Summary: about shockwaves, the various catastrophic threats to civilization — even to life on Earth. There are so many, often with believers who warn that this threat deserves the most drastic action. At the end is a recommendation, a better way to prepare.
Shockwaves: low probability but high impact events. Difficult to predict when they will hit. Difficult to forecast their probability of occurrence. Results: perhaps catastrophic to civilization, to humanity, perhaps to life on Earth.
For mysterious reasons, some people focus on one specific shockwave scenario. It’s potential for damage mesmerizes them, and — blind to other shockwave scenarios — they call for massive resources to prevent it or mitigate the resulting damage. Peak oil and human-caused climate change are perhaps the major examples of this in our time, as pollution and atomic war were for the previous quarter-century. Note that to many true believers the latter were almost-certain dooms, yet we seem to have avoided them with only moderate effort (both remain as threats, however). Perhaps we were just lucky.
Another shockwave — from the sky
Here we briefly consider another “shockwave” — collision of a large meteoroid, asteroid or comet (generically: bolides) with the Earth. For background see the entry on impact events on Wikipedia.
This post does not compare different shockwaves scenarios — AGW vs. asteroids vs. super-volcano eruptions. That would be valuable, but requires a multi-disciplinary team of experts (see my recommendation at the end of the post). The intent here is to remind ourselves that this is a dangerous world containing many threats. We must not let awareness of some threats blind us to the others.
1. “Mega-tsunamis more common than we think“, ABC 16 November 2006 — Like so many articles about shockwaves, they allude to “critics” who dispute the danger, but do not actually quote any — or describe the basis for their skepticism.
2. “The Sky Is Falling“, Greg Easterbrook, The Atlantic, June 2008 — “The odds that a potentially devastating space rock will hit Earth this century may be as high as one in 10. So why isn’t NASA trying harder to prevent catastrophe?” Excerpt:
{Dallas} Abbott believes that a space object about 300 meters in diameter hit the Gulf of Carpentaria, north of Australia, in 536 A.D. An object that size, striking at up to 50,000 miles per hour, could release as much energy as 1,000 nuclear bombs. Debris, dust, and gases thrown into the atmosphere by the impact would have blocked sunlight, temporarily cooling the planet-and indeed, contemporaneous accounts describe dim skies, cold summers, and poor harvests in 536 and 537. “A most dread portent took place,” the Byzantine historian Procopius wrote of 536; the sun “gave forth its light without brightness.” Frost reportedly covered China in the summertime. Still, the harm was mitigated by the ocean impact. When a space object strikes land, it kicks up more dust and debris, increasing the global-cooling effect; at the same time, the combination of shock waves and extreme heating at the point of impact generates nitric and nitrous acids, producing rain as corrosive as battery acid. If the Gulf of Carpentaria object were to strike Miami today, most of the city would be leveled, and the atmospheric effects could trigger crop failures around the world.
At the start of her research, which has sparked much debate among specialists, Abbott reasoned that if colossal asteroids or comets strike the sea with about the same frequency as they strike land, then given the number of known land craters, perhaps 100 large impact craters might lie beneath the oceans. In less than a decade of searching, she and a few colleagues have already found what appear to be 14 large underwater impact sites. That they’ve found so many so rapidly is hardly reassuring.
Other scientists are making equally unsettling discoveries. Only in the past few decades have astronomers begun to search the nearby skies for objects such as asteroids and comets (for convenience, let’s call them “space rocks”). What they are finding suggests that near-Earth space rocks are more numerous than was once thought, and that their orbits may not be as stable as has been assumed. There is also reason to think that space rocks may not even need to reach Earth’s surface to cause cataclysmic damage. Our solar system appears to be a far more dangerous place than was previously believed.
3. Letter in response to Easterbrook’s article, Prof Nicholas Pinter and Assoc Prof Scott Ishman (Geology, Southern Illinois University), The Atlantic, September 2008:
Gregg Easterbrook paints a vivid picture of impending cataclysmic impacts and urges a massive repositioning of government funding toward asteroid defense. Easterbrook is a distinguished science journalist, but he has spun a sensational Chicken Little story. His article suggests that the probability of a “devastating” Earth impact this century is as high as one in 10. Multiple research studies based on craters, atmospheric strikes, and counts of near-Earth objects suggest probabilities hundreds to thousands of times lower.
The difference between catastrophic Earth impacts every 300,000 years and every 1,000 years is the difference between an infinitesimal threat and looming Armageddon. Guided mostly by solid science, NASA and other national and international agencies have prioritized their programs rationally—monitoring near-Earth objects but not massively shifting resources to some Star Wars–style defense system aimed upward.
Historical and geological records stretching back thousands of years indicate that floods, earthquakes, volcanoes, and tsunamis kill thousands of humans worldwide on a regular basis. In contrast, there’s no evidence that any human anywhere has ever been killed by an extraterrestrial impact. Societies do little enough to mitigate the real and pressing threats from earthly natural hazards without shifting resources to imagined dangers from the wild fringes of the solar system and the wild fringes of science.
