Environmental Damage from Asteroid and Comet Impacts

by Michael Paine (mpaine AT tpgi.com.au)
Updated 27 May 2004. Caution: Many items are speculative at this stage.

This table is associated with my article "Source of the Australasian Tektites?" that appeared in the February 2001 issue of Meteorite (no longer online). PDF preprint (300K).  Update 9 Jan 20 Livescience: 800,000 Years Ago, a Meteor Slammed Into Earth. Scientists Just Found the Crater (thanks Paul Curnow ) Comment: the crater is estimated to be only about 15km across but is thought to be elliptical, suggesting a glancing impact which might account for the extensive tektite field. The asteroid/comet would have had a diameter of about 800m which means that the destroyed trees at Bose appear to be too far away to have been knocked over by this impact.

See also the Bioastronomy 2002 paper by Michael Paine and Benny Peiser: The Frequency and Consequences of Cosmic Impacts Since the Demise of the Dinosaurs (280K PDF).

There are many environmental effects from the impact of a large asteroid or comet (diameter 1 kilometre or more) with the Earth. These effects depend mainly on:

• the characteristics of the asteroid or comet (size, speed, mass, material composition and strength, trajectory)
• the characteristics of the impact site (land, ice or ocean, latitude, types of rocks) and
• the prevailing  climatic conditions (stage of ice age, association with other impacts, seasons - for smaller impacts).

For the effects of smaller impactors see Tsunami from Asteroid Impacts. For some of the consequences of impacts see Impacts and Extinctions.
I have not had a chance to check these values against the new (9 Apr 04) calculator available at the University of Arizona.

Asteroid Diameter	1 km (1000 yards)	2 km (1.2 miles)	5 km (3 miles)	10 km (6 miles)
Kinetic Energy (millions of megatons of TNT)	0.1	1	10	100
Average impact interval (years)	200,000	500,000	10 million	100 million
Crater Diameter - rim to rim and [transient]	24 km  [11 km]	46 km [20 km]	100 km [40 km]	200 km [70 km]
Radius for ignition from fireball radiation (within seconds)	150 km	250 km	600 km (but see ballistic ejecta)	1800 km (but see ballistic ejecta)
Blast radius for 4psi overpressure (500km/h winds, buildings destroyed). Also bombardment by debris  [1 psi overpressure] (trees knocked over, glass windows shatter) (within hours)	130 km [300 km]	180 [400 km]	470 km [1100 km]	1800 km [4000 km]
Dust and debris fallout cover the ground and cause severe mud flows. (months)	300 km	400 km	1100 km	4000 km
Area for firestorm ignition due to radiation from ballistic reentry of ejecta (within hours)	Local	Local (600 km radius)	Regional (5000 km radius)	Global in hours
Earthquakes, hurricanes and tsunami (hours to months)	Regional	Regional	Global	Global
Dark skies and cooling from dust, soot and oxides of sulfur.	Regional freezing for weeks. Moderate global effects for weeks (equivalent to Tambora volcanic explosion).	Skies darker than darkest cloud cover. Global drop of 8C for weeks then moderate global effects for months (no summer).	Severe global effects, day becomes night for months.	Very severe global effects. Day becomes night for months. Freezing conditions away from coastlines.(KT event "winter" lasted around 3 years)
Acid Rain,  pyrotoxins (poisons from fires) and heavy metals.	Regional for months	Regional for months	Global for months	Global for years
Ozone destruction (hazard from UV radiation)	Partial global destruction for years	Severe global destruction for years	Total global destruction for years	Total global destruction for decades
Global Greenhouse heating from water and CO2	Negligible	Minor for years	Moderate for decades	Major for centuries
Global iridium layer (nanograms per square cm) - a signature of the impact.	0.4	2	8	80
Plant growth and extinctions.	Disrupted for months. Some global crop failures.	Disrupted for years. Some regional extinctions. Global crops failures.	Photosynthesis stops for months. Decades for plants to recover. Major regional extinctions.	Hundreds of years. Global mass extinctions

