Glossary

As with many specialised topics, climate science discussions are often littered with confusing abbreviations, acronyms and technical jargon. This can be quite intimidating to people who are new to the field of climate science. So, on this page, we are trying to compile a list of some of the more commonly-used jargon, and their meanings.

If there is some other climate science-related term or abbreviation/acronym you keep seeing mentioned elsewhere, but don’t know what it means, then please mention it in the comments section at the end of the page. If it is appropriate, we will try to add a brief explanation to this list.

We have grouped the jargon into the following two sections:

1. Abbreviations & acronyms

On the internet, some of the more popular climate blogs are often referred to by their initials, e.g.,

AGW

An acronym for Anthropogenic Global Warming, i.e., man-made global warming

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BEST

Berkeley Earth Surface Temperature. A global temperature estimate constructed by the Berkeley Earth group, in response to concerns over the reliability of other estimates. The Berkeley Earth group is run by Prof. Richard Muller.

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CAGW

An acronym for Catastrophic Anthropogenic Global Warming, often used by climate sceptics who believe that there might be some, but not much man-made global warming, to distinguish man-made global warming theory from the more catastrophic predictions of the likes of Al Gore.

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CO2

The chemical formula for carbon dioxide.

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CRU

The University of East Anglia’s Climate Research Unit, or CRU, is based in the UK. It was initially set up in 1972, because its founding director, Prof. Hubert Lamb, believed that the climate has always been changing, and we should learn more about the climate of the past. But, subsequent directors (including their current director, Prof. Phil Jones), have mainly focused on man-made global warming theory.

The CRU maintain one of the weather station based global temperature estimates, CRUTEM, which makes up the land-component of the HadCRUT and IPCC “land-and-sea” global temperature estimates. They also have been involved in several of the “hockey stick” paleoclimate studies.

E-mails which were hacked (or possibly leaked) from the CRU in November 2009 and November 2011, formed the basis for the “Climategate” controversy.

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GCM

GCM is an abbreviation of either Global Climate Model or General Circulation Model. Both terms are generally used synonymously, but have slightly different historical significance. The terms refer to the computer models which are used for modelling how climate varies over time. The current models assume that climate is heavily influenced by changes in Greenhouse Gas concentrations. As a result, most of the current models predict that projected increases in atmospheric carbon dioxide will lead to dramatic Man-Made Global Warming in the coming decades.

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GHE

GHE is an abbreviation for the “greenhouse effect theory”.

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GHG

GHG is an abbreviation for a “greenhouse gas”.

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IPCC

The Intergovernmental Panel on Climate Change, or IPCC, is an organisation set up in 1988 by the United Nations and the World Meteorological Organization to investigate what effects (if any) man-made global warming would have on future climate, and what should be done about it. Since then, every few years, they have published a set of reports, attempting to summarise the scientific consensus on climate science. The reports are written by various researchers working in the field, in a complex heirarchical manner, and are divided into three separate Working Groups, with each Working Group releasing their own reports.

Working Group 1 (WG1) is the group dealing with the physical science, whereas Working Group 2 is concerned with the effects of present and future climate change and Working Group 3 assesses ways in which humans can mitigate future climate change. Working Groups 2 and 3 are heavily based on the assumption that man-made global warming theory is reliable.

The Summary for Policymakers (“SPM”) of the Working Group 1 reports are often assumed to represent the “scientific consensus” on man-made global warming theory.

The fourth set of reports (“4AR”) were published in 2007, and the Working Group 1 part of the fifth set (“5AR”) was published in September 2013.

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NASA GISS

National Aeronautics and Space Administration’s Goddard Institute for Space Studies, or NASA GISS is a branch of NASA studying “global change”, with a particular focus on climate change and man-made global warming.

NASA GISS maintain one of the weather station-based global temperature estimates (GISTEMP) and have developed several of the main Global Climate Models.

NASA GISS are located at Columbia University in New York City, New York (USA), just above the iconic “Tom’s Restaurant”, which featured in the popular TV sitcom, Seinfeld and was the basis for Suzanne Vega’s “Tom’s Diner” song.

