"It would seem to me that if global warming were the trend, the trend would be observable over a period of a decade, when the instruments for measuring that trend had steadily improved, and world wide science was focused on the issue of worldwide climate change (as it was on cooling from the 1950s through the 1970s)."

It has nothing to do with the ability to measure. Its the level of signal to noise in the system itself.

But as I've linked before the trend for the past decade is in fact positive.

Now, we are getting to the point where we can measure total energy content which should show far less variation than surface temperatures. These measurements show its still warming.