An A-Z Primer on the Climate Crisis

Whatever your stance on "global warming," there’s no denying the drastic weather patterns and natural disasters of late that at least make you question the cause. Perhaps it’s just cyclical, or maybe it is, in fact, a product of climate change. And while the science is there to support both sides of the argument, more and more evidence is emerging that the world is warming up and humans are contributing to it. For example, according to the World Health Organization, over the last 50 years, human activities — particularly the burning of fossil fuels — have released sufficient quantities of carbon dioxide and other greenhouse gases to affect the global climate. And that’s just the beginning. To better understand what climate change is all about and how you can do your part to fight it, we’ve compiled a list of terms, keywords, and phrases that cover all the basics from A to Z.

Anthropocene The time period in which humans have had the ability to affect the global climate. Humans (and all other creatures) have always affected their local climates, whether through slash-and-burn agriculture employed by Native Americans, or the widespread deforestation of Easter Island by the Rapanui people in the 9^th century. Only since the widespread burning of coal, beginning with the Industrial Revolution, have human practices released enough greenhouse gases into the atmosphere to alter the climate of the entire planet. This is not an officially recognized geological era, such as the Paleozoic or Cenozoic eras, but an informal chronological term often used by geologists and other types of environmental scientists.

Biodiversity The degree of variation of life forms within an ecosystem. It is a measure of the health of ecosystems — greater biodiversity implies greater health. Biodiversity is threatened by climate change. Changes in local climates, including temperature and precipitation, can lead to habitat loss. It takes time for species to adapt or move to a new habitat, and many will fail to do so quickly enough to survive.

Carbon Cycle Carbon is the building block of organic matter. It is also the central element of some of the most important greenhouse gases, including carbon dioxide and methane. Carbon dioxide is essential for plant growth, and through the process of photosynthesis is turned into organic matter (the stuff we’re made of). When organic matter decays or is burned, the carbon is converted back into carbon dioxide. Carbon naturally cycles between carbon dioxide and organic matter, however, for the last several decades, carbon dioxide has been introduced into the atmosphere faster than the rate it is turned back into organic matter (partially due to the burning of fossil fuels, which had previously been buried, and were not part of the carbon cycle), and the global levels of atmospheric CO₂ has steadily risen.

Deforestation The removal of a forest where the land is thereafter converted to a non-forest use, such as for farms, ranches, or urban use. Tropical deforestation is responsible for approximately 20 percent of world greenhouse gas emissions. Trees and other plants remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis. Deforestation not only destroys the trees that are constantly removing CO₂ from the atmosphere, it also releases much of the already stored carbon back into the atmosphere.

Extinction The permanent eradication of a species. It is estimated that with a rise in global temperature of 2 degrees Celsius, some 20 percent of species will become extinct, and with a rise of 4 degrees, it’s estimated that 70 percent would die off. This “mass extinction” has happened only five times in the history of the universe, the last of which occurred 65 million years ago, when the dinosaurs died off.

Fossil fuels are fuels, such as oil and coal, formed by natural processes of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years (that’s right, your car runs on dinosaur bones!), therefore, fossil fuels are a non-renewable resource. Fossil fuels are one of the major sources of greenhouse gases produced by human activities.

Greenhouse Gases trap infrared radiation as it attempts to leave the atmosphere, leading to an increase in the amount of energy in the atmosphere. Because of this, greenhouse gases are essential to life on Earth. With no greenhouse gases at all, the Earth would be too cold for humans to inhabit. However, too much greenhouse gas can trap too much energy in the atmosphere, which can cause temperatures to rise and the global climate to change. Some greenhouse gases, such as carbon dioxide, occur naturally, while others are created and emitted solely through human activities. The principal greenhouse gases that enter the atmosphere because of human activities are carbon dioxide, through the burning of fossil fuels; methane, which is emitted during the production and transport of coal, natural gas, and oil; nitrous oxide, which is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste; and fluorinated gases, which are emitted from a variety of industrial processes.

Health hazards Based on its research, the World Heath Organization estimates that around 150,000 deaths now occur in low-income countries each year, with young children making up almost 85 percent of these excess deaths, due to the effect climate change has on crop failure and malnutrition, diarrhoeal disease, malaria, and flooding.

Intergovernmental Panel on Climate Change (IPCC) is a group of 2,400 scientists worldwide, established by the United Nations to advise on climate change and its potential environmental and socio-economic impacts.

