Climate Change Glossary
Word Definitions Related to
Climate Change and Global Warming
Radiation
Energy transfer in the form of electromagnetic waves or particles that release energy when absorbed by an object. See ultraviolet radiation, infrared radiation, solar radiation, longwave radiation.
Radiative Forcing
Radiative forcing is the change in the net vertical irradiance (expressed in Watts per square metre: Wm-2) at the tropopause due to an internal change or a change in the external forcing of the climate system, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun. Usually radiative forcing is computed after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with all tropospheric properties held fixed at their unperturbed values. Radiative forcing is called instantaneous if no change in stratospheric temperature is accounted for. Practical problems with this definition, in particular with respect to radiative forcing associated with changes, by aerosols, of the precipitation formation by clouds, are discussed in Chapter 6 of the IPCC Third Assessment Report Working Group I: The Scientific Basis.
Radiative forcing scenario
A plausible representation of the future development of radiative forcing associated, for example, with changes in atmospheric composition or land-use change, or with external factors such as variations in solar activity. Radiative forcing scenarios can be used as input into simplified climate models to compute climate projections.
Radio-echosounding
The surface and bedrock, and hence the thickness, of a glacier can be mapped by radar; signals penetrating the ice are reflected at the lower boundary with rock (or water, for a floating glacier tongue).
Rapid climate change
The non-linearity of the climate system may lead to rapid climate change, sometimes called abrupt events or even surprises. Some such abrupt events may be imaginable, such as a dramatic reorganisation of the thermohaline circulation, rapid deglaciation, or massive melting of permafrost leading to fast changes in the carbon cycle. Others may be truly unexpected, as a consequence of a strong, rapidly changing, forcing of a non-linear system.
Recycling
Collecting and reprocessing a resource so it can be used again. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products.
Reforestation
Planting of forests on lands that have previously contained forests but that have been converted to some other use.
Regimes
Preferred patterns of climate variability.
Relative Sea Level (RSL)
Sea level measured by a tide gauge with respect to the land upon which it is situated. Mean Sea Level (MSL) is normally defined as the average Relative Sea Level over a period, such as a month or a year, long enough to average out transients such as waves.
Renewable energy
energy derived from the wind, the sun, the tides and other sources that, for all practical purposes, cannot be depleted (unlike fossil fuels, for example).
Reservoir
A component of the climate system, other than the atmosphere, which has the capacity to store, accumulate or release a substance of concern, e.g. carbon, a greenhouse gas or a precursor. Oceans, soils, and forests are examples of reservoirs of carbon. Pool is an equivalent term (note that the definition of pool often includes the atmosphere). The absolute quantity of substance of concerns, held within a reservoir at a specified time, is called the stock.
Residence Time
The average time spent in a reservoir by an individual atom or molecule. With respect to greenhouse gases, residence time usually refers to how long a particular molecule remains in the atmosphere. See atmospheric lifetime.
Respiration
The process whereby living organisms convert organic matter to CO2, releasing energy and consuming O2.
Response time
The response time or adjustment time is the time needed for the climate system or its components to re-equilibrate to a new state, following a forcing resultinsg from external and internal processes or feedbacks. It is very different for various components of the climate system. The response time of the troposphere is relatively short, from days to weeks, whereas the stratosphere comes into equilibrium on a time-scale of typically a few months. Due to their large heat capacity, the oceans have a much longer response time, typically decades, but up to centuries or millennia. The response time of the strongly coupled surface-troposphere system is, therefore, slow compared to that of the stratosphere, and mainly determined by the oceans. The biosphere may respond fast, e.g. to droughts, but also very slowly to imposed changes.
See: Lifetime, for a different definition of response time pertinent to the rate of processes affecting the concentration of trace gases.
Reuse
Reuse is using an item more than once. This includes conventional reuse where the item is used again for the same function, and new-life reuse where the item is used for a new function. In contrast, recycling is the breaking down of the used item into raw materials which are used to make new items.
Reuse can have financial and environmental benefits, either of which can be the main motivation for it. The financial motivation historically did, and in the developing world still does, lead to very high levels of reuse, but rising wages and consequent consumer demand for the convenience of disposable products made the reuse of low value items such as packaging uneconomic in richer countries, leading to the demise of many reuse schemes. Current environmental awareness is gradually changing attitudes and regulations, such as the new packaging regulations, are gradually beginning to reverse the situation.