Notes:
1. Most values are very approximate - within an order of magnitude. LPL has a page on the environmental effects of impacts.
2. Crater diameters were derived from Jay Melosh's Crater Calculator, using dense rock impactor and target surface and a 45 degree impact angle. Two diameters are given, the transient crater formed at the instant of the explosion and the rim-to-rim crater that forms after the transient crater collapses, the ground slumps (usually in concentric rings - see Melosh 1997)  and the "rim" spreads further out. The transient crater is important for calculating environmental effects since it is associated with ejected material. The rim-to-rim crater is the one that geologists should be looking for. It is possible that the Indo-China event involved a very low impact angle.
3. Fireball ignition radius and ballistic ejecta ignition radius from Toon Figure 16. See updated figures at SWRI News Release  (Aug 04)
4. 4 psi Blast radius from Toon Figure 5. 1 psi blast radius based on 4 psi radius times 2.3 (average resulting from a simulation using Lewis's software). Rock projectiles are assumed to be deadly over a similar range to the 4 psi blast wave. The dust and debris fallout is assumed to affect an area which is similar to that of the 1 psi blast wave, as was apparently the case with the Mt St Helens volcanic eruption. Dust fallout and projectiles tend to be ignored in most papers on environmental effects of impacts - perhaps because they tend to be confined to regions already devastated by the blast wave. However, the fallout would severely hamper the recovery of a region - as was the case with Mt St Helens.  Update May 04: The LPL calculator gives a blast radius substantially less than  that shown here (about one fifth). Jay Melosh informs me that the earlier work did not account sufficiently for the limited depth of the atmosphere and the Earth's surface curvature.
5. According to Turco, atmospheric nitrous oxide created by the "small" 1908 Tunguska event probably caused the 30% depletion in the northern hemisphere ozone shield that was observed in the year following the explosion.
6. Global iridium from Gersonde. Note that there will be greater concentrations of iridium near the impact site, particularly with the smaller impacts.
7. "Earthquakes" are mostly due to premature initiation of terrestrial earthquakes as the impact shockwaves pass around the Earth's crust.
8. Another indirect consequence of impacts may be the release of huge amounts of methane (a potent Greenhouse gas) from undersea deposits of methane hydrates. See:

• Flammable Ice, Scientific American, Nov 1999,
• Did Asteroid-Induced Firestorm Destroy the Dinosaurs? (speculation that the earthquakes associated with the KT impact disturbed methane hydrate deposits and released the methane) and
• 'Termination of global warmth at the Palaeocene/Eocene boundary through productivity feedback', Nature 14 Sep 2000 (release of methane hydrates in this case may have been due Greenhouse warming from CO2 - an impact does not appear to be associated with this boundary).

References and further reading

Ball P (2000)  When it's cool to be cool , Nature Science Update 4 August 2000.

BBC (1998) Meteorite is possible ice age culprit - 3.3 million years ago but discuss impacts and climates.

Chapman C. (2001) White Paper on Impact Hazard, South West Research Institute.

Garshnek V., Morrison D. and Burkle F. (2000) 'The mitigation, management and survivability of asteroid/comet impact with Earth'  J Space Policy Vol 16 (2000) 213-222 (not online)

Gersonde R., Kyte F.T., Bleil U., Diekmann B., Floress J.A., Gohl K., Grahl G., Hagen R., Kuhn G., Sierros F.J., Volker D., Abelmann A. and Bostewick J.A. (1997) 'Geological record and reconstruction of the late Pliocene impact of the Eltanin asteroid in the Southern Ocean', Nature No.390, 357-363, 27 Nov 1997. http://www.nature.com/

Gerasimov M.V. (2000) 'Production of toxins during an impact and their possible role in a biotic mass extinction', International Conference on Catastrophic Events and Mass Extinctions: Impacts and Beyond, 9-12 July 2000, Vienna, Austria, abstract no.3051.

Glass B.P. and Pizzuto J.E. (1994) 'Geographic variation in Australasian microtektite concentrations: Implications concerning the location and size of the source crater', J of Geophysical Research vol 99 no.E9, 19075-19081, Sept 1994 (abstract only)

Howard K.T., Bunopass S., Burret C.F., Haines P.W. and Norman M.D. (2000) 'The 770KA tektite producing impact event: evidence for distal environmental effects in NE Thailand', Proceedings of 31st Lunar and Planetary Science Conference, March 2000. http://www.lpi.usra.edu/meetings/lpsc2000/

Harington C.R. - editor (1992) The year without a summer? world climate in 1816. Canadian Museum of Nature, Ottawa 1992. Includes research on Tambora volcanic explosion.

Hartung J. and Koberl C. (1994) 'In search of the Australasian tektite source crater: the Tonle Sap hypothesis', Meteoritics.

Koeberl C.  and B.P. Glass (2000) 'Tektites and the Age Paradox in Mid-Pleistocene China', Science, 289, No 5479, 28 Jul 2000, p. 507. and the response by Potts et al. http://www.sciencemag.org/
Kring D.A., Melosh H.J. and Hunten D.M (1995) 'Possible climate perturbations produced by impacting asteroids and comets', Meteoritics.

Kring D.A. and Durda D.D. (2001) 'The distribution of wildfires iginited by high-energy ejecta from the Chicxulub impact event', Proceedings of 32nd Lunar and Planetary Science Conference. March 2001.

Larick R. and Ciochon R. (1996) 'The African emergence and early asian dispersals of the Genus Homo', American Scientist, Nov-Dec 1996. http://www.amsci.org/articles/96articles/Larick.html

Lewis J.S. (1999) Comet and asteroid impact hazards on a populated Earth, Academic Press. Comes with simulation software.

Melosh H. J. (1997) 'Multi-ringed revelation', Nature 390, 439 - 440 (1997) Macmillan Publishers Ltd.

