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Environmental Data and Scenarios

Welcome to the Environmental Data Section of the Data Distribution Centre (DDC) of the Intergovernmental Panel on Climate Change (IPCC). Acknowledging that changes in environmental conditions other than climate may need to be considered when conducting climate change impact and vulnerability assessments, the Environmental Data pages of the DDC provide access to baseline and scenario data for a range of non-climate conditions in the atmospheric, aquatic and terrestrial environments. These include data on atmospheric composition (e.g. carbon dioxide, ozone), land use and land cover, sea level, and water availability and quality. Most projections are consistent with the driving factors and emissions presented in the Special Report on Emissions Scenarios (SRES).

Explanations and illustrations of procedures for incorporating this information in impact and vulnerability assessments can be found on the DDC Guidelines pages. Data for other environmental variables will be added in due course.

Scenario data for the atmospheric environment

Carbon Dioxide

A number of gases and other atmospheric constituents may have important effects on the exposure unit. Perhaps the most important of these is carbon dioxide. CO2 is well mixed in the atmosphere, so observations of concentrations from a single site are adequate for most impact applications.

CO2 concentration is commonly required as a direct input to models of plant growth, since it can affect both the growth and water use of many plants. Since it is also a major greenhouse gas associated with global climate change, the CO2 concentration adopted should be consistent with concentrations during the climatological baseline period.

Conventionally, the baseline CO2 concentration is assumed fixed at a given level. This might be the reference concentration in which plants have been grown in CO2-enrichment experiments. Alternatively, it might be the default value assumed in an impact model, usually a value representative of the late 20th century. However, a word of caution is necessary when testing impact models for conditions over a 30-year or longer baseline period. CO2 concentrations have increased rapidly during the 20th century, and if the exposure unit is responsive to CO2, this temporal trend should be accounted for.

Further information and data relating to CO2 is available here.

Tropospheric ozone:

Another gas of importance in some impact studies is tropospheric ozone. This is toxic for a wide range of living organisms, its concentrations being highly variable in space and time, registering its highest concentrations over industrial regions under certain weather conditions. Time series of ozone concentrations are available for some regions, especially in developed countries. They are usually expressed in terms of background concentrations and peak concentrations. Global model estimates of ozone abundance and gridded model results are available from the DDC.

Stratospheric ozone:

Concentrations of stratospheric ozone have been measured operationally at many high latitude sites in recent years, especially following the discovery of the seasonal "ozone hole" over Antarctica in 1985. Ozone depletion is associated with increased ultraviolet radiation, which can be harmful for life on earth. Daily forecasts of exposure risk to UV-radiation are issued in many countries at mid to high latitudes, especially during the spring and early summer when levels of stratospheric ozone are generally at a minimum.

Sulphur and nitrogen compounds:

Concentrations of sulphur and nitrogen compounds, which are both major contributors to acid precipitation in many parts of the world, are also measured in some regions. Furthermore, it has been estimated that sulphate aerosol concentrations in industrial regions have contributed a cooling effect on climate in some regions in past decades, which has counteracted the warming effect of greenhouse gases.

Smoke and particulates:

Smoke and other particulate matter in the atmosphere, bi-products of fossil fuel burning, land clearance or other human activities, can have important regional impacts on visibility and human health. These are increasingly being observed using satellites as well as ground based instruments.

Sea level:

One of the key factors to evaluate for many impact studies in low lying coastal regions is the current level of the sea relative to the land. Globally, eustatic sea level (the volume of water in the oceans) appears to have been rising during the past century. However, there are large regional deviations in relative sea level from this global trend due to local land movements. Subsidence, due to tectonic movements, sedimentation, or human extraction of groundwater or oil, enhances relative sea-level rise. Uplift, due to post glacial isostatic rebound or tectonic processes, reduces or reverses sealevel rise. The main source of information on relative sea level is tide gauge records, and the major global data source is the Permanent Service for Mean Sea Level.

As a reference, most studies of vulnerability to sea-level rise use the mean sea-level at a single date. For instance, studies employing the IPCC Common Methodology use the level in 1990. However, to assess coastal vulnerability to sea-level effects, baseline tide gauge and wave height observations are required. These reflect tidal variations in combination with the effects of weather such as severe storms and atmospheric pressure variations.

Inland water levels:

The levels of lakes, rivers and groundwater also vary with time, usually for reasons related to the natural balance between water inflow (due to precipitation and runoff) and losses (due to evaporation and seepage). Human intervention can also affect water levels, through flow regulation and impoundment, land use changes, water abstraction and effluent return and large scale river diversions. Sometimes these fluctuations in levels can be very large (often much larger than mean changes anticipated in the future). Thus, where time series are available, it is important to be able to identify the likely causes of fluctuations (i.e. natural or anthropogenic), as this information could influence the selection of an appropriate baseline period.

Scenario data the terrestrial environment (land use and land cover - SRES)

Land cover and land use:

On land, data on land cover and land use change are of great importance in many impact studies. Geographical data and time series have been compiled by a number of research groups working at national, continental and global scale, based on satellite imagery, aerial photographs and ground survey. Many datasets have been collected as part of a major international research effort - the Land Use and Land Cover Change Programme (LUCC) of the International Geosphere Biosphere Programme (IGBP) and International Human Dimensions Programme on Global Environmental Change (IHDP). For instance, a global integrated model, IMAGE 2, has been used to study the dynamics of land use change. The model was initialised using baseline land use data from 1970. A continually updated time series of observed global land use up to the 1990s can then be used to test the model's predictions during the period after 1970. National land cover/land use statistics have also been tabulated by the IPCC and are available from the DDC.


Baseline information is also commonly required on the state of the soil where this has been changing over time, for example, nutrient status, pH and salinity. Data sources for this information tend to be national or regional in scope.

Agricultural practices:

In agriculture, data on farm management practices are of vital importance in describing the reference conditions. This covers, for instance, fertilizer applications, use of pesticides and herbicides, tillage practices, stocking rates and irrigation. Baseline information on these is important, not only because they have been responsible for dramatic increases in productivity in many regions in recent decades, but also because they have contributed to soil erosion or pollution of soils, surface waters and groundwater in many regions. Data for different countries are collected annually by the United Nations Food and Agriculture Organization.


There has been considerable concern in recent years about the endangerment and loss of natural species, mainly attributable to human activities. There have been a number of national and international initiatives to document and catalogue biodiversity, and baseline statistics representative of the 1990s have been compiled for each country by the World Conservation Monitoring Centre, were published for an IPCC report on Regional Impacts of Climate Change (available from this page).


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Content last modified: 18 June 2013