“Feeling under the weather?”
BIOWEATHER
Pests: locustsParasites: worms, flukes
and spirochetesDiseases: ‘emerging’
viruses
Locusts and grasshoppers
in Africa
Desert locustsLocusts eat their own weight (about 4 g) in plant matter per day; a swarm may consist of a billion insects, and 100 swarms may be on the move during a plague (eating 400 kilotons per day).A swarm can fly 300 km in one day, remain afloat out at sea (and take off again), and remain active even when covered by snow.
egg
juvenile
solitary hopper
gregarious locust
Source: BBC website
Last major locust plague (1987-89)
Outbreak: 1967-68. Drought in Africa in 1970’s and early 80’s produced a recession in the locust cycle. Heavy rains in 1987-89. In Jan. 1987 large swarms formed in Saudi Arabia. Despite the Saudis’ massive control efforts some of the swarms crossed the Red Sea and gradually moved west to Mauritania and north to Algeria. Western Sahara had heavy rains, and threat to the states in North Africa was so grave that Morocco deployed 200 000 soldiers to combat the swarms.Strong winds aloft (associated with Hurricane Joan) carried some of these locusts across the Atlantic to the Caribbean in October 1988. They reached as far west as Jamaica.
Upsurges in 1990’s
1996-1998: Local upsurge in Red Sea Basin (from Yemen - Saudi Arabia to
Sudan - Ethiopia - Somalia -Eritrea)
2004 outbreaka) map of outbreakb) swarms in Mauritaniac) Aerial spraying
in the western Sahara
a b
c
CYPRUS,EGYPT
Nov.
Source: BBC website
QuickTime™ and aDV/DVCPRO - NTSC decompressor
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Monthly snapshots of outbreaks from Nov. 2003-Nov. 2004
gregarious adults gregarious juveniles
Rainfall and the Australian
plague locust
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Sources: BBC website; www.affa.gov.au; www.bom.gov.au/silo/products/cli_chg
Sca
le o
f out
brea
k
2004 plague
Combating locusts
Good news:•Prediction of swarm development and movements much easier with satellites which can identify areas of new plant growth and wind patterns in remote desert areas.•Aerial spraying of young (pre-swarm) populations with insecticide (e.g. malathion) is still effective.•New biopesticide (Metarhizum fungus = “Green Muscle”) kills locusts and grasshoppers in 3 - 4 weeks.•Trigger for gregarious behaviour (hind leg stimulation!) recently identified; may lead to suppression techniques.•Locusts are more nutritious than beef - “Cooking with Sky Prawns” (20 recipes for cooking locusts from Australia)
Combating locustsBad news:•Highly cyclical nature leads to poor maintenance of surveillance and control equipment during recessions.•Political conflicts create refuge areas for swarms: The western Sahara desert is littered with land mines from the Polisario war.Morocco-Algeria-Libya are reluctant to cooperate;The Sudan is currently in the midst of a civil war; locust control is not a priority for the local government or for international humanitarian agencies.
Malaria (Ital: “bad air”)
Currently: ~3 000 M people at risk; ~50% of the world’s population; 300-500 M cases; ~80% in sub-Saharan Africa)
Deaths: ~1 M annually
Vector: transmitted by bites of female mosquitoes in the genusAnopheles (50-60 of the >300 species), usually at night.
Parasites: Four species of Plasmodium. P. falciparum causes the most severe symptoms.
Symptoms: high fever, dehydration, death in severe cases
Global incidence of malaria
Map area equivalent to cases per 100 people (92% of all cases in Africa)
Source: www.worldmapper.org/posters/worldmapper_map229_ver5.pdf
Role of climate in malaria outbreaks
Moisture: Breeding success of mosquitoes is maximized in nutrient-rich pools; populations are most abundant in wet weather. Too much rain, however flushes breeding pools and reduces mosquito populations.
At temperatures between 25-30°C the malarial parasites and mosquito larvae mature quickly, the adult mosquitoes live longer, and female mosquitoes feed more frequently. The transmission cycle is <30 days under these conditions.
Climate and malaria outbreaks
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Weekly malaria prevalence in Niger for the period 2001-2003, and average monthly precipitation in the Sahel (thick blue line)
rain >> pools >> evaporation >> nutrient enrichment >> mosquito breeding
Malaria epidemic: Sri Lanka (Ceylon) 1934-5
Malaria was hyperendemic in the dry north of island but rare in the wet south (heavy rains flush mosquito larvae away). Southern population had little natural immunity.
