Course:Cons452/WorldClim

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WorldClim Global Climate Data

Description

World Clim is a series of global climate raster layers to be used in mapping and spatial modelling. It gives you monthly data on several climatic variables at a spatial scale that you can adjust to fit your research needs. In the first version, you can also access climate data from the past and into the future based on IPCC report's different GHG scenarios. WorldClim has 2 versions:

  • Version 1 has the following data for the period 1960-1990 (averaged across those years). Version 1 also has data for the past and the future, please see below.
    • min temperature (°C * 10)
    • max temperature (°C * 10)
    • average temperature (°C * 10)
    • precipitation (mm)
    • 19 bioclimatic variables (see below)
  • Version 2 has the following data for the period 1970-2000 (averaged across those years). Notice there are a couple more variables here than in the first version.
    • min temperature (°C * 10)
    • max temperature (°C * 10)
    • average temperature (°C * 10)
    • precipitation (mm)
    • 19 bioclimatic variables (see below)
    • solar radiation (kJ m-2 day-1)
    • wind speed (m s-1)
    • water vapour pressure (kPa)

The 19 "bioclimatic variables" are simply variables that have been derived from the monthly temperature and rainfall data that are more biologically/ecologically meaningful. For example, mean temperature of the wettest quarter, precipitation of driest month, and temperature seasonality are 3 of the 19 bioclimatic variables available for download in both versions. These variables have more direct ecological applications: the temperature seasonality variable would affect the agricultural crops that could be grown in that area. (Note: you can create these values yourself by using the 'biovars' function in the R package "dismo")

Some past and future climate datasets are available in Version 1 only. For the past, it is based on global climate simulation models. There is data for the Mid-Holocene (~6000 years ago) and the Last Glacial Maximum (~22,000 years ago). These could serve as historical baselines for you in your research. The future data is based on global climate model projections using the IPCC's 5th assessment report for four different potential scenarios of GHG emissions. Both datasets have the same variables available at the same resolutions as the current climate data in Version 1.

Metadata

Metadata Component Description
Theme World Climate Data
Source Robert J. Hijmans, Susan Cameron, and Juan Parra out of the University of California Berkeley (in collaboration with Peter Jones, Andrew Jarvis, and Karen Richardson)
Purpose to provide freely available global climate data to be used in GIS and ecological modelling
Time Frame Depending on the version, either 1960 - 1990 (Version 1) or 1970 - 2000 (Version 2). Version 1 has past, current, and future layers; while Version 2 currently only has the "current" layer available
File Type Spatial
File Format GeoTiff (.tif)
Structure Raster
Projection and coordinate system Geographic (Latitude/Longitude) - WGS 84
Extent Global
Resolution or scale You have the option to download the layers from a spatial res of 1 km (30 seconds) to 340 km (10 minutes)

Common Problems

  • Due to the low density of available climate stations overall (in contrast to the 1 km spatial resolution), the climate surfaces do not capture all of the variation that may occur at a resolution of 1 km, particularly of precipitation in mountainous areas.[1]
  • The temperature data are in °C * 10. This means that a value of 243 represents 24.3 °C. This does lead to some confusion, but it allows for much reduced file sizes which is important as for many downloading large files remains difficult. The unit for precipitation data is mm.[2]

Downloading Instructions

Go to the url: https://www.worldclim.org/

  1. Navigate on the page to which version you would like, Version 1 (at times called 1.4) or Version 2.0
  2. On the following page, navigate to the variable of your choice.
  3. You can download the variables for different spatial resolutions, from 30 seconds (~1 km2) to 10 minutes (~340 km2). Once you select a layer, it downloads as a .zip file that contains 12 .tif files, one for each month of the year. January = 1 December = 12.

Restrictions on Use

Version 1:

Creative Commons Attribution-ShareAlike 4.0 International License

Please see https://creativecommons.org/licenses/by/4.0/legalcode for full license terms but this essentially means that you are free to use, share, and adapt this data as long as you attribute it and indicate how you have manipulated or built upon the data (if you do so). If you adapt or remix this data, you must share your contributions under the same license as this one.

Version 2:

Free to use in your research for academic purposes, but remember to cite appropriately. You are not allowed to redistribute these data.

  1. Hijmans, Robert J.; Cameron, Susan E.; Parra, Juan L.; Jones, Peter G.; Jarvis, Andy (2005). "Very high resolution interpolated climate surfaces for global land areas". International Journal of Climatology. 25: 1965–1978.
  2. n.d. (n.d.). "Data Format". WorldClim - Global Climate Data. Retrieved December 16, 2019.