I challenge you to find a scientistic who is concerned with the issue who refutes this logic. In fact, this is a major part of the great debate. The fact that we can't know if this is merely a period of climatic fluctuation as is normal with Astral bodies in the solar system, or whether the cause is something more sinister such as the burning of fossil fuels is what constitutes the largest portion of the entire debate. I think we've got some more studying to do before we jump to conclusions .. like perhaps several generations worth.
Another way to put it: If, in 40 years, the average temperature of Earth plummetted over 40 degrees, wouldn't that leave the global warming conspiracists feeling a little confused? This is why time spent researching is critical.