The Atmosphere and Climate Modeling - Introduction to Carbon Capture and Sequestration - page 84

Pinatubo

Santa Maria

Agung

El Chichon

Figure 2.5.6 Temperatures on an earth without anthropogenic greenhouse gas
emissions
Comparison between global mean surface temperature anomalies (°C) from observa-
tions and climate model simulations without anthropogenic CO 2 emissions. The black
line represents experimental data. The thin blue lines are the results of 19 simulations
produced by 5 models with only natural forcings. The thick blue line is the average of
these 19 simulations. The thin vertical lines indicate volcanic events. Figure from IPCC,
reproduced with permission [2.2].

Future emissions

Future climate predictions are predicated on models for how humans
behave. In Box 2.5.1 various scenarios of human behavior are discussed
[2.13]. Figure 2.5.7 shows the predictions of the average surface tem-
perature for each of the scenarios described in Box 2.5.1 [2.2]. All sce-
narios give a signifi cant increase in global surface temperature. The
orange line describes a scenario in which the concentration of green-
house gasses is frozen at the 2000 level. Even in this case, the next two
decades will still show a warming trend. The reason for the delay
between the changes in the greenhouse gas emissions (e.g., ceasing all
CO 2 emissions) and changes in climate is the “lag time” owing to the
response of the oceans to changes in CO 2 levels. Similar predictions
have been made for the amount of sea ice ( Figure 2.5.8 ) or sea levels
( Figure 2.5.9 ) [2.2]. The other important effect of climate change is the
occurrence of more extreme weather patterns. In Figure 2.5.10 , the