A second limitation rests relates to the spatial scales at which sustainability concerns can be addressed. In the case of Russia, China and South Africa, the extreme carbon dependence of national economies can hardly be addressed by interventions at the scale of a city-region. There may be more space for regional interventions in China than in the other case as municipalities are empowered to provide their own electricity supply, and there is national support for changing the energy profile away from fossil fuels. In Russia, however, national support for a sustainable transition remains ambiguous while in South Africa a policy commitment to reducing carbon-dependence has not been matched by the necessary changes in institutions and regulations. Electricity-production remains overwhelming in the hands of a single national state-owned enterprise that is locked into a coal-based pathway.  

The water sector is different and regional approaches to supply and distribution are more common. There is however often a significant disjuncture in the territorial requirements for water security and the delineation of city-regions for other purposes (for example, using criteria of economic linkage, commuting flows or contiguous urban footprints). The governance of water supply is generally constructed around river catchments and the demand for water from large urban agglomerations often requires the harnessing of water from more than one catchment, with complex technical arrangements for inter-basin transfers that extend territorially far beyond the reach of a city-region. In the case of the GCR in South Africa, water is sourced from as far as the Lesotho highlands in a grand transnational water transfer scheme while the massive South to North Water Diversion Project to support Beijing extends deep into central China. As the “ultimate survival good”[20], water security may compel regional-scale collaboration but it may also provoke intense conflict as in the case of the inter-state rivalries in India or, more locally, within the structures of water governance in the São Paulo Metropolitan Region.

Air pollution is another example of territorial mismatch. Urban agglomerations are the source of much of their own pollution and steps can be taken to clean their own backyards (for example, through a shift to public transport and stronger regulation of polluting industries). The most effective examples of sector-based city-region governance may, in fact, be in relation to the management of transport systems. In the case of the BRICS the Joint Councils on Transport Coordination in the Russian Federation are examples. However, there are many contexts where causes of air pollution are geographically expansive, and where more complex inter-scalar governance arrangements, and additional forms of horizontal coordination, may be required as a response. This is the case for Greater Delhi where air pollution is the outcome of interlocking rural and urban causes in the dense agglomeration of settlements crossing state and national boundaries in the 1 700 km Indus Valley. In South Africa, prevailing winds draw into the GCR the severe SO₂-related pollution from the mega cluster of coal-fired stations across the provincial boundary in Mpumalanga.

The third limitation relates to the politics of sustainability. Even where structures of city-region governance are in place, and sustainability concerns can be meaningfully addressed at the scale of the city-region, there is no guarantee that sustainability concerns will be addressed. Much depends on the configuration of power and interests within the city-region. Historically, sustainability concerns have not figured strongly in the agendas of the political elites in the BRICS nationally, and at regional- and city-scales. In Russia it does not pay the elites to shift from a growth path premised on cheap carbon-based energy. In China, the early reform era was characterised by a doctrine that may be described as growth at all costs, and the doctrinal commitment cascaded down the governmental hierarchy. In India, the developmental ideologies of the post-colonial elite supported industrialisation and the development of modern infrastructure such as large dams without evident concern for environmental consequences. In South Africa, post-apartheid state and society, the elites are under immense pressure to respond to the immediate economic and social consequences of apartheid, with far less pressure to address the mounting environmental crisis.   

There are tough constraints in forging a strong nexus between city-regionalism and sustainability, but there are also emergent possibilities revealed through the BRICS study which provide a platform for collaborative action in the future. Brazil has been on an uneven path towards stronger regional-scale collaboration and the current reversal will, hopefully, not prove permanent. Emergent practices including voluntary collaborations between municipalities, more formally structured metropolitan councils and regionally structured water committees provide a resource for future collaborations. Brazil has the advantage of non-carbon-based energy supply, but must still ensure integrated transport systems, water security for its largest cities, and improved environmental conditions in its favelas, or informal settlements.

The post-Soviet story in Russia is of the disintegration of regional-scale collaboration but there has been a recent return to partial, and sector-specific, forms of collaboration, that offers a demonstration effect for integration in other domains. The aggravation of severe road congestion, rather than an environmental commitment, goaded national authorities to compel regional actors to collaborate around transport, and the practical consequence of other types of environmental damage may produce new forms of regional-scale interaction.

In India, a succession of initiatives to support collaborations at metropolitan- and city-region have been undermined by powerful state interests and weakly developed local authorities. However, the politics is changing as the consequence of the environmental crisis for daily life is becoming increasingly unbearable. Whereas the shocking environmental conditions of India’s slums previously affected the economically and political marginal, the severe levels of air pollution, and threats of water cuts, impact also on the lives of the elites. India’s high courts have been the leading edge of a new environmentalism but, increasingly, other agencies of government will need to show their environmental commitment if they are to ensure sustained legitimacy and this may drive new regional-scale collaborations. In China, there has already been a significant shift towards and sustainability rationale for city-region scale collaborations. The devastating environmental consequence of a decades-long economic boom has compelled China’s leadership to shore up its legitimacy by emphasising environmental reconstruction. In South Africa, environmental concerns are only gradually synthesising with developmental concerns but the recent work of the GCRO has brought environmental concerns into discussion around city-regionalism.

City-regionalism is not the panacea for sustainability and comes with multiple challenges but it does potentially play a productive role within a wider framing of inter-scalar governments which allows sustainability challenges to be addressed simultaneously through different forms of territorialisation. While historical evidence for meaningful action at the scale of the city-region is limited, the practical politics of addressing the consequences of environmental crisis may be gradually strengthening the nexus between city-regionalism and sustainability.