All these hurricanes we’ve been having have gotten me thinking …
I know that the Earth’s climate varies over time, and I’ve read on several occasions that the Earth’s climate was generally warmer in the Jurassic, Triassic and Cretaceous periods. I also know that for a portion of that time, all the Earth’s land mass was on a single supercontinent, called “Pangaea” I believe.
I was thinking, all that ocean, warmer temps than we now have meaning warmer water temperatures … and just one continent to slow them down … must have made for some HELLACIOUS hurricanes.
Is there any information on the presence or absence of dinosaur-sized 'canes in dinosaur days?
Pangea was a land mass near the South Pole and I don’t believe there were dinosaurs living on it. It takes more than warm waters to develop a cane and land masses are not the only elements that stop a cane. But there have been hurricanes throughout the planet’s existence, most likely. Very dramatic shearing forces were probably very active to prevent formations of too many super canes. Even now, in the southern hemisphere, there have been only two recorded canes, one striking Brazil and one in the Pacific. The shearing forces there are too strong.
That said, hurricanes are a natural phenomenon. They cause much destruction to mankind because we have built artificial objects, which the canes destroy. Canes also play havoc with natural objects, but nature rebounds. When Hugo hit my area in 1989, the imported trees, such as pines, were uprooted, but native trees, such as the palmettos, were not. Palmettos had evolved a root structure to prevent their upheaval. Such is Nature. It is only when Man enters the picture and disrupts Nature that catastrophes occur.
Bull’s Island shortly after Hugo suffered significant destruction. If you go there now, you will see how Nature has rebounded. The upheaval of tall trees has allowed underbrush to prosper. Just the types of greenery and forestry has changed, temporarily at least. The tall trees have gone, but have allowed the smaller trees and vegetation to grow, until such time as the trees that need height once again move in. The cycle of Nature is relentless. Woodpeckers that rely upon dead trees are now frequent. The red-cockaded woodpecker, an endangered species, lives in live loblolly pines, and many of them were destroyed. However, the forest rangers have created holes for them in the surviving loblollies, and they are prospering.
Weather impacts, even severe ones, don’t tend to be preserved over geologic time frames. Certainly some of the particular fossil aggregations may have been formed by natural disasters. To take the classic example, the Burgess Shale resulted from the slump of a shallow-water mudbank containing a thriving ecocommunity into a nearby anoxic depression – not a catastrophic event by our standards, though certainly one for the creatures which died and were preserved as a result.
Pangaea, however, preceded most of the time of the dinosaurs, and was basically a Permian-Triassic event. By the late Triassic, Pangaea had split into Laurasia and Gondwanaland, and by the mid-Cretaceous, the modern continents were well on their way to the present status. The Atlantic Ocean as we know it today began as a rift between halves of the two continents sometime in the Jurassic.
It might be noted that the effects of a hurricane over water, while significant in and of themselves, do not create any major impact on life forms – it’s when a hurricane moves onto land that damage and destruction occur (other than to creatures using the ocean surface, which prior to man were a rather restricted commodity – Portuguese men-of-war, for example). So while the Panthalassa that occupied the rest of the world’s surface when Pangaea was most of the land surface may have spawned some tremendous cyclonic storms, only the ones that impacted the continent, which would be quite few in number by comparison with those that stayed out to sea, would be significant.
Taking that all in all, I’d say that there were fewer hurricanes, cyclones, or typhoons making landfall in the Permian and Triassic than today, though the ones that did probably did more ecological damage, having had opportunity to grow much bigger. During dinosaur times, there were no doubt far fewer Atlantic storms and many more Pacific storms, the former being smaller and less destructive and the latter as a rule larger and more destructive than typical developments today, for an average of about the same effects as today.
I was wondering if it would be possible to do a computer model that would cover the possibilities – I know direct evidence would be hard to come by, though there is direct evidence of plenty of other natural disasters – the mud slumps already cited and volcanic eruptions are well-known fossil creators, and the distribution of bones in some sites has made it evident that they came from a river flood. Lightning strikes, when they hit sand, also produce fossils. It’s hard to say what the fossil mark of 'cane might be.
A computer model that consistently produced 'canes of the size and frequency we now have, based on current atmospherics and land mass distribution, might be interesting if applied to, say, an early Triassic scenario before the continents became too widely separated. I don’t know enough about shearing forces to say whether it would be possible to come up with an accurate model of them that far back.
I recommend reading Stephen Barnes’ Mother of Storms in this context. This SF book postulates significantly-warmer oceans as a result of methane outgassing in the Arctic, and enormously-more-powerful hurricanes as a result.
Near the beginning of the book, he has a warm-water lane (27C and above) all the way across the Pacific. The warm water is wide enough that, after traveling westwards in the lower latitudes and growing as usual, a storm can travel eastwards in the midlatitudes and keep growing. The resulting hurricane reaches windspeeds of 330 km/h and scrubs Hawai’i to bare rock.
Though of course the duration and water load of the winds could make a significant difference, I doubt 330 km/hr (205 mph) winds would scrub Hawaii to bare rock. I life in New England, and we’ve had recorded winds (Mt Washington Weather Station) of 372 km/hr (231 mph) Admittedly, the top of Mt. Washington is mostly bare rock anyway, but what little there was (like the early 1900s wood cabins housing the weather station) survived nicely. If you’d visited the next day, you’d never have known anything had happened.
Perhaps a more apt example was 1997’s Typhoon Paka in Guam, which had sustained winds of “merely” 282 kph (175 mph) but had peak recorded winds of 230 mph (370 kph). While it was devastating, it didn’t come anywhere near scrubbing Guam down to bare rock. Though several other large typhoons also hit Guam and its surrounding islands that year, the landscape was not appreciably affected.
Picking up on Sunspace’s point – Barnes set up a near-future scenario in which a set of coincidences caused a sudden and substantially higher change in the greenhouse effect, producing much larger “hurricane breeding zones” and hence a couple of monster hurricanes – the “Mother of Storms” of the book title.
It would be quite interesting to explore the real-world scenario and impacts of that ‘what if’ situation – suppose the areas where hurricanes can form were significantly larger and in place for more of the year than they are at present, whether from the impacts of global warming or sheer coincidence of an abnormally warm summer season. What might be the real results? I suspect the scouring of large Pacific islands and massive “Deep Impact”-style destruction in East Asia and on the U.S. coasts would not be the case – but what would happen?
