Editing IPCC:AR6/WGII/Chapter-2 (section)

=== 2.1.2 Points of Departure ===

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Species diversity and ecosystem function influence each other reciprocally, while the latter forms the necessary basis for ecosystem services ( [[#Hooper--2012|Hooper et al., 2012]] ; [[#Mokany--2016|Mokany et al., 2016]] ). Drivers of impacts on biodiversity, ecosystem function and ecosystem services have been assessed in reports by the IPCC, the Food and Agriculture Organization (FAO), the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) and the Global Environmental Outlook ( [[#Settele--2014|Settele et al., 2014]] ; [[#FAO--2018|FAO, 2018]] ; [[#IPBES--2018b|IPBES, 2018b]] ; [[#IPBES--2018e|IPBES, 2018e]] ; [[#IPBES--2018c|IPBES, 2018c]] ; [[#IPBES--2018d|IPBES, 2018d]] ; [[#IPBES--2019|IPBES, 2019]] ; [[#UNEP--2019|UNEP, 2019]] ; [[#Secretariat%20of%20the%20Convention%20on%20Biological%20Diversity--2020|Secretariat of the Convention on Biological Diversity, 2020]] ). Most recently, the IPCC Special Report on Climate Change and Land (SRCCL) provided an assessment on land degradation and desertification, GHG emissions and food security in the context of global warming ( [[#IPCC--2019c|IPCC, 2019c]] ), and the IPBES–IPCC joint report on biodiversity and climate change provided a synthesis of the current understanding of the interactions, synergies and feedbacks between biodiversity and climate change ( [[#Pörtner--2021|Pörtner et al., 2021]] ). This chapter builds on and expands the results of these assessments.

Assessment of the impacts of climate change on freshwater systems has been limited in previous assessments, and inter-linkages between terrestrial and freshwater processes have not been fully explored ( [[#Settele--2014|Settele et al., 2014]] ; [[#IPBES--2019|IPBES, 2019]] ). Improved treatment of impacts on terrestrial and freshwater systems is critical, considering the revisions of international sustainability goals and targets, especially the conclusion that many of the proposed post-2020 targets of the CBD cannot be met due to climate change impacts ( [[#Arneth--2020|Arneth et al., 2020]] ).

Previous reports highlighted the possibility of new ecosystem states stemming from shifts in thermal regimes, species composition, and energy and matter flows ( [[#Settele--2014|Settele et al., 2014]] ; [[#Shin--2019|Shin et al., 2019]] ). Projecting such “tipping points” (see Glossary Appendix II) has been identified in previous reports as a challenge since monitoring programmes, field studies, and ecosystem and biodiversity modelling tools do not capture the underlying species–species and species–climate interactions sufficiently well to identify how biological interactions within and across trophic levels may amplify or dampen shifts in ecosystem states ( [[#Settele--2014|Settele et al., 2014]] ; [[#Shin--2019|Shin et al., 2019]] ). Building on these previous analyses and the recent literature, [https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-2 Chapter 2] of AR6 provides new insights compared to those of previous assessments by (i) emphasising freshwater aspects and the interlinkages between freshwater and terrestrial systems, (ii) assessing more clearly the link between biodiversity and ecosystem functioning, (iii) assessing the impacts associated with climate change mitigation scenarios versus those of climate change including interactions with adaptation, and (iv) where possible, places findings in the context of the United Nations (UN) SDGs 2030 and services for human societies.

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