Extinction risk from climate change
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The extinction risk of climate change is the risk of species becoming extinct due to the effects of climate change. This may be contributing to Earth's sixth major extinction, also called the Anthropocene or Holocene extinction. While the past extinctions have been due to primarily volcanic eruptions and meteorites, this sixth major extinction is attributed to human behaviors. Climate change is occurring at an alarming rate: Studies done by the Intergovernmental Panel on Climate Change (IPCC) show that it is estimated that the temperature will rise from about 1.4 to 5.5 degrees Celsius (2.5 to 10 degrees Fahrenheit) within the next century. These rising rates, to a certain degree, may benefit some regions while harming others. However, after about 5.4 degrees Fahrenheit of rising temperature, it will get into harmful climate change. Efforts have been made such as the Paris Climate Agreement, in attempt to stop or reduce the effects of a rising temperature, or at least decrease the number in which the temperature rises. However, even if this goal is accomplished, it is estimated that about 25% of their particular animal species will be lost.
Latest consensus on projections
The scientific consensus in the 2014 IPCC Fifth Assessment Report is that:
A large fraction of both terrestrial and freshwater species faces increased extinction risk under projected climate change during and beyond the 21st century, especially as climate change interacts with other stressors, such as habitat modification, over-exploitation, pollution, and invasive species. Extinction risk is increased under all RCP scenarios, with risk increasing with both magnitude and rate of climate change. Many species will be unable to track suitable climates under mid- and high-range rates of climate change during the 21st century. Lower rates of climate change will pose fewer problems.— IPCC, 2014
Some predictions of how life would be affected:
- Mediterranean Monk Seal: These animals have lost about 60% of their population in the past sixty years.
- Miombo Woodlands of South Africa: If the temperature were to rise by at least 4.5 degrees Celsius, this area would lose about 90% of its amphibians, 86% of birds, and 80% of mammals.
- The Amazon could lose 69 percent of its plant species.
- In southwest Australia 89 percent of amphibians could become locally extinct.
- 60 percent of all species are at risk of localised extinction in Madagascar.
- The Fynbos in the Western Cape Region of South Africa, which is experiencing a drought that has led to water shortages in Cape Town, could face localized extinctions of a third of its species, many of which are unique to that region." - WorldWildLife Fund
Temperature increase would affect the amount of rainfall and therefore the amount of drinking water animals need to survive. It would affect plant growth and desertification. This would further spread in other issues including overgrazing and loss of biodiversity.
Extinction risks reported
In one study published in Nature in 2004 found that between 15 and 37% of 1103 endemic or near-endemic known plant and animal species will be "committed to extinction" by 2050. More properly, changes in habitat by 2050 will put them outside the survival range for the inhabitants, thus committing the species to extinction.
Other researchers, such as Thuiller et al., Araújo et al., Person et al., Buckley and Roughgarden, and Harte et al. have raised concern regarding uncertainty in Thomas et al.'s projections; some of these studies believe it is an overestimate, others believe the risk could be greater. Thomas et al. replied in Nature  addressing criticisms and concluding "Although further investigation is needed into each of these areas, it is unlikely to result in substantially reduced estimates of extinction. Anthropogenic climate change seems set to generate very large numbers of species-level extinctions." On the other hand, Daniel Botkin et al. state "... global estimates of extinctions due to climate change (Thomas et al. 2004) may have greatly overestimated the probability of extinction..."
Mechanistic studies are documenting extinctions due to recent climate change: McLaughlin et al. documented two populations of Bay checkerspot butterfly being threatened by precipitation change. Parmesan states, "Few studies have been conducted at a scale that encompasses an entire species" and McLaughlin et al. agreed "few mechanistic studies have linked extinctions to recent climate change."
In 2008, the white lemuroid possum was reported to be the first known mammal species to be driven extinct by climate change. However, these reports were based on a misunderstanding. One population of these possums in the mountain forests of North Queensland is severely threatened by climate change as the animals cannot survive extended temperatures over 30 °C. However, another population 100 kilometres south remains in good health.
The risk of extinction does need to lead to a demonstrable extinction process to validate future extinctions attributable to climate change. In a study led by Barry Sinervo, a mathematical-biologist at the University of California Santa Cruz, researchers analyzed observed contemporary extinctions (since dramatic modern climate warming began in 1975). Results of the study indicate that climate-forced extinctions of lizard families of the world have already started. The model is premised on the ecophysiological limits of an organism being exceeded. In the case of lizards, this occurs when their preferred body temperature is exceeded in their local environment. Lizards are ectotherms that regulate body temperature using heat sources of their local environment (the sun, warm air temperatures, or warm rocks). Surveys of 200 sites in Mexico showed 24 local extinctions (= extirpations), of Sceloporus lizards. Using a model developed from these observed extinctions the researchers surveyed other extinctions around the world and found that the model predicted those observed extirpations, thus attributing the extirpations around the world to climate warming. These models predict that extinctions of the lizard species around the world will reach 20% by 2080, but up to 40% extinctions in tropical ecosystems where the lizards are closer to their ecophysiological limits than lizards in the temperate zone.
