One of the tricks that the global warming boys use is to NOT put things into context. You will always see statements of this nature: “This is the warmest period in the last 400/1000/1300 years.” That sounds scary, and it sort of implies that this is the warmest period we know about – since how could we have temperature records before 1300 years ago?
The implication is that the earth’s climate is remarkably stable, and has only recently changed, and the change can only be atributed to man.
They never tell you about the entire climatic record. They scrupulously avoid any mention of it at all. This, to me, is an indication that they want to mislead you. Instead, they come up with hockey sticks that eliminate the Medieval Warming Period, and reinforce the idea that Earth’s climate has been the same – until very recently.
Here is a series of graphs, excellently presented on JoNova. These show a snapshot of 65 million years of climate, then 5 million years, then 10,000 years.
First, 65 million years:
You can see we are currently (lower right of graph) in a cold spell. The earth has been much, much warmer, back in the Eocene Optimum. At that point, there were no icecaps at all. Alligators lived at the North Pole. But the tropics were not insufferably hot; they seem to have been pretty much what they are like today.
5 million years worth of climate history:
You can see things are still cooling. We are on the upward spike though. Note that the climate keeps swinging from cold to warm and back again, and the oscillations are greater the nearer you come to today. The bottoms are ice ages, the tops are interglacial periods. We are in an interglacial period now.
Here is the last 10,000 years.
This is since the end of the last ice age. The red at the far right of the graph is the current round of warming, since about 1850. You can see the earth was significantly warmer in the Medival age, in the Roman times, and in the time when the Minoan culture flourished.
But nothing is happening that hasn’t happened hundreds of times before. This latest jump is but a tiny jump.
Here is another wonderful set of graphs showing the whole thing, starting from today and working backwards. It tells basically the same story.
Here is one from that series, which indicates something important. This one shows the last 500,000 years of climate history.
The reason this one is important is because the global warming boys say that “CO2 is higher than it has been for 400,000 years”. Well no wonder. If, as the skeptics say, CO2 rises AFTER it gets warmer, then you see there has been a prolonged warm period for the last 10,000 years. So no wonder CO2 has risen.
The one thing I am afraid of is this: The CO2 levels continue to rise, but the temperature seems to have leveled off:
What if this is what happens when a new ice age starts? That is the real fear.
Another very good post by Lubos Motl explaining all of this.