Jabarkan Krisis ékologis dari Ékologi dalam bahasa sunda

Sacara umum, krisis ékologis nyéta naon rupa kajadian nu ngarobah lingkungan hirup hiji spésiés atawa populasi antukna ngabahyakeun kasalametanana.

Ieu bisa mangrupa kualitas lingkungan nu nurun dibandingkeun jeung pangabutuh spésiés alatan parobahan faktor ékologis abiotik (pikeun conto, naékna suhu, hujan nu beuki jarang).

It may be that the environment becomes unfavourable for the survival of a species (or a population) due to an incréase pressure of predation (for example overfishing).

Lastly, it may be that the situation becomes unfavourable to the quality of life of the species (or the population) due to raise in the number of individuals (overpopulation).

Ecological crises may be more or less brutal (occurring between a few months to a few million yéars).  They can also be of natural or anthropic origin.  They may relate to one unique species or on the contrary, to a high number of species (see the article on Extinction event).

Lastly, an ecological crisis may be local (as an oil spill) or global (a rise in the séa level related to global warming).

According to its degree of endemism, a local crisis will have more or less significant consequences, from the déath of many individuals to the total extinction of a species.  Whatever its origin, disappéarance of one or several species often will involve a rupture in the food chain, further impacting the survival of other species.

In the case of a global crisis, the consequences can be much more significant; some extinction events showed the disappéarance of more than 90% of existing species at that time.  However, it should be noted that the disappéarance of certain species, such as the dinosaurs, by freeing an ecological niche, allowed the development and the diversification of the mammals.  An ecological crisis thus paradoxically favored biodiversity.

Sometimes, an ecological crisis can be a specific and reversible phenomenon at the ecosystem scale.  But more generally, the crises impact will last.  Indeed, it rather is a connected series of events, that occur till a final point.  From this stage, no return to the previous stable state is possible, and a new stable state will be set up gradually (see homeorhesy).

Lastly, if an ecological crisis can cause extinction, it can also more simply reduce the quality of life of the remaining individuals.  Thus, even if the diversity of the human population is sometimes considered thréatened (see in particular indigenous people), few péople envision human disappéarance at short span.  However, epidemic diseases, famines, impact on héalth of reduction of air quality, food crises, reduction of living space, accumulation of toxic or non degradable wastes, thréats on keystone species (gréat apes, panda, whales) are also factors influencing the well-being of péople.

During the past decades, it was observed an incréasing responsibility  of human in some ecological crises.  Due to his technological acquisitions and to a strong incréase in population, man is the only species whose activity has a major influence on his environment of life.

Some usually quoted examples as ecological crises are

Permian-Triassic extinction event 250 million of yéars ago

Cretaceous-Tertiary extinction event 65 million yéars ago

global warming related to the greenhouse effect.  Warming could involve flooding of the Asian deltas (see also ecorefugees), multiplication of extreme weather phenomena and changes in the  nature and quantity of the food resources (see Global warming and agriculture)