### Temperature

#### Indicators:

Global surface temperature change (since the pre-industrial age) Oceanic temperature change (since the pre-industrial age) Annual mean temperature Change of annual temperature (relative to 1990) | Temperature change since 1990 (monthly) Rate of temperature change Rate of temperature change (monthly)

The indicators presented in this box show the temperature changes as calculated in IMAGE 2.4 in different ways. The global-mean temperature change is calculated in the Upwelling-Diffusion Climate Model (UDCM). This information is scaled in the Geographical Pattern Scaling (GPS) to determine the local temperature changes, important for several natural processes such as growth and migration.

| #### Global surface temperature change (since the pre-industrial age)
| unit: oC (degrees Celcius) dimension: None

The global surface temperature change since pre-industrial times (1765) is calculated in the upwelling-diffusion climate model (UDCM). In the UDCM four boxes are distinguished: land in northern and southern Hemisphere and ocean in northern and southern hemisphere. The temperature change of each of these boxes is based on the heat-absorbing capacity of the 40 oceanic layers. This heat-absorbing capacity is modelled for each oceanic box with an upwelling-diffusion energy-balance model. Therefore, each box has a different profile of temperature change. The global surface temperature is calculated as a weighted mean of the four boxes. The weights depend on the area within each box.

| #### Oceanic temperature change (since the pre-industrial age)
| unit: oC (degrees Celcius) dimension: None

The global oceanic temperature change since pre-industrial times (1765) is calculated in the upwelling-diffusion climate model (UDCM). In the upwelling-diffusion energy-balance model of UDCM the ocean is divided in 40 layers to compute the distribution of heat between the mixed layer and the bottom layer of the ocean. Initially, the temperature in the oceanic mixed-layer is assumed 17.2oC and in the bottom layer 1oC. With a vertical diffusivity of 3155.76 m2 per year and an initial upwelling rate of 4 m per year, the temperature change of each oceanic layer is calculated. To take the decline of the thermohaline circulation into account, part (30%) of the upwelling rate decreases in a linear fashion with the increasing oceanic mixed-layer (surface layer) temperature.

The temperature change patterns differ considerably between the various GCMs. On the main disc the default pattern is from HADCM2.

| #### Annual mean temperature
| unit: oC (degrees Celcius) dimension: None

This map presents the annual mean temperature. The global surface temperature change is scaled using a GCM and added to the observed temperature for the climatic normal period of 1961-1990, taken from the gridded climatology database.

The temperature change patterns differ considerably between the various GCMs. On the main disc the default pattern is from HADCM2.

| #### Change of annual temperature (relative to 1990)
| unit: oC (degrees Celcius) dimension: None

The global surface temperature change is scaled using a GCM. This view presents the temperature change relative to observed temperature for the climatic normal period of 1961-1990, taken from the gridded climatology database.

The temperature change patterns differ considerably between the various GCMs. On the main disc the default pattern is from HADCM2.

| #### Temperature change since 1990 (monthly)
| unit: oC (degrees Celcius) dimension: month, landcover type, latitudinal band

The distribution of landcover types is spatially heteregeneous. This indicator shows the monthly temperature change since 1990, with optional views for 6 different latitudinal bands (90oN-60oN, 60oN-30oN, 30oN-0o, 0o-30oS, 30oS-60oS and 60oS-90oS) and the 19 different land-cover types of IMAGE 2.4. With the Time Manager, the temperature change over the period 1990 to 2100 can be analyzed.

The temperature change patterns differ considerably between the various GCMs. On the main disc the default pattern is from HADCM2.

| #### Rate of temperature change
| unit: oC/decade (degrees Celcius per decade) dimension: None

Apart from the absolute temperature and the temperature change, the rate of temperature change is very important. At high rates of temperature change, sensitive ecosystems may not be able to adapt. The Dutch Ministry of Housing, Spatial Planning and the Environment has formulated a long-term climate target for global temperature increase of 0.1oC per decade. For comparison: the observed global rate of temperature increase was 0.15oC per decade between 1910 and 1945 per decade and 0.2o C per decade between 1976 and 1995.

The rate of temperature change already differs in 2000 for the high and low climate sensitivity runs, caused by different initializations from 1765.

| #### Rate of temperature change (monthly)
| unit: oC/decade (degrees Celcius per decade) dimension: Month, landcover type, latitudinal band

Apart from the absolute temperature and the temperature change, the rate of temperature change is very important. At high rates of temperature change, sensitive ecosystems may not be able to adapt. This view presents the rate of temperature change per decade for each month and for the different landcover types, occurring at the specified latitudinal bands (90oN-60oN, 60oN-30oN, 30oN-0o, 0o-30oS, 30oS-60oS and 60oS-90oS).

The rate of temperature change already differs in 2000 for the high and low climate sensitivity runs, caused by different initializations from 1765.