IPCC Sixth Assessment Report

In April 2016, at the 43rd session which took place in Nairobi, Kenya, the topics for three Special Reports (SR) and one methodology report on Greenhouse Gases (GHG) inventories in the AR6 assessment cycle were decided. • The Physical Science Basis of Climate Change in August 2021 One of the assumptions is that enough GDP and technology derived from fossil fuels development will permit to adapt even to temperature rise. Some experts assume, that while the odds for a worst-case scenario (5 °C) and the best base-case (1.5 °C) today seem lower, the most plausible outcome is around . Special reports during same assessment cycle Sequence of release dates of special IPCC reports during the same assessment cycle: • Special Report on Global Warming of 1.5 °C (SR15) in October 2018 • 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories in May 2019 • Special Report on Climate Change and Land (SRCCL) in August 2019 • Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) in September 2019 == Working Group 1 report (physical science basis) ==

(1850–2019) relative to the 1850–1900 average (blue line), as reported in the Summary for Policymakers (SPM) A total of 234 scientists from 66 countries contributed to the first of three working group reports. Important findings of WG 1 report The Working Group 1 (WGI) report, Climate Change 2021: The Physical Science Basis comprises thirteen chapters and is focused on the foundational consensus of the climate science behind the causes and effects of human greenhouse gas emissions. Compared with previous assessments, the report included much more detail on the regional effects of climate change, The global carbon budget to keep below 1.5 °C is estimated at 500 billion more tonnes of greenhouse gas, which would need the whole world to be net zero before 2050. The report says that rapidly reducing methane emissions is very important, to make short-term gains to buy time for carbon dioxide emission cuts to take effect. == Working Group 2 report (impacts, adaptation and vulnerability) ==

The second part of the report, a contribution of working group II (WGII), was published on 28 February 2022. Entitled Climate Change 2022: Impacts, Adaptation & Vulnerability, the full report is 3675 pages, plus a 37-page summary for policymakers. It contains information on the impacts of climate change on nature and human activity. Topics examined included biodiversity loss, migration, risks to urban and rural activities, human health, food security, water scarcity, and energy. It also assesses ways to address these risks and highlights how climate resilient development can be part of a larger shift towards sustainability. The report was published during the first week of the 2022 Russian invasion of Ukraine. In the context of the conflict, the Ukrainian delegation connected the Russian aggression to the global dependency on oil, and a Russian official, Oleg Anisimov, apologized for the conflict despite the possible repercussions. The Ukrainian delegation also called for news reporting on the war not to overshadow the WGII report. If emissions continue on their current path, Africa will lose 30% of its maize cultivation territory and 50% of its land cultivated for beans. The report also cites evidence that China will pay the highest financial cost if the temperature continue to rise. The impacts will include food insecurity, water scarcity, flooding, especially in coastal areas where most of the population lives due to higher than average sea level rise, and more powerful cyclones. At some point part of the country may face wet-bulb temperatures higher than humans and other mammals can tolerate more than six hours. Overall, the report identified 127 different negative impacts of climate change, some of them irreversible. People can protect themselves to some degree from the effects of climate change, which is known as adaptation. Overall, progress on adaptation has been made in all sectors and regions, although this progress is unevenly distributed and many initiatives prioritise immediate risks over longer-term transformational changes. Still, there are feasible and effective adaptation options available and many adaption actions have benefits beyond reducing climate risks, including positive effects on the Sustainable Development Goals. For example, the majority of current adaptations address water-related risks; adaptations like improved water management, water storage and irrigation reduce vulnerability and can also provide economic and ecological benefits. Similarly, adaptation actions like agroforestry, farm- and landscape diversification and urban agriculture can increase food availability, while at the same time improving sustainability. The report further highlighted the need for conservation in order to maintain biodiversity, and mitigate the effects of climate change. The report reads, "Recent analyses, drawing on a range of lines of evidence, suggest that maintaining the resilience of biodiversity and ecosystem services at a global scale depends on effective and equitable conservation of approximately 30% to 50% of Earth's land, freshwater and ocean areas, including currently near-natural ecosystems." The report was critical of technological approaches to carbon dioxide removal, instead indicating that urbanisation could help drive adoption of mitigation strategies such as public transport and renewable energy. The report also warns there are high risks associated with strategies such as solar radiation management; planting forests in unnatural locations; or "poorly implemented bioenergy, with or without carbon capture and storage". In line with the emphasis on adaptation limits, the report also highlights loss and damage, meaning negative consequences of climate change that cannot be avoided through adaptation. The report states that such losses and damages are already widespread: droughts, floods and heatwaves are becoming more frequent, and a mass extinction is already underway. Taking near-term actions to limit warming to below 1.5 °C would substantially reduce future losses and damages, but cannot eliminate them all. Previously, rich countries have resisted taking responsibility for these losses. The report states that even a temporary overshoot of the 1.5 degree limit will lead to negative effects on humans and ecosystems. According to the report: "Depending on the magnitude and duration of overshoot, some impacts will cause release of additional greenhouse gases (medium confidence) and some will be irreversible, even if global warming is reduced (high confidence)". Climate resilient development will be more difficult if the global temperature will rise by 1.5 degrees above pre-industrial levels, while if it will rise by more than 2 degrees it will become impossible "in some regions and sub-regions". Although the report's outlook is bleak, its conclusion argues that there is still time to limit warming to by drastic cuts to greenhouse gas emission, but such action must be taken immediately. Moreover, climate resilient development can have both adaptation and mitigation benefits, but it requires international cooperation and collaborations with local communities and organisations. == Working Group 3 report (mitigation of climate change) ==

The report was presented on 4 April 2022. Some observers are worried that the conclusions might be watered down, considering the way the reports are adopted. According to The Observer, some countries "have sought to make changes that would weaken the final warnings". According to the report demand side mitigation measures can reduce GHG emissions by 40–70% by the year 2050 compared to scenarios in which countries will fulfill its national pledges given before 2020. For being implemented successfully those measures should be linked "with improving basic wellbeing for all". The report compares different methods of carbon dioxide removal (CDR) including agroforestry, reforestation, blue carbon management, restoration of peatland and others. Buildings emitted 21% of global GHG emissions in the year 2019. 80–90% of their emissions can be cut while helping to achieve other Sustainable Development Goals. The report introduces a new scheme for reducing GHG emissions in buildings: SER = Sufficiency, Efficiency, Renewable. Sufficiency measures do not need very complex technology, energy supply, maintenance or replacement during the life of the building. Those include, natural ventilation, green roofs, white walls, mixed use of spaces, collective use of devices etc. Reducing GHG emissions from buildings is linked to sharing economy and circular economy. The IPCC found that decent living standards could be achieved using less energy than prior consensus assumed. According to the report for reaching well being for all, the required energy consumption is "between 20 and 50 GJ cap-1 yr-1 depending on context." More equitable income distribution can lower emissions. Mitigation pathways based on low demand and high efficiency can achieve decent living standards and well being for all. Pathways based on reducing consumption, involving sustainable development have less negative outcomes than pathways based on high consumption and narrow mitigation. According to table TS30, narrow mitigation can increase habitat loss by 600%, while avoiding habitat degradation by around 95%. Mitigation with sustainable development did not harm forest cover and biodiversity. The report mentions some improvement in global climate action. For example, the rate of deforestation slowed after 2010 and the total forest cover increased in the latest years due to reforestation in Europe, Asia and North America. == Reactions to all three working group reports ==