3.3.2.4 Novel impact types

Passing ESTPs can reverse current regional trends in climate, upsetting existing expectations, adaptation frameworks and plans. Current adaptation plans and measures may be inappropriate in the face of such trend reversals, and investments in climate-resilient infrastructure might become useless. For example, in case of a collapse of the AMOC, places like Northern Europe, that are currently adapting to marked warming and wetting, would have to adapt to radical cooling and drying instead (see Table 3.3.1 and Figure 3.3.2). Trend reversals would represent significant challenges for public communication of climate change and the justification of policy measures.

Further, the transgression of ESTPs can fundamentally alter the ecological basis of regions and livelihoods and can expose affected people and locations to novel threats. For example, the tipping of the Amazon rainforest into a savannah-like state would imply the permanent loss of the region’s current ecosystems and associated loss of biodiversity, permanent changes to the region’s hydrology and corresponding water availability, agriculture and power generation, and the removal of a major carbon sink. This would create tremendous cultural, economic and political disruption for all affected communities and countries, removing the foundations for much of the current organisation of social, cultural and economic life in the region (e.g. the potential for agriculture and cattle ranching). This would have radical implications for people’s livelihoods, food and water security, the trajectory of industries and economic sectors, the generation of taxes, international trade and tourism, and national, regional and individual identities.

Another example is the loss of tropical coral reefs, which would impact the livelihoods of half a billion people. Loss of the fisheries they support would take away a major source of livelihood, while loss of the protection they provide to coastlines would leave them exposed to storm surges and erosion.