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.
In physical geography, tundra is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term comes from the Finnish word tunturia, meaning "treeless plain". There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.
Proceedings of the National Academy of Sciences of the United States of America is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to Journal Citation Reports, the journal has a 2022 impact factor of 11.1. PNAS is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the mass media, PNAS has been described variously as "prestigious", "sedate", "renowned" and "high impact".
Clovis culture is a prehistoric Paleoamerican archaeological culture, named for distinct stone and bone tools found in close association with Pleistocene fauna, particularly two Columbian mammoths, at Blackwater Locality No. 1 near Clovis, New Mexico, in 1936 and 1937, though Paleoindian artifacts had been found at the site since the 1920s. It existed from roughly 11,500 to 10,800 BCE near the end of the Last Glacial Period.
Afforestation is the establishment of a forest or stand of trees (forestation) in an area where there was no recent tree cover. In comparison, reforestation means re-establishing forest that have either been cut down or lost due to natural causes, such as fire, storm, etc. There are three types of afforestation: natural regeneration, agroforestry and commercial plantations. There are several benefits from afforestation such as carbon sequestration, increasing rainfall, prevention of topsoil erosion, flood and landslide mitigation, barriers against high winds, shelter for wildlife, employment and alternative sources of wood products.
Jonathan Dallas George Jones is a senior scientist at the Sainsbury Laboratory and a professor at the University of East Anglia using molecular and genetic approaches to study disease resistance in plants.
The cation channels of sperm also known as Catsper channels or CatSper, are ion channels that are related to the two-pore channels and distantly related to TRP channels. The four members of this family form voltage-gated Ca2+ channels that seem to be specific to sperm. As sperm encounter the more alkaline environment of the female reproductive tract, CatSper channels become activated by the altered ion concentration. These channels are required for proper fertilization. The study of these channels has been slow because they do not traffic to the cell membrane in many heterologous systems.
There are several plausible pathways that could lead to an increased extinction risk from climate change. This is because every plant and animal species has evolved to exist within a certain ecological niche, and as climate change represents the long-term alteration of temperature and average weather patterns, it can push climatic conditions outside of the species' niche, which will 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 so unprecedented, that even under "mid-range" scenarios of future warming, only 5% of current ectotherm locations are within 50 km of a place which could serve as an equally suitable habitat at the end of this century.
David Locke Webster was an American physicist and physics professor, whose early research on X-rays and Parson's magneton influenced Arthur Compton.
Hyloidea is a superfamily of frogs. Hyloidea accounts for 54% of all living anuran species. The superfamily Hyloidea branched off from its closest relative, the Australobatrachia, during the mid-Cretaceous. The fossil evidence found during the Cretaceous-Paleogene extinction event could not determine the effects upon the frogs, due to the lack of fossils. Increased forestation erupted after this extinction, possibly leading to more arboreal adaptations of these anurans to be best suited for this habitat.
Forest dieback is a condition in trees or woody plants in which peripheral parts are killed, either by pathogens, parasites or conditions like acid rain, drought, and more. These episodes can have disastrous consequences such as reduced resiliency of the ecosystem, disappearing important symbiotic relationships and thresholds. Some tipping points for major climate change forecast in the next century are directly related to forest diebacks.
In climate science, a tipping point is a critical threshold that, when crossed, leads to large, accelerating and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society and may accelerate global warming. Tipping behavior is found across the climate system, for example in ice sheets, mountain glaciers, circulation patterns in the ocean, in ecosystems, and the atmosphere. Examples of tipping points include thawing permafrost, which will release methane, a powerful greenhouse gas, or melting ice sheets and glaciers reducing Earth's albedo, which would warm the planet faster.
Climate change in California has resulted in higher than average temperatures, leading to increased occurrences of drought and wildfires. During the next few decades in California, climate change is likely to further reduce water availability, increase wildfire risk, decrease agricultural productivity, and threaten coastal ecosystems. The state will also be impacted economically due to the rising cost of providing water to its residents along with revenue and job loss in the agricultural sector. California has taken a number of steps to mitigate impacts of climate change in the state.
The Paleocene, or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek παλαιός palaiós meaning "old" and the Eocene Epoch, translating to "the old part of the Eocene".
Hans Joachim "John" Schellnhuber is a German atmospheric physicist, climatologist and founding director of the Potsdam Institute for Climate Impact Research (PIK) and former chair of the German Advisory Council on Global Change (WBGU). Since 1 December 2023 he is the Director General of IIASA.
A genetically modified tomato, or transgenic tomato, is a tomato that has had its genes modified, using genetic engineering. The first trial genetically modified food was a tomato engineered to have a longer shelf life, which was on the market briefly beginning on May 21, 1994. The first direct consumption tomato was approved in Japan in 2021. Primary work is focused on developing tomatoes with new traits like increased resistance to pests or environmental stresses. Other projects aim to enrich tomatoes with substances that may offer health benefits or be more nutritious. As well as aiming to produce novel crops, scientists produce genetically modified tomatoes to understand the function of genes naturally present in tomatoes.
Deforestation is a primary contributor to climate change, and climate change affects forests. Land use changes, especially in the form of deforestation, are the second largest anthropogenic source of atmospheric carbon dioxide emissions, after fossil fuel combustion. Greenhouse gases are emitted during combustion of forest biomass and decomposition of remaining plant material and soil carbon. Global models and national greenhouse gas inventories give similar results for deforestation emissions. As of 2019, deforestation is responsible for about 11% of global greenhouse gas emissions. Carbon emissions from tropical deforestation are accelerating. Growing forests are a carbon sink with additional potential to mitigate the effects of climate change. Some of the effects of climate change, such as more wildfires, insect outbreaks, invasive species, and storms are factors that increase deforestation.
Pupa Gilbert is an American biophysicist and geobiologist. She has been pioneering synchrotron spectromicroscopy methods since 1989, and she continues to use and develop them today. Since 2004 she has focused on biomineralization in sea urchins, mollusk shells, and tunicates. She and her group are frequent users of the Berkeley-Advanced Light Source.
Noah S. Diffenbaugh is an American climate scientist at Stanford University, where he is the Kara J Foundation Professor of Earth System Science and Kimmelman Family Senior Fellow at the Stanford Woods Institute for the Environment, and an affiliate at the Precourt Institute for Energy. From 2015-2018, he served as editor-in-chief of the peer-review journal Geophysical Research Letters. He is known for his research on the climate system, including the effects of global warming on extreme weather and climate events such as the 2011-2017 California drought.
David Schlessinger is a Canadian-born American biochemist, microbiologist, and geneticist. He is known for his directorship of the development of the map of the X chromosome.
