CIEL & HBF: Beyond the Limits
The latest report of the Intergovernmental Panel on Climate Change (IPCC) regarding Climate Change Impacts, Adaptation and Vulnerability (Working Group II Contribution to the IPCC Sixth Assessment Report) confirms that climate change is already causing severe and permanent loss and damage to human and natural systems, that exceeding 1.5°C warming–even temporarily– would result in further irreversible harm, and that strategies premised on the possibility of returning from such overshoot through the use of solar radiation modification (SRM) or technological carbon dioxide removal (CDR) court grave danger.
The IPCC finds that warming above 1.5°C would cause extensive human and ecological damage, including irreversible impacts from which recovery or adaptation would be difficult if not impossible. The Sixth Assessment Report explicitly considers the risks introduced not just by climate change, but by human responses to it. Working Group II recognizes that such measures can have significant adverse impacts, compounding climate damage, eroding resilience, and exacerbating vulnerabilities. This is critical because a growing majority of climate scenarios—and the climate plans and policies being adopted by nations and companies alike—rely heavily on technologies and strategies not expected to make meaningful contributions to climate mitigation for decades. Two categories of such strategies—large-scale CDR and deployment of SRM—have emerged as the primary approaches for returning to 1.5°C in the event of temperature overshoot. These strategies have gained increasing prominence in climate discourse, in national climate commitments, and in government funding decisions. These strategies may not only prove ineffective in reversing warming and impotent against its consequences, such as sea level rise, but also cause significant adverse impacts of their own, such as rainfall disruption, termination shock, water depletion, and erosion of human and ecological resilience.
In affirming that climate change is already causing, and will continue to cause, severe loss and damage, with disproportionate impacts on the most vulnerable human and ecological systems, the IPCC’s findings support growing calls for financing commitments to address those mounting impacts. While the Working Group II (WGII) report does not directly discuss climate change mitigation measures, its findings fundamentally underscore the need for urgent action and near- term emissions reductions, including a halt to all oil and gas expansion and the phaseout of fossil fuels—not strategies that assume overshoot and hope for return to 1.5°C or below by relying on risky and unproven technologies. More than any preceding IPCC publication, this report empha- sizes that social justice and equity are critical to such urgent action. The IPCC concludes that toeffectively reduce vulnerability and enhance adaptation, responses to the climate crisis must involve participatory decision-making processes and integrate considerations of justice and equity, Indigenous and local community knowledge, and the gender dimensions of climate change and climate actions.
The WG II report must be read against the background of the IPCC’s prior reports, such as the Working Group I Contribution to the Sixth Assessment Report (2021) and the Special Report on Global Warming of 1.5°C (2018). 1 Collectively these volumes signal an unambiguous warning— dangerous climate change is already unfolding, its impacts will worsen, and failure to limit warming to 1.5°C risks irreparable consequences including grave threats to human rights.
The following analysis examines the WG II report in this context and with specific attention to its findings and significance for: overshoot scenarios, technologies and approaches common to those scenarios, and the implications of climate change and responses to it for human rights, Indigenous Peoples’ rights, and social justice. It highlights three critical messages and themes that emerge from the WG II report:
- Even temporary overshoot of 1.5°C is exceptionally dangerous and would result in adverse impacts irreversible on time-scales from centuries to millennia, or in the case of species extinctions, simply irreversible;
- Approaches that deploy unproven technologies to reverse or mask overshoot may prove ineffective and risk further disaster;
- Climate responses, including adaptation, must integrate social justice and equity and center Indigenous and local knowledge.
A recognition of these critical messages is important both to a proper understanding of the WGII report itself and to evaluating the mitigation options to be discussed in the forthcoming report of IPCC Working Group III.
Some of Working Group II's most sobering findings were diluted or deleted from the final Summary for Policymakers approved by State Parties. But Parties cannot negotiate away the science. The underlying chapters of the WGII report, including the technical summary, leave no doubt: surpassing 1.5°C will lead to irreparable harm, whether or not return to lower temperatures is even possible. Technologies like SRM and large-scale CDR that purport to enable such return may not only fail to deliver their claimed climate benefits, they also may trigger significant adverse impacts of their own. Policy choices that lock the world into overshooting 1.5°C and gambling on return, rather than immediately and drastically slashing emissions— including through rapid phaseout of fossil fuel production and use and a halt to deforestation— invite permanent loss and irreversible damage to humans and ecosystems around the world. In the face of this latest IPCC report, such choices are indefensible.
 IPCC, Working Group I Contribution to the IPCC’s Sixth Assessment Report on The Physical Science Basis (2021) and component chapters [WGI], available at: https://www.ipcc.ch/report/ar6/wg1/; IPCC, Global Warming of 1.5°C: An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty (2018) [SR 1.5], available at https://www.ipcc.ch/sr15/.