Model Projections of Future Global Warming

According to IPCC 2007:

“For the next two decades, a warming of about 0.2°C per decade is projected for a range of … scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected.”

Projected temperatures up to the year 2099

The IPCC scientists modelled the probable effects on the Global Mean Temperature of six possible alternative scenarios of future global economic activity (discussed in the “Special Report on Emissions Scenarios”, 2000 ).

In the best-case scenario (scenario B1) the likely range of temperature increase is between 1.1 to 2.9 degrees Celsius. In the worst-case scenario (scenario A1F1), average temperature rises to between 2.4 Celsius and 6.4 Celsius (see Table 1).

Table 1: Projected global average surface warming at the end of the 21st century for six different emission scenarios
(Source: IPCC 2007 b  p.13.)  

SRES Scenario*

Temperature Change (oC ) **

Temperature Change (oC ) **





Best estimate

Likely range

Constant, continuing, Year 2000 atmospheric concentrations


0.3 – 0.9

A1T scenario 


1.4 – 3.8

A1B scenario 


1.7 – 4.4

A2 scenario 


2.0 -  5.4

A1F1 scenario


2.4 – 6.4

B1 scenario 


1.1 – 2.9

B2 scenario 


1.4 – 3.8


Notes  for this Table:
 *  SRES refers to the scenarios described in the IPCC Special Report on Emissions Scenarios (SRES, 2000).
 ** Temperature changes are estimated as the difference between the projected Global Mean Temperature in 2090-2099 and the Global Mean Temperature that was measured in 1980-1999