External links
- Faculty biography page Archived 2008-03-21 at the Wayback Machine
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Lee Hannah is a conservation ecologist and a Senior Researcher in Climate Change Biology at Conservation International. Hannah is one of many authors who published an article predicting that between 15% and 37% of species are at risk of extinction due to climate change caused by human greenhouse gas emissions. [1]
Lee Hannah received his B.A. in Biology with High Honors in June 1978 from the University of California, Berkeley. His honors thesis at Berkeley was “Renewable Energy Potentials and Impacts". Hannah received his Doctorate in Environmental Science and Engineering from the University of California, Los Angeles in June 1985. His UCLA dissertation was “Protection of Hawaii’s Native Birds in Geothermal Energy Development,”. Since 2000, Hannah has been a Senior Researcher in Climate Change Biology at Conservation International. Since 2004, he has also been working as a visiting researcher and adjunct professor at the Bren School of Environmental Science & Management at the University of California, Santa Barbara. His classes at UCSB include Climate Change Biology, Landscape Ecology, and Conservation Planning. [2] Hannah collaborates with the South Africa National Biodiversity Institute at Kirstenbosch (in Cape Town) to study biodiversity changes as a result of global warming. [3]
Hannah is involved in three societies, the American Association for the Advancement of Science (AAAS), the Ecological Society of America, and the Society for Conservation Biology. He holds many honors and awards, including being a National Merit Scholar in 1974; Environmental Science and Engineering Class President in UCLA from 1981–82; the American Institute of Biological Sciences Congressional Fellow in Washington D.C. from 1986–87; and the American Association for the Advancement of Science, a Science and Diplomacy Fellow, in Washington D.C. from 1987–89.
Hannah's work is primarily centered on how climate change affects biodiversity. He uses that research to see how climate change is affecting conservation efforts. Because of his work, he infers climate change needs to be strongly considered when planning conservation. Lee Hannah strongly supports creating protected areas such as parks and reserves. He is also an advocate of habitat corridors and believes they are necessary for the survival of animals. [4] Hannah argues that each species have a certain tolerable range of temperature that they can handle. If a certain area that once was hospitable to the species becomes unsuitable, the species will migrate to a cooler area. Thus, habitat connectivity is needed so that plants and animals will be able to move to find suitable climatic conditions [3] Finally, Hannah supports lowering greenhouse gas emissions. [3]
One of Hannah's most notable publications was in the January 2004 edition of Nature . In the article, Extinction risk from climate change, Hannah and his coauthors attempt to predict how biodiversity will be affected by climate change. [1] The study was done by computer simulations and based on the ecological law of the species-area curve, which amounts to the bigger the piece of livable land, the more species it harbors. [5] The paper concluded that as a result of climate changes that will take place from now till 2050, between 15% and 37% of species will be on a path to extinction. [1] Thus, all of those species will not be extinct by 2050, but they will be committed to extinction by human greenhouse gas pollution that occurs in that timeframe. The conclusions of the study are therefore based on the assumption that climate change will continue at approximately its current pace. If international policy action results in climate change starting to level-off, it would reduce the number of extinctions projected by the study. [5] Critics of the study point to the all-computer simulation, saying too many unknowns in computers give skewed results. Likewise, some believe that just because living area shrinks, it is not necessarily indicative of the exact number of species that will go extinct. [5] Other critics point to the fact that plants and animals are able to adapt, and though there will be an impact on life, there will not be as great an impact as this study predicts. [5]
Hannah co-edited Climate Change and Biodiversity with Thomas Lovejoy on climate change (Yale University Press 2005). [6] It was honored by Choice magazine as one of the “Outstanding Academic Titles” in 2005.
Hannah authored the first undergraduate textbook on climate change and biological systems, Climate Change Biology (Elsevier 2010). He has authored over 50 papers on climate change and nature conservation.
