Human-induced climate change is causing widespread disruption in nature and threatening the wellbeing of billions of people around the world, the Intergovernmental Panel on Climate Change (IPCC) has warned. “The rise in weather and climate extremes has led to some irreversible impacts as natural and human systems are pushed beyond their ability to adapt,” according to the report published on February 28 by the panel’s Working Group II. The scientists estimate that 3.3 to 3.6 billion people live in contexts and areas that “are highly vulnerable to climate change”. People and ecosystems least able to cope will be hit hardest. Livelihoods have already “been affected through changes in agricultural productivity, impacts on human health and food security,” the authors write. “The report is a dire warning about the consequences of inaction. It shows that climate change is a grave and mounting threat to our well-being and a healthy planet,” IPCC chair Hoesung Lee said during the press conference. “It also shows that our actions today will shape how people adapt to climate change and how nature responds to increasing climate risks.”

The Working Group II report is the second instalment of the IPCC’s Sixth Assessment Report (AR6) and considers over 34,000 cited references. The 3,675 pages were prepared by 270 authors from 67 countries supported by a large number of review and contributing authors. Working Group I had already published a first instalment about the physical science basis of climate change in August 2021. The new report examines the impacts of climate change on nature and people around the globe, reviews vulnerabilities and the capacities and limits of the natural world and human societies to adapt to climate change. Its Summary for Policymakers (SMP) was approved on February 27th by 195 member governments of the IPCC in a virtual session that was held over the previous two weeks.

The first section deals with observed and projected impacts and risks. “Human-induced climate change, including more frequent and intense extreme events, has caused widespread adverse impacts and related losses and damages to nature and people,” is the first headline statement. The IPCC warns in a press release that “increased heatwaves, droughts and floods are already exceeding plants’ and animals’ tolerance thresholds, driving mass mortalities in species such as trees and corals. These weather extremes are occurring simultaneously and have exposed millions of people to acute food and water insecurity, especially in Africa, Asia, Central and South America, on Small Islands and in the Arctic.” Moreover, economic damages from climate change negatively affect sectors such as agriculture, forestry, fishery, energy, and tourism. People are faced with decreasing yields, hunger, the destruction of homes and infrastructure, and the loss of property and income, “with adverse effects on gender and social equity”. The vulnerability of ecosystems and people to climate change differs substantially among and within regions but in general, the most vulnerable are disproportionately affected, says the report. “Vulnerability is higher in locations with poverty, governance challenges and limited access to basic services and resources, violent conflict and high levels of climate-sensitive livelihoods (e.g., smallholder farmers, pastoralists, fishing communities).” The authors project that the future of ecosystems will strongly depend on human influence, such as unsustainable consumption and production, increasing demographic pressures, as well as persistent unsustainable use and management of land, ocean, and water. “While agricultural development contributes to food security, unsustainable agricultural expansion, driven in part by unbalanced diets, increases ecosystem and human vulnerability and leads to competition for land and/or water resources.”

The report differentiates between risks in the near term (2021-2040) and mid to long-term risks (2041–2100). There is high confidence that “global warming, reaching 1.5°C in the near-term, would cause unavoidable increases in multiple climate hazards and present multiple risks to ecosystems and humans.” Beyond 2040 and depending on the level of global warming, climate change will lead to numerous risks to natural and human systems: “Climate change will increasingly put pressure on food production and access, especially in vulnerable regions, undermining food security and nutrition.” Droughts, floods and heatwaves will become more frequent, intense and severe and continued sea level rise will increase risks to food security in vulnerable regions from moderate to high between 1.5°C and 2°C global warming level. “At 2°C or higher global warming level in the mid-term, food security risks due to climate change will be more severe, leading to malnutrition and micro-nutrient deficiencies, concentrated in Sub-Saharan Africa, South Asia, Central and South America and Small Islands,” the authors warn.

The second section deals with adaptation. The authors observe progress in current planning and implementation of adaptation measures but “adaptation progress is unevenly distributed”. They note a certain short-sightedness because “many initiatives prioritize immediate and near- term climate risk reduction which reduces the opportunity for transformational adaptation.” The good news is that there are feasible and effective adaptation options which can reduce risks to people and nature. With respect to agriculture and food security, the scientist say that “effective adaptation options, together with supportive public policies enhance food availability and stability and reduce climate risk for food systems while increasing their sustainability.” According to the report, effective options include “agroforestry, community-based adaptation, farm and landscape diversification, and urban agriculture”. There is high confidence that “agroecological principles and practices, ecosystem-based management in fisheries and aquaculture, and other approaches that work with natural processes support food security, nutrition, health and well-being, livelihoods and biodiversity, sustainability and ecosystem services”, the authors write. These services include pest control, pollination, buffering of temperature extremes, and carbon sequestration and storage. “Healthy ecosystems are more resilient to climate change and provide life-critical services such as food and clean water”, said IPCC Working Group II Co-Chair Hans-Otto Pörtner. “By restoring degraded ecosystems and effectively and equitably conserving 30 to 50 per cent of Earth’s land, freshwater and ocean habitats, society can benefit from nature’s capacity to absorb and store carbon, and we can accelerate progress towards sustainable development, but adequate finance and political support are essential.”

The IPCC underlines that integrated, multi-sectoral solutions that address social inequities and differentiate responses based on climate risk and local situation will enhance food security and nutrition. Finally, the authors point out that “adaptation strategies which reduce food loss and waste or support balanced diets (as described in the IPCC Special Report on Climate Change and Land) contribute to nutrition, health, biodiversity and other environmental benefits.” Pörtner added: “The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.” (ab)