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NOAA NCDC

National Oceanic and Atmospheric Administration’s National Climatic Data Center, or NOAA NCDC is a branch of the US’ scientific agency, NOAA, which compiles and archives various climatic datasets. They are co-located between Asheville, North Carolina (USA) and Boulder, Colorado (USA). Their current director is Dr. Tom Karl.

The North Carolina section maintain one of the weather station-based global temperature estimates (GSTA) as well as a Sea Surface Temperature global temperature estimate, and a combined “land-and-sea” estimate. The Boulder section house the useful World Data Center for Paleoclimatology, which offers a public archive where Paleoclimatologists can upload their data.

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SST

SST is an abbreviation of Sea Surface Temperature. When attempting to combine weather station-based global temperature estimates with global temperature estimates for the oceans, some groups were uncertain about the reliability of actual measurements of air temperature taken on ship decks. As a result, most groups discarded such Marine Air Temperature (MAT) measurements, and preferred to rely on measurements of water temperatures near the ocean surface, i.e., Sea Surface Temperatures. Unfortunately, the available sea surface temperature datasets have a large number of inconsistencies, e.g., most late 19th century and early 20th century measurements were carried out using different types of “buckets” thrown overboard, while in the mid-20th century many ships started using engine-inlet measurements, and since the 1980s, many measurements are made by weather buoys. Hence, groups analysing sea surface temperatures often introduce controversial adjustments to try and account for the differences.

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2. Commonly used terms

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Anthropogenic

A more scientific-sounding word for human-made or man-made. Often used when describing Man-Made Global Warming (i.e., anthropogenic global warming) or Man-Made Climate Change (i.e., anthropogenic climate change).

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Anthropogenic Climate Change

A more scientific-sounding version of Man-Made Climate Change.

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Anthropogenic Global Warming

A more scientific-sounding version of Man-Made Global Warming.

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Carbon dioxide

Carbon dioxide is a naturally-occurring gas, which is essential for life as we know it.

However, the use of fossil fuels (or any carbon-based fuel) releases carbon dioxide into the atmosphere. As a result, there seems to have been a gradual increase in carbon dioxide concentrations since the Industrial Revolution. Specifically, carbon dioxide currently makes up about 0.04% of the atmosphere (by volume), but before the Industrial Revolution, it is estimated to have been only about 0.03%.

According to the greenhouse effect theory, it also influences the temperature of the atmosphere. So, this has led many people to worry that fossil fuel usage might be causing “man-made global warming”.

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Climate

Climate refers to the average weather conditions over a specific period of time, usually 30 years. See also Weather.

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Climate Change

If the average Weather conditions change from one 30 year period to another, then that is “climate change”. An example of climate change could be confined to some localised area, i.e., “regional climate change”, or else occur simultaneously over large sections of the planet, i.e., “global climate change”.

The term is sometimes mistakenly treated as a synonym for Man-Made Climate Change. This is incorrect as the term does not itself indicate the cause of the climate change, e.g., whether there is a contribution from human activity or a naturally-occuring change. It is also sometimes assumed to be another term for Man-Made Global Warming. Again, this is incorrect. While Global Warming would be an example of climate change, climate change is a more general term, and the specific term Man-Made Global Warming refers to global warming that has been attributed to increasing atmospheric CO2 concentrations.

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Climategate

Climategate was a controversy over the content of a large set of e-mails which were hacked (or possibly leaked) from the University of East Anglia’s Climate Research Unit (CRU) in November 2009 and November 2011.

The e-mails contained correspondence between a number of prominent climate scientists, many of whom had been (and in most cases still are) actively arguing that man-made global warming is a real crisis which will have devastating consequences for the planet. However, the e-mails suggested to many that the basis for these claims, and the justification for criticism of climate sceptics, were a lot less solid than had been implied publically. The various insights into the climate science community that arose from these e-mails became known as “Climategate”.

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Global Cooling

We can say there has been global cooling, if the average global temperature has, on average, been falling for some period of time.

The term global cooling does not itself indicate the cause of the cooling (e.g., man-made, or natural), and does not indicate how long the period of global cooling has been. See also Global Warming.

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Global Warming

We can say there has been global warming, if the average global temperature has, on average, been rising for some period of time.

