If we want to test the timeline proposed by Young-Earth Creationists (YEC’s), we need not look far back in geological time. Given that the accepted and documented age of the Earth is over 4.5 billion years, YEC’s reject all but a tiny sliver of Earth history. I want to present you, therefore, with a case example, which demonstrates both that our dating methods are sound and that the last sliver of Earth history cannot span less than ~10,000 years.
A frozen wasteland, chock full of data
Since the 1980’s, multinational research teams have recovered ice cores from more than a half-dozen sites across Greenland. From these cores, scientists have recovered a treasure trove of paleoclimate information, mainly by analyzing trends in stable-isotopes of oxygen and hydrogen, alongside salt abundance, which generally reflect regional temperature and wind/storm patterns (O’Brien et al., 1995).
As many of you already know, ice cores can be dated simply by counting the annual bands visible in each core, and this method is effective back to ~20,000 years or more, depending on the site. But to ensure accuracy, ice cores are also dated by counting seasonal variations in ice and dust chemistry, as well as by matching volcanic ash deposits to known eruptions in neighboring Iceland. Combined, these characteristics make ice cores one of the most precise geological archives of the Late Quaternary.
A Holocene Cold Snap: Rediscovery of the 8.2 ka Event
When the stable-isotope data from Greenland were first published, the researchers immediately noticed a sharp negative peak at approximately 8,200 years ago. Based on the modern relationship between isotopes and temperature, they interpreted the peak to reflect a cooling event that lasted a couple hundred years or more.
Amazingly, the timing of this event is identical between ice cores (within uncertainty), no matter what part of Greenland you look at. This overlap tells us that the cooling event was regional, perhaps originating in the North Atlantic ocean. For example, a temporary reduction in the strength of thermohaline circulation or the Gulf Stream could hypothetically cool off Greenland. If that were the case, however, then the event should have been expressed in other regions sensitive to sea-surface temperature in the North Atlantic, such as Europe, Asia, and—well, nearly the entire globe is connected to what happens in that part of the world!
As early as the 1960’s, at least one such ‘cold snap’ had been documented in Norway, known locally as the Finse Event, but its timing was not well constrained. Since then, dating techniques have markedly improved, so let’s see how the hypothesis has panned out with more recent studies.
Too many assumptions!
If you believe that the Earth is young, then you’re probably tired of hearing that ice cores date back hundreds of thousands of years. In fact, you’ve probably read some articles arguing that our dating of ice cores is flawed, because it makes faulty assumptions, or that these ice sheets could have accumulated rapidly in a post-Flood ice age. And if that were the case, then the 8.2 ka event, whatever it was, happened less than 4,000 years ago—not 8,200.
To clarify, I am fully aware of these claims by Oard and others. We can all be skeptical, and that’s just fine. But we don’t have to speculate. Instead, why not consider this overview a test of the standard interpretation and chronology of the Greenland ice core data? Let’s test whether or not the ‘8.2 ka event’ shows up elsewhere at 8.2 ka. If it doesn’t, then potentially we have a problem with our conventional dating methods. But if it does, then we know that the assumptions behind them are valid.
Scandinavian Lake Records
If there were an abrupt cooling event in the North Atlantic ocean, then Scandinavia would have felt it, because the climate of northernmost Europe depends on those ocean currents to deliver warm, moist air masses to high latitudes. Hence our first test involves a survey of lake records, which accumulated local pollen grains in their sediments since the last ice age.
Keep in mind, however, that these twelve lake records were dated by the radiocarbon method, and changes in temperature are inferred from pollen abundances found in the layers of sediment. Ice cores are not. Thus we have two independent dating methods and two independent climate proxies searching for the same event. What do we find at 8.2 ka?
Of course, we find evidence for a cooling event that lasted a couple hundred years, centered precisely at 8.2 thousand years ago. In addition, the cooling was more pronounced at sites most sensitive to the North Atlantic ocean, around 60°N latitude. Therefore, the hypothesis of a regional cooling event has been corroborated, as well as our test of the dating methods used to pin down the timing of that event. Whether we count annual banding in glaciers, which makes one set of assumptions, or measure levels of radioactive carbon, which makes its own set of assumptions, the result is the same: this cooling event was centered around 8,200 years before present.
North Atlantic Sediment Records
We can also look at ocean sediment cores, in which the chemistry of microscopic shells—called foraminifera—is commonly used to reconstruct sea-surface temperature and salinity. The data below were obtained from a sediment core off the southwestern coast of Iceland, right where we’d anticipate a drop in ocean temperature associated with cooling over Greenland and Europe. What did they find? A multicentennial cooling of 3.3–4.6°C centered at 8.2 ka, according to radiocarbon dating of the marine sediments and correlation with a known volcanic eruption.