Joseph Fourier is the French mathematician and physicist who originally proposed the concept of the greenhouse effect in 1824.

Kyoto Protocol is an international and legally binding agreement to reduce greenhouse gas emissions worldwide, entered into force on February 16, 2005. The protocol to the United Nations Framework Convention on Climate Change aimed at fighting the global climate crisis had been signed and ratified by 193 states as of March — the U.S. is not among them.

Limits to Growth is a 1972 book that was popularized by the “Club of Rome” to counter the popular belief that growth can continue indefinitely. It models the consequences of a rapidly growing world with finite supplies.

Methane is an important greenhouse gas. Though lesser known than its partner in crime, carbon dioxide, it traps more than 11 times more energy per molecule than CO₂. Meat production is a significant source of atmospheric methane.

Northern hemisphere warms faster than the Southern hemisphere because it has more land than water. Water has a high specific heat, and because there's more of it in the Southern hemisphere, it absorbs more energy and moderates the temperature rise down there. 

Offsets are reductions in emissions of carbon dioxide made in order to compensate for — or offset — an emission made elsewhere. One carbon offset represents the reduction of one metric ton of carbon dioxide or its equivalent in other greenhouse gases.

Paleoclimatology is the study of climate prior to the widespread availability of records of temperature, precipitation, and other instrumental data. Through this area of study, we have found that the global climate has changed dramatically throughout the Earth’s history, cycling between cooling and warming periods. The climate change debate is not about whether the global climate can change, or even if it is changing right now (it is). The debate is about whether or not human activities are directly changing the global climate in ways that will alter the Earth’s capacity to support life, and what we should be doing to mitigate the effects of climate change.

Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale. Organizations such as the American Quaternary Association perform research in a vast range of topics including geology, geophysics, oceanography, and climatology and their effects on the environment.

Rainforests are a significant part of the world’s lungs and the carbon sink. Some climate models predict a large loss of Amazonian rainforest around 2050 due to drought, forest dieback, and the subsequent release of more carbon dioxide. In other words, the more the climate changes, the more rainforest will be lost, which will lead to even more greenhouse gas emissions and more severe effects of climate change.

Sea levels Rising sea levels threaten many low-lying areas of the globe. Many climate scientists believe melting of the Greenland Ice Sheet will be one of the main drivers of sea level rise during the 21st century. And because warm water expands, atmospheric warming contributes to rising sea levels as well. Entire countries, such as Maldives in the Indian Ocean, are expected to be completely underwater within the next century.

Thermohaline circulation, more commonly known as ocean currents, is one of the biggest factors in regional climates. For example, San Francisco and Washington, D.C. are about as far north of the equator as one another, but anyone who has spent a winter in either place will tell you that the climates are drastically different. This is because Washington is next to a warm water current, while San Francisco is next to a cold water current. If ocean temperatures rise enough, or if the polar ice caps melt and change the salinity or density of the ocean water enough, this can drastically change the pattern of ocean currents, and completely alter the climates of entire regions.

United Nations Framework Convention on Climate Change (UNFCCC), adopted in 1992 as the basis for a global response to the problem of climate change. With 194 Parties, the Convention has near-universal membership. The ultimate objective of the Convention is to stabilize greenhouse gas concentrations in the atmosphere at a level that will prevent dangerous human interference with the climate system.

Vulnerability of human societies to climate change mainly lies in the effects of extreme weather events rather than gradual climate change.

Water Scarcity According to the World Health Organization, water scarcity already affects four out of every 10 people globally. A lack of water and poor water quality can compromise hygiene and health. Water scarcity encourages people to transport water long distances and store supplies in their homes, which can increase the risk of household water contamination, causing illnesses. Glaciers and mountain snow pack are two major sources of clean water that are threatened by global climate change.

ExxonMobil is among the companies that have challenged the IPCC climate change scenarios, and have argued that the costs of stricter environmental controls are prohibitive to conducting business as usual.

Young Voices on Climate Change, a film series of young people making a difference, founded by illustrator and author Lynne Cherry. You can watch the movies and get involved at YoungVoicesOnClimateChange.com.

Zero Emission Vehicle, or ZEV, is a vehicle that emits no tailpipe pollutants from the onboard source of power. These include human-powered, animal-powered, and electric-powered vehicles. While electric vehicles don't have tail pipe emissions, they still have an environmental impact and do emit greenhouse gas, although not at the same rate or in the same quantity as traditional vehicles.