0 25 50 75 days
case
s
Drought in 1934-5 resulted in major epidemic in south. 30% of population fell ill; 80,000 died. Illustrates Ross’s “math of malaria” (~25d fever cycle)
1500
1000
>2000
Summer monsoon
1000
100
100
1
2005-6 ~10 000 cases in South Africa2006-7 ~3 000 cases in South Africa
Malaria resurgence ….. and decline
The demise of malaria in the
USA (1882-1946)
Why was malaria widespread in northern Europe in the LIA?
from: Reiter, P. 2000. "From Shakespeare to Defoe: Malaria in England during the Little Ice Age” Emerging Infectious Diseases vol. 6
LittleIce Age
Climate and viral diseaseViral disease transmission
Ecology of flavivirus outbreaks(e.g. dengue, West Nile encephalitis)
Ecology of bunyavirus outbreaks(e.g. sin nombre)
Emerging viruses
Flavi- Yellow feverDengueEncephalitis
Mosquitoes (Aedes)Mosquitoes (Aedes)Mosquitoes+birds
Arena- Lassa feverMachupoJu nín
Aerosols+rodentsAerosols+rodentsAerosols+rodents
Bunya- HantafeverSabíaRift Valleyfever
Aerosols+rodents
Aerosols+rodentsMosquitoes+sheep & cattle
Filo- EbolaMarburgfever
direct? + monkeysmonkeys
Family Disease Vector and Reservoir
West Nile virus •West Nile virus is a strain of flavivrus, closely related to Japanese encephalitis. Previously reported from Africa and adjacent areas of southern Europe and western Asia. Previous outbreaks in Israel, France and S. Africa. and Romania (1996; 450 cases, 39 deaths).•It joins at least four other encephalitis viruses in North America, one of which [St. Louis encephalitis] is widespread. •Likely introduced into N. America by an infected international traveler or as a result of the importation of exotic birds.
fever, aches, stupor, (brain lesions, coma, paralysis, death?)
direct transmission?
1999
1999 to 2001
November, 2003
November, 2004
Total number of cases by state
2002 2003 2004 2005 2006
Nova Scotia 0 2* 0 1* 0
New Brunswick 0 1* 0 1* 0
Québec 20 17 3 4 1
Ontario 394 89 13 95 42
Manitoba 0 142 3 55 50
Sask. 0 937 5* 58 19
Alberta 0 272 1* 10 39
BC 0 20* 0 0 0
Yukon/NWT 0 1* 0 0 0
CANADA 414 1481 25 225 151
Is the WNV threat over in N. America?
*related to travel outside province
WNV cases - Canada
Impactors
Geog 312Ian Hutchinson
The ThreatRisk Assessment
Protection(?)
Asteroids
• Asteroid orbits continuously modified by gravitational perturbation of asteroid belt.
• About 2000 asteroids currently have orbits that cross that of Earth (= NEO’s :Near Earth Objects).
• Orbital trajectories of 200 NEO’s are known; i.e. the paths of 90% of the asteroids that threaten Earth are unknown.
• Largest NEO’s have diameters of about 8 km; the orbits of about 35% of asteroids >5 km diameter are known.
Comets• About 10-20% of comets (piles of
rubble and ice with tail =“coma”) are in Earth-crossing orbits.
• Some 700 long-period comets (>200 yrs) known.
• Periodic comets (≤200 yrs) - 95% have lost their coma (= “stealth comets”) 25 known, 1500 > 1 km diameter may exist.
• Our first warning is likely to be their initial entry into Earth’s atmosphere.
Effects
• Direct (predominantly local)Impact crater plus blast-wave and firestorm
• Indirect effects (may be global)Dust veil (large impactors)Acid rain (large impactors)Tsunami (oceanic impacts)
Impact craters on Mercury
indicative of the protective effects of Earth’s atmosphere
Impactors
• <10 m diameter - burnup in atmosphere.
• Category 1: 10-100 m diameter - disintegrate in atmosphere; exploding fragments create “airburst” (e.g. Tunguska event).
• Category 2: 100 m - 1 km diameter - capable of striking surface, forming impact craters, effects local (e.g. Meteor Crater, AZ).
• Category 3: > 1 km in diameter may cause severe global effects (e.g. Chicxulub impactor, Mexico)
Category 1: Tunguska
• 50-60 m diameter stony meteor? exploded in June 1908 above central Siberia. Energy release ~ 10-30 MT TNT (~1 000 – 3 000 Hiroshima bombs)
• Radius of destruction: 25 km (= 2 000 km2).
