What sort of net zero? Implications for climate change, biodiversity and human well-being

Against the background of the recent controversy about the UK’s net zero climate target and concerns about the potential weakening of environmental protection, this blog sets out the important interlinkages between biodiversity and climate change, and unpacks the slippery concept of net zero. There are different ways to achieve net zero, each with different implications for people and the planet. This blog also highlights some of the outstanding scientific questions that are important to inform an effective and coordinated response to these two urgent challenges for the UK and globally.

Common origins and interlinkages

The most recent IPCC assessment noted that “Biodiversity loss, and degradation, damages to and transformation of ecosystems are already key risks for every region due to past global warming and will continue to escalate with every increment of global warming”[1]. How climate change and biodiversity loss unfold and feedback on each other in the coming decades has the potential to utterly transform the conditions for human and non-human life on the planet. As the two are intrinsically interlinked, effective, coordinated action on both is urgently needed.

Nature-based solutions (NbS) recognise the role of terrestrial and marine ecosystems in moderating the extent of climate change. NbS can contribute both through carbon dioxide sequestration, offering a mechanism for mitigation, and by enhancing resilience to climate hazards[2],[3]. However, NbS can be perceived as a way of avoiding hard mitigation choices involving structural societal changes. Moreover, although by definition NbS should have positive effects for climate action, biodiversity and people, poorly planned or badly implemented solutions can have the opposite effect on one or more of these aspects[4]. Given that climate change contributes to biodiversity loss and impacts ecosystems, implementing NbS may become more challenging under more severe emissions scenarios.

The slippery concept of “net zero”

Net zero refers to a balance in the emissions and removals from the atmosphere of greenhouse gases (e.g. carbon dioxide) to stop the continuing rapid rise in greenhouse gas concentrations in the atmosphere and limit the risks associated with climate change[5]. The UK goal is to achieve net zero by 2050[6]. Net zero, however, may be compatible with a range of different global warming outcomes: 1.5°C, 2°C or even 4°C.  The greater the cumulative level of carbon dioxide and other greenhouse gases emitted to the atmosphere due to human activities by the time net zero is achieved globally, the greater the warming. So net zero on its own is not a sufficient policy target.

Deep and rapid reductions in greenhouse gas emissions are needed globally over each of the next three decades in order to limit global warming to 2°C and even give a chance of approaching 1.5°C, a key goal of the 2015 Paris Agreement. The IPCC assesses that by 2050, net global greenhouse gas emissions need to fall by 63% (assuming immediate action) in emissions pathways that limit global warming to 2°C with > 67% chance, and by 84% for limiting to 1.5°C with >50% chance, compared to 2019 levels[7]. Net zero global carbon dioxide emissions would occur around 2070-75 for a 2°C pathway and around 20 years earlier to achieve 1.5°C.

The IPCC’s latest assessment identified a number of different (illustrative) emission pathways to achieve a 1.5°C goal[8]. One has a high but declining reliance on fossil fuels throughout the century, with a relatively slow growth in renewables and massive investment in carbon dioxide removal (CDR) from the atmosphere, whether by ecosystems or technologies. However, CDR technologies are expensive and still a long way from being deployable commercially at a large enough scale. This means there are significant policy and financial risks to any approach that is overly dependent on them. There is also a risk of creating damaging trade-offs, e.g. between the use of land or water for either fuel, food or biodiversity, depending on the types of CDR implemented.

Alternative pathways to 1.5°C have lower levels of energy demand and lower fossil energy, and are thus less reliant on CDR technologies, though these technologies will still be needed if only to deal with hard-to-abate sectors. Land-use trade-offs and impacts on biodiversity are likely to be lower in these pathways, which limits the growth in demand for energy materials for renewables and energy storage[9]. Such lower-demand pathways are also likely to include different approaches to agriculture and food that help tackle agricultural emissions, unsustainable production and unhealthy diets.

The emissions pathways taken, globally and nationally, to achieve the Paris goal are therefore hugely important. They can either contribute to or undermine our parallel efforts to tackle the biodiversity crisis, as well as a range of other social and economic issues[10]. The term “net zero”, even with a date attached, can imply vastly different potential outcomes.

The UK Prime Minister’s decision to delay the ban on the sale of petrol and diesel cars[11] and his earlier decision to approve new oil and gas exploration are claimed to be consistent with the UK’s net zero target[12]. This puts the UK on the fossil fuel intensive pathway to net zero, with greater dependence on risky, future investments in CDR technologies, delays in the further ramping up of renewables and of energy efficiency improvements.

Given the UK’s earlier international leadership on climate and biodiversity issues (e.g. the 2008 Act, the Climate Change Committee, Carbon Budgets, ambitious stance at CBD COP15 etc), this sends a very worrying signal internationally ahead of COP28 to large emitting countries that need to make more ambitious emissions reductions than they have so far committed to. The Paris Agreement depends on collective action, built incrementally through action, finance and transparency. The UK currently appears to be going backwards on all three[13].

The role of ecologists

The ecological scientific community has informed the debate on the feasibility and implications of different emissions pathways for climate, biodiversity and the potential contributions of nature-based solutions to mitigating and adapting to the impacts of climate change. Yet there are still key gaps that the ecological scientific community can help fill to contribute to the debate on how we achieve net zero targets.

