UN Climate Scientist Advocates “Beyond Net Zero” — Emphasis on Active Carbon Removal as Temperatures Edge Above 1.5 °C

Leading United Nations scientists and multiple international assessments now argue that, with global temperatures at or slightly above 1.5 °C, mitigation policy must expand from net zero to “beyond net zero” strategies that include large-scale, durable carbon dioxide removal (CDR). The rationale: limiting peak warming and avoiding long-term overshoot increasingly requires not only rapid emissions cuts but also active removal of CO₂ from the atmosphere (direct air capture, BECCS, enhanced weathering, durable biochar, etc.). This article synthesizes the evidence base, describes the principal CDR technologies and constraints, examines governance and ethical issues, and provides practical policy recommendations for governments and institutions.

Context — United Nations & IPCC

Global assessments underline two linked facts: (1) limiting long-term warming to 1.5 °C requires immediate, deep, economy-wide emissions reductions and net-zero CO₂ by mid-century; and (2) if temperatures overshoot 1.5 °C (or if near-term emissions reductions fall short), removing CO₂ from the atmosphere at scale becomes necessary to return temperatures toward that target and to avoid persistent climate impacts. The IPCC’s Special Report on 1.5 °C documents that global temperature stabilisation for 1.5 °C requires net-zero CO₂ in the early 2050s and that pathways often include some form of CO₂ removal.

The United Nations and affiliated expert groups have repeatedly emphasised that current national pledges (NDCs) are insufficient and that additional policy instruments will be needed to bridge the gap. With observed and near-term global temperatures flirting with 1.5 °C, several UN-linked scientists are urging explicit planning for net negative outcomes (i.e., “beyond net zero”) to reduce peak warming and long-term cumulative forcing.

What “Beyond Net Zero” means in practice

“Beyond net zero” denotes a strategic posture that combines:

• Rapid and sustained emissions reductions across all sectors (energy, transport, industry, agriculture, buildings).
• Planned deployment of durable CDR to remove historical and residual emissions from the atmosphere, with clearly defined targets for removal volumes and permanence.
• Short-lived climate pollutant control (notably methane) to reduce near-term warming alongside CO₂ removal.
  This approach shifts the policy objective from balancing emissions and removals at a target date toward achieving net negative cumulative CO₂ for a period sufficient to pull peak temperatures down and reduce risks of long-term climate tipping points. The policy literature has proposed separate accounting and explicit negative-emissions targets to avoid conflating reductions and removals.

Active carbon removal technologies — overview, maturity, limits

Key CDR options fall into several families:

1. Direct Air Capture with Storage (DACCS). Mechanical/chemical systems capture CO₂ from ambient air; captured CO₂ is then compressed and stored geologically or used in long-lived products. DAC is location-flexible but currently expensive and energy-intensive; scaling depends on low-cost clean electricity, CO₂ transport and storage infrastructure, and cost reductions through learning and scale. The International Energy Agency describes DAC as an enabling technology for net-zero pathways if costs fall and infrastructure scales.
2. Bioenergy with Carbon Capture and Storage (BECCS). Combines biomass feedstocks with carbon capture at bioenergy combustion/processing sites; when CO₂ is stored, BECCS yields net removal. BECCS can produce large removals in some models but raises land-use, biodiversity, and food-security trade-offs at large scale and requires sustainable biomass sourcing and secure storage. (See DOE and other technical assessments for governance needs.)
3. Soil and biomass sinks (afforestation, reforestation, improved soil carbon, biochar). Lower cost per ton in some contexts but with less permanence and saturation risks; these methods are best integrated with land-use planning and social safeguards.
4. Enhanced rock weathering and ocean-based CDR. Early stage; potential for durable storage but with environmental, scalability, and governance uncertainties.

Comprehensive reviews and policy reports emphasise that a portfolio approach is required, since no single technology alone is plausibly sufficient, affordable, and risk-free at the scale needed.

