It doesn't preclude it by any means - those pesky scientists attribute that warming period to increased solar output and a reduction in volcanic activity.
"One of the most often cited arguments of those skeptical of global warming is that the Medieval Warm Period (800-1400 AD) was as warm as or warmer than today. Using this as proof to say that we cannot be causing current warming is a faulty notion based upon rhetoric rather than science. So what are the holes in this line of thinking?
Firstly, evidence suggests that the Medieval Warm Period may have been warmer than today in many parts of the globe such as in the North Atlantic. This warming thereby allowed Vikings to travel further north than had been previously possible because of reductions in sea ice and land ice in the Arctic. However, evidence also suggests that some places were very much cooler than today including the tropical pacific. All in all, when the warm places are averaged out with the cool places, it becomes clear that the overall warmth was likely similar to early to mid 20th century warming.
Since that early century warming, temperatures have risen well-beyond those achieved during the Medieval Warm Period across most of the globe. The
National Academy of Sciences Report on Climate Reconstructions in 2006 found it plausible that current temperatures are hotter than during the Medieval Warm Period. Further evidence obtained since 2006 suggests that even in the Northern Hemisphere where the Medieval Warm Period was the most visible, temperatures are now beyond those experienced during Medieval times (Figure 1). This was also
confirmed by a major paper from 78 scientists representing 60 scientific institutions around the world in 2013.
Secondly, the Medieval Warm Period has
known causes which explain both the scale of the warmth and the pattern. It has now become clear to scientists that the Medieval Warm Period occurred during a time which had higher than average solar radiation and less volcanic activity (both resulting in warming). New evidence is also suggesting that changes in ocean circulation patterns played a very important role in bringing warmer seawater into the North Atlantic. This explains much of the extraordinary warmth in that region. These causes of warming contrast significantly with today's warming, which we know cannot be caused by the same mechanisms.
Overall, our conclusions are:
a)
Globally temperatures are warmer than they have been during the last 2,000 years, and
b)
the causes of Medieval warming are not the same as those causing late 20th century warming."
We can swap pieces that support our beliefs all day I suspect.
Let's carry on as we are and see how things are in 100 years then. That way we can be sure if our activities are influencing things or not. Or perhaps it might just be sensible to go with a safer plan and try to mitigate the effects, even if you don't believe they are our fault?
The problem with a lot of this is there are way too many people with axes to grind or positions to support/defend. The cold fusion thing was a good example of how scientists and researchers will happily suck up money just to keep themselves employed. Being a scientist doesn't mean you aren't human and thus open to the temptations we all suffer. It would be nice to think that every scientists is utterly and totally unbiased and honest, but I'm not that naive. Same goes for people in positions of power and influence - they tend to get there because they will do and say anything to get what they want. Truth rarely comes into it unless it's convenient. Principles are expensive and very few are prepared to pay the price.
As for a piece in any tabloid....not where I choose to get my critical & independent thinking from TBH.
Ultimately, most of us are obliged to decide who we are going to believe and trust, as very few are in a position to actually test these ideas for veracity. I choose to trust the overwhelming majority and places like NASA or others with less to gain. Follow the money is a wise adage.
Anyway, I'm done with this - it's turned into an argument about faith, which is pointless. It matters little what any of us may believe - world governments are shifting opinion and policy toward supporting the notion of anthropogenic climate change so we can howl at the moon about it or applaud it as befits our position.