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The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event caused by humans during the Holocene epoch. These extinctions span numerous families of plants and animals, including mammals, birds, reptiles, amphibians, fish, and invertebrates, and affecting not just terrestrial species but also large sectors of marine life. With widespread degradation of biodiversity hotspots, such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background extinction rates and is increasing. During the past 100–200 years, biodiversity loss and species extinction have accelerated, to the point that most conservation biologists now believe that human activity has either produced a period of mass extinction, or is on the cusp of doing so. As such, after the "Big Five" mass extinctions, the Holocene extinction event has also been referred to as the sixth mass extinction or sixth extinction; given the recent recognition of the Capitanian mass extinction, the term seventh mass extinction has also been proposed for the Holocene extinction event.
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic, species, and ecosystem levels. Biodiversity is not distributed evenly on Earth; it is usually greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than 10% of Earth's terrestrial surface and contain about 50% of the world's species. There are latitudinal gradients in species diversity for both marine and terrestrial taxa. Marine coastal biodiversity is highest globally speaking in the Western Pacific ocean steered mainly by the higher surface temperatures. In all oceans across the planet, marine species diversity peaks in the mid-latitudinal zones. Terrestrial species threatened with mass extinction can be observed in exceptionally dense regional biodiversity hotspots, with high levels of species endemism under threat. There are 36 such hotspot regions which require the world's attention in order to secure global biodiversity.
Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an interdisciplinary subject drawing on natural and social sciences, and the practice of natural resource management.
An ecological or environmental crisis occurs when changes to the environment of a species or population destabilizes its continued survival. Some of the important causes include:
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes, ponds, rivers, streams, springs, bogs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic, lotic and wetlands. Freshwater ecosystems contain 41% of the world's known fish species.
In conservation biology, a flagship species is a species chosen to raise support for biodiversity conservation in a given place or social context. Definitions have varied, but they have tended to focus on the strategic goals and the socio-economic nature of the concept, to support the marketing of a conservation effort. The species need to be popular, to work as symbols or icons, and to stimulate people to provide money or support.
Human impact on the environment refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans. Modifying the environment to fit the needs of society is causing severe effects including global warming, environmental degradation, mass extinction and biodiversity loss, ecological crisis, and ecological collapse. Some human activities that cause damage to the environment on a global scale include population growth, neoliberal economic policies and rapid economic growth, overconsumption, overexploitation, pollution, and deforestation. Some of the problems, including global warming and biodiversity loss, have been proposed as representing catastrophic risks to the survival of the human species.
Wildlife conservation refers to the practice of protecting wild species and their habitats in order to maintain healthy wildlife species or populations and to restore, protect or enhance natural ecosystems. Major threats to wildlife include habitat destruction, degradation, fragmentation, overexploitation, poaching, pollution, climate change, and the illegal wildlife trade. The IUCN estimates that 42,100 species of the ones assessed are at risk for extinction. Expanding to all existing species, a 2019 UN report on biodiversity put this estimate even higher at a million species. It is also being acknowledged that an increasing number of ecosystems on Earth containing endangered species are disappearing. To address these issues, there have been both national and international governmental efforts to preserve Earth's wildlife. Prominent conservation agreements include the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the 1992 Convention on Biological Diversity (CBD). There are also numerous nongovernmental organizations (NGO's) dedicated to conservation such as the Nature Conservancy, World Wildlife Fund, the Wild Animal Health Fund and Conservation International.
Pelusios is a genus of African side-necked turtles. With 17 described species, it is one of the most diverse genera of the turtle order (Testudines).
