Legacy effects from historical environmental changes dominate future terrestrial carbon uptake

The carbon balance of terrestrial ecosystems is determined by environmental drivers (chiefly related to climate and land use) which interact with each other and change over time. In particular, ecosystems are presently still affected by past environmental changes because they have not yet reached equilibrium with their environment. However, the magnitude and drivers of this legacy effect for the upcoming decades are still unclear. Here, we use the dynamic global vegetation model LPJ-GUESS to calculate the effects of historical (1850-2015) and future (2015-2099, exemplarily for the high emission/moderate deforestation scenario SSP5-8.5) environmental changes on historical and future terrestrial carbon cycling and to quantify the contributions of the following environmental drivers: climate change, CO2 fertilization, agricultural expansion, shifting cultivation frequency, wood harvest, nitrogen deposition, and nitrogen fertilization.According to our simulations, the land represented a cumulative net carbon source (-154 GtC) over the historical period mainly due to deforestation, wood harvest, and negative climate change impacts partly offset by carbon uptake via increased CO2 levels and nitrogen input. In contrast, the land is simulated to act as a net carbon sink (+118 GtC) over the 21st century. This is mostly a result of historical environmental changes as ecosystems still adapt to present-day CO2 and nitrogen availability as well as long-term vegetation regrowth following agricultural abandonment and wood harvest. The net impact of future environmental changes on future carbon cycling is much smaller because effects from individual environmental drivers largely compensate. Historical environmental changes dominate future terrestrial carbon cycling at least until mid-century when legacy effects gradually diminish and future environmental changes start to trigger carbon accumulation. Our results suggest that legacy effects persist even many decades after environmental changes occurred and need to be considered when interpreting alterations of the terrestrial carbon cycle.

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Legacy Effects from Historical Environmental Changes Dominate Future Terrestrial Carbon Uptake

Earth s Future ◽

10.1029/2020ef001674 ◽

2020 ◽

Vol 8 (10) ◽

Author(s):

A. Krause ◽

A. Arneth ◽

P. Anthoni ◽

A. Rammig

Keyword(s):

Environmental Changes ◽

Carbon Uptake ◽

Legacy Effects ◽

Terrestrial Carbon

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Temperature alters the physiological response of spiny lobsters under predation risk

Conservation Physiology ◽

10.1093/conphys/coaa065 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Felipe A Briceño ◽

Quinn P Fitzgibbon ◽

Elias T Polymeropoulos ◽

Iván A Hinojosa ◽

Gretta T Pecl

Keyword(s):

Climate Change ◽

Predation Risk ◽

Environmental Changes ◽

Environmental Drivers ◽

Climate Change Scenarios ◽

Metabolic Rates ◽

Energetic Costs ◽

Predator Prey ◽

Predator Prey Model ◽

Spiny Lobsters

Abstract Predation risk can strongly shape prey ecological traits, with specific anti-predator responses displayed to reduce encounters with predators. Key environmental drivers, such as temperature, can profoundly modulate prey energetic costs in ectotherms, although we currently lack knowledge of how both temperature and predation risk can challenge prey physiology and ecology. Such uncertainties in predator–prey interactions are particularly relevant for marine regions experiencing rapid environmental changes due to climate change. Using the octopus (Octopus maorum)–spiny lobster (Jasus edwardsii) interaction as a predator–prey model, we examined different metabolic traits of sub adult spiny lobsters under predation risk in combination with two thermal scenarios: ‘current’ (20°C) and ‘warming’ (23°C), based on projections of sea-surface temperature under climate change. We examined lobster standard metabolic rates to define the energetic requirements at specific temperatures. Routine metabolic rates (RMRs) within a respirometer were used as a proxy of lobster activity during night and day time, and active metabolic rates, aerobic scope and excess post-exercise oxygen consumption were used to assess the energetic costs associated with escape responses (i.e. tail-flipping) in both thermal scenarios. Lobster standard metabolic rate increased at 23°C, suggesting an elevated energetic requirement (39%) compared to 20°C. Unthreatened lobsters displayed a strong circadian pattern in RMR with higher rates during the night compared with the day, which were strongly magnified at 23°C. Once exposed to predation risk, lobsters at 20°C quickly reduced their RMR by ~29%, suggesting an immobility or ‘freezing’ response to avoid predators. Conversely, lobsters acclimated to 23°C did not display such an anti-predator response. These findings suggest that warmer temperatures may induce a change to the typical immobility predation risk response of lobsters. It is hypothesized that heightened energetic maintenance requirements at higher temperatures may act to override the normal predator-risk responses under climate-change scenarios.

