Climate change is one of the greatest challenges facing humanity. Many decarbonization initiatives aim to reduce or eliminate greenhouse gas (GHG) emissions, with the aim of limiting global warming. However, a question remains: even if we stopped all emissions today, is it possible to stop or reverse climate change in the short term? According to reports from the IPCC (Intergovernmental Panel on Climate Change), the answer is more nuanced than one might hope.

I. The role of CO2 and the slowness of natural regulatory mechanisms

When we emit carbon dioxide (CO₂), it stays in the atmosphere for decades or even centuries. Some is absorbed by oceans and forests, but these natural carbon sinks are not fast enough to offset anthropogenic emissions.

• The carbon cycle: Carbon emitted by human activities is distributed among the atmosphere, oceans and terrestrial ecosystems. The rate of absorption of this carbon by natural sinks is slow. For example, about 50% of emitted CO₂ remains in the atmosphere for decades, and some of the remainder can remain there for centuries.
• Absorption mechanisms: Oceans absorb around 25% of global CO₂ emissions each year. However, this process is limited by ocean acidification and the erosion effect of marine biodiversity. Forests, for their part, also act as carbon sinks, but massive deforestation limits their effectiveness.

So even if we stopped all emissions today, the amount of CO₂ already in the atmosphere would continue to cause climate change for centuries.

II. The concept of climate inertia

Climate inertia refers to the latency between GHG emissions and observable effects on the climate. This inertia is caused by the time it takes for Earth systems to adjust to new GHG concentrations.

• Thermal inertia of the oceans: The oceans, which absorb much of the excess heat, take centuries to balance this energy with the atmosphere. This means that even if we managed to reduce emissions to zero, warming would continue for several decades due to the build-up of heat already present in the oceans.
• Multi-generational effects: Future generations will therefore inherit this warming, even if major decarbonization efforts are undertaken immediately. According to IPCC reports, a large part of climate damage (melting of glaciers, rising sea levels, extreme events) is already inevitable for the coming decades, and potentially for the next 3 to 4 generations.

III. The expected impacts despite a drastic reduction in emissions

• Inevitable Warming: The IPCC estimates that even with drastic reductions in GHG emissions, global temperatures will continue to rise at least until the end of the century. This is due to the historical accumulation of CO₂ and the response time of climate systems. Optimistic climate stabilization scenarios only predict a reversal of trends after several decades.
• Tipping points: The climate is subject to tipping points, critical thresholds beyond which irreversible changes occur. The melting of the ice sheets of Greenland and Antarctica, for example, is a phenomenon likely to continue even if temperatures are stabilized. These processes, once started, cannot be stopped quickly.

IV. Mitigation scenarios: What we can do

If we cannot hope for a return to a pre-industrial climate for the next generations, decarbonization efforts are not useless. There are ways to mitigate the impacts:

• Limit future damage: By drastically reducing emissions, we can limit the extent of warming and its consequences. Although the effects are not immediately visible, every fraction of a degree of warming avoided will reduce climate disasters for future generations.
• Carbon capture technologies: Emerging technologies, such as carbon capture and storage (CCS), can accelerate the reduction of CO₂ in the atmosphere, although their large-scale implementation remains a challenge.
• Ecosystem restoration: Increasing forest areas and restoring wetlands would strengthen the Earth’s natural capacity to absorb CO₂. However, these solutions take time to become fully operational.

V. Conclusion: A climate future under surveillance

Reducing carbon emissions will not produce immediate results on ongoing climate change. Future generations will have to deal with the consequences of past emissions for decades, even centuries. However, limiting emissions remains crucial to avoid even more dramatic scenarios. By combining decarbonization efforts, ecosystem restoration, and carbon capture technologies, humanity can hope to limit the most severe impacts for future generations.