The article attempts to conflate two things: high concentrations of "carbon" in the atmosphere, and melted ice caps.
Ice core studies have shown that 55 million years ago, our ice caps melted.
Scientists are not sure what caused the warming, which occurred over a relatively rapid geological period of 100,000 years. But they think it may have been due either to the release of vast deposits of carbon-containing methane stored on the sea floor, or the massive release of carbon dioxide from volcanic eruptions.
The article states that the cause "must have been" a "dramatic increase" in atmospheric carbon; but does not assign a magnitude to what a "dramatic increase" is. The article goes on to say that it would require a large volcanic eruption every day for centuries to get that much carbon dioxide into the atmosphere from volcanic sources.
The scientists also found that the Arctic is currently experiencing one of the fastest temperature rises on record, with more sea ice melting each summer than at any time in hundreds and possibly thousands of years.
That paragraph appears earlier in the article than the previously-quoted one, by the way.
The article does not say how quickly the ice returns come winter, nor even whether it does. I think we are expected to assume that it does not, but I doubt that's the actual reality of the situation.
What the article also does not say is that the required atmospheric carbon increase for this level of warming, and the actual atmospheric carbon increase over the past two hundred years, are vastly dissimilar.
A typical volcanic eruption spews millions of tons of gasses into the atmosphere, gasses which are heavily regulated by the EPA when they come from man-made sources: various sulfur oxides, nitrogen oxides of various flavors, ozone, etcetera. A single volcano--Mount Saint Helens--emitted more sulfur oxides in one eruption than Man has in his entire history. And that wasn't all that big of an eruption.
The point is, it takes a lot of carbon dioxide to produce warming. Eight degrees celcius of warming (the amount required to allow tropical plants to flourish at the north pole, apparently) requires "...something like a Vesuvius-sized eruption each day for centuries...."
The article also mentions the idea of a methane hydrate eruption. There is an enormous amount of methane (and other gasses) locked in a solid form at the bottom of the ocean. The phenomenon is, as far as I can tell, relatively unstudied. But I think it's a lot more likely than the carbon dioxide model they're trying to support with this article.
Where it all falls down is in proportion. The article slyly hints that since we're seeing "record" warming of the arctic, obviously anthropogenic global warming is the culprit, and we're running the risk of having the ice caps melt. "Surface temperatures in some parts of the world were then 8° higher than now."
The fact that we are currently nowhere near 8° of warming is, naturally, omitted...and I'm sure that some parts of the world are at vastly different temperatures now than they were even when that article was written. "Some parts of the the world" does not equal "global". I'm pretty sure that "global" means "all over the world", not "some parts" of it.
Eight degrees of warming is not enough to let tropical plants flourish in an arctic environment. And if one argues that eight degrees is the average of the global temperatures, then I have to ask: why would the arctic warm more than the equator? What mechanisms exist at the equator to move its warming to the poles? How can you explain a naturally-occurring heat pump with that kind of efficiency? Are their any decent models of this behavior? Does this system work now? Do we see evidence that the poles are "heat sinks" for the equatorial regions?
If one tries to argue that the poles have more "room" to gain temperature than the equator, that's nonsense. If the entire environment heats, why would some areas gain more than others? In fact it may be just as valid to claim that the equator would get hotter than the poles; certainly this model is operating now, since the poles have ice on them and the equator does not. If the poles warmed enough to melt the ice caps, wouldn't the equator warm enough to become uninhabitable?
It makes no sense that only the poles would warm. In fact, each pole is out of the sunlight for three months of the year; and since there is no global warming without the sun's input, I find it hard to believe that the poles could possibly warm more than the equator, which receives about the same amount of sunlight year-round.
Most discussions of global warming center around atmospheric composition, and almost none center on the prime mover of global temperature: the sun.
Without the sun, global cooling is the order of the day; look at Pluto. Look at the moons of Jupiter and Saturn, too. Without the sun, the Earth would freeze solid. The oceans would turn to ice, all the way down to the floor; the muck on the ocean floor would turn rock-hard. The only life which would survive on Earth would be the sightless creatures around ocean thermal vents. Only volanoes would melt through the glaciers of water ice and frozen atmosphere.
There is NO global warming AT ALL without the sun.
Our sun is a mildly variable star. We have documented several cycles in the few hundred years that we've been able to measure its variations. We know that its output is variable, but reasonably steady. The sun oscillates and vibrates with periods of years, like a glob of fusing jell-o, and it is the sole reason life can exist on Earth. Without the sun, the Earth is a dirty ice cube.
But solar forcings are not well understood by climatologists, and most of their models assume a steady-state input from the sun: the sun's output is always the same. But the sun's output is not always the same; this is why we are seeing higher global temperatures on Mars and the other planets, not just on Earth...higher temperatures which coincide with the temperature rise on Earth.
The sun is getting hotter. This is no reason for panic, because this is the kind of thing it does. It gets warmer; it gets cooler. A main sequence G star like the sun is not going to blow up, nor is it due for any other major change for another 5 billion years. But it is mildly variable, and right now the sun is warmer than it was a few decades ago.
But here is the "inconvenient truth" about solar forcings: no one can do squat about them.
Even if we study solar forcings to death, it won't amount to a hill of beans. We can't possibly change the sun's "thermostat". No policy change, no environmental accord, no sweeping change in human behavior can fix it. If we bent our planet's entire effort towards changing the behavior of the sun, it would mean millennia of wasted effort. The sun is too big to effect.
(There are things we could do, theoretically, to cause the sun to abruptly increase its output. But it would take a bit of doing. Maybe dumping Jupiter into the sun would be enough....)
And therein lies the rub. The sun's too big; people are easily swayed but they're not that stupid--most people will look at the sun, shrug, and say, "Well, there's not much we can do about that."
So they'll keep driving their big SUVs and making money.
But if the sun isn't the problem--if the problem can be defined as a man-made problem--then suddenly climatology becomes vitally important. Climatologists can garner huge government grants to study the climate, and how it's changing. The Kyoto Accords become important. Emissions of greenhouse gases become important. Climatologists become important!
So: the article I referenced at the beginning of this makes no mention whatsoever about the role that the sun may have played in the "tropical arctic" model it discusses. "55 million years ago" is a long time, and we really don't know what the sun was doing back then.
Since we don't know the energy input at that time, how can we know what degree of warming was due to atmospheric forcings? I can sum up what this study proves rather easily:
1) the Earth was once much warmer than it is now, warm enough to have tropical flora at the poles.
2) the ice caps weren't always there.
3) artic ice is currently melting pretty quickly.
The study does not prove anthropogenic global warming; it does not prove that increased atmospheric carbon can cause a "runaway greenhouse effect"; and it does not prove that Earth's climate is delicately balanced.
In fact, it disproves those points quite nicely. The Earth has been colder since then! The level of atmospheric carbon required to support 8° of warming is--by the article's own admission!--much higher than it is at present, even factoring in the atmospheric carbon generated by human activity. And the Earth recovered from that period of warming; it did not just get hotter and hotter and hotter until everything perished.
BUT--again, none of these points fits the "impending eco-catastrophe" template. So you will not see anyone trumpeting the facts. They're too inconvenient to those whose livlihoods depend on global warming.