Impact case study database

Influence on public policy, nationally and internationally

Exeter’s research contributions have been used by governments and public bodies across the globe, and have formed a vital part of the evidence base for climate policies in Africa, Germany, Australia, Canada, the Netherlands, the United States and the UK, as outlined below.

4.1 Providing vital evidence underpinning goals to limit global warming to well below 2°C

Exeter’s research has identified how the risks posed by climate tipping points increase with global warming, and has been extensively cited in policy responses to the 2015 Paris Agreement goal of limiting global warming “to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C”, now ratified by 189 Parties to the UNFCCC.

Lenton was a contributing author to the 2018 Intergovernmental Panel on Climate Change (IPCC) Special Report on ‘Global Warming of 1.5°C’ (SR1.5) [ 5.1a], commissioned in response to the Paris Agreement. The special report makes the case for ‘Avoiding Regional Tipping Points by Achieving More Ambitious Global Temperature Goals’, and repeatedly cites Exeter’s work [ 3.4]. The 2019 IPCC ‘Special Report on the Ocean and Cryosphere in a Changing Climate’ (SROCC) [ 5.1b] cites Exeter’s work [ 3.4, 3.5] on the irreversibility of tipping points and their potential to amplify climate change and concludes: “If carbon emissions decline, the risk of…abrupt changes are reduced” [ 5.1b] . These two IPCC reports have influenced global policy directly, and the SR1.5 report is widely used to underpin ambitious mitigation policies and net zero targets.

Research by Lenton and his team also underpins a wide range of policy documents internationally. These use climate tipping points to determine targets to mitigate greenhouse gas emissions. The World Bank’s ‘Next Generation Africa Climate Business Plan’ [ 5.2a] warns that “a 2°C warming could activate important tipping elements, raising the temperature further”, citing [ 3.5]. The UK Government’s ‘Net Zero – The UK’s contribution to stopping global warming’ [ 5.2b] notes that without action, “Risks of crossing irreversible tipping points within the climate system…would be high”. The German ‘coal exit commission’ strategy for phasing out coal-fired power generation by 2038 [ 5.2c], recognises that “without a dramatic reduction in emissions, the Earth could even be propelled into a ‘hot age’”, citing [ 3.5]. Australia’s ‘Northern Territory Climate Change Response Towards 2050’ [ 5.2d] cites [ 3.1, 3.5] to support the Paris Agreement target, and cites [ 3.5] in recognising that “Global greenhouse gas (GHG) emissions need to decline rapidly to net zero”.

4.2 Providing an eight-fold increase in the estimate of the social cost of carbon

Lenton and colleagues’ research to add climate tipping points to the DICE model [ 3.3, 3.4] increased its estimates of the social cost of carbon up to >8-fold. William Nordhaus won the Nobel Prize in Economic Sciences in 2018 for developing Integrated Assessment Models, the first generation of which was the DICE model, and Exeter’s research [ 3.3] is cited in the presentation information [ 5.3]. This crucial finding has had widespread influence on policy. The United Nations Environment Programme (UNEP) ‘Inquiry into the Design of a Sustainable Financial System’ [ 5.4a] cites Exeter’s work [ 3.3] in recognising that “irreversible climate events … could individually cost 10% of global GDP over 50 years”. The 2018 IPCC SR1.5 [ 5.1a] cites [ 3.4] and the 2019 IPCC SROCC [ 5.1b] cites [ 3.3, 3.4] in recognising that “including extremes and abrupt changes, such as AMOC weakening, ice sheet collapse … leads to a several-fold increase in the cost of carbon emissions”. The Inter-American Development Bank cites [ 3.4] to underline the “needed ambition” of emission reduction for climate stabilisation at a safe level [ 5.4b].

4.3 Informing adaptation advice to international governments on tipping point risks and early warning systems

Lenton and team’s identification of climate tipping point risks and early warning systems for them [ 3.1, 3.2] has informed climate change adaptation advice to governments.

Lenton’s work helped drive the “commitment to climate and environmental action” of the Environmental Commissioner of Ontario (2015-19) [ 5.5a]. This commitment led to “three climate and four energy reports …delivered to the Ontario Legislature”, including a 2018 report citing [ 3.5] in a section on ‘Getting ready for what’s coming’ [ 5.5b]. In a subsequent report, the Council of Canadian Academies’ Expert Panel on Climate Change Risks and Adaptation Potential [ 5.5c] recognises the risk of “a large-scale dieback of the boreal forest”, and notes that the associated “release of carbon stocks” can “exacerbate climate change”, citing [ 3.1]. The European Environment Agency [ 5.6a] recognises that “potential tipping points in the climate system give rise to serious concerns”, citing [ 3.5]. The Netherlands’ Environmental Assessment Agency [ 5.6b] also recognises the risk of “onomkeerbare kantelpunten” (irreversible tipping points), citing [ 3.6].

