Abstract:The ancient idea of the balance of nature continues to influence modern perspectives on global environmental change. Assumptions of stable biogeochemical steady states and linear responses to perturbation are widely employed in the interpretation of geochemical records. Here, we review the dynamics of the marine carbon cycle and its interactions with climate and life over geologic time, focusing on what the record of past changes can teach us about stability and instability in the Earth system. Emerging themes… Show more
“…This can be understood as follows: only evolutionary adaptation can damp the negative outcomes of changing x *, and so on timescales too short for it to play a role there is an effective ‘critical amount’ of change to induce extinction. Similar logic has been considered in the context of past mass extinctions [20,34,35]; if indeed valid in this context, one significance of the scaling relationship is that it could allow a rigorous comparison of the fast anthropogenic Earth system perturbation to the slow perturbations of the deep past. Figure 4The scaling of the critical rate with time, in the minimal differential-equation model.…”
Section: Minimal Model Of Evolutionary Rescue and Rate-induced Extinc...mentioning
confidence: 87%
“…For example, in the evolutionary rescue literature, there is evidence that entire communities of microbes can undergo ‘community rescue’ [53]. On the vastly larger scale of the global biosphere, there is empirical evidence for a critical rate of environmental change to induce mass extinction [20,34,35]. Note that in mass extinctions, unlike the models considered above, a large abrupt nonlinear destructive transition occurs but does not have to lead to the complete destruction of the system—we refer to this more generally as a ‘collapse’.…”
Section: Discussion: Rate-induced Collapse In Any Evolutionary System?mentioning
Recent work has highlighted the possibility of ‘rate-induced tipping’, in which a system undergoes an abrupt transition when a perturbation exceeds a critical rate of change. Here, we argue that this is widely applicable to evolutionary systems: collapse, or extinction, may occur when external changes occur too fast for evolutionary adaptation to keep up. To bridge existing theoretical frameworks, we develop a minimal evolutionary–ecological model showing that rate-induced extinction and the established notion of ‘evolutionary rescue’ are fundamentally two sides of the same coin: the failure of one implies the other, and vice versa. We compare the minimal model’s behaviour with that of a more complex model in which the large-scale dynamics emerge from the interactions of many individual agents; in both cases, there is a well-defined threshold rate to induce extinction, and a consistent scaling law for that rate as a function of timescale. Due to the fundamental nature of the underlying mechanism, we suggest that a vast range of evolutionary systems should in principle be susceptible to rate-induced collapse. This would include ecosystems on all scales as well as human societies; further research is warranted.
“…This can be understood as follows: only evolutionary adaptation can damp the negative outcomes of changing x *, and so on timescales too short for it to play a role there is an effective ‘critical amount’ of change to induce extinction. Similar logic has been considered in the context of past mass extinctions [20,34,35]; if indeed valid in this context, one significance of the scaling relationship is that it could allow a rigorous comparison of the fast anthropogenic Earth system perturbation to the slow perturbations of the deep past. Figure 4The scaling of the critical rate with time, in the minimal differential-equation model.…”
Section: Minimal Model Of Evolutionary Rescue and Rate-induced Extinc...mentioning
confidence: 87%
“…For example, in the evolutionary rescue literature, there is evidence that entire communities of microbes can undergo ‘community rescue’ [53]. On the vastly larger scale of the global biosphere, there is empirical evidence for a critical rate of environmental change to induce mass extinction [20,34,35]. Note that in mass extinctions, unlike the models considered above, a large abrupt nonlinear destructive transition occurs but does not have to lead to the complete destruction of the system—we refer to this more generally as a ‘collapse’.…”
Section: Discussion: Rate-induced Collapse In Any Evolutionary System?mentioning
Recent work has highlighted the possibility of ‘rate-induced tipping’, in which a system undergoes an abrupt transition when a perturbation exceeds a critical rate of change. Here, we argue that this is widely applicable to evolutionary systems: collapse, or extinction, may occur when external changes occur too fast for evolutionary adaptation to keep up. To bridge existing theoretical frameworks, we develop a minimal evolutionary–ecological model showing that rate-induced extinction and the established notion of ‘evolutionary rescue’ are fundamentally two sides of the same coin: the failure of one implies the other, and vice versa. We compare the minimal model’s behaviour with that of a more complex model in which the large-scale dynamics emerge from the interactions of many individual agents; in both cases, there is a well-defined threshold rate to induce extinction, and a consistent scaling law for that rate as a function of timescale. Due to the fundamental nature of the underlying mechanism, we suggest that a vast range of evolutionary systems should in principle be susceptible to rate-induced collapse. This would include ecosystems on all scales as well as human societies; further research is warranted.
