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Climate risk glossary

The glossary helps novices to learn a bit about weather and climate.

But also the experienced researcher can find out how CRA looks on the climate risk science and what definitions CRA adopts. So we both speak a common language.

The glossary is updated and enlarged frequently.

   
Atmosphere The envelope of gases surrounding the Earth.
Biosphere The part of the Earth and its atmosphere where life can exist.
Climate
Long-term weather.

The World Meteorological Society defines "long" as taking 30 years or longer.

"Climate" refers to the long-term average (trend) and also to the size of the variations around the trend (climate variability).

Modern views consider not only the long-term state of the atmosphere, but also those of the hydrosphere, cryosphere and biosphere.

Climate archive Contains information about past climate changes. Examples: stalagmites, corals, ice cores and sediment cores.
Climate change Changes of the mean state and/or changes of the variability of climate variables. Causes of climatic changes are natural as well as human.
Climate risk
Risk that variables in the climate/weather system reach values that affect human life adversely.

This relates to extreme values of the climate or weather variables: high wind speed (storm), high river water stages (flood), low water stages (drought), and so forth.

This general, "anthropocentric" definition can, of course, be adapted to satisfy the needs of specific groups: companies interested more in economic values, a home owner wishing to protect his or her home against flood risk, or conservationists wishing for an ecosystem to survive without species losses.

The crucial point is that when climate changes, climate risk can change. Acquiring knowledge about climate risks is the first step toward managing it, reducing it, or living with it. This knowledge is acquired by means of climate risk analysis.

Climate risk analysis
In risk analysis of climate or weather data, the objective is to quantify the climate risk.

Climate risk analysis includes data selection and generation, adaptation of risk analysis methods and the interpretation of the results.

Climate risk analysis is the initial step in managing the risk, and in making decisions in what can be a challenging situation.

Coral Corals often grow in bands, from which we can extract time information by taking a core sample. The oxygen or carbon isotopic levels provide indirect ("proxy") evidence about changes in temperature and precipitation.

Corals are climate archives, containing information on local to regional space scales and short-term timescales.

Cryosphere Water on Earth in its frozen form, including floating ice, glaciers and polar ice caps.
Documentary data Observations of weather made by humans and preserved in written records (pamphlets, notes, handwritten documents, etc.).

Such data can provide significant time and space details. Its reading often requires methods of historical text interpretation.

Drought Dry weather over an extended period of time.

A well known example, the Dust Bowl, affected large areas of the Great Plains in central USA through the 1930s, and led to the migration of approximately 2.5 million people.

Flood A rising body of water that leads to its natural or artificial confines to be exceeded.

As an example, the river Elbe/Labe, which flows from the Czech Republic to Germany, flooded in August 2002, resulting in 36 casualties, and approximately 15 billion USD in property damages.

Ice core The ice on Greenland, Antarctica and elsewhere, accumulates with time, with young ice on the top of a core sample, and old ice on the bottom. This gives time information on short-term to long-term scales.

Much information can be extracted from the ice. For example, water isotopes inform indirectly about temperature changes. Sulfate records tell about volcanic activity on global or hemispheric scales.

Air bubbles contained in the ice archive are important. They supply us with the most accurate carbon dioxide data on Late Pleistocene timescales (the past 800 thousand years).

Hydrosphere Water on Earth in its liquid form, such as oceans and lakes.
Risk
Probability (number between 0 and 1) that event with adverse effects occurs.

Other definitions exist, but this one has the highest relevance for the practitioner.

Risk analysis
In a narrow sense, statistical sub-discipline that estimates the risk, using mathematical models and data.

In a wider sense, risk analysis includes the identification of potential sources of risk and a strategy of how to obtain accurate information (data) about these sources.

Sediment core The floor of lakes or oceans accumulates in layers, with young sediment on top, and old sediment on the bottom. A core sample of those sediments bears time information on short and long scales.

Much information can be extracted from a sediment core. In addition to examining chemical elements or isotopes, one may count the pollens in this climate archive to determine past changes in local vegetation.

Stalagmite Carbonate precipitate that develops upwards from the floor of a cave. An important archive containing high-resolution information about changes in past temperatures and rainfall.
Statistics
Mathematical technique to extract information from a sample of data.

In climate sciences, the aim is to learn about the climate processes. This allows, for example, prediction and the management of climate risk.

Storm High wind speed, above some defined threshold.

Hurricanes are tropical storms in the West Indies (North Atlantic) region. An example is Hurricane Katrina, which struck the U.S. Gulf Coast in August 2005 and led to nearly 2000 casualties, and approximately 90 billion USD property damages.

Time series A data sample taken at successive time points. The Dow Jones Industrial Average index is an example of time series data. Another example, this one related to climatology, is the global-average surface-air temperature over the past millennium.
Time series analysis Mathematical technique to extract information from a time series. A sub-field of statistics.

Time series analysis is used when estimating time-trends in climate risk.

Weather
Describes the state of the atmosphere. The major weather variables are temperature and precipitation.

"Weather" refers to the short-term average (trend) and also to the size of the variations around the trend (weather variability).

"Short-term" means usually variations taking place over a period of 30 years or less.