The US Congress commissioned a 2013 report by the National Research Council focused entirely on ‘Abrupt Impacts of Climate Change: Anticipating Surprises’, for which Lenton was a reviewer [ 5.7a] . The report cites [ 3.1] and “recommends development of an abrupt climate change early warning system”. The report’s conclusion highlights the need “to be serious about the threat of tipping points so as to better anticipate and better prepare ourselves for the inevitable surprises”.

The UK’s Global Food Security programme invited Lenton to co-author a 2017 report on ‘Environmental tipping points and food system dynamics’ [ 5.7b], which cites [ 3.1, 3.3] and explores the impacts of an AMOC collapse on food security, stating: “Early warning to allow mitigation and/or adaptation is key to minimising the global disruption this might cause”. The 2019 IPCC SROCC [ 5.1b] agrees: “A specific adaptation action is a monitoring and early warning system using observation and prediction systems, which can help to respond in time to effects of an AMOC decline”. That report cites [ 3.2] to show that “the observation arrays that are in place may allow the development of such an early warning system”.

Influence on public understanding, learning and participation

Lenton and team’s research has also enhanced public understanding of climate tipping points.

4.4 Stimulating public interest and engagement; Informing awareness and understanding

Research by Lenton and his team formed the basis of a 6-episode television series on ‘The Tipping Points’, featuring Lenton (opening episode), which has aired in over 50 countries worldwide to an estimated 500 million viewers [ 5.8a]. Lenton and his tipping points research featured in BBC1’s ‘Climate Change: The Facts’, with 3.56 million viewers [ 5.8b].

‘Climate tipping points – too risky to bet against’ [ 3.6] (Altmetric attention score >9000), was covered by >150 news outlets [ 5.9a]. One article referring to [ 3.6] in Metro received 135.6 million shares [ 5.9b]. Coverage focused on how more than half of the climate tipping points identified a decade ago are now active, with evidence for cascading interactions between them. Lenton appeared on ITV News at Ten (3.7 million viewers) [ 5.8c], BBC Radio 4: World at One (3 million listeners) [ 5.8d], and Newsday on BBC World Service (~1.3 million weekly listeners) [ 5.8e]. The European Parliament voted to declare a climate emergency on the day after [ 3.6] was published, with The Guardian [ 5.9c] linking this vote directly to their coverage [ 5.9d] of [ 3.6]. Reflecting in December 2020, the New York Times stated that [ 3.5] and ‘Timothy Lenton’s overview of tipping points’ [ 3.6] ‘have galvanized the climate movement’ [ 5.9e]. Also Exeter’s climate tipping points research has been shared with the public through a Massive Open Online Course, ‘Tipping Points: Climate Change and Society’ (lead educator: Lenton), with >13,000 enrolments [ 5.10].

4.5 Contributing to a change in public perception and mood

‘Trajectories of the Earth System in the Anthropocene’ [ 3.5] was the 4^th ranked article of 2018 on Altmetric [ 5.9f] (attention score 5694 in 2018, >7000 in Dec. 2020) with coverage in >350 news outlets [ 5.9g]. CarbonBrief ranked it the most impactful climate research paper of 2018 [ 5.9h]. Media coverage focused on the possibility that an irreversible cascade of tipping points could lead to a ‘Hothouse Earth’ state. Dr Gail Bradbrook cites “the Hothouse Earth paper” [ 3.5] in an influential video that helped motivate the Extinction Rebellion protest movement [ 5.11a]. ‘Hothouse state’ became a new buzz phrase mentioned in the UK parliament [ 5.12a], and in Germany ‘ Heißzeit’, a term already linked to [3.5] [5.12b], was voted word of the year 2018 [ 5.12c]. Extinction Rebellion also shared a J. P. Morgan special report [ 5.11b] which cited [ 3.5] regarding the risk that interacting tipping elements could trigger “a domino-like cascade”. This mass awareness-raising has contributed to a shift in public perception, part of a popular movement which led to declarations of a climate emergency in the UK and the EU in 2019.