Documentation

This page contains the documentation for the TYN CY 3.0 data-set, and comprises:

Data

  • A graphic for each country - see the graphics table.
  • A summary of the possible climate changes by the end of the 21st century, broken down by country and climate variable. See the country table. (Each individual file contains all the scenarios, for all seasons, for a particular country and climate variable.)
  • A summary of the possible climate changes by the end of the 21st century, broken down by climate variable and scenario. See the scenario table. (Each individual file contains all the countries, for all seasons, for a particular scenario and climate variable.)
  • A set of scalers to apply to the changes for the 2080s, to obtain changes for any given period in the 21st century.

Updates

4th August 2003
The reference for this data-set has been updated to: Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme,M., New, M., 2003: A comprehensive set of high-resolution grids of monthly climate for Europe and the globe: the observed record (1901-2000) and 16 scenarios (2001-2100). Journal of Climate: submitted.

9th May 2003
The second part of the TYN CY 3.0 data-set was released. There are now data files representing changes in climate over the course of the 21st century.

10th February 2003
The first part of the TYN CY 3.0 data-set was released, comprising (for each country) a graphic displaying the climate changes over the course of the 21st century.

Introduction
The data set described here provides a summary of some of the possible changes in climate that may be experienced during the 21st century in 289 countries and territories.

  • There are five climate variables included.
  • Information is provided for the year,all 12 calendar months, and four seasons.
  • Four state-of-the-art climate models are included: CGCM2, CSIRO2, PCM, HadCM3. (See Models.)
  • Four emissions scenarios are included: A1FI, A2, B2, B1 from the IPCC SRES scenarios (see IPCC or IPCC-DDC websites).
The 16 combinations of climate model and emission scenario included here covers 93% of the possible range of global climate change envisaged in the Third Assessment Report (TAR) of the IPCC.

Guidance

The purposes for which this data-set are relevant differ from the purposes of the observed data-set (TYN CY 1.0). The primary purpose here is to permit an assessment to be made of the plausible extent of climate change over the 21st century, driven by anthropogenic emissions of greenhouse gases and sulphur dioxide. It is reasonable to do this at the spatial scale of individual countries because the spatial scales at which climate change may occur (as measured here) are much larger than the spatial scales of the climate itself (as measured in the observed data-set.)

However, a number of caveats should be noted.

  • The climate models shown here do not explicitly recognise the smaller countries within their grids.
  • Since climate changes may depend on elevation, not just latitude and longitude, these models (which only represent elevation on scales of hundreds of kilometres) may misrepresent climate changes in smaller countries at high elevations.
  • Where a country includes a number of different climatic regions (i.e. regions in which climate varies coherently), it is possible that the models may represent the changes accurately in each region, but that the average change over the country as a whole may not be physically meaningful.

All users of this data-set ought to reflect upon a number of limitations to this data-set:
  • Although a variety of climate models are included (four), this sample does not include all conceivable representations of the climate system.
  • We use four different representations of what may happen to human emissions in the 21st century - the A1FI, A2, B2, B1 SRES scenarios. Obviously, the number of possible futures is infinite, and these four scenarios ought to be viewed only as a reasonable illustration of that range.
  • We only provide the 30-year mean changes for the period 2070-99, and changes in variability (whether natural or induced by humans) on shorter time-scales may be equally or more important.

Data Manipulation
The different forms in which the data are available are specified at the top of this page. The data is all given in the form of anomalies in the 2080s (2071-2100), compared to 1961-90. This data may be modified by the user as follows:

  • To obtain changes (relative to 1961-90) for a period other than the 2080s (2071-2100), use the scalers. Identify the correct column, which depends on the model (GCM) and emissions scenario (SRES) in the scenario you have chosen. Average together all the values in that column for the period in which you are interested. Then multiply the 2080s change by this average to obtain the change for your chosen period.
  • To obtain absolute values (rather than changes), add the observed 1961-90 mean to the climate change. Please bear in mind that the 1961-90 information is based on observations, and the changes for 2071-2100 are based on models. Therefore it is entirely possible that by combining the two you will produce physically impossible values (e.g. negative precipitation). In such cases, the simplest remedy is to limit the acceptable range of values to the range of the physically possible. So if, for example, you obtain a precipitation total of -10mm in the 2080s, alter this total to 0mm.
  • To obtain minimum or maximum temperature, divide the diurnal temperature range by two and subtract or add it to the mean temperature.
Ownership
The creator of this data set (Dr. T. D. Mitchell) retains full ownership rights over it. The data set may be freely used for non-commerical scientific and educational purposes, provided it is described as TYN CY 3.0 and attributed to:

Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme,M., New, M., 2003: A comprehensive set of high-resolution grids of monthly climate for Europe and the globe: the observed record (1901-2000) and 16 scenarios (2001-2100). Journal of Climate: submitted.

Disclaimer
The author bears no responsibility for the accuracy of the data set. The countries listed below include a variety of sovereign states, dependent territories, and disputed territories. No political statement is being made by the inclusion or exclusion of a particular territory, or by the labelling of a particular territory by a particular name.

Data Processing
This data-set is based on the TYN SC 2.0 0.5 degree gridded data-set. For details of the construction of the grids, refer to the TYN SC 2.0 documentation. We used the allocation of grid cells to individual countries developed for the observed data (see below) to aggregate grid cells into countries.

The method of allocating countries was as follows. We assigned each box to a single country. For each country we calculated the weighted mean of the values from its constituent grid boxes for each month in turn. Each grid box was weighted by surface area, using the cosine of the latitude. For further information see the paper published in Area (electronic version here).

Models
The four climate models used here are the set of models used by the IPCC (2001) in the Third Assessment Working Group 1 Report. Further details about the individual models may be obtained from that report (Tables 8.1 and 9.1).


model short IPCC number
CGCM2 CCCma 7
CSIRO mk 2 CSIRO2 10
DOE PCM PCM 30
HadCM3 UKMO 23