User:TurtlePond20/Ecosystem collapse

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An ecosystem is considered collapsed when its unique biotic (characteristic biota) or abiotic features are lost from all previous occurrences. Ecosystem collapse causes ecological collapse within a system; essentially altering its stability, resilience, and diversity levels. It is, however, possible to reverse through careful restoration, and is thus not completely equivalent to species extinction. It occurs after a system has reached a so-called ecological ‘tipping point’, or crossed a critical threshold, and can no longer adequately respond to rapid changes in ecological conditions; either due to the suddenness or the scale of the changes.

It is important to note that—while certain types of accelerated ecosystem collapse or mass ecosystem collapse are typically viewed in a negative light—rapid environmental change and collapse have always been an integral part of the evolution and dynamics of the biosphere and marine ecosystems throughout geologic time. These processes historically contribute to ecosystem diversity by creating new types, or maintain and strengthen resilient systems while destroying non-resilient ones.

Drivers of Collapse

While collapse events can occur naturally with disturbances to an ecosystem—through fires, landslides, flooding, severe weather events, disease, or species invasion—there has been a noticeable increase in human-caused disturbances over the past fifty years. The combination of environmental change and the presence of human activity is increasingly detrimental to ecosystems of all types, as our unrestricted actions often increase the risk of abrupt (and potentially irreversible) changes post-disturbance; when a system would otherwise have been able to recover. Some behaviors that induce transformation are: human intervention in the balance of local diversity (through introduction of new species or overexploitation), alterations in the chemical balance of environments through pollution, modifications of local climate or weather with anthropogenic climate change, and habitat destruction or fragmentation in terrestrial/marine systems.

Despite the strong empirical evidence and highly visible collapse-inducing disturbances, anticipating collapse is a complex problem. The collapse can happen when the ecosystem's distribution decreases below a minimal sustainable size, or when key biotic processes and features disappear due to environmental degradation or disruption of biotic interactions; . These different pathways to collapse can be used as criteria for estimating the risk of ecosystem collapse. Although states of ecosystem collapse are often defined quantitatively, few studies adequately describe transitions from pristine or original state towards collapse.

Risk Assessment

There are two tools commonly used together to asses risks to ecosystems and biodiversity: generic risk assessment protocols and stochastic simulation models. The most notable of the two tactics is risk assessment protocol, particularly because of the IUCN Red List of Ecosystems (RLE), which is widely applicable to many ecosystems even in data-poor circumstances. However, because using this tool is essentially comparing systems to a list of criteria, it is often limited in its ability to look at ecosystem decline holistically; and is thus often used in conjunction with simulation models that consider more aspects of decline such as ecosystem dynamics, future threats, and social-ecological relationships.

The IUCN RLE is a global standard that was developed to assess threats to various ecosystems on local, regional, national, and global scales, as well as to prompt conservation efforts in the face of the unparalleled decline of natural systems in the last decade. And though this effort is still in the earlier stages of implementation, the IUCN has a goal to assess the risk of collapse for all of the world’s ecosystems by 2025. The concept of ecosystem collapse is used in the framework to establish categories of risk for ecosystems, with the category Collapsed is used as the end-point of risk assessment. Other categories of threat (Vulnerable, Endangered and Critically Endangered) are defined in terms of the probability or risk of collapse. A paper by Bland et al. suggests four aspects for defining ecosystem collapse in risk assessments:

1. qualitatively defining initial and collapsed states
2. describing collapse and recovery transitions
3. identifying and selecting indicators of collapse
4. setting quantitative collapse thresholds.

Effects of Ecosystem Collapse

Ecosystem collapse can lead to catastrophic declines of carrying capacity and mass extinction, and can also pose existential risk to human populations. They provide recourses that are essential for life—air, water, food, shelter, and energy— and so their health inherently impacts the Earth’s habitability. Many of the major negative ecological changes of the last few decades can be contributed to this deterioration of the world’s ecosystems. For example, increases in atmospheric greenhouse gas concentrations, widespread deforestation, massive biodiversity loss worldwide, and the decline of marine ecosystems are all influenced by declines in global ecosystems and directly effect human life .

Conservation and Reversal

As of now there is still not much information on effective conservation or reversal methods for ecosystem collapse. Rather, there has been increased focus on the predictability of ecosystem collapse, whether it is possible, and whether it is productive to explore.