“…3B ). This will lead to slow “quasistatic” changes in the surface temperature ( 45 ), even while the carbon cycle remains in steady state with respect to input and output fluxes. We suggest that it is precisely this class of changes that lead to fluctuations increasing again at the longest time scales.…”
The question of how Earth’s climate is stabilized on geologic time scales is important for understanding Earth’s history, long-term consequences of anthropogenic climate change, and planetary habitability. Here, we quantify the typical amplitude of past global temperature fluctuations on time scales from hundreds to tens of millions of years and use it to assess the presence or absence of long-term stabilizing feedbacks in the climate system. On time scales between 4 and 400 ka, fluctuations fail to grow with time scale, suggesting that stabilizing mechanisms like the hypothesized “weathering feedback” have exerted dominant control in this regime. Fluctuations grow on longer time scales, potentially due to tectonically or biologically driven changes that make weathering act as a climate forcing and a feedback. These slower fluctuations show no evidence of being damped, implying that chance may still have played a nonnegligible role in maintaining the long-term habitability of Earth.
“…For POCO, 𝜏 𝑝𝑎𝑠𝑠 was estimated both through laboratory experiments (Section 3. 6 When the system is in the vacuum phase, the dynamics are more complicated because the system has both a source (via the membrane) and a sink (via the vacuum pump). Additionally, the membrane is selective (more permeable to some gases) but the vacuum pump is not.…”
“…The planet has entered the 'Anthropocene': a time period where the influences of human activity rival geological forces [1][2][3]. The ocean acts as a critical buffer for the planet by stabilizing the climate, absorbing anthropogenic carbon dioxide (CO 2 ), and hosting a significant portion of the planet's primary production [4][5][6][7][8]. Unfortunately, over time the ocean has become warmer, more acidic, and less well oxygenated, diminishing the ocean's ability to act as a buffer [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”
To predict and mitigate anthropogenic impacts on the ocean, we must understand the underlying systems that govern the ocean’s response to inputs (e.g. carbon dioxide, pollutants). Analytical models can be used to generate predictions and simulate intervention strategies, but they must be grounded with empirical observations. Unfortunately, there exists a technological gap: in situ instrumentation is often lacking or nonexistent for key parameters influenced by anthropogenic inputs. While discrete bottle samples can be collected and analyzed for these parameters, their limited spatiotemporal resolution constrains scientific inquiry. To help fill the technological gap, this dissertation presents the development of instrumentation for the ocean inorganic carbon system and microplastics. The first few chapters present the development process of CSPEC, a deep-sea laser spectrometer designed to measure the ocean carbon system through alternating measurements of the partial pressure of carbon dioxide (pCO2) and dissolved inorganic carbon (DIC). CSPEC uses tunable diode laser absorption spectroscopy (TDLAS) to measure the CO2 content of dissolved gas extracted via a membrane inlet. Chapter 2 derives membrane equilibration dynamics from first principles, thus enabling informed design decisions. The analytical results showed that cross-sensitivity to other dissolved gases can be introduced by the equilibration method, regardless of the specificity of the gas-side instrumentation. A new method, hybrid equilibration, leverages the membrane equilibration dynamics to improve time response without incurring cross-sensitivity. Chapter 3 presents POCO, a surface pCO2 instrument that employs TDLAS and a depth-compatible membrane inlet. Through laboratory and field-testing, POCO demonstrated that hybrid equilibration overcame the gas flux limitation of deep-sea membrane inlets. Chapter 4 presents CSPEC, which successfully mapped the carbon system near different hydrothermal features at 2000 m in Guaymas Basin, becoming one of the first DIC instruments field-tested at depth. Chapter 5 introduces impedance spectroscopy for quantifying microplastics directly in water. Microplastics were successfully counted, sized, and differentiated from biology in the laboratory: a step toward in situ quantification. The analytical tools and measurement systems presented in this dissertation represent a significant step towards increasing the spatiotemporal resolution of carbon system and microplastic measurements, thus enabling broader scientific inquiry in the future.
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