Mots clés : #climate change #impacts #climate risks #adaptation #climate resilient #development
The interdependence of climate, human societies, ecosystems and biodiversity is a concept that need to be understood to evaluate impacts and risks of non-climatic global trends such as biodiversity loss, human demographic shifts, land and ecosystems degradation… This assessment integrates knowledge across the natural, ecological, social and economic sciences.
In the current climate, it is more important than ever to assess the risks and impacts of climate change until the end of the century and what are the actions we must take to transition to a climate-resilient development.
This article is a synthesis of the Summary for Policymakers of the IPCC AR6 WGII.
Interactions between the different systems
Figure 1 is a representation of the different interactions between the three coupled systems that are climate, ecosystems and human society. Biodiversity is also included in the ecosystems. Part (a) is the actual situation and depicts the impacts and risks of climate change on human society and ecosystems. Both can adapt and mitigate these impacts, but the impacts will inevitably lead to losses and damages. Human society causes climate to change because of its greenhouse gas emissions. Human society and ecosystems interact together through conservation and restoration from the human society while ecosystems provide livelihoods and ecosystems services to human society.
Part (b) of Figure 1 represents the actions required to transition from the actual situation to climate-resilient development. These actions can be enabled by governance, finance, knowledge and capacity, technologies and catalyzing conditions. The decisions must be taken with the aim of achieving human health and well-being (in equity and justice), ecosystem and planetary health.
The concept of risk is the result of the vulnerability and exposure of human and ecological systems to climate-related hazards. To reduce vulnerability and exposure, systems must demonstrate adaptation through ecological and evolutionary processes. Only the human systems can anticipate their adaptation.
Observed and future risks and impacts
Through the years, knowledge of impacts and risks related to climate hazards, vulnerability and exposure has developed. In this part, the expression of impacts and risks in terms of damage, economic harm and non-economic losses will be discussed. The projection of risks is done for a short-, mid-, and long-term effect (respectively 2021-2040, 2041-2060 and 2081-2100).
In the current situation, the climate change has caused impacts, losses and damages to nature and people because of extreme events which tend to be more frequent and intense. Even though the vulnerability of systems has been reduced thanks to development and adaptation, the most vulnerable systems are disproportionately impacted. Some systems already suffered from irreversible impacts and human systems sometimes exhausted their ability to adapt. The vulnerability of ecosystems and people is different among and within areas. Factors taken into account are socio-economic development, unsustainable ocean and land use, marginalization, historical and current inequities (e.g. colonialism) and governance. Between 40 and 45% of the global population lives in highly vulnerable contexts to climate change and the on-going unsustainable development patterns increase the exposure of systems to climate hazards.
Each observed impacts on systems are measured with a confidence factor concerning the attribution to climate change. In addition to this factor, it specified whether the impacts are only negative or also positive at the same time for human systems.
Part (a) of Figure 2 concerns the observed impacts of climate change on ecosystems. Globally, in most of the terrestrial, freshwater and oceanic ecosystems, climate change has affected ecosystems structure, species geographic ranges and phenology (life cycles) with high confidence.
Part (b) of Figure 2 is about the impacts of climate change on human systems and focus on water scarcity/food production, health and well-being and cities, settlements and infrastructures. At a global scale, climate change mostly has adverse impacts on these elements.
Risks in the near future (2021-2040) are estimated by considering the temperature increase of 1.5 °C. This temperature rise would inevitably cause an increase in climate hazards and multiply the risks for ecosystems and humans. The actions that would cap global warming to these 1.5 °C would restrain losses and damages in comparison to other scenarios with more important levels of warming. Unfortunately, eliminating this increase remains impossible.
On a mid to long-term scale (2041-2100), the assessment of climate-related risks depends on the level of global warming that be reached at this time. For over 100 known risks, the estimated level of impact will reach up to multiple times the current rates. Near term adaptation and mitigation decisions are the key to keep the magnitude of risks arising from climate change at lower rates.
Here is a list of some risks for different systems:
- Ecosystems: in every environment (terrestrial, freshwater and oceans), the species will be subject to higher risk of extinction, between 3% and 48% depending on the location and the level of temperature increase. This loss of range will directly affect the ecosystems structures and the phenology.
- Water scarcity: with a 2 °C temperature raise, snowmelt water allocated for irrigation should decrease by 20% and around 18 ± 13% of the global glacier mass will be lost. This will impact agriculture, hydropower and human settlements.
- Human health and well-being: vulnerable populations (youth, elderly and people with health problems) will face mental health troubles such as anxiety and stress due to the increasing global warming.
- Cities, settlements and infrastructures: the percentage of people potentially affected by a 100-year coastal flood will increase by 20% if the sea level rises by 0.15 m and by 60% in the case of a 1.4 m raise.
All sectors and regions has made progress concerning planning and implementing adaption, thus creating benefits towards the reduction of climate-related risks. However, the distribution of the progress has not been made evenly. A lot of these progress are focused on near-term effect, leading to a decrease in the opportunity for transformational adaptation.
Across the years, countries and cities decided to implement adaptation in climate policies, due to the rising public and political awareness around climate change. There is an increase in the use of other means like decision support tools or climate services, projects and experiments are conducted in different sectors. All these actions not only help to reduce the risks and damages, but also they provide benefits for human society in many fields (health and well-being, food, biodiversity conservation…).
