Climate change long-term consequences

Concurrently with medium term climate change consequences on our planet, scientists are drawing scenarios to expand our field of vision beyond 2100 and consider future scenarios. These studies provide crucial information to clarify the long term destiny of Planet Earth’s climate and the public consultation on measures to be taken.

The study based on digital simulations considers 4 total carbon emissions produced in the atmosphere. It shows that even if we use approximately 15% of existing resources, very significant changes are anticipated: a high probability of going over the +2°C limit mentioned in the Paris Agreement and approximately a 10 metre global sea level rise. In this reduced emissions scenario, there is a population of 1.3 billion people living in 2010 on to-be flooded land due to future sea-level rise. This scenario lets us produce 1.5 times the total quantity of CO2 emitted since the industrial revolution. At the current pace this should take 70 years, beyond which all emissions should stop.

For the most pessimistic scenario, the use of 70 to 90% of existing resources would most likely lead to over 5°C temperature increase for over 10,000 years. Concurrently, a 2 to 4 metre sea level rise per century is expected during the next millennium. The sea level could end up going beyond its current 25 to 50m level.

These results confirm the importance of efficient actions to leave as much available fossil fuel as possible underground. On the contrary, merely reducing CO2 emissions even significantly, does not resolve anything in the long term.

In order to understand long term effects of our current emissions, two factors must be considered: 1) a great part of anthropic CO2 that we produce remains active in the atmosphere for a very long time; 2) planet Earth’s climate system has great inertia (mostly due to the ocean), which means that when disturbed it takes several millennia to adjust, in temperature for instance.

As a result, current and future generations will suffer a small part of consequences due to current CO2 anthropic emissions. Our children’s descendants will suffer the majority of these consequences for hundreds of generations. The authors therefore support a presentation of climate risks not only limited to the next 85 years in order for decisions and public consultations to include very long term consequences of current emissions.