Exploring the Interface Between Planetary Boundaries and Palaeoecology

Abstract

The concepts of planetary boundaries are influential in the sustainability literature and assist in delineating the 'safe operating spaces' beyond which critical Earth system processes could collapse. Moving away from our current trajectory towards 'hothouse Earth' will require knowledge of how Earth systems have varied throughout the Holocene, and whether and how far we have deviated from past ranges of variability. Such information can inform decisions about where change could be resisted, accepted or where adaptation is inevitable. The need for information on long-term (Holocene) change provides an interface for palaeoecology and sustainability that remains underexploited. In this position paper, we explore this interface, first discussing the need for long-term perspectives and introducing examples where palaeoecology has been used in defining safe operating spaces and constraining limits of acceptable change. We describe advances in quantitative methods for analysis of time-series data that strengthen the contribution of palaeoecology to the concepts of planetary boundaries and safe operating spaces. We consider the importance of issues of scaling from landscape to regional and global scales in operationalising planetary boundaries concepts. We distil principles for this field of research going forward and introduce three case studies which will form the basis of research on these topics.

Keywords: palaeoecology; planetary boundaries; resilience; safe operating space; sustainability; tipping points; variability.

FIGURE 1

The 2023 update to the planetary boundaries. Azote for Stockholm Resilience Centre, based on analysis in Richardson et al. (2023). Licensed under CC BY‐NC‐ND 3.0.

FIGURE 2

Conceptual diagram showing how knowledge of variability throughout the Holocene could help inform safe operating spaces. The dark‐green area shows the Holocene range of variability and the grey sphere shows present and future positions of the system, and dotted lines represent alternative trajectories. The safe operating space expands in the Anthropocene (shown in paler green) as we accept that Holocene conditions may no longer be feasible, in which case adaptation to novel conditions will be needed (after Dearing et al. 2014).

FIGURE 3

(A) The Princessvlei (PV) catchment is located on the Cape Flats, (B) the percentage abundance of PV diatoms based on nutrient requirements over the last 2600 years, (C) Eilandvlei (EV) is part of the Wilderness Complex, (D) the percentage abundance of EV diatoms based on salinity preferences over the last 8000 years and (E) both sites are located in South Africa. Map lines delineate study areas and do not necessarily depict accepted national boundaries. Data from Kirsten et al. (2018) and Kirsten and Meadows (2016).

FIGURE 4

Sketch map of the Taihu Lake Basin in the Yangtze River Delta, East China, with the locations of sediment core sampling sites (site 1, site 2, site 3). The inset in the bottom right corner presents the chlorophyll‐a (Chla) concentration results for each site over the past century, derived from sediment pigment analysis. Map lines delineate study areas and do not necessarily depict accepted national boundaries. Data from Lin et al. (2021).

FIGURE 5

The Murray–Darling Basin in Australia and figure showing shifts in planktonic diatoms over time. Data from Map lines delineate study areas and do not necessarily depict accepted national boundaries. Data from Gell (2024).