The kinder, gentler model from the Hadley Centre for Climate Prediction and Research in the United Kingdom estimated a wetter, warmer
future: Rainfall may increase 20 percent to 25 percent,
mean annual temperatures could increase 2 degrees Fahrenheit by 2030 and 4 degrees by 2100.
Global
mean annual temperature (GMAT) is the metric most commonly employed by the IPCC and adopted in the international policy arena to summarise
future changes in global climate and their likely impacts (see Chapter 19, Box 19.2).