Using simulation and modeling techniques, CLIMEX predicts the effect of climate change on species distribution. CLIMEX attempts to mimic the biological mechanisms that limit species' geographical distribution and determine their seasonal phenology and relative abundance.

Case Study: GM Crop

Future distribution patterns for species: Prediction of the naturalisation potential and weediness risk of transgenic cotton in Australia

CLIMEX 3.0.2


CLIMEX helps you understand the impact of climate change on species distribution and the potential risk from invasive species to an agricultural region.

CLIMEX enables you to assess the risk of a pest establishing in a new location and the potential success or failure of a biological control agent with no knowledge of the species, except for knowing the current locations they do occur.

In almost forty countries around the world, Climex is used to model, predict and help control invasive insects. Insect infestation destroys billions of dollars worth of commercial crops annually and monitoring and controlling invasive insects in a warming world is increasingly important.

The CLIMEX software contains two quite different climate-matching tools. There is the CLIMEX model (referred to as 'CLIMEX' or as the 'CLIMEX model'), and the CLIMEX 'Match Climates' function. The latter is a tool for comparing the meteorological data of different places without reference to any particular species.

The CLIMEX simulation model was first described by Sutherst and Maywald (1985) and a number of enhancements and further caveats and insights into using the model have been described in a series of publications listed at the end of the user manual, particularly (Sutherst et al 1995, Sutherst 1998). The model is based on the assumption that if you know where a species lives you can infer what climatic conditions it can tolerate. In other words, CLIMEX attempts to mimic the mechanisms that limit species' geographical distributions and determine their seasonal phenology and to a lesser extent their relative abundance.

CLIMEX enables the user to estimate the potential geographical distribution and seasonal abundance of a species in relation to climate. It does not try to match the patterns of climate and species' distribution in the same way that a statistical fitting would seek to achieve.

CLIMEX is applied to a species by selecting values for a set of parameters that describe its response to temperature, moisture and light. The term 'population' is used as the target entity, representing an average population of an animal or plant species or biotype for example. An Annual Growth Index (GIA) describes the potential for growth of a population during the favourable season. Four stress indices (Cold, Hot, Wet and Dry), and in some cases their interactions, describe the extent to which the population is reduced during the unfavourable season. The Growth and Stress Indices are combined into an Ecoclimatic Index (EI), to give an overall measure of favourableness of the location or year for permanent occupation by the target species. Two limiting conditions, ie the length of the growing season and obligate diapause, act as overall constraints to the EI value where relevant. Results are presented as tables, graphs, or maps.

A species' climatic requirements are inferred from its known geographical distribution (either in its native range or in another region where it has been established for a long time), relative abundance and seasonal phenology. Some laboratory data, such as developmental threshold temperatures, can be used to fit or fine tune CLIMEX parameter values. Initial estimates of parameter values are fine-tuned by comparing the indices with the known presence or absence, seasonal phenology and, preferably, relative abundance of the species in each location.

Once the parameter values have been estimated and where possible validated against independent data, CLIMEX can be used to make predictions for other, independent locations. Independent data means that there is no connection between the data and those data used for fitting the model, hence it is not appropriate to sub-sample a geographical distribution and then use the remaining data to test the model.

CLIMEX helps you understand the impact of climate on species distribution using the following features:

  • MS Windows Interface
    Users are able to display several maps, graphs and tables simultaneously as well as having the option of including one or two species in a run. This package includes the MetManager and MapManager modules that facilitate the manipulation of meteorological data and customisation of maps. CLIMEX offers graphical capabilities, drop-down menus, easy-to-use dialog boxes and a detailed online Help system.

  • Climate/Irrigation Scenarios
    CLIMEX allows users to consider the potential implications of climate change or of irrigation on the abundance and distribution of species. The 'Greenhouse' option simulates the impact of different temperature and rainfall conditions, and the 'Irrigation' option allows users to apply a given amount of water per week. With either option, different scenarios can be applied in summer and winter months.

  • Maps/Graphs/Tables
    CLIMEX contains tools for customising maps and for manipulating meteorological data. MapManager allows editing, selection and customisation of map displays, whilst MetManager allows extra meteorological data to be reformatted into the CLIMEX format and added to the database, and subsets of data to be created.

