At present there is no demonstrable evidence about the possible consequences of the average temperature of the Earth rising by more than 2°C. Even so, many people declare that the goal of limiting the increase in temperature to 2°C, approved in Copenhagen in 2009, will not be sufficient to prevent the effects on the climate and their consequences. The consensus between the parties and the Intergovernmental Panel of Experts on Climate Change (IPCC) determined that, if the overall temperature of the planet exceeds the temperature of the preindustrial age by more than 2°C, it is more than likely that we will see irreversible catastrophic consequences.
The effects of climate change are currently already indisputable. On the one hand, we have the clearest effects: melting of the poles or of the glaciers in different parts of the planet and the increase in extreme meteorological situations. On the other hand, there are effects which are less visible but constantly advancing, such as the acidification of the seas, the increase in their level, the variation in the ocean currents and the destruction of ecosystems. The inequality of the effects of climate change on the Earth will increase the vulnerability of certain geographic areas compared with others, limiting access to resources and quality of life.
In this respect, the agreement obtained in the COP21 was historical. The countries recognized that the limit of 2°C is insufficient and imposed more restrictive ceilings, committing the signatories to the agreement to make efforts to limit the increase in temperatures to 1.5 degrees.
Decarbonization pathways are an instrument to ensure that the mitigation contributions of countries are sufficient to attain this goal. Each country must bear its share and establish its reduction targets, reviewable downwards every five years to ensure that the objective of not reaching this increase in temperature is effective. As a monitoring tool, the agreement commits the signatory countries to reporting, in a transparent and homogeneous manner, on their emissions and their efforts to reduce them.
Developing countries, emerging powers and countries which have this goal within reach must ratify the agreement to make it legally binding and convert it into an effective tool against climate change.
This is a compromise limit, between the scientific world and the economic interests of countries, the consequences of which will be seen in the future.