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Wildfires are a natural phenomenon in many ecosystems, including forests along the U.S. Pacific West Coast, as natural fires serve to rejuvenate ecological communities. However, from mid-August through mid-September 2020, forests in California,…

A branch of meteorology that examines the effects and impacts of weather and climate on crops, rangeland, livestock, and various agricultural operations. Agricultural meteorology, or agrometeorology, addresses topics that often require an…

Natural and artificial substances in the atmosphere that affect human health or well-being, or the well-being of any other organisms in the environment. Air pollution also applies to situations in which contaminants affect structures and artifacts…

Microplastics are raining down on national parks and other protected areas in the western United States at the rate of about 132 pieces of microplastic per square meter every day, according to a report in the journal Science (June 2020).…

A disease of the nervous system characterized by a progressive dementia that leads to profound impairment in cognition and behavior. Dementia occurs in a number of brain diseases where the impairment in cognitive abilities represents a decline from…

A psychiatric disorder in which a dramatic reduction in caloric intake consequent to excessive dieting leads to significant bodily, physiological, biochemical, emotional, psychological, and behavioral disturbances. Anorexia nervosa is one of three…

A group of distinct psychiatric disorders including generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, specific phobia, and posttraumatic stress disorder. Whereas fear is an adaptive emotion that is…

A neurodevelopmental condition that impairs the way that a person relates to and communicates with other people. Persons with autism have difficulties with social communication and interaction. They also can have unusual behaviors, such as…

The study of the cycling of chemicals between organisms and the surface environment of the Earth. The chemicals either can be taken up by organisms and used for growth and synthesis of living matter or can be processed to obtain energy. The chemical…

Unwanted, aggressive behavior that involves a real or perceived power inequity. The behavior of bullying is often chronic and includes actions such as threats, spreading rumors, attacking someone physically or verbally, and purposefully excluding or…

The long-term records of precipitation, temperature, wind, and all other aspects of the Earth's climate. Climate, like the Earth itself, has a history extending over several billion years. Climatic changes have occurred at time scales ranging from…

Construction of a mathematical model of the climate system of the Earth capable of simulating its behavior under present and altered conditions. The Earth's climate is continually changing over time scales ranging from hundreds of years to a few…

The scientific study of climate. Climate is the expected mean and variability of the weather conditions for a particular location, season, and time of day. The climate is often described in terms of the mean values of meteorological variables such…

The visual perception of different wavelengths of light. Light can be understood both as electromagnetic waves and as particles called photons. Photons can have different energies. The energy of a photon determines the frequency and wavelength of…

Obscured by a hazy atmosphere 100 times thicker than Earth's, Venus is a notoriously difficult world to study. Ground temperatures on Venus exceed 450°C (842°F)—enough to melt lead and to have quickly degraded the Soviet robotic landers last placed…

The novel coronavirus SARS-CoV-2 that emerged in central China in late 2019 and subsequently spread across the world in 2020 led to the COVID-19 pandemic. The emergence of a previously unknown pathogen—such as the novel coronavirus—that could affect…

A calcarenite or clastic limestone whose detrital particles are chiefly fossils, whole or fragmented. The term coquina is most frequently used for an aggregate of large shells more or less cemented by calcite (see illustration). If the rock consists…

The response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral skeleton visible. Corals (Fig. 1) are animals that live in a partnership (symbiosis) with…

Pathological conditions affecting the health of coral and causing its physiological dysfunction. Broadly defined, coral disease (Fig. 1) is any impairment to coral health resulting in physiological disturbance and breakdown. It usually involves…

A measure of the three-dimensional structure of live coral communities on reefs. Coral reef structural complexity is an intrinsic element of coral reef ecosystems and quantitates the surface area of coral in relation to its linear area. The…