“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

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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

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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