Dear Patty Lou,
You are on a very different page than me. In brief, you are using 4 billion years worth of history to argue variability in climate. I think this approach is rather a bit like stating the blindingly obvious.
This is not true. Although geologists study events in deep time, I prefer to study a more recent epoch, the Pleistocene. This ranges back from ~10,000 years ago to 1.2 - 2 million years. There is no way that stating comparisons in weather today to past climate thousands or millions of years back to gain insight can be labelled blindingly obvious.
I am arguing a simple causal relationiship between the last 150 years of human activity and a warming climate.
But this gives you tunnel vision. You are looking at the Industrial Age and EXPECTING it to be the cause for warming. There have been much warmer periods in Earth history WITHOUT fossil fuels. One way we can tell this is looking at fossil leaves of the time period. Tropical foliage found in frigid regions today tell us it was much warmer in the past. Glossopteris fossil leaves found at the Arctic by Scott is an example. Fossil narwhal bones found beached way above sea level in Siberia tell us that sea levels were different over 20,000 years ago.
In other words, we approach the question in two very different ways.
Yes you have made up your mind, and will not consider all the possibilities. I try to consider all the possibilities I can think of.
Here's a fun activity. What is the probability that the warming we have observed, would occur naturally... in any random 150 year period... of the past millions of years, without human contribution?
Compare to past warm periods, study and make comparisons. Then we may know better.
We probably won't have a very productive interaction.
This just tells me you have prejudged me, and have a negative, arrogant attitude. Why are you even here if you already have your mind made up and don't want to discuss things? Pack it up and go home.
NQ: Don't just take my word for it that the Sahara was green... This is research from the University of Colorado at Boulder. (my boldface)
PL:I mean, why would something like this be considered surprising at all? No one is saying the planet is unable to survive under very different climatic conditions (there was no O2 on the planet for the first billion years, for example, but life got along just fine - I doubt you'd like to return to those conditions?)...
It is quite surprising to me that hippos and giraffes once roamed what is now the Sahara Desert. I wonder about that. How can it have happened? I'd really like to know. And once again, Patty Lou, I am not talking about billions of years back regarding the Sahara. Just thousands.
...we are saying that such abrupt changes pose significant dangers to biodiversity, many numerous species will be threatened or killed, economics will be adversely affected, sea level is rising ... in short - we could return to any number of "past" Earth climatic scenarios ---- but I doubt it'd happen without a lot of unecessary suffering and at great loss to the richness of life on our present blue-green gem!
Who is "we"? You and who else is saying this?
Nature has a way, if there is an extinction event, of opening up a place for new species. Did you know we had a pretty significant extinction event about 11,500 years ago? Many kinds of animals disappeared from the planet forever (mostly Northern hemisphere), and man was not the culprit there.
Some of the victims:
woolly mammoths, Columbian mammoths, woolly rhino, saber toothed cat, cave bear, short faced bear, cave lion, camel and horse (went extinct from North America), Jefferson's ground sloth, giant beaver, giant armadillo, mastodont, stag-moose. Many other species radically moved their range. Musk ox and reindeer made it through the event somehow. But how?
And yet we have diversity today.
All of these animals survived the peak of the last ice age ~21,000 years ago, continuing another ~10,000 years.
If we can understand what happened to them, we can better understand what may happen again, and there is a curious cyclicity to the workings of our planet
http://www.nationmaster.com/encyclopedia/Image:Ice-Age-Temperature.png
ice cores reveal a pattern
http://muller.lbl.gov/papers/BenthicStack.pdf
Look at page 16. A graph of isotopes taken from deep sea sediment cores.
This does not look random
(There is an updated benthic stack by Lisiecki and Raymo but the link was not available)