I too think comparing Chris past predictions with his great mega projects studies, plus a comparison of predicted new projects vs. delays, would be very useful in calculating a current world decline rate. Roughly, if Chris has been expecting 1Mb/d more each year, and if we are actually flat/down a bit, then his number for world decline (4.5%?) should be adjusted upward, say to 5.5% or so. Unfortunately, it looks like the rate is accelerating...

Why don't you take a stab at it?

That's a good idea, looking at Figure 8 it looks like the decline rate should be more around 7-10%.