L
lynnvinc
Guest
It’s great that people are so interested in the MWP, since it’s part of our climate change history and can reveal important aspects of climate change.
Here are some points about it that help shed some light (from skepticalscience.com/medieval-warm-period.htm ):
Firstly, evidence suggests that the Medieval Warm Period was in fact 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. This has been confirmed by the National Academy of Sciences Report on Climate Reconstructions. Further evidence (Figure 1) 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.
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 2000 years, and
b) the causes of Medieval warming are not the same as those causing late 20th century warming.
http://www.skepticalscience.com/pics/Moberg_Hockey_Stick.gif
Figure 1: Northern Hemisphere Temperature Reconstruction by Moberg et al. (2005) shown in blue, Instrumental Temperatures from NASA shown in Red.
The more interesting question to me is why do people use this MWP as part of their anti-green arsenal? What do they hope to gain? Do they actually want us to go into a much warmer phase than the MWP just to see what will happen?
They say curiosity killed the cat. Plus we know from much warmer periods than the MWP in the past (e.g., 55 mya & 251 mya) that a large portion of life could die out if we go well above the MWP — and kill many cats…and people.
I guess another important Q would be where do motivated people find all their cop-outs to let them off the hook for taking personal responsibility for AGW? And who is behind those websites & books, and what are their motives for their anti-green philosophy?
Here are some points about it that help shed some light (from skepticalscience.com/medieval-warm-period.htm ):
Firstly, evidence suggests that the Medieval Warm Period was in fact 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. This has been confirmed by the National Academy of Sciences Report on Climate Reconstructions. Further evidence (Figure 1) 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.
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 2000 years, and
b) the causes of Medieval warming are not the same as those causing late 20th century warming.
http://www.skepticalscience.com/pics/Moberg_Hockey_Stick.gif
Figure 1: Northern Hemisphere Temperature Reconstruction by Moberg et al. (2005) shown in blue, Instrumental Temperatures from NASA shown in Red.
The more interesting question to me is why do people use this MWP as part of their anti-green arsenal? What do they hope to gain? Do they actually want us to go into a much warmer phase than the MWP just to see what will happen?
They say curiosity killed the cat. Plus we know from much warmer periods than the MWP in the past (e.g., 55 mya & 251 mya) that a large portion of life could die out if we go well above the MWP — and kill many cats…and people.
I guess another important Q would be where do motivated people find all their cop-outs to let them off the hook for taking personal responsibility for AGW? And who is behind those websites & books, and what are their motives for their anti-green philosophy?