This isn't climate science, we could see the economic effect immediately. That is simple enough for most people to draw a connection. I think the problem is more that some people want to hurt the US IT industry for political gain.
I disagree on how 'soon' the effect can be 'seen.' Any adverse effects would be rhetoric'd away by those in power at the moment. Their supporters would not 'see' (or if they did, acknowledge) any bad effects, and those in power would likely find another scapegoat. It's only after they are out that their supporters might (but no guarantees..) understand what happened. There will always be folks who can see through the bullshit, I wasn't referring to those good people in my original comment.
You mean quickly as in the global temperature warming from roughly 1.53 degrees Fahrenheit (0.85 degrees Celsius) from 1880 to 2012?