The statement is often made that (e.g. see; Comment #3)
“Because of lags in the climate system, the climate of the next few decades has already been determined by prior emissions. Emissions reductions currently being discussed will therefore have an effect primarily on the climate in the 2nd half of the 21st century.”
This perspective is used to conclude that the radiative effect of anthropogenic CO2 is a particularly pernicious influence on the environment, which is much greater then due any of the other climate forcings.
However, this view, in the context of climate science, fails to recognize that a variety of diverse climate forcings have very significant long term influences on the climate.
The reason for the focus on the radiative effect of added CO2 is associated with the emphasis of climate assessments on the atmospheric portion of the climate system. However, as clearly described in the 2005 National Research Council Report , the climate system also includes the oceans, land, and cryosphere, in addition to the atmosphere.
The claim that aerosols could be eliminated as a climate concern in the climate system in just a few weeks (through atmospheric cleansing if their emssion is halted), fails to recognize that the aerosols are just being transfered to a different component of the climate system, and their effects can last for decades and even longer!
Three examples of long term climate forcings, beyond the radiative forcing of anthropogenic caronf dioxide inputs, include:
nitogren deposition (e.g. see )
land use/land cover change (e.g. see )
black carbon deposition (e.g. see )
Each of these climate forcings persist with long term effects on all aspects of climate including weather patterns. The nearly exclusive focus on the climate forcing of the atmospheric component of the climate system (i.e. the radiative forcing of CO2) with respect to long term lags is scientifically flawed.
This also means that we can not treat the climate system different from weather in that both are sensitive to initial conditions (e.g. see
Pielke, R.A., 1998: Climate prediction as an initial value problem. Bull. Amer. Meteor. Soc., 79, 2743-2746.).