We need to understand the impacts of different pathways to achieving net zero on global and domestic biodiversity targets. We need to assess the impacts of scaling up renewable energy installations on biodiversity and ecosystems and develop effective landscape planning to guide the installation of solar, wind, hydro and biomass energy technologies to deliver net gain for biodiversity and a wide range of ecosystem services. We also need to better quantify and model emissions from land-use and land-use change, including carbon uptakes, long-term viability of carbon stores in peatland, woodland, grassland, saltmarshes and seagrass under different climate change or management scenarios, and outcomes of restoration efforts and peatland and woodland creation targets. Finally, we need to identify synergies and trade-offs between climate change mitigation, adaptation and wider well-being policies, evaluating their outcomes whilst remembering to account for the intrinsic worth of nature. Particular attention must be paid to the social-cultural nexus of these policies. For example, whilst the large-scale restoration of parts of the Scottish Highlands may provide carbon storage and/or biodiversity benefits, this transition must also be socially just and economically feasible.

Concluding remarks

The deep interdependence between climate change and biodiversity should be highlighted in political and public debates. Policy responses and financial support up to now have overwhelmingly prioritised climate change. This is slowly beginning to change, with the 2022 Kunming-Montreal Global Biodiversity Framework being celebrated as biodiversity’s “Paris moment”. But while developed countries are still making efforts to achieve their commitment for climate finance, international public finance for biodiversity action remains at least an order of magnitude smaller and below that associated with large payment for ecosystem services programmes[14].

In recent years, the headwinds of the COVID pandemic and its repercussions, including for public debt, conflict and associated resource scarcity, inflation and geopolitical tensions, have meant that political focus and financial resources have been diverted elsewhere. Yet the approaches taken to tackle other pressing economic and security challenges have major implications for efforts to address the climate and biodiversity crises, which are at least as urgent as the other crises we face. Furthermore, action on climate change and biodiversity loss can also open opportunities for win-win solutions to many of the other challenges facing the world[15].

The UK government’s recent decisions to delay the ban on fossil fuel cars and to approve new oil and gas exploration puts at risk its own commitments for 2030 and beyond by further increasing the “carbon entanglement” of the UK economy[16] and delaying the scale up of renewables and energy efficiency measures. Missing from the media storm about whether or not the Prime Minister’s decisions are consistent with net zero is serious scrutiny or debate about what sort of pathway to “net zero” the UK should take and what this means for the global transition and for biodiversity. The current path taken by the government suggests that the achievement of net zero by 2050 will depend on the large-scale deployment of carbon dioxide removal technologies, with increased risks for climate outcomes, biodiversity and human well-being. This is a failed opportunity to address the multiple crises we now face.

The British Ecological Society Climate Change Ecology Special Interest Group:

Simon Buckle, Phillipa Gillingham, Ellie Harris, Regina Kolzenburg, Charlotte Ndiribe, Adam Pellegrini, Sarah Rehman, Andy Stott, Toryn Whitehead and Orly Razgour

The opinions expressed in this blog are held by the authors and not necessarily those of the British Ecological Society or the organisations they belong to.

[1] SPM.B.4.1 in IPCC, 2022: Summary for Policymakers. In: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

[2] Griscom, B.W., Adams, J., Ellis, P.W., Houghton, R.A., Lomax, G., Miteva, D.A., Schlesinger, W.H., Shoch, D., Siikamäki, J.V., Smith, P. and Woodbury, P., 2017. Natural climate solutions. Proceedings of the National Academy of Sciences, 114, 11645-11650.

[3] https://www.britishecologicalsociety.org/wp-content/uploads/2022/02/NbS-Report-Final-Updated-Feb-2022.pdf

[4] Seddon, N., Smith, A., Smith, P., Key, I., Chausson, A., Girardin, C., House, J., Srivastava, S. and Turner, B., 2021. Getting the message right on nature‐based solutions to climate change. Global Change Biology, 27, 1518-1546.

[5] See NOAA for data, https://gml.noaa.gov/ccgg/

[6] https://commonslibrary.parliament.uk/research-briefings/cdp-2023-0124/

[7] IPCC, 2022: Summary for Policymakers. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

[8] There are a range of different pathways and different ways in which they could be achieved. See the discussion of Illustrative (Mitigation) Pathways in IPCC (2022) cited above.

[9] See for example, Lèbre, É., Stringer, M., Svobodova, K., Owen, J.R., Kemp, D., Côte, C., Arratia-Solar, A. and Valenta, R.K., 2020. The social and environmental complexities of extracting energy transition metals. Nature communications, 11, 4823.

[10] See for example, Buckle, S., Ellis, J., Jaber, A.A., Rocha, M., Anderson, B. and Bjersér, P., 2020. Addressing the COVID-19 and climate crises: Potential economic recovery pathways and their implications for climate change mitigation, NDCs and broader socio-economic goals.

[11] See the press release, which also included a number of other measures: https://www.gov.uk/government/news/pm-recommits-uk-to-net-zero-by-2050-and-pledges-a-fairer-path-to-achieving-target-to-ease-the-financial-burden-on-british-families#:~:text=The%20Prime%20Minister%20Rishi%20Sunak,eases%20the%20burdens%20on%20families

[12] https://www.bbc.co.uk/news/live/uk-politics-66357043

[13] On climate finance, see https://www.theguardian.com/environment/2023/jul/04/revealed-uk-plans-to-drop-flagship-climate-pledge-rishi-sunak

[14] See https://www.oecd.org/environment/resources/tracking-economic-instruments-and-finance-for-biodiversity-2020.pdf

[15] See report to the UN on the Sustainable Development Goals underlined in terms of climate action:  Synergy Solutions for a World in Crisis:  Tackling Climate and SDG Action Together, September 2023 sdgs.un.org/sites/default/files/2023-09/UN%20Climate%20SDG%20Synergies%20Report-091223B.pdf.

[16] Lecture by the former OECD Secretary General, 9 October 2013  https://web-archive.oecd.org/2015-07-03/251995-the-climate-challenge-achieving-zero-emissions.htm