2. Mapping the indirect impacts of climate change

To understand this proposition, we must first link various direct physical impacts of warming to relevant socio-political effects, and map key interlinkages between the latter. How all this may influence the politics of climate mitigation is described in the subsequent section.

Central among these indirect effects is the widening of socioeconomic inequalities, both within and between countries, which can occur via numerous pathways. The literature on climate change and inequality is substantial and can broadly be divided into (i) that studying inequalities in contributions to emissions (i.e. the emissions attributable to given entities) and (ii) vulnerability to the negative impacts of warming (i.e. the potential to suffer from climate-driven environmental changes). Generally, more affluent populations have higher carbon and energy footprints (Bruckner et al., Reference Bruckner, Hubacek, Shan, Zhong and Feng2022; Chancel, Reference Chancel2021; Oswald et al., Reference Oswald, Owen and Steinberger2020; Piketty & Chancel, Reference Piketty and Chancel2015) and are primary drivers of investments in high-carbon activities (Ceddia, Reference Ceddia2020; Manych et al., Reference Manych, Steckel and Jakob2021), while simultaneously being less exposed to climate impacts and more able to adapt to (or recover from) the impacts they do suffer (Bathiany et al., Reference Bathiany, Dakos, Scheffer and Lenton2018; Byers et al., Reference Byers, Gidden, Leclère, Balkovic, Burek and Ebi2018; Levy & Patz, Reference Levy and Patz2015). Current inequalities are thus reflected in both contributions and vulnerability (IPCC, 2022). Absent political effort to the contrary, such inequalities will be further increased by warming (King & Harrington, Reference King and Harrington2018; Shiogama et al., Reference Shiogama, Hasegawa, Fujimori, Murakami, Takahashi and Tanaka2019), with poorer populations trapped in a vicious cycle where current inequalities leave them suffering disproportionately from climate impacts (Cappelli et al., Reference Cappelli, Costantini and Consoli2021; Islam & Winkel, Reference Islam and Winkel2017). In contrast, affluent populations on the coast, in the forest or the city can relocate, smoke-proof their homes from wildfires, hire private firefighters or install air conditioning. At the apex of this trend are the billionaires purchasing survival bunkers in New Zealand.

Another critical socioeconomic effect of warming relates to migration. The World Bank estimate that, without concerted mitigation action, the number of within-country climate migrants could exceed 200 million by 2050 (Clement et al., Reference Clement, Rigaud, de Sherbinin, Jones, Adamo and Schewe2021) – and this estimate omits extreme weather events like cyclones. The number of international climate migrants is expected to be significantly smaller and quantitative estimates don't yet exist (IPCC, 2022), due largely to the multi-casual nature of migration (Black et al., Reference Black, Adger, Arnell, Dercon, Geddes and Thomas2011). Complicating factors include the speed of onset of climate impacts: ruptures like cyclones can leave people involuntary immobile – without the resources necessary for migration to even remain an option – while slow-onset events such as prolonged droughts induce relatively more international migration (Kaczan & Orgill-Meyer, Reference Kaczan and Orgill-Meyer2020). Glossing over this complexity, academic, policy and public discourses on climate migration have tended to frame predictions of mass migration from the Global South to the Global North as the consensus view (Boas et al., Reference Boas, Farbotko, Adams, Sterly, Bush and van der Geest2019). Such alarmism has been cautioned against due to the potential for it to bolster securitisation discourses, xenophobia and support for harder borders (Bettini, Reference Bettini2013). Nonetheless, there is evidence that warming can have a significant effect on international migration to rich countries (Coniglio & Pesce, Reference Coniglio and Pesce2015) – a trend likely to continue as warming increases if border policies in wealthier countries allow (McLeman, Reference McLeman2019). Overall then, while the debate is highly contested – and complexity may continue to prohibit quantitative projections – there are various direct and indirect pathways through which warming could substantially increase international migration. This is made more salient given that, within fifty years, over a billion people in the Global South may find themselves in climatic conditions warmer than anywhere today (Xu et al., Reference Xu, Kohler, Lenton, Svenning and Scheffer2020), with a subset of these exposed to heatwaves that humans simply cannot survive (Raymond et al., Reference Raymond, Matthews and Horton2020).

Other indirect impacts of warming are the greater risk of intergroup conflict, for example, over basic resources such as water (Hsiang et al., Reference Hsiang, Burke and Miguel2013); increased interpersonal violence and crime during high-temperature periods (Mares & Moffett, Reference Mares and Moffett2016; Miles-Novelo & Anderson, Reference Miles-Novelo and Anderson2019); and increased economic instability due to economic damages caused by warming and stranded assets (Burke et al., Reference Burke, Davis and Diffenbaugh2018). Like migration, the relationship between warming and conflict has been fiercely debated (Barnett, Reference Barnett2018), in large part because pre-existing social, economic and political factors are the dominant causal factors. The influence of warming on the Syrian war is particularly contested, with some arguing that it played a negligible role (Selby et al., Reference Selby, Dahi, Fröhlich and Hulme2017). It has thus been argued that when these wider factors are crowded out of debates, it risks inappropriate militarised and securitised solutions being employed (Gleditsch, Reference Gleditsch2012). Nonetheless, there is a growing consensus that warming is a risk factor in armed conflict, violence, hate speech and crime (Burke et al., Reference Burke, Hsiang and Miguel2015; Mach et al., Reference Mach, Kraan, Adger, Buhaug, Burke and Fearon2019; Stechemesser et al., Reference Stechemesser, Levermann and Wenz2022).