4. “Sandia supercomputers offer new explanation of Tunguska disaster“, Sandia National Laboratories, 17 December 2007 — “Smaller asteroids may pose greater danger than previously believed.” Esp note the videos! Excerpt:
The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.
“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”
Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, “We should be making more efforts at detecting the smaller ones than we have till now.”
Note: This is the press release describing “Low-altitude airbursts and the impact threat”, International Journal of Impact Engineering, M.B.E. Boslough and D.A. Crawford, December 2008 — Subscription or purchase only. Abstract and link available here.
There are other shockwaves from the sky!
“Severe Space Weather Events – Understanding Societal and Economic Impacts“, National Academy of Sciences, 2008 — Hat tip on this to Erasmus. Excerpt:
Because of the interconnectedness of critical infrastructures in modern society, the impacts of severe space weather events can go beyond disruption of existing technical systems and lead to short-term as well as to long-term collateral socioeconomic disruptions. Electric power is modern society’s cornerstone technology, the technology on which virtually all other infrastructures and services depend. Although the probability of a wide-area electric power blackout resulting from an extreme space weather event is low, the consequences of such an event could be very high, as its effects would cascade through other, dependent systems.
… we begin with a description of the magnetic superstorms of August-September 1859, by some measures the most severe space weather event on record. {approximately four times larger than anything seen in the past 50 years}. Known as the Carrington event, the 1859 storms were referred to throughout the workshop as an example of the kind of extreme space weather event that, if it were to occur today, could have profound societal and economic consequences, with cascading effects throughout the complex and interrelated infrastructures of modern society.
… The disruption of the telegraph system in 1859 caused problems in communication, but because modern society is so dependent on large, complex, and interconnected technical systems — and because these systems not only are vital for the functioning of the economy but also are vulnerable to electromagnetic events — a contemporary repetition of the Carrington event would cause significantly more extensive (and possibly catastrophic) social and economic disruptions.
About shockwaves
As said on this post many times (originally here) Studying them individually tells us little, as the correct public policy response is “so what?” Shockwave analysis is useful only with analysis of the scenario’s impact AND probability. Otherwise these are just nightmares.
Today analysis of shockwaves is done almost exclusively by special interest groups (often academic or non-profits). We allocate resources to shockwave scenarios based on several factors:
- the group’s access to elite opinion,
- the group’s ability to raise funds,
- their degree to which their shockwave resonates with the public.
Many studies have shown the people have little grasp of these kind of issue, and less understanding of the relevant statistics (probability and risk). There is a better way to do this. Allocation of our limited resources towards these require sketching out (as best as can be done) the full universe of such dangers.
A modest suggestion about applying the precautionary principle to prepare for shockwaves
The precautionary principle is usually applied in an irrational manner to individual threats, such as climate change. There are many high impact – low probability threats, which I call “shockwaves”. Also, the US and world have many mundane needs that deserve funding. Since resources are finite, we must access their relative importance — which few of these special interest groups around each shockwave bother to do. I discuss this in greater length at this post; here is my suggestion:
Commission a group to collect as many shockwave scenarios as possible, with a brief analysis of each. Fortunately there are thousands of interest groups willing to pitch in and help! Then apply a common analytical framework to rate them on both dimensions: probability and impact. The results would prove quite interesting, and allow more rational public policy discussion about which to act upon.
Afterword
If you are new to this site, please glance at the archives below. You may find answers to your questions in these.
Please share your comments by posting below. Per the FM site’s Comment Policy, please make them brief (250 words max), civil, and relevant to this post. Or email me at fabmaximus at hotmail dot com (note the spam-protected spelling).
For more information from the FM site
To read other articles about these things, see the FM reference page on the right side menu bar. Of esp relevance to this topic:
- Posts about Science, Nature, and Geopolitics– articles about shockwaves from climate change and solar cycles.
- One of the most likely “shockwave events: Peak Oil and Energy – my articles and Peak oil and energy – studies and reports.
Posts on the FM site about shockwaves:
- Spreading the news: the end is nigh!, 8 May 2008
- The most dangerous form of Peak Oil<, 8 April 2008
- The “Oil Shockwave” project: well-funded analysis of the obvious, 10 April 2008
- Peak Oil Doomsters debunked, end of civilization called off, 8 May 2008
- What does $120 oil mean for the global economy?, 15 May 2008
- There is no “peak water” crisis, 19 June 2008
- A reply to comments on FM site about Global Warming, 17 November 2008
- We are so vulnerable to so many things. What is the best response?, 30 December 2008
- Comment: warnings about a reversal of Earth’s magnetic field, 30 December 2008
- About our certain doom from the Yellowstone supervolcano, 11 January 2009
