The fight against climate change is mainly divided into two complementary domains of action, to be integrated into a global strategy: mitigation, which aims to reduce or limit our greenhouse gas emissions and to preserve or enhance natural carbon sinks, and adaptation, which aims to reduce vulnerabilities to the present and future impacts that have become inevitable.
The fifth global assessment report of the Intergovernmental Panel on Climate Change (IPCC) published in 2013 and 2014 confirmed, with more than 95% probability (compared to 90% in 2007 and 66% in 2001, in its previous reports), the anthropogenic influence on current climate change1. In its special report on a 1.5°C global warming published in 2018, the IPCC underlines that “Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence)” 2. Since the industrial revolution, our development models have been based mainly on the intensive and massive exploitation of coal, oil and gas (figure below).3.
In this context, it has become vital to reduce our GHG emissions by preserving and enhancing natural carbon sinks (forests, wetlands, peatlands, oceans and seas, soils (humus), etc.) and by redefining our energy models, based on three complementary objectives :
Energy sobriety is about minimizing our demand for energy services. This requires less energy-consuming lifestyles, taking also into account the energy needed to produce everything we consume. This also involves promoting new models based, for example, on a territorial organisation that limits transport needs and favours soft (cycling, walking) and public modes of transport, on agriculture models that are bio and less intensive in chemical fertilisers and pesticides, or on the construction of buildings that are better adapted to local climates (bioclimatic architecture).
Energy efficiency is complementary to energy sobriety and aims to reduce the amount of energy required to provide a given energy service. This includes, for example, promoting the most efficient modes of transport, lighting, equipment, heating, ventilation and air conditioning systems, or improving energy production, transport and supply networks, including electricity networks.
Renewable and low-carbon energy supply
Renewable, low-carbon energies having a limited impact on the environment must supply most of the so-called incompressible demand (which cannot be reduced through sobriety or energy efficiency measures). These include for example thermal and electrical solar energy (photovoltaic, concentrated solar power), wind power, hydropower, geothermal energy, marine energy and modern biomass (provided it is exploited in a sustainable way).
Adaptation measures are complementary to mitigation measures and aim to reduce the vulnerability (or increase the resilience) of a community, economic sector, country, etc. to the impacts of climate change. The implementation of policies in this area requires first and foremost a good knowledge of climate change and its impacts.
The level of warming of temperatures was estimated by the Intergovernmental Panel on Climate Change (IPCC) in its fifth assessment report at +0.85°C on average since 1880, with very large regional disparities. This warming could reach +2.6°C and +4.8°C by 2100, well beyond the long-term objectives set by the international community, depending on emissions scenarios (Representative Concentration Pathways - RCP).6.
Warmer temperatures lead to the melting of ice and rising sea levels (of 0.2m on average since the beginning of the 20th century - the highest rate in the last two millennia), which could reach 1 metre by 2100. It also causes disruptions in precipitation systems, ocean acidification and the intensification of extreme climatic events (storms, droughts, tornadoes, hurricanes, etc.).
These changes have major impacts on marine and terrestrial ecosystems, the availability of natural resources such as water, and on human societies (impacts on health, food production, infrastructure, etc.).
The challenge is to anticipate these different impacts and implement appropriate measures to limit vulnerabilities. This may include a wide range of actions such as building dikes to cope with floods, changing agricultural practices, for example from rice to aquaculture in deltas exposed to saline intrusion, raising awareness among vulnerable populations, greening urban areas to limit temperature warming and flood risks, preserving forests to combat soil erosion, etc.
However, the exercise is complex. The impacts of climate change take many and varied forms, are sometimes very localized, and concern a wide range of areas. They are often interlinked, complex to understand and require studies and simulations at reduced spatial scales, associated with high degrees of uncertainty. Addressing these can only be done through a global approach integrating the specificities of each territory.
Moreover, our development models often exacerbate vulnerabilities, creating lock-in effects that limit our societies' ability to adapt. We can take as example the Mediterranean basin, a hotspot to climate change, where risks are often reinforced by a rapid and sometimes chaotic coastal urban development. The acceleration and globalisation of certain lifestyles make adaptation actions more difficult to apprehend.
Finally, developing countries are generally the most exposed and do not have sufficient technical and financial resources to face these new challenges, which add up to already fragile and complex realities. To this regards, multilateral and international cooperation remains essential.