How can one reconcile "global warming doesn't mean it will be warmer everywhere" with "the MWP wasn't global"

Question

It didn't warm around the world at exactly the same time during the MWP - the "anecdotes" don't all come from exactly the same time, and it would appear that the NH warmed first.

And at least one spot in the central Pacific may have cooled slightly.

At one point it looks like there was a prolonged La Nina that may have significantly affected local temperatures in some areas (noise not signal).

These are the arguments used to dismiss the MWP as "a truly global phenomenon."

But, the fact pattern is very similar today, and these arguments are dismissed as rebuttals of a present "global warming."

Which is it? Does "truly global warming" require universal warming or doesn't it?

Does the climate system work differently than it did 1000 years ago?

Answer 1

Take a bowl of water and let it represent the oceans.  Now begin dropping ice cubes into the bowl of water, and let them represent the glaciers breaking off from the caps.  As the glaciers move away from the caps they have a cooling effect on the oceans.  Global warming means global cooling.  Another ice age.

Answer 2

A 128 years of global average temperatures means nothing in the grand scheme of things. It's a tool for moderation and not necessarily extremes. It can show opposites just as readily as it can compliment data. Which it has done lately. They won't express climate change in terms of cooling but only warming. "Glass half empty or half full analogy." When they can physically connect the two hemispheres I might actually listen to the rhetoric. Considering the earth is 2/3's water and they use sea surface temps combined with land. I don't see a true average.Yep...they have a problem. Why stop there, included the average internal core temp and really scare(create pandemonium) the h_ll out of everyone.

Answer 3

Your first statement is a response to people who mistakenly believe that it will be noticeably hotter everywhere, all the time.  They don't understand that normal weather variations, even extreme ones, will still occur.

Your second statement refers to climate, long term trends over hundreds of years.  If the MWP existed in Europe but not elsewhere, then it was a regional efefct perhaps due to changing currents in the Atlantic Ocean, and it has nothing to do with the current global warming that we're witnessing.

Confusing weather with climate is a typical misinformation tactic.  Are you promoting that tactic on purpose?

Answer 4

JS,

The MWP occurred in more than just Europe and Greenland, but all over the world:

http://www.co2science.org/data/mwp/mwpp....

Not all of these studies show a warm period in exactly the same time period, but a majority show one in the rough time period in question.

Like now, the warming is not uniform.

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Edit:

Ken said

"regions that have experienced a warming of 2 - 4 C (Antarctica Peninsula even more)."

Over the last century, the antarctic peninsula has warmed 3.7 +/- 1.6 degrees C. Over the last 50 years, ~2 degrees celsius.

http://neptune.gsfc.nasa.gov/publication...

Ken then said:

"Since you don't provide any context for who actually said "global warming doesn't mean it will be warmer everywhere" (for all I know the following words are "every day of the year"), it's hard to comment on that."

Bruce Wielicki of NASA says

"'global warming' does not mean uniform temperature change over the entire Earth.

The climate system is sufficiently complex that like the economic analogy: it does not do anything in a simple uniform way. So even when the global average temperature is increasing, a few places will actually be cooling."

http://www.earthsky.org/article/20-scien...

Climate researcher John M. Wallace of the University of Washington said

"When people use the term "global warming" they mean the temperature averaged over the surface of the earth is getting warmer. That doesn't mean to imply that there is warming everywhere on Earth."

http://seattletimes.nwsource.com/html/na...

Etc...

Answer 5

It sounds like someone hedging their bets as they did when they changed global warming to climate change.  I think tree rings made the MWP look less significant.  There are climate proxies all over the world but they are not equal and none are completely reliable; however, together they paint a pretty accurate picture, I think.  You can look in the silts in bays in Washington, you can look at tree rings in the White mountains of California, sea shells in the Sargasso Sea (This one really makes the MWP look warm), ice cores in the Arctic, Greenland, and Antarctica, and various other sources.

Answer 6

We just don't know, and probably will never know, exactly how the climate behaved 1000 years ago.  There simply aren't reliable records, and ice cores can only tell us so much.

Answer 7

When the globally computed average temperature from the MWP periods are compared with the globally computed average temperature from now, our present warming exceeds that of the MWP (in the realm of 0.4 - 0.7 C).  People who confuse the MWP issue, often try to compare the regional warming of the MWP with the currently measured global warming, and that's an apples & oranges comparison.

If you want to compare regional warming with regional warming, then we already have regions that have experienced a warming of 2 - 4 C (Antarctica Peninsula even more).

Since you don't provide any context for who actually said "global warming doesn't mean it will be warmer everywhere" (for all I know the following words are "every day of the year"), it's hard to comment on that.

Edit:

bob - Thank-you for the correction.  The Antarctic peninsula has only warmed 3.7 ± 1.6 ◦C, not more than 4 C (as I indicated).  I was looking at a single months warming (which exceeded 4C) and not the annual warming.  However, there do appear to be some regions in the Arctic that have exceeded the 4C range, so my point of comparing regional with global temperatures being apples and oranges is clearly still valid.

Answer 8

Global warming means that the atmosphere is warming "on average" everywhere.  Changing weather patterns will cause some places to warm and some places to cool, some places to get more rain or snow and other places to get less.  But on average, the atmosphere gets warmer.  As for the MWP, we know only that it was colder in North England and Greenland, we do not have measurements to support that the average around the world was colder; it may just be that it was warmer elsewhere.  It requires measurements around to world to estimate total global warming or cooling.