Finally, there are various direct and indirect interlinkages (Figure 1). Economic instability may further increase inequalities, if the political response is such that the poorest are hit hardest by financial crisis while the affluent find ways to profit. Climate-related increases in economic inequalities may further increase the number of climate-related migrants if poorer populations in poorer countries struggle to secure reasonable standards of living (Kikstra et al., Reference Kikstra, Mastrucci, Min, Riahi and Rao2021) while affluent countries become more attractive destinations (McLeman, Reference McLeman2019). Larger inequalities between countries may also add to the risk of violent conflict if the ability of poorer countries to secure access to basic resources like water and food is further compromised; conflicts which could add yet further to international migration. Finally, larger within-country inequalities are well-known to increase the prevalence of interpersonal violence and other crime (Wilkinson & Pickett, Reference Wilkinson and Pickett2011).

Figure 1. Illustration of the direct impacts of climate change (black box), some indirect effects of this warming (grey boxes), interlinkages between indirect effects, the politics these effects may catalyse (red boxes) and how this may present barriers to mitigation. Note, the figure illustrates the ways that climate change may influence inequality, nationalism, etc., but it's not intended to capture other influences upon these beyond warming.

3. Authoritarian populism and climate impacts

This seemingly disparate collection of climate impacts has been laid out due to their association with factors contributing to the rise of nationalist, authoritarian populist leaders across Europe, the USA, Brazil and elsewhere in the 21st century (Norris & Inglehart, Reference Norris and Inglehart2019). The literature on this subject is extensive and evolving. However, it is broadly accepted that three important factors in the rise of authoritarian parties have been: discontent with levels of immigration (Edo et al., Reference Edo, Giesing, Öztunc and Poutvaara2019) in all but the most urban areas (Dustmann et al., Reference Dustmann, Vasiljeva and Piil Damm2018); persistent economic inequality, insecurity and disadvantage (Inglehart & Norris, Reference Inglehart and Norris2017; Rodríguez-Pose, Reference Rodríguez-Pose2018), which is often framed as resulting from globalisation (Rodrik, Reference Rodrik2021); and fears about both global security (Homolar & Scholz, Reference Homolar and Scholz2019; Wright & Esses, Reference Wright and Esses2019) and local crime (Burscher et al., Reference Burscher, van Spanje and de Vreese2015; Dinas & van Spanje, Reference Dinas and van Spanje2011).

Potential interlinkages between climate impacts and politics can now be sketched out, and the way the former may foster authoritarian populism can be mapped (Figure 1). But various provisos must be acknowledged here. First, there are deeper interrelations, especially in discourse – for example, populist leaders often attempt to link immigrants to crime and job insecurity, and public fears are deeply connected (Dinas & van Spanje, Reference Dinas and van Spanje2011). Second, researchers have emphasised the largely separate role of cultural backlash in driving contemporary populism (Norris & Inglehart, Reference Norris and Inglehart2019). Third, the strength of some interlinkages may be weak. For example, it's been suggested that crime rates in the USA may rise ~1–5% this century due to warming (Burke et al., Reference Burke, Hsiang and Miguel2015) – this may have at most a marginal effect on support for populism, not to mention that other socioeconomic factors influence crime rates far more strongly. Most importantly, this analysis should not be taken as environmental determinism, but rather as suggesting one potential future with no specified likelihood.

Nevertheless, the fundamental point is that we should take seriously the considerable overlap between key socio-political impacts of climate change – within which socioeconomic inequalities are central – and key factors underpinning the rise of nationalist, authoritarian politics. Similar concerns have been highlighted by others: some warn of the danger of a fossil fascism that exploits the climate crisis by feeding upon anti-immigration sentiments and promising to aggressively defend the privileges of the Global North (Malm & Collective, Reference Malm and Collective2021); others of the multi-scale fortress mentality that environmental insecurity can provoke (White, Reference White2014). More broadly, such nationalism is precisely the type of politics underpinning the resurgent nationalism that characterises the IPCC's most pessimistic SSP3 pathway (Fujimori et al., Reference Fujimori, Hasegawa, Masui, Takahashi, Herran and Dai2017), where mitigation and adaptation challenges are highest, and keeping temperature rise below 2 °C becomes almost infeasible.