Ecosystems are showing symptoms of resilience loss

Juan C. Rocha
Swedish Young Academy of Sciences

Forest to savanna

Regime shifts are large, abrupt and persistence critical transitions in the function and structure of (eco)systems

Coral transitions

Regime shifts are large, abrupt and persistence critical transitions in the function and structure of (eco)systems

Fisheries collapse

Regime shifts are large, abrupt and persistence critical transitions in the function and structure of (eco)systems

Where are regime shifts likely to occur?

Depends on our ability to observe and measure resilience

Data & methods

• Terrestrial:
  - Gross primary productivity (2001:2018) - Ecosystem respiration (2001:2018) - Leaf area index (1994:2017)
• Marine:
  - Chlorophyll A (1998:2018)
• >1M pixels, weekly obs, 0.25 degree grid resolution

Critical slowing down

• \(\uparrow\) Variance and autocorrelation
• \(\Delta\) skewness and kurtosis

Dakos et al. 2012. PLoS ONE; Kéfi et al. 2014. PLoS ONE

Critical speeding up

• \(\downarrow\) Variance and autocorrelation

Titus & Watson 2020 J Theor Ecol

Fractal dimension

• \(\uparrow\) adaptive capacity
• Measure of self-similarity across scales

West, Geoffrey. 2017. Scale; Gneiting et al. 2012. Statistical Science.

Analysis: one pixel

The generic resilience indicators do not necessarily align with critical slowing down or speeding up theories

Detection

In the absence of ground truth, if \(\Delta\) is > 95% or < 5% of the distribution is considered a signal of resilience loss

~30% of ecosystem show symptoms of resilience loss, boreal forest and tundra particularly strong signals

~25% of ecosystem show symptoms of resilience loss, Easter Indo-Pacific and Tropical Eastern Pacific Oceans particularly strong signals

So what?

Tipping points have impacts on people, who is exposed and who can do something about it?

Identify places prone to regime shifts

Places at risk due to drivers or showing symptoms or resilience loss

• Heatwaves: event when the SST exceeds the 99th percentile wrt 30yrs ref period\(^1\), severe and extreme events exceed 3 and 4 times the 90th percentile\(^2\)
• NOAA SST observations [1981-2022 at 0.25\(^\circ\)] to calculate heatwave events
• ESA ocean color observations [1998-2018 at 0.25\(^\circ\)] to calculate proxies of resilience loss\(^3\)

\(^1\)Frölicher 2018 Nature ; \(^2\)Hobday 2018 Oceanography ; Smith 2023 Ann. Rev., \(^3\)Rocha 2022 ERL

Identify economic activities & companies

• >70k vessels around the world
• 16 878 vessels fishing in high risk areas
• Currently 2981 companies (Lloyds)
• For 855: 1825 shareholders (Orbis)

Kroodsma 2018 Science (N = 70k vessels)
Global Fish Watch V2.0 (N = 114k vessels)

Who can make a difference?

Networks: micro-macro dynamics

Networks: micro-macro dynamics

Conclusions

• Ecosystems around the world are showing symptoms of resilience loss
• ~30% of terrestrial and ~25% of marine areas
• Identify who is exposed and can do something about it
• Identify areas for management

Questions?: juan.rocha@su.se