Projected future climatic forcing on the global distribution of vegetation types

Abstract

Most emissions scenarios suggest temperature and precipitation regimes will change dramatically across the globe over the next 500 years. These changes will have large impacts on the biosphere, with species forced to migrate to follow their preferred environmental conditions, therefore moving and fragmenting ecosystems. However, most projections of the impacts of climate change only reach 2100, limiting our understanding of the temporal scope of climate impacts, and potentially impeding suitable adaptive action. To address this data gap, we model future climate change every 20 years from 2000 to 2500 CE, under different CO 2 emissions scenarios, using a general circulation model. We then apply a biome model to these modelled climate futures, to investigate shifts in climatic forcing on vegetation worldwide, the feasibility of the migration required to enact these modelled vegetation changes, and potential overlap with human land use based on modern-day anthromes. Under a business-as-usual scenario, up to 40% of terrestrial area is expected to be suited to a different biome by 2500. Cold-adapted biomes, particularly boreal forest and dry tundra, are predicted to experience the greatest losses of suitable area. Without mitigation, these changes could have severe consequences both for global biodiversity and the provision of ecosystem services. This article is part of the theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’.

Navigating ecological novelty towards planetary stewardship: challenges and opportunities in biodiversity dynamics in a transforming biosphere

“…From the second subtheme, on biodiversity projections under global change, it is clear that the call to extend our temporal perspective beyond 2100 is not just a theoretical consideration but a practical necessity. The analyses in Ordonez et al and Allen et al, both in this theme issue, show that while high levels of climatic novelty and climatic forcing of biome shifts can be expected to become widespread even under moderate climate scenarios already before 2100, these dynamics are likely to continue in the following centuries [54,55]. Importantly, dynamics in the direction of such trajectories are already emerging [59,91,92].…”

“…Holistic approaches allow a focus on changes in the overall state of a system. For instance, in this theme issue, Allen et al [55] used this approach to assess the global changes in the climate forcing of biome states from now until 2500. Their findings show that under the somewhat optimistic but still possible representative concentration pathway (RCP) 4.5 climate scenario, up to 40% of the terrestrial area is predicted to undergo climatic shifts towards a new biome state, i.e.…”

“…Given the ongoing and uncertain nature of expected changes in the Anthropocene era, managing ecological systems requires us to project changes in biodiversity under alternative scenarios, consider the rates of ecological change [ 40 ], and take a long-term perspective [ 51 ]. Models may be based on individualistic species dynamics [ 52 ], be designed as interactive multi-species models [ 52 ], focus on the mechanisms of organismal responses [ 10 , 53 ], or take a more holistic assemblage, ecosystem or environmental approach [ 10 , 54 , 55 ]. Further, projection models can be built either on first principles [ 23 , 53 , 55 ], statistical associations [ 36 , 52 ] or involve transformations of environmental changes into measures of ecological response [ 54 ].…”

“…Models may be based on individualistic species dynamics [ 52 ], be designed as interactive multi-species models [ 52 ], focus on the mechanisms of organismal responses [ 10 , 53 ], or take a more holistic assemblage, ecosystem or environmental approach [ 10 , 54 , 55 ]. Further, projection models can be built either on first principles [ 23 , 53 , 55 ], statistical associations [ 36 , 52 ] or involve transformations of environmental changes into measures of ecological response [ 54 ].…”

“…Variability among climate models introduces uncertainties in quantifying the drivers and pathways of ecological change. Climate policies and socioeconomic developments define possible climatic futures, resulting in alternative RCPs that would mean alternative trajectories of climatic novelty [ 54 ] and climatic forcing of biome shifts [ 55 ]. Lastly, dynamics in the mechanisms of ecological change, such as biotic mixing owing to globalization and associated changes in biotic network structure [ 19 ], defaunation [ 38 , 58 ], mismatches in the dynamics of different dimensions of biodiversity [ 10 ], prevalent disequilibrium dynamics [ 27 , 59 ], as well as mis-specified spatio-temporal contexts for change assessment [ 8 , 60 ] generate challenges for projecting ecological changes.…”