Biodiversity and Climate Change Assessment: Review of Draft Chapters (2025)
Chapter: Summary
Summary
Ecosystems across North America and around the globe are experiencing unprecedented rates of change. Biodiversity—the rich variety of living things that, woven together, support and sustain life on Earth—is being lost at rates that far surpass those in millions of years except during episodes of mass extinctions. This biodiversity loss has wide ranging implications for environmental and human health, as well as economies at multiple scales. This is due to biodiversity and associated natural resource management practices influencing billions of dollars earned and climate change-related damages avoided globally. Biodiversity loss is inextricably intertwined with human-driven climate change. Organisms are being exposed to warming temperatures, altered precipitation patterns, and other changes that are affecting ecosystems and individual species on land, and in inland waters and oceans. At the same time, biodiversity affects climate change, mitigating change by drawing greenhouse gases out of the atmosphere and storing the carbon in terrestrial and aquatic environments. Diverse ecosystems can also adapt to climate change impacts and provide societal benefits such as flood protection and disease regulation.
Extensive evidence clearly demonstrates changes in biodiversity and climate and the strong connections between them. This information is collectively captured in Indigenous Knowledge, Local Ecological Knowledge, and Western science, providing a strong understanding of the interlinkages and the current status and trends across many ecosystems and scales. When synthesized, this knowledge can provide valuable information for natural resource management and decision-making.
In 2022, the U.S. Geological Survey was directed by the U.S. Congress to conduct an assessment of the current state of knowledge concerning linkages between biodiversity and climate change in the U.S. Recognizing that biodiversity and climate change span national and other borders, the assessment was expanded to be North American in scope and is being produced in collaboration with Canada and Mexico. This Biodiversity and Climate Change Assessment (BCCA), examines direct effects of climate change on biodiversity; interactions of climate change with other drivers of biodiversity loss; consequences of biodiversity loss for nature’s contributions to people; interactions among climate mitigation, climate adaptation, and biodiversity conservation; biodiversity and climate change in an international context; and examines relevant laws and policies as well as options and solutions moving forward, detailed for Canada, the U.S., Mexico, and in the transnational/transboundary context.
The National Academies of Sciences, Engineering, and Medicine convened an ad hoc committee (the “Committee”) to conduct an expert review of the first order draft of the BCCA chapters concurrent with the public comment period beginning in Fall 2024. The draft BCCA was relatively early in development when the
Committee received it. This review is intended to provide the BCCA authors with guidance on how to strengthen their assessment. It can also serve as a resource to others interested in biodiversity and climate change and to future assessments that bring these topics together. The Committee considered whether the draft chapters adequately and transparently assess the relevant scientific literature and evidence, address the most pressing issues of biodiversity and climate change, and communicate findings in policy-relevant language accessible to a broad audience.
The Committee appreciates the opportunity to provide suggestions to strengthen the BCCA and commends the USGS and the international authoring team for developing an assessment focused on these issues within Canada, the U.S., Mexico, and across borders. The Committee offers conclusions that highlight overarching areas for improvement in the draft BCCA and also provide more general guiding principles the Committee thinks are essential to the development of any assessment focused on changes in biodiversity and climate. This new assessment will make an important contribution to understanding and addressing changes in biodiversity and climate in North America and serve as a foundational input to forthcoming related assessments. The Committee concludes that:
1. A robust scientific assessment of the multiple interactions between biodiversity and climate change can provide key information as input to effective resource management policies and decisions that benefit society.
Scientific assessments are distinct from other scientific documents in that they evaluate the breadth of available information and synthesize and prioritize evidence rather than providing an exhaustive literature review. When developing a robust scientific assessment, the Committee concludes that:
2. A strong conceptual framework is foundational to developing an effective assessment that prioritizes key messages and logically connects materials across the report.
The draft BCCA would be strengthened with the adoption of a consistent conceptual framework used across chapters. This would help to maintain consistent coverage of ecosystem types, balance local, regional, and national perspectives (as appropriate), synthesize multiple evidence sources, and connect findings to specific audience needs.