Despite the efforts made to set up these actions, a gap still exists with the level of adaptation required to fully counter the impacts and reduce the risks. The actions are mainly fragmented and focused on planning instead of actual implementation. Most of the time, the estimated costs of the measures does not match the allocated budget to conduct the project. In lower income population groups, the adaptation gaps are at the highest rate.
Figure 3 gathers the different feasible responses that humanity could set up to reduce the main risks of climate change and the impact they would have on system transitions (Land/ocean ecosystems, urban and infrastructures systems, energy systems and cross-sectoral). These information are given for a global scale at near term and within the 1.5 °C temperature increase. Above this temperature increase, the feasibility of the measures may be different. The scaling for the feasibility of climate responses take into account six dimensions (economic, technological, institutional, social, environmental, and geophysical) and their synergies with mitigation.
Figure 4 represents the benefits of climate responses and adaptation options for ecosystems, social groups and the 17 Sustainable Development Goals (SDG).
The adaption options depicted in the above figures (3 and 4), will result in a decrease of risk to people and ecosystems. However the feasibility of these options differs depending on the sector or the region they are implemented in. Moreover, the effectiveness decreases as the global warming increases.
Here are some measures that are feasible and the system that would benefit from it:
- Land, oceans and ecosystems: early warning systems and structural measures for inland flooding in order to reduce human losses.
- Urban, rural and infrastructure transition: partnerships including governments, civil society and private sector organizations to upgrade the ability of adaptation of vulnerable populations.
- Energy system transition: development of different energy sources, integrating renewable energy (solar, wind…) reduces the vulnerability of populations.
- Cross cutting options: improving surveillance, warning systems and vaccine development help are effective adaptation options to manage vector borne diseases.
However, despite the set up actions, soft and hard limits to systems adaptation exist. The soft limits that strikes human systems include the lack of literacy and information or the inequity and poverty that restrain adaptation. The soft limits can be overcome by working on the fields of finance, governance, institutions and policies. On the other hand, natural systems are subject to hard limits, such as coral reefs, coastal wetlands or rainforests.
These adaptation options require enabling conditions to be implemented, accelerated and sustained in human and ecological systems. Enabling conditions means political commitment, institutional frameworks, policies, knowledge on impacts and solutions, financial resources as well as monitoring, evaluation and governance processes.
Political commitment will require large investments (in terms of human, financial and technological resources) at the beginning and the results could take a decade or more to be tangible.
Institutional frameworks and policies will provide clear objectives for adaptation and set the responsibilities amongst the actors and governments. Adaptation options will be enhanced by the integration of measures in financial and policies planning cycles.
Acquiring knowledge about risks, impacts and their consequences promotes societal and policy solutions. Using this concept at every scale like education, information programs, arts, Indigenous knowledge… will deepen climate knowledge, facilitating awareness, risk perception and influence behavior.
The access to financial resources are necessary to implement adaptation options and reduce the existing gaps for vulnerable groups, regions and sectors. Finance and public mechanisms can be a lever to private sector finance for adaptation by addressing real and perceived regulatory, cost and market barriers, through public-private partnerships for example.
Monitoring and evaluation of adaptation options are the key to track progress and to provide an effective adaptation. At the moment this process is limited and focused on planning and implementation. The next step is to increase the monitoring on outcomes to track effectiveness.
Inclusive governance prioritizing equity and justice concerning the adaptation obtains more effective and sustainable outcomes. Carefully designing and implementing laws, policies, processes and interventions reduces vulnerabilities and climate risks. This approach focus on capacity-building of the most vulnerable and marginalized groups so that they can access to key resources to adapt.
Climate resilient development
A climate resilient development (CRD) includes the adaptation measures and their enabling conditions depicted sooner, with mitigation to provide sustainable development for all. The concept integrates system transitions (in land, ocean, cities, energy, industry and society) and includes adaptations for human, ecosystems and planetary health.
The evidence of observed impacts, future risks, vulnerabilities and adaptation limits proves that the transition to a worldwide resilient development action is becoming urgent. Responses can use the synergies and reduce the gap between adaptation and mitigation for a sustainable development.
Figure 5 represents the pathways that will lead to different outcomes depending on our actions. Part (a) is the two different axes that can be chosen, either going towards higher CRD or a lower one. Part (b) is about the cumulation of societal choices that will define the level of CRD. The past conditions cannot be changed and already eliminated pathways towards a higher level. The progress to a high CRD becomes more and more difficult as the global warming increases. The final part (c) shows the actions and outcomes of the different pathways.
“It is unequivocal that climate change has already disrupted human and natural systems. Past and current development trends (past emissions, development and climate change) have not advanced global climate resilient development […]. Societal choices and actions implemented in the next decade determine the extent to which medium-and long-term pathways will deliver higher or lower climate resilient development […]. Importantly climate resilient development prospects are increasingly limited if current greenhouse gas emissions do not rapidly decline, especially if 1.5°C global warming is exceeded in the near term […]. These prospects are constrained by past development, emissions and climate change, and enabled by inclusive governance, adequate and appropriate human and technological resources, information, capacities and finance […].”
IPCC WGII Sixth Assessment Report – Summary for Policymakers, SPM.D.5
Working Group II of the IPCC (27-02-2022) Climate change 2022 Impacts, Adaptation and Vulnerability [PDF File], IPCC. https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_SummaryForPolicymakers.pdf