What is more profound, perhaps, is that the researchers also found evidence for freshening of the surface water—that is, a drop in salinity—at the same time the ocean cooled off. Why is that? Well, it had been hypothesized that the 8.2 ka event was initiated by a sudden release of glacial meltwater from North America into the Atlantic and Arctic oceans. Since glacial ice is comprised wholly of fresh water, dumping it all into the ocean would make the surface layer less salty.
This hypothesis has since been confirmed through dating of lake sediments in south-central Canada, where a massive lake—essentially the size of Hudson Bay—had formed around the glacial margin. But during the century or so preceding the 8.2 ka event, the ice dam that held back the water melted, and most of the lake discharged into the surrounding oceans.
In case this sounds familiar, you might remember a similar event took place in Montana and Washington to create the famed scablands. The drainage of Lake Agassiz was less catastrophic in reshaping the land scape, but it occurred on a much larger scale. In fact, the water volume was sufficient to raise global sea level by ~10 feet or more, which has been documented in several cave and coral records.
More relevant to our topic, however, is that the mass of freshwater significantly weakened thermohaline circulation in the North Atlantic ocean, cooling off the northern hemisphere and shifting climate zones around the world. Thus our initial hypotheses pass the third test. You see, all of the evidence we have for the emptying of this great lake dates to around 8.2 ka. And all of the evidence we have for a slowdown in ocean circulation and cooling of the North Atlantic dates to around 8.2 ka. Is that a coincidence? Well, if the Earth is less than 10,000 years old, then it must be a fluke—pure happenstance—that we find so much corroboratory evidence for this climate event.
Tropical droughts and the ‘8.2 ka Event’
But the story doesn’t end there. As I mentioned, nearly every part of the globe is somehow connected to climate in the North Atlantic region. And when that part of the world cooled off, it caused the equatorial monsoon regions to shrink and weaken as well. Essentially, climate zones contract when the poles cool down, and they expand when the poles warm up.
Whether we look in South America, Arabia, or southeast Asia, there are dozens of stalagmites—i.e. cave records—that record a multicentennial drought, centered precisely at 8.2 ka. In Oman, for example, the climate became so dry, that one stalagmite stopped growing entirely.
Now, up to this point, you might have been tempted to think, “Well, most of these climate records were dated by radiocarbon, so of course they’ll have the same age! But that age must be inflated, due to the effect of Noah’s Flood on carbon in the atmosphere.”
Unfortunately for the YEC, that explanation doesn’t fly. Not only can we date the 8.2 ka event by counting layers in the ice—a process totally independent from radiocarbon—but now we have a third dating technique: the Uranium-Thorium disequilibrium method. And this technique assumes nothing about carbon in the atmosphere or seasonality in glacial ice.
Take a look, for example, at the following plot from Wang et al. (2005), which illustrates 9,000 years worth of stable-isotope data from the best-dated stalagmite in the world in Dongge Cave, south China. Take note how many U-Th dates were obtained, as well as the fact that all of the dates (44 in total!) get older toward the bottom of the stalagmite. Isn’t it strange how that works if this radiometric dating stuff is all bunk? In any case, you’ll find the 8.2 ka event clearly expressed in the oxygen-isotope values, which are related to the strength of the Asian summer monsoon (more rainfall results in a more negative δ18O value).
Lastly, let’s take a quick look at Central and South America. You might recognize the name of the first locality, the Cariaco Basin off the coast of Venezuela, because its sediments contain tens of thousands of well-defined varves—another reason to reject the YEC timeline. Whether we count those varves back to ~8,200 years ago or date the sediments directly by the radiocarbon method, there is evidence for a sudden spike in surface salinity associated with the 8.2 ka event (Lin et al., 1997). In other words, the weather on land got drier due to a shift in climate zones, so less freshwater was pouring into the basin via rivers.
In this stalagmite from Costa Rica (lines C and D), the same story emerges from yet another tropical cave—multicentennial drought centered around 8,200 years ago, once more dated by the U-Th method. The timing of that drought corresponds perfectly to arid winds over the Cariaco Basin (line B) and cooling in Greenland (line A):
How did the globe cool abruptly, 2.2 thousand years before it even existed?
So far, we have surveyed only a small fraction of the records from around the world, which document this famed climate event 8,200 years ago. Our methods for reconstructing the past, therefore, are not fundamentally flawed or undermined by so-called ‘evolutionary’ assumptions. The ubiquitous expression of the ‘8.2 ka event’ provides outstanding confidence, rather, in the conventional age of the Earth and the geological timeline.
Since geologists are able to pin down this event with multiple dating methods, we find that the assumptions behind each technique are indeed valid, contrary to the claims of young-Earth ministries. We must conclude, therefore, that even the last sliver of Earth history, known to geologists as the Holocene, is not less than 8,200 years old—not by a long shot. Even by looking at the relatively recent past, we find evidence for great antiquity in God’s creation, which completely invalidates the YEC timeline of events.
Featured image: Emerald ice on Lake Baikal, by Alexey Trofimov