan of about 12 years.
- N₂O, emitted primarily from agriculture and fertilizers, is about 270 times more potent and persists for over a century. Collectively, these gases account for nearly one-third of total global warming.
Global Climate Governance:
- The recent data from WMO raises serious questions about the efficacy of international climate regimes, particularly the Paris Agreement (2015) under the United Nations Framework Convention on Climate Change (UNFCCC).
- The Agreement seeks to limit global temperature rise to well below 2°C while pursuing efforts to cap it at 1.5°C.
- Yet, a decade later, global emissions continue to rise, and most Nationally Determined Contributions (NDCs) are insufficient to meet the 2030 mitigation targets.
- The gap between scientific warnings and policy implementation reveals structural challenges in global governance such as unequal responsibilities between developed and developing nations, inadequate financial transfers for green technology, and continued dependence on fossil fuels.
Way Forward:
The record surge in CO₂ levels between 2023 and 2024 is not merely a statistical anomaly it is a warning of the accelerating pace of climate change and the inadequacy of current global responses. Unless the world moves decisively toward deep emission cuts and ecosystem restoration, the cumulative impact of greenhouse gases could push the planet toward irreversible climatic tipping points.