3. A large body of existing literature provides guidelines for developing effective assessments, including those for biodiversity and climate change. Guidance includes how to synthesize available evidence, identify knowledge gaps, and address uncertainties. Learning from and building on this guidance strengthens any assessment.
The draft BCCA would benefit from considering existing guidelines for assessments and applying a consistent approach to evaluating the evidence included in the BCCA. This includes consideration of what materials are included, how they are synthesized, and how they are presented to reach the intended audience.
4. Language and graphics tailored to the intended audience(s) of an assessment can be highly effective in conveying important findings and making information accessible for improving understanding and decision-making.
The draft BCCA would benefit from a clear articulation of who the assessment is meant to reach. Adopting greater consistency across draft chapters in the level of technical detail would also improve readability and usability by likely audiences.
Within the large body of evidence demonstrating changes in biodiversity and climate and the linkages between these topics, an assessment is most effective when it has a central focus and synthesis of available information. The Committee concludes that there are foundational elements to conveying the science and providing information that can be used to inform decision-making. Revising the BCCA to improve in all of these areas will strengthen the assessment and enhance its influence.
5. A large body of evidence documents changes in biodiversity and climate change, the linkages between them, and interactions with other factors. The Biodiversity and Climate Change Assessment can be most influential if it provides a full picture of the influence of biodiversity on climate change mitigation and adaptation and climate change impacts on biodiversity.
6. Measurements and observations have documented numerous changes in biodiversity, climate change, and interactions between them across North American ecosystems. Revising the draft Biodiversity and Climate Change Assessment to provide more thorough representation of the range of changes in different ecosystems, particularly increasing discussion of Arctic, marine, and freshwater ecosystems, would provide necessary information for a broader audience.
7. Ecosystems and species do not stop at borders; an assessment focused on North America, including the Biodiversity and Climate Change Assessment, provides an opportunity to convey information that informs transboundary coordination and collaboration efforts to address and manage for combined biodiversity and climate change goals.
8. A scientifically robust biodiversity and climate change assessment robustly assesses published research, Indigenous Knowledge, and Local Ecological Knowledge for detection of changes and attribution of changes to anthropogenic climate change (as opposed to non-climate change factors), as well as evaluates and conveys associated uncertainties in terms appropriate for the intended audience.
Bringing together available Indigenous Knowledge, Local Ecological Knowledge, and Western science introduces opportunities to reach a more holistic understanding of biodiversity and climate change than could be achieved otherwise. The Committee concludes that:
9. Synthesizing Indigenous Knowledge, Local Ecological Knowledge, and Western science when assessing linkages between biodiversity and climate change creates a synergistic, deeper understanding of historical relationships at multiple scales (local to landscape) underlying current status and trends and provides a more holistic perspective to inform strategic management and policy options.
A key element of the study and assessment of biodiversity and climate change is the connection to people. All humans benefit from nature and healthy, diverse ecosystems underpin healthy communities. The Committee concludes that:
10. Biodiversity and climate interactions are fundamental to supporting human wellbeing (clean air, clean water, agriculture, forestry, fisheries, mental health, etc.). The Biodiversity and Climate Change Assessment would be strengthened by more explicit evaluation of the implications for well-being across different segments of society and communication of the importance to society in language accessible to the intended audience(s).
Assessments that synthesize the science and existing policies for the region of study and highlight key issues can serve as a reference for a wide range of audiences and foster greater understanding of the role of management and policy in shaping the future for biodiversity and climate. Assessments can also inform decisions about how to manage ecosystems and create policies that critically examine trade-offs and benefits for biodiversity and/or climate as well. Bringing together the science and policy aspects of biodiversity and climate change across three nations and many Indigenous communities, as the draft BCCA has done, also provides an opportunity to compare and contrast national-scale approaches and learn from one another.
11. The Biodiversity and Climate Change Assessment has a distinct opportunity to compare biodiversity and climate change resource management approaches and policies across countries and to connect current and future policy options. Adopting greater consistency across Chapters 2 and 8 would help to foster this type of analysis.
The Committee provides a detailed review of each individual chapter of the draft BCCA that complements the overarching guidance.