The term is often mistakenly used synonymously with the term man-made global warming, and often thought to represent a continuous warming trend since the Industrial Revolution. But, the term global warming does not itself indicate the cause of the warming (e.g., man-made, or natural), and does not indicate how long the period of global warming has been. See also Global Cooling.

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Greenhouse Effect

The greenhouse effect theory proposes that atmospheric temperatures are predominantly controlled by radiative processes, and that they are therefore strongly influenced by the relative concentrations of the various Greenhouse Gases. It forms the basis for Man-Made Global Warming theory and is a major component in current computer models of the climate.

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Greenhouse Gas

Greenhouse gases are gases which have absorb and emit radiation in the infrared (IR) region.

This does not apply to the main atmospheric gases, i.e., nitrogen (N2), oxygen (O2) and argon (Ar). However, many of the trace atmospheric gases do. The most abundant of these is water vapour (H2O), followed by carbon dioxide (CO2), methane (CH4) and ozone (O3). The Greenhouse Effect theory, which forms the basis for Man-Made Global Warming theory, assumes that atmospheric temperatures are strongly influenced by the concentrations of greenhouse gases.

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Hockey Stick Graph

A series of Temperature Proxy based studies which suggested that 20th century temperatures were unusually warm relative to the last millennium or so.

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Man-Made Climate Change

Man-made climate change is a form of Climate Change which has been attributed to human activity, of some form or another. Possible examples would be the altering of the local hydrological system, by land irrigation or by the planting of different crops. Urban Heat Islands are well-documented examples of localised man-made climate change.

Although Global Warming would be an example of climate change, on this website, we do not consider the theory that the burning of fossil fuels causes global warming an example of man-made climate change, as that theory is already widely-known as Man-Made Global Warming theory.

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Man-made Global Warming

Man-made global warming is a Global Warming trend that is alleged to be caused by human activities – specifically the production of “greenhouse gases”, mainly carbon dioxide (CO2) released as a by-product of burning fossil fuels. It is sometimes referred to by the synonym, Anthropogenic Global Warming

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Ocean Acidification

A theory that increasing atmospheric concentrations of carbon dioxide (CO2) also leads to a slight reduction in the average pH of the oceans.

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Paleoclimate

Climate of the past – usually refers to the era before weather records began, i.e., the “pre-instrumental era”. Climate scientists who study paleoclimate are often referred to as paleoclimatologists. Paleoclimate is the US spelling and Palaeoclimate is the UK spelling.

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pH

A measure of how acidic/basic a solution is. The pH scale is a logarithmic scale, which means that an increase/decrease of 1 unit corresponds to an increase/decrease in magnitude of 10. Mathematically, it represents -log [H+], where [H+] is the concentration of hydrogen ions (“acid”) in the solution (in moles per litre). A pH of 0 corresponds to pure acid, while a pH of 14 corresponds to pure base. Therefore, decreasing the pH of a solution makes it more acidic, while increasing the pH makes it more basic. Also, since alkali are one of the main types of base, sometimes a basic solution is referred to as an alkali solution, and increasing the pH of a solution is referred to as making it more alkaline.
Neutral solutions, e.g., distilled water, have a pH of 7. The average pH of the oceans tends to be slightly alkaline (pH=7.5-8.5).

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Temperature Proxy

Some series of measurements (e.g., tree rings, ice core layers), which are thought to have been influenced by changing local temperatures over the years. As most weather station records only began a few decades (or in some cases centuries) ago, some Paleoclimatologists attempt to estimate temperatures of the pre-instrumental era, using these proxies.

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Urban Heat Island

Increased local temperatures, associated with urban development. Due to this effect, weather stations which are located in areas which have seen some urbanization may show artificial warming trends, due to Urbanization Bias.

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Urbanization Bias

Bias introduced to weather station records because of urbanization of the surrounding area. The bias is usually a warming bias, due to the Urban Heat Island effect.

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Weather

Weather refers to the state of the atmosphere at a given time and place, in terms of sunlight/cloud cover, wind (speed & direction), types of precipitation (rain, sleet, snow, fog, mist, etc), humidity, pressure and, finally, temperature. See also Climate.

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