According to research published in the January 4, 2012 Proceedings of the Royal Society B current climate models may be flawed because they overlook two important factors: the differences in how quickly species relocate and competition among species. According to the researchers, led by Mark C. Urban, an ecologist at the University of Connecticut, diversity decreased when they took these factors into account, and that new communities of organisms, which do not exist today, emerged. As a result, the rate of extinctions may be higher than previously projected.
According to research published in the 30 May 2014 issue of Science, most known species have small ranges, and the numbers of small-ranged species are increasing quickly. They are geographically concentrated and are disproportionately likely to be threatened or already extinct. According to the research, current rates of extinction are three orders of magnitude higher than the background extinction rate, and future rates, which depend on many factors, are poised to increase. Although there has been rapid progress in developing protected areas, such efforts are not ecologically representative, nor do they optimally protect biodiversity. In the researchers' view, human activity tends to destroy critical habitats where species live, warms the planet, and tends to move species around the planet to places where they don't belong and where they can come into conflict with human needs (e.g. causing species to become pests).
According to a long-term study of more than 60 bee species published in the journal Science said that climate change effect drastic declines in the population and diversity of bumblebees across North America and Europe.This research show that bumblebees are disappearing at rates same as "consistent with a mass extinction."North America's bumblebee populations fell by 46% during the two time periods the study used which is from 1901 to 1974 and from 2000 to 2014.North America's bumblebee populations fell by 46% because bee populations were hardest hit in warming southern regions such as Mexico.According to the study, more frequent extreme warm years, which exceeded the species’ historical temperature ranges.
In 2016 the Bramble Cay melomys, which lived on a Great Barrier Reef island, was reported to probably be the first mammal to become extinct because of sea level rises due to human-made climate change.
Extinction risks of the Adelie penguin are being reported because of climate change. The Adelie penguin (Pygoscelis adeliae) species is declining and data analysis done on the breeding colonies is used to estimate and project future habitat and population sustainability in relation to warming sea temperatures. By 2060, one-third of the observed Adelie penguin colony along the West Antarctic Peninsula (WAP) will be in decline. The Adelie penguins are a circumpolar species, used to the ranges of Antarctic climate, and experiencing population decline. Climate model projections predict sanctuary for the species past 2099. The observed population is similarly proportional to the species-wide population (one-third of the observed population is equal to 20% of the species-wide population).
Sex ratios for sea turtles in the Caribbean are being affected because of climate change. Environmental data were collected from the annual rainfall and tide temperatures over the course of 200 years and showed an increase in air temperature (mean of 31.0 degree Celsius). These data were used to relate the decline of the sex ratios of sea turtles in the North East Caribbean and climate change. The species of sea turtles include Dermochelys coriacea, Chelonia myads, and Eretmochelys imbricata. Extinction is a risk for these species as the sex ratio is being afflicted causing a higher female to male ratio. Projections estimate the declining rate of male Chelonia myads as 2.4% hatchlings being male by 2030 and 0.4% by 2090.
The fires affect water chemistry (such as decreasing the amount of dissolved oxygen in the water), temperature, and erosion rates, which in turn affects fish and mammals that depend on fish, such as the giant otter (Pteronura brasiliensis).
The unprecedented fires of the 2019–20 Australian bushfire season that have swept through 18 million acres (7 million hectares) have claimed 29 human lives and have stressed Australia's wildlife. Before the fires, only 500 tiny Kangaroo Island dunnarts (Sminthopsis aitkeni) lived on one island; after half the island was burned, it is possible only one has survived. Bramble Cay melomys (Melomys rubicola) became the first known casualty of human-caused climate change in 2015 due to rising sea levels and repeated storm surges; the greater stick-nest rat (Leporillus conditor) may be next.
Emus (Dromaius novaehollandiae) are not in danger of extinction, although they might be wiped out in Australia. The loss of 8,000 koalas (Phascolarctos cinereus) in NSW alone was significant, but the animals are endangered but not functionally extinct.
- Atelopus varius
- Ecosystem services
- Gastric-brooding frog
- Golden toad
- Guajira stubfoot toad
- Keystone species
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