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Effect of increasing CO2 on the terrestrial carbon cycle

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1407302112 ◽

2014 ◽

Vol 112 (2) ◽

pp. 436-441 ◽

Cited By ~ 244

Author(s):

David Schimel ◽

Britton B. Stephens ◽

Joshua B. Fisher

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

Terrestrial Ecosystems ◽

Future Climate Change ◽

Carbon Uptake ◽

Model Diagnostics ◽

Terrestrial Carbon ◽

Terrestrial Carbon Cycle ◽

New Space ◽

Improved Model

Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation.

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Synergistic effects of four climate change drivers on terrestrial carbon cycling

Nature Geoscience ◽

10.1038/s41561-020-00657-1 ◽

2020 ◽

Vol 13 (12) ◽

pp. 787-793

Author(s):

Peter B. Reich ◽

Sarah E. Hobbie ◽

Tali D. Lee ◽

Roy Rich ◽

Melissa A. Pastore ◽

...

Keyword(s):

Climate Change ◽

Carbon Cycling ◽

Synergistic Effects ◽

Terrestrial Carbon ◽

Climate Change Drivers

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Faculty Opinions recommendation of Synergistic effects of four climate change drivers on terrestrial carbon cycling.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.739132852.793590036 ◽

2021 ◽

Author(s):

Carly Stevens

Keyword(s):

Climate Change ◽

Carbon Cycling ◽

Synergistic Effects ◽

Terrestrial Carbon ◽

Climate Change Drivers

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Nitrogen feedbacks increase future terrestrial ecosystem carbon uptake in an individual-based dynamic vegetation model

Biogeosciences Discussions ◽

10.5194/bgd-11-151-2014 ◽

2014 ◽

Vol 11 (1) ◽

pp. 151-185 ◽

Cited By ~ 7

Author(s):

D. Wårlind ◽

B. Smith ◽

T. Hickler ◽

A. Arneth

Keyword(s):

Carbon Sequestration ◽

Nitrogen Cycle ◽

Environmental Changes ◽

Nitrogen Dynamics ◽

Carbon Uptake ◽

Terrestrial Carbon ◽

Vegetation Model ◽

Carbon And Nitrogen ◽

Dynamic Vegetation Model ◽

Ecosystem Carbon

Abstract. Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use the dynamic vegetation model LPJ-GUESS to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one exemplary "business-as-usual" climate scenario). Single factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C–N interactions, compared to the C-only version of the model, as documented in previous studies. Under a RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics until present. However, during the 21st century nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contradicts earlier model results that showed an 8 to 37% decrease in carbon uptake, questioning the often stated assumption that projections of future terrestrial C dynamics from C-only models are too optimistic.

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Quantifying forest growth and uncertainty across Brazil under potential future climates: combing models and Earth Observation

10.5194/egusphere-egu2020-16550 ◽

2020 ◽

Author(s):

Thomas Smallman ◽

David Milodowski ◽

Mathew Williams

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

Carbon Cycling ◽

Earth Observation ◽

Forest Growth ◽

Forest Carbon ◽

Carbon Accumulation ◽

Terrestrial Ecosystem Model ◽

New Forest ◽

The Impact

Forest play a major role in the global carbon cycle storing large amounts of carbon in both living and dead organic matter. Forests can be either a sink or source of carbon depending on the net of far larger fluxes of carbon into (photosynthesis) and out of (mortality, decomposition and disturbance) forest ecosystems. Due to the potential for substantial accumulation of carbon in forests, has led to nationally determined commitments (NDCs) by Governments across the world to protect existing and plant large areas of new forest. However, significant uncertainty remains in our understanding of current forest carbon cycling, especially mortality and decomposition processes, and how carbon cycling will change under climate change. These uncertainties present two connected challenges to effective forest protection and new planting; (i) which existing forests are under the greatest risk to climate change and (ii) where are the most climate safe locations for new forest planting to maximise carbon accumulation.Here we combine a terrestrial ecosystem model of intermediate complexity (DALEC) with Earth observation (e.g. leaf area, biomass, disturbance) and databased information (soil texture and carbon stocks) within a Bayesian model-data fusion framework (CARDAMOM) to retrieve location specific carbon cycle analyse (i.e. parameter retrievals) across Brazil at 0.5 x 0.5 degree spatial resolution between 2001 and 2015. CARDAMOM allows us to retrieve, independently for each location analysed, an ensemble of parameters for DALEC which are consistent with the location specific observational constraints and their uncertainties. These ensembles give us multiple potential, but observation consistent, realisations of forest carbon cycling and ecosystem traits. We directly quantify our uncertainty in forest carbon cycling and ecosystem traits from these ensembles. The DALEC parameterisations are then simulated into the future under a range of climate scenarios from the CMIP6 model dataset. From these simulations we will, with defined uncertainty, quantify the impact on forest carbon accumulation of existing forest and the potential accumulation of new planting. This information can feed into national planning identifying locations which have the greatest confidence of being a net sink of carbon under climate change highlighting forest areas which are most important to protect and suitable for new planting.

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