Scientific evidence on benefits and urgency

• Temperature control: Removing CO₂ reduces radiative forcing and, if scaled sufficiently, can reduce peak global temperatures and shorten the time of overshoot. Models used in IPCC scenarios show that incorporating CDR can materially change peak warming trajectories and long-term equilibrium temperatures.
• Risk reduction: Rapid removal, combined with methane cuts, reduces near-term extremes (heatwaves, drought amplification) and lowers the probability of triggering some tipping elements. Recent scientific commentary and modelling underscore the limited window for reducing the chance of irreversible thresholds.

Economic, social, and ethical constraints

• Cost and finance. Current DAC and large-scale BECCS costs are high; public finance, carbon markets with robust integrity, and targeted subsidies (R&D, first-of-a-kind plants) will be required to bridge the viability gap while ensuring value for money. IEA and EU analyses stress policy instruments to drive cost declines and scale.
• Land and food security. Large BECCS/afforestation at scale can conflict with food production and biodiversity unless stringent sustainability criteria are enforced.
• Permanence and monitoring. CDR solutions require long-term monitoring, verification, and liability frameworks for stored CO₂. Geological storage necessitates rigorous site characterisation and legal clarity about ownership and long-term stewardship.
• Moral hazard concerns. Critics warn that promises of future removal should not delay rapid mitigation today; governance must separate emissions reductions commitments from removal procurement and avoid perverse incentives.

Governance and policy design principles

To operationalise “beyond net zero” responsibly, policymakers should adhere to core principles:

1. First, deep emissions cuts. CDR is complementary, not a substitute. Emissions abatement remains the highest priority. (IPCC emphasis.)
2. Clear, separate targets for removals. Distinguish reduction targets from removal targets in national planning and international accounting frameworks. (Scholars and policy briefs have argued for separate negative-emissions targets to preserve transparency.)
3. Robust MRV and permanence standards. Internationally aligned measurement, reporting and verification systems are essential, with conservative rules for permanence and leakage.
4. Sustainability safeguards. Land-based CDR must meet social and biodiversity safeguards, and communities should be partners, not passive recipients.
5. Phased procurement and public finance. Use public R&D funding, advanced market commitments, and carbon-removal procurement (public and corporate) to create demand while ensuring cost-effectiveness and equity. IEA and EU studies recommend targeted incentives and infrastructure planning.

Recommendations for national and institutional actors

• Governments: adopt explicit national removal strategies (with quantitative targets), fund R&D, establish storage permitting and liability regimes, and build CO₂ transport-and-storage infrastructure plans.
• International organisations: create common MRV standards for removals, facilitate finance for technology transfer and capacity building, and integrate removals into global stocktakes without weakening emissions-reduction obligations.
• Private sector & investors: finance demonstration projects, disclose removal procurement plans, and avoid double-counting in corporate climate claims.
• Research & civil society: prioritise cross-disciplinary research on removal durability, lifecycle impacts, and social implications; develop participatory governance models.

Conclusion — balancing urgency and caution

As global temperatures approach or exceed 1.5 °C, the scientific and policy communities increasingly recognise that beyond net zero — i.e., planned, durable removal of atmospheric CO₂ at scale — will be necessary in many scenarios to limit peak warming and reduce long-term risk. However, the deployment pathway must be governed by strict sequencing (cuts first), robust safeguards, international alignment on measurement and permanence, and equitable finance. Well-designed policy can unlock innovation and scale for DAC, BECCS, and other durable removals while protecting ecosystems and communities.

Key references (selected)

1. IPCC — Special Report: Global Warming of 1.5 ºC (Summary for Policymakers).
2. International Energy Agency — Direct Air Capture overview and policy brief.
3. U.S. Department of Energy — Carbon Dioxide Removal: Purpose, Approaches, and Recommendations (January 2025).
4. European Parliament study — role of DAC and DACCS in EU decarbonisation (2025).
5. McLaren D.P., “Beyond ‘Net-Zero’: A Case for Separate Targets” — policy analysis on negative-emissions accounting.
6. NewClimate / technical reviews on durable CDR pathways and trade-offs.