• Recorded by seismograms in Irkutsk and barograms in London.
Tunguska impact areafrom a local perspective
First photos of the effects of the Tunguska fireball were taken by a Soviet expedition in the 1920’s, more than a decade after the
event.
Category 2: Meteor (a.k.a. Barrington) Crater, AZ.
1200 m wide, 180 m deep
Impact occurred about 50 000 years ago; it is likely that all plant and animal life
within 10 km of the impact site was vapourized.
Category 3
Category 3
Veil of dust in atmosphere for months/years
Crater 10 - 15x diameter of impactor
Reduced sunlight
Food chain collapses
Reduced photosynthesis Lowered global temperature
Polar and temperate areas uninhabitable
Category 3
Firestorm spreads from impact site
Very high temperatures at impact site
Intense smokefrom firestorm:
reduced sunlight, etc.
Reduced photosynthesis; food chain collapses
N2 in atmosphere burns
Nitric acid produced;acidic precipitation
Clay
Sandstone
Coal
Asteroid impact dust deposit (clay layer) marking K-T boundary at 65 Ma BP in Colorado, 2500 km from impact
site.
Shale
Tertiary
Cretaceous
Rock hammer for scale
Risk Assessment:Spacewatch Project
• Initiated at the University of Arizona in early 1980’s, the Spacewatch project involves automated searches of the sky for 20 nights per month for new asteroids (particularly NEOs) and short-period comets. Now includes cooperative efforts with other observatories in North America, Europe and Australia.
Hazardclassification
The Palermo scale was developed to categorize potential impact risks. Intended for use by specialists.
The scale value PS is given by
PS = log10 [PI / (fB . DT)],
where PI is the impact probability of the event in question and DT is the
time until the potential event, measured in years. The annual background impact frequency,
fB = 0.03 . E-4/5
is the annual probability of an impact event with energy (E, in megatons of TNT) at least as large as the event in
question.
Hazardclassification
The scale was devised by
delegates to an international
symposiumin Torino (Turin; Italy) in 1999 as
a means of communicating
risk to the public.
Potential impactor: (2002 NT7: Feb 01/2019?)
2002 NT7 is 2 km in diameter
Initial reports based on on
only a handful of observations of NT-7’s orbit
in 2002
based on an assumed initial velocity of 25 km/s
*
*
The NT7 scare [2002]
NEO Year rangePotentia
l impacts
Probability of
impact
Velocity (km/s)
Diam.
(km)
Palermo scale
Torino Scale
2007 VK184
2048-2057 4 1.0e-04 15.630.13
0-1.82 1
2004 MN4 2036-2069 3 2.2e-05 5.870.27
0-2.41 0
2004 XY130
2009-2107 87 5.0e-07 3.060.50
3-2.73 0
Current* top three NEOs(ranked by Palermo scale)
* as of Nov. 27, 2008 (http://neo.jpl.nasa.gov/risk/)
Extremely unlikely to collide with Earth in this period
The probability of impact during this time is 0.0001 (~1:10,000)
VK184 will cross the Earth’s orbit four times between AD2048 and 2057.
N.B. 2002 NT7 no longer features on the list of potential impactors.
NT7
Ocean impact tsunami
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
Source: www.lanl.gov/worldview/news/tsunami.mov (Stephen Ward)
airbursts
after Ward and Asphaug (2000)
NT7
vi=impactor velocity; i=impactor density; h=water depth
Tsunamis reach all coasts within 10 hours of impact
after Ward and Asphaug (2000)
1000-year probabilities (%) of impact tsunami exceeding critical wave height at typical coastal and mid-ocean sites in the
Pacific Ocean
Waves Tokyo,Japan
Hilo,Hawaii
5m 4.2 8.310m 1.6 2.325m 0.4 0.550m 0.1 0.2
after Ward and Asphaug (2000)
Impact tsunamis: bathymetric effects
Impact site
“Barriers” =ridges
“Fingers of God”
N. America
AfricaEurope
=abyssal canyons;up to five-fold
increase in wave height at coastline
Deep Impact Project
NASA detonated a 370 kg impactor (= 5 T of dynamite) in a near-Earth comet (9P/TEMPEL-1) on July 4, 2005.
• The primary purpose was to study cometary structure (which proved to be less icy and dustier than expected), but the experiment may illustrate the effects of trying to deflect or fragment such objects before they reach Earth.
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•BUT - is it advisable to create numerous projectile fragments?
View of the nucleus of the comet 9P/Tempel-1
from impactor