O'Keefe J., Lyons J. and Ahrens T. (2000) 'Impact mechanics and implications for extinctions', International Conference on Catastrophic Events and Mass Extinctions: Impacts and Beyond, 9-12 July 2000, Vienna, Austria, abstract no.3142.

Robock Alan (2001) Volcanic eruptions and climate

Schmidt G., Zhou L and Wasson J. (1993) 'Iridium in sediments containing large abundances of Australasian microtektites from DSDP hole 758B in the Eastern Indian ocean and from DSDP hole 769A in the Sulu Sea', 24th Lunar and Planetary Science Conference (abstract only)

Schmidt G. and Wasson J.T. (1993) 'Masses of the impactor, the Australasian tektites, and size estimates of the main source crater', Meteoritics, vol 28 no.3, 430, Jul 1993.

Schnetzler C.C. and Mchone J.F. (1996) 'Source of the Australasian tektites: Invetsigating possible impact sites in Laos', Meteoritics and Planetary Science, no.31 73-76, 1996.

Steel D. (1995) Rogue asteroids and doomsday comets, Wiley.

Toon O., Morrision D., Turco R.P. and Covey C. (1997) 'Environmental perturbations caused by the impacts of asteroids and comets', Reviews of Geophysics, vol 35, no.1, 41-78, Feb 1997.

Turco R., Toon O., Park C., Whitten R., Pollack J. and Noerdlinger P. (1982) 'An analysis of the physical, chemical, optical and historical impacts of the 1908 Tunguska meteor fall', Icarus vol. 50 Apr 1982 1-52.

Yamei H., Potts R., Baoyin Y., Zhengtang G., Deino A., Wei W., Clark J., Guangmao X and , Weiwen H. (2000) 'Mid-Pleistocene Acheulean-like stone technology of the Bose Basin, South China', Science, vol 287 1622-1626.

Vrba E. - editor (1995) Paleoclimate and evolution, with emphasis on human origins, Yale University Press.
 

Updates (latest at end)

• 30 Jan 01 Scientific American: The Modern Human Origins Morass.
• 31 Jan 01 Science: WHAT DRIVES SOCIETAL COLLAPSE? - the accumulation of high-resolution paleoclimatic data ... provide an independent measure of the timing, amplitude, and duration of past climate events. These climatic events were abrupt, involved new conditions that were unfamiliar to the inhabitants of the time, and persisted for decades to centuries. (copy at CCNet).
• 21 Feb 01: A PRELIMINARY SEARCH FOR EVIDENCE OF IMPACT-RELATED BURNING NEAR THE MJØLNIR IMPACT STRUCTURE,BARENTS SEA Wendy S.Wolbach 1 ,Susanna
  
Widicus 2 ,and Henning Dypvik, Lunar and Planetary Science XXXII (2001)
• 2 Mar 01: THE COMET/ASTEROID IMPACT HAZARD: A SYSTEMS APPROACH - new paper by Chapman, Durda and Gold has a similar table of environmental effects.
• 6 Mar 01: THE YEARS WITHOUT SUMMER: TRACING A.D. 536 AND ITS AFTERMATH   .
• 24 Mar 01 ENN: Researcher Says Tons of the Moon on the Earth; Tektite Events May Have Triggered Extinctions - claims that lunar volcanic explosions produced the tektites on Earth.
• 16 Jun 01 JPL: Pinatubo: 10 Years After the Big One.
• 27 Jul 01 BBC: Disaster that struck the ancients - no suggestion of an impact-related event (so far!) but an interesting report on the effects of climate change.
• 24 Aug 01 Scientific American: Triggering a Snowball - DID METHANE ADDICTION SET OFF EARTH'S GREATEST ICE AGES?
• Scientific American June 1979: The Year without a Summer  - far reaching effects of the 1816 Tambora volcanic explosion (not online). Also Kratatau, Nov 1983, Mt St Helens Mar 81.
• 19 Jan 02 Uni Arizona: Environmental effects of impacts (site under development)
• 24 Jan 02 GSA: The K-T Impact Extinctions: Dust Didn't Do It
• 22 Feb 02 ABC (Dr Karl): Tibet Cooled The World - 50 million years ago when India collided with Asia at the frightening speed of 20 centimetres per year...
• 4 Sep 02 Uni Arizona: Earth Suffered Pulses of Misery in Global Wildfires of 65 Million Years Ago.
• 6 Dec 02 Science:  Environmental Effects of Large Impacts on Mars - Science 2002 298: 1977-1980. [Abstract]
• 4 Nov 03 Uni Arizona: Impact generated wildfires.
• 19 Nov 03 SciAm: The Day the World Burned - Chicxulub impact (payment needed for full article)
• 21 Jan 04 Nature: Volcanic impact not so chilling - Super-eruptions might not be as environmentally devastating as we thought (CC)
• Spaceguard Foundation - advice about climatic effects of ocean impacts (there is much to learn).
• 9 Apr 04 Uni Arizona:  WEB-BASED PROGRAM CALCULATES EFFECTS OF AN EARTH IMPACT -