Over the past week or so several creationist sites have written about how the ice age fits into the Biblical chronology. The most prominent of these being Answers in Genesis, who wrote a “special feature” on the matter. This trend is rather surprising given that, as the sensuous curmudgeon eloquently notes, there are only a scattering of references to “ice” in the Bible and none to any long period of glaciation.
Despite this lack of Biblical support Answers in Genesis believes there is enough secular evidence to prove there was indeed an ice age. So they attempt to create a narrative of this period in the earth’s 6,000 year history based on purely science! Be warned, that way lie dragons.
They weave a grand story, of how
As a massive ice sheet expanded over Canada, it drove out most living things, and then it continued to push south into the Ohio valley. Eventually, the heavy snows stopped and the earth warmed. Once the ice began to melt, animals returned to Big Bone Lick, along with spear-wielding humans.
The timeframe given for this dramatic sequence of events is 250 years or so. Since this is a narrative based on science we can use palaeoclimate data to help flesh out this description of the Biblical ice age.
Scientifically speaking, the period we’re looking at is the Pleistocene, which was the last era during which glaciers covered significant portions of the earth. Traditionally this period is thought to have lasted from 2.6 million years ago until ~10,000 years ago; although AiG has condensed this down into their neat 250 year time frame.
We have many ways of investigating the palaeoclimate during the Pleistocene. For example, isotope ratios (variants of elements with a different number of neutrons) in the ocean vary with the climate. These isotopes are incorperated in the shells of microscopic marine organisms, providing a snapshot of the ratio (and climate) during their life. This isotope data can also be obtained from arctic ice and caves across the world. Sediment which forms under glaciers is different from that which does not, allowing us to track how far they extended (and when). Pollen records shows us what kind of plants were living in an area, telling us what the environment was like and what was living there.
All of these lines of inquiry correlate. When isotopes indicate that there was a warmer period we find evidence glaciers retreated and pollen records tell us warm adapted plants spread further north, colonising previously inhospitable environments. The opposite is also true, with the disappearance of these warmth-loving plants coinciding with glacial expansion and appropriate isotope variation. The fact that these independent pieces of evidence all agree with each other provides strong evidence they are accurate. Whilst Answers in Genesis may quibble over the length of time these climate records represent, surely they cannot reasonably quarrel with the accuracy of the story they tell.
This raises something of a problem for the creationists. You see, this climate evidence shows that the single, grand glacial expansion AiG talks of simply didn’t happen. The ice age was full of multiple periods of warm and cold, corresponding with glaciers retreating and expanding several times (and associated changes in the vegetation). Graphs showing the temperature during the ice age typically look like this:
On this graph “0″ refers to the present day temperature (you can just see the tiny spike on the left that is the climate we’re experiencing). As you can see there were several periods where the temperature during the ice age was the same as it is today! There were many, many climate oscillations as the earth fluctuated between cold glacial and warm inter-glacial. As you might expect this also means there was extensive variation in the size of glaciers during the ice age.
That graph tells of how much ice there was on the earth during part of the ice age. Like the prior graph the values are relative to the present, so 0 = the same as the modern day. As you can see there are periods during the ice age where glaciers in North America are no bigger than they are today. The rest of the world also gets pretty close to present day glacial coverage at several points.
So the climate was a lot more varied than Answers in Genesis suggests, so what? The thing is that all of this variation has to be condensed down into the 250 year ice age they give. This data comes from Pleistocene deposits which they acknowledge were formed during the ice age, so must be squeezed into the period they claim the ice age happened in. The first graph records over 100 significant changes in the climate, 34 of which are considered to be major shifts.
Under the creationist model this amounts to significant climate change every couple of years or so, with big changes occurring roughly every 7 years. This means that Answers in Genesis wants you to believe that entire forests can become established in a few years and that glaciers will grow to huge sizes in less time than it takes a child to reach the 1st grade. The speed at which climate change must occur for the creationist model to remain valid is simply absurd.
No doubt that Answers in Genesis can conjure up some special pleading explanation to resolve this issue. Maybe less “damage” to the DNA as a result of original sin had accumulated, allowing plants to grow quicker than in the present. Ken Ham – president of AiG – has already endorsed an Atlantis-esque mythology claiming that Noah had more advanced technology than we do because his brain hadn’t been harmed by such damage.
However, when they start concocting such excuses their attempt to be scientific has thoroughly failed. Trying to come up with a scientific model for creationism results in absurdities that must be magicked away. When will they realise it’s actually creationism which needs to disappear?