Protected lands are important for conservation, but islands of biodiversity aren't sufficient for the realities of the 21 st century. We need to restore habitat at scale so that animals can move with shifting climate patterns. Working lands can provide invaluable breeding grounds and migratory corridors for threatened species like the monarch butterfly. It will require creative thinking and an open mind to unexpected conservation partnerships and approaches.
Farmers are essential allies in the fight against extinction and can't be expected to bear all of the costs. Policymakers, businesses and conservationists must collaborate with them to find innovative ways to increase funding for proactive conservation of key ecosystems, and to protect bedrock conservation principles. The U. But the researchers also stressed that by implementing fishery reforms , we can boost sustainable seafood production, while replenishing food supplies on which these vulnerable mammals depend for their survival.
Science shows that such reforms work. By moving faster to change how fisheries operate — and by pulling out all stops to try to limit global warming to less than 2 degrees Celsius — the ocean can produce nearly one-third more fish by , allowing struggling fishing communities to prosper and threatened species to recover.
Adding to the plight of Earth's species are the rising impacts from rising global temperatures. Climate change is a "direct driver" speeding up the depletion of species, the U. About half the world's live cover on coral reefs has been lost since the s, for example, with accelerating losses in recent decades as a warming ocean exacerbated other threats to corals. The good news is that that just by catching methane leaks from oil and gas facilities, we can make a significant dent in greenhouse gas emissions.
By curbing methane, a very potent greenhouse gas, and by taking steps to rein in other forms of emissions, we can avert even more catastrophic climate impacts, and buy time for solutions that will allow more resilient land and marine ecosystems to flourish. Every day more than 60 people sign up for news and alerts, to find out when their support helps most. Will you join them? Recent studies estimate about eight million species on Earth, of which at least 15, are threatened with extinction.
A number of scientists grapple with improving methods for estimating extinction rates. Judging from the fossil record, the baseline extinction rate is about one species per every one million species per year.
Scientists are racing to catalogue the biodiversity on Earth, working against the clock as extinctions continue to occur. At five other times in the past, rates of extinction have soared. These are called mass extinctions, when huge numbers of species disappear in a relatively short period of time.
Paleontologists know about these extinctions from remains of organisms with durable skeletons that fossilized. End of the Cretaceous 66 million years ago : Extinction of many species in both marine and terrestrial habitats including pterosaurs, mosasaurs and other marine reptiles, many insects, and all non-Avian dinosaurs. The scientific consensus is that this mass extinction was caused by environmental consequences from the impact of a large asteroid hitting Earth in the vicinity of what is now Mexico.
Late Triassic million years ago : Extinction of many marine sponges, gastropods, bivalves, cephalopods, brachiopods, as well as some terrestrial insects and vertebrates. The extinction coincides with massive volcanic eruptions along the margins of what is now the Atlantic Ocean. Most scientific evidence suggests the causes were global warming and atmospheric changes associated with huge volcanic eruptions in what is now Siberia.
Late Devonian million years ago : Extinction of many marine species, including corals, brachiopods, and single-celled foraminiferans, from causes that are not well understood yet. Late Ordovician million years ago : Extinction of marine organisms such as some bryozoans, reef-building brachiopods, trilobites, graptolites, and conodonts as a result of global cooling, glaciation, and lower sea levels.
Smithsonian Paleobiologists continue to study the role that past extinctions had on plants, animals, and other species. Gene Hunt studies how the relatedness and diversity of organisms relates to what happens to them in an extinction event. Richard Bambach conducts research on variation in marine biodiversity in relation to different extinction events.
By studying the evolution and extinction of tiny organisms called foraminifera, Dr. Brian Huber assesses how Earth's conditions have changed over time. At the end of the last ice age, 10, years ago, many North American animals went extinct, including mammoths , mastodons , and glyptodonts. And while much concern over extinction focuses on globally lost species, most of biodiversity's benefits take place at a local level, and conserving local populations is the only way to ensure genetic diversity critical for a species' long-term survival.
In the past years, we know of approximately 1, species that have gone extinct, from the woodland bison of West Virginia and Arizona's Merriam's elk to the Rocky Mountain grasshopper, passenger pigeon and Puerto Rico's Culebra parrot — but this doesn't account for thousands of species that disappeared before scientists had a chance to describe them [ 4 ].
Nobody really knows how many species are in danger of becoming extinct. Noted conservation scientist David Wilcove estimates that there are 14, to 35, endangered species in the United States, which is 7 to 18 percent of U. The IUCN has assessed roughly 3 percent of described species and identified 16, species worldwide as being threatened with extinction, or roughly 38 percent of those assessed.
In its latest four-year endangered species assessment, the IUCN reports that the world won't meet a goal of reversing the extinction trend toward species depletion by [ 5 ]. What's clear is that many thousands of species are at risk of disappearing forever in the coming decades. Scientists estimate that a third or more of all the roughly 6, known species of amphibians are at risk of extinction [ 6 ].
Frogs, toads, and salamanders are disappearing because of habitat loss, water and air pollution, climate change, ultraviolet light exposure, introduced exotic species, and disease.
Because of their sensitivity to environmental changes, vanishing amphibians should be viewed as the canary in the global coal mine, signaling subtle yet radical ecosystem changes that could ultimately claim many other species, including humans. BIRDS Birds occur in nearly every habitat on the planet and are often the most visible and familiar wildlife to people across the globe. As such, they provide an important bellwether for tracking changes to the biosphere.
Declining bird populations across most to all habitats confirm that profound changes are occurring on our planet in response to human activities. A report on the state of birds in the United States found that 31 percent of the species in the country are of conservation concern [ 7 ]. Habitat loss and degradation have caused most of the bird declines, but the impacts of invasive species and capture by collectors play a big role, too.
FISH Increasing demand for water, the damming of rivers throughout the world, the dumping and accumulation of various pollutants, and invasive species make aquatic ecosystems some of the most threatened on the planet; thus, it's not surprising that there are many fish species that are endangered in both freshwater and marine habitats.
The American Fisheries Society identified species of freshwater or anadromous fish in North America as being imperiled, amounting to 39 percent of all such fish on the continent [ 8 ]. In North American marine waters, at least 82 fish species are imperiled. Across the globe, 1, species of fish — 21 percent of all fish species evaluated — were deemed at risk of extinction by the IUCN in , including more than a third of sharks and rays.
Of the 1. Freshwater invertebrates are severely threatened by water pollution, groundwater withdrawal, and water projects, while a large number of invertebrates of notable scientific significance have become either endangered or extinct due to deforestation, especially because of the rapid destruction of tropical rainforests.
In the ocean, reef-building corals are declining at an alarming rate: 's first-ever comprehensive global assessment of these animals revealed that a third of reef-building corals are threatened. MAMMALS Perhaps one of the most striking elements of the present extinction crisis is the fact that the majority of our closest relatives — the primates — are severely endangered.
0コメント