Papua New Guinea together with the West Papua region of Indonesia make up a major tropical wilderness area that still contains 5% of the original and untouched tropical high-biodiversity terrestrial ecosystems. PNG in itself contains over 5% of the world's biodiversity in less than 1% of the world's total land area. The flora of New Guinea is unique because it has two sources of origin; the Gondwana flora from the south and flora with Asian origin from the west. As a result, New Guinea shares major family and genera with Australia and the East Asia, but is rich in local endemic species. The endemicity is a result of mountainous isolation, topographic and soil habitat heterogeneity, high forest disturbance rates and abundant aseasonal rainfall year round. PNG boasts some 15–21,000 higher plants, 3,000 species of orchids, 800 species of coral, 600 species of fish, 250 species of mammals and 760 species of birds and 8 species of tree-kangaroos out of which 84 genera of animals are endemic. Ecosystems range from lowland forests to montane forests, alpine flora down to coastal areas which contains some of the most extensive pristine mangrove areas in the world. Much of this biodiversity has remained intact for thousands of years because the ruggedness of the terrain made the interior lands inaccessible; furthermore low population density and restrictions on the effectiveness of traditional tools, ensured that these biodiversity was never overexploited.
There are several plausible pathways that could lead to an increased extinction risk from climate change. Every plant and animal species has evolved to exist within a certain ecological niche. But climate change leads to changes of temperature and average weather patterns. These changes can push climatic conditions outside of the species' niche, and ultimately render it extinct. Normally, species faced with changing conditions can either adapt in place through microevolution or move to another habitat with suitable conditions. However, the speed of recent climate change is very fast. Due to this rapid change, for example cold-blooded animals may struggle to find a suitable habitat within 50 km of their current location at the end of this century.
Global biodiversity is the measure of biodiversity on planet Earth and is defined as the total variability of life forms. More than 99 percent of all species that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 2 million to 1 trillion, but most estimates are around 11 million species or fewer. About 1.74 million species were databased as of 2018, and over 80 percent have not yet been described. The total amount of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at 5.0 x 1037, and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).
There is an ongoing decline in plant biodiversity, just like there is ongoing biodiversity loss for many other life forms. One of the causes for this decline is climate change. Environmental conditions play a key role in defining the function and geographic distributions of plants. Therefore, when environmental conditions change, this can result in changes to biodiversity. The effects of climate change on plant biodiversity can be predicted by using various models, for example bioclimatic models.
Defaunation is the global, local, or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of Neotropical forests. Since then, the term has gained broader usage in conservation biology as a global phenomenon.
Malaysia faces several environmental issues. Malaysia's environment possesses megadiverse biological diversity, with globally significant endemism and biodiversity, but is threatened by several issues. Deforestation is a major issue in the country that has led to many species becoming threatened with extinction. As a major economic sector, palm oil production has had a substantial environmental impact. Air pollution is also a major issue, with the country one of the most affected countries by seasonal Southeast Asian haze. The country is also affected by climate change.
Stuart Leonard Pimm is the Doris Duke Chair of Conservation Ecology at Duke University. His early career was as a theoretical ecologist but he now specialises in scientific research of biodiversity and conservation biology.
Cuba possesses a diverse range of natural habitats, housing a wide variety of species, including many endangered ones. However, the country has faced environmental challenges, particularly deforestation, since the arrival of European settlers. Forest areas have been cleared for agricultural purposes, leading to the loss of forests and the extinction of certain species. The cutting down of trees for fuel and construction materials has further contributed to this issue.
Assisted migration is "the intentional establishment of populations or meta-populations beyond the boundary of a species' historic range for the purpose of tracking suitable habitats through a period of changing climate...." It is therefore a nature conservation tactic by which plants or animals are intentionally moved to geographic locations better suited to their present or future habitat needs and climate tolerances — and to which they are unable to migrate or disperse on their own.
Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in biological diversity in a given area. The decrease can be temporary or permanent. It is temporary if the damage that led to the loss is reversible in time, for example through ecological restoration. If this is not possible, then the decrease is permanent. The cause of most of the biodiversity loss is, generally speaking, human activities that push the planetary boundaries too far. These activities include habitat destruction and land use intensification. Further problem areas are air and water pollution, over-exploitation, invasive species and climate change.
Erika S. Zavaleta is an American professor of ecology and evolutionary biology at the University of California, Santa Cruz. Zavaleta is recognized for her research focusing on topics including plant community ecology, conservation practices for terrestrial ecosystems, and impacts of community dynamics on ecosystem functions.