  • User's Guide & Help System and Tutorials
    CLIMEX comes with an extensive User's Guide that explains the theory behind CLIMEX, its algorithms and parameter setting procedures. CLIMEX also comes with an Online Help system and 50 pages of tutorials and answers that act as a 'Teachers Resource'.

  • CLIMEX Meteorological Database
    CLIMEX is shipped with a database of records from about 2400 meteorological stations worldwide. It needs monthly long term average maximum and minimum temperatures, rainfall, and relative humidity. The Metmanager allows the user to edit lists of stations into subsets, and to add new data for specific locations of interest. It also allows the use of grid-based data so long as it conforms to the CLIMEX format with space delimited data.

New Features

The following list includes the major differences between Version 2 and Version 3. In addition, a large number of minor improvements have been made to the program.

  • Two species can now be fitted with interactions between them (either competition or synergy) specified via parameters. 

  • Radiation is available as an additional component to the Growth Index.

  • Two non-specific components (definable by the user) can be added to the Growth Index. These are the Physical Substrate Index and the Biotic Substrate Index. The variables determining these indices can either be specified as a single value for all locations or they can be location specific and read from the MetManager.

  • Automatic fitting of the parameter values that determine the Stress indices is available via a genetic algorithm based fitting routine.

  • “Regional matching” (i.e, the use of a set of locations for the ‘Home’ location in the Match Climates function) is available.

  • The MetManager application has been extended to allow the importation of up to 5 user-defined location constants as well as up to 5 user-defined variables.

Enhancements from version 1

CLIMEX has been considerably enhanced from Version 1.1. For users familiar with Version 1.1, the following list details the major differences. Those changes that may cause models to behave differently when moved to Version 2 are shown in italics.

  • CLIMEX is now a DYMEX application. This has meant a radical change to the user interface and operation of the program which will require some relearning by users of CLIMEX V1.1. However, it has also allowed CLIMEX to use the very flexible display facilities provided by DYMEX. In particular, map capabilities are now much more powerful, with zoom and pan support. In addition, maps are constructed from standard shape files, many of which are available from various internet sites. A new MapManager allows map region files to be defined visually. Many map projections have been provided. Map printing has been enhanced and a Print Preview function provided.

  • The same flexibility is also now available for Tables and Charts, which can be configured in a multitude of ways, and the configurations can be saved and reused in subsequent runs. Results can be saved as Microsoft Access® database tables. Charts and maps can be exported in raster (Windows bitmap, bmp or jpg) or vector (Windows enhanced metafile, emf) form.

  • The new MetManager program is a Microsoft Access application and overcomes the data importing problems that users commonly had with the previous version. It is easy to create multiple databases of meteorological data and Location Selections from them. Data can still be imported with the .loc/.met format, as well as from .bmt files or Access files. A 0.5º world grid of meteorological data is included for those tasks where the standard database is not sufficient. Acknowledgement should be given to the Climatic Research Unit (CRU), Norwich ( when the data is used. A reformatted 0.1° grid is available for non-commercial applications by courtesy of the CRU Norwich ( and users are required to agree to comply with CRU restrictions. 

  • Soil Moisture and Average Temperature have been added as variables that can be included in the Match Index for Match Climates.

  • Species Parameters are now stored in a separate file for each species (with the extension .cxp). The comments related to a species are stored in its parameter file. A conversion utility (cxdxconvert.exe) is provided to convert species and comment files from the Version 1 format to Version 2.

  • The degree-day dependent Cold Stress uses degree-days based on a new threshold parameter (DVCS) rather than DV0. Note, however, that the default value of DVCS is the same as DV0. The new flexibility allows the users to use thresholds other than DV0.

  • A third component has been added to the Cold Stress. This component acts in the same way as the component based on minimum temperature, but uses average temperature instead of the minimum. It is useful when comparing responses to climates with different diurnal ranges of temperature.

  • The Interaction Stresses now include the time since the stress began as part of the calculation (as is done for all other Stress Indices). When such parameter files are converted using the conversion utility, the new parameter file will contain an indicator that directs CLIMEX to use the old Interaction Stress method. These species should preferably be refitted to use the new method.

  • The differences in the Ecoclimatic Index (EI) can be plotted on a map after two sequential runs using the same locations. Thus users can quickly appreciate the changes that would result from, for example, the application of a Climate Change Scenario or a change in a parameter value.


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