The phrase "actual forcings" refers to the real factors or influences that cause a certain event or outcome to happen. It represents the true reasons or causes behind a situation. Full definition
Researchers can thereby calculate an optimal force - velocity profile for an athlete, as well as their current actual force - velocity profile. (strengthandconditioningresearch.com)
I think that Scenario B is close enough to observed emissions that, in the absence of NASA being able or willing to re-run the actual 1988 model with actual forcings, one can be reasonably use Scenario B for comparisons. (climateaudit.org)
Update Note: People have inquired about actual forcing in these terms. (climateaudit.org)