The 20 th century was a time of accelerating global change:

The 20th century was a time of accelerating global change:

time

• the human population spike• the consumption spike• the carbon dioxide/global temperature spike• the extinction spike

4 “spikes” of global change

Animated mapHuman

Population clock

Future Population Growth

Geographic Distribution of Human Consumption

Per-capita consumption

UNEP statistics

Increases in per-capita consumption is driven by developing countries

The “new consumers”:

New consumers are persons with purchasing power of at least $2,500 per year.

In 2000, the number of recently emerged “new consumers” was estimated at 1 billion. They join 850 million long-established consumers.

Most new consumers come from developing or transition countries.(China, India, Indonesia, Brazil, Russia, Mexico, Philippines, Turkey, Thailand….)

Most significant environmental impact comes from:

• diet shift towards meat (8 kg grain per 1 kg beef)• cars

Myers and Kent, PNAS, 2003:

• Forest converted to pasture or production of cattle feed.• Desertification of marginal rangelands in semi-arid and arid regions.• Production of greenhouse gases (CO2, methane, nitrous oxide).

• Decreased water quality through runoff from fertilized fields and feed lots.• Introduction of invasive species.

1.28 billion cattle occupy nearly 24 percent of earth’s landmass.

They weight more than the entire human population.

The carbon dioxide and associated temperature spike took off in the early 20th century

Extinctions

Half of forest cover destroyed after the Agricultural Revolution.

The Age of Exploration: millions of birds, seals and porpoises slaughtered by European hunters, hundreds of

species lost.

The Green Revolution kills off crop diversity and decimates wild pollinators and soil microbes.

Rapidly accelerating habitat destruction, connecting previously isolated ecosystems, allowing bioinvasions

Over 100,000 slash and burn fires set each year. Tropical forests lost at a rate of one football field per second.

Three species extinctions per hour.

Global warming. World temperature highest in human history. Migratory animals begin to die off.

Biologists surveyed by the Museum of Natural History (NY) say that current extinction rate exceeds last mass

extinction event, when dinosaurs died.

“God’s Last Offer”, Ed Ayres, 1999

The species extinction spike

Number sof species eliminated world-wide per year

What about mass extinctions?

Cretaceous-Tertiary Date: About 65 million years agoDeath Toll: Up to 75% of marine genera; 18 percent of land vertebrates, & the dinosaurs

Late TriassicDate: About 200 million years agoDeath Toll: 52% of marine generaPossible Causes: Severe volcanism; global warming

Permian-TriassicDate: 286-248 million years ago;  Death Toll: 84% of marine genera; 90-95% of marine species; 70% of land species.Possible Causes: Asteroid or comet impact; severe volcanism; dramatic fluctuations in climate or sea level

Late DevonianDate: About 365 million years ago Death Toll: 55 percent of marine generaPossible Causes: Global cooling; loss of oxygen in oceans; impact

Late OrdovicianDate: About 440-450 million years ago;  Death Toll: 60 percent of marine generaPossible Cause: Dramatic fluctuations in sea level

Late Pre-cambrianDate: About 650 million years ago;  Death Toll: most unicellular organismsPossible Cause: O2 enrichment of atmosphere.

The other major extinction events in earth history:

Just some of the hundreds of similar headlines:

One Quarter Of All Mammal Species Face Extinction Soon (IUCN-- 2000)

Monkeys, Apes Are Being Eaten to Extinction (Associated Press)

Mass Extinction of Freshwater Creatures Forecast (WWF Report)

90% OF ALL LARGE FISH GONE FROM WORLD'S OCEANS (Nature-- 2003)

North Sea Undergoing Ecological Meltdown (U.K. Independent)

Amphibians Declining Worldwide (Boston Globe)

Reptiles Vanishing Faster Than Amphibians (CNN)

Migratory Birds and Animals Rapidly Dying Out (Environment News Service)

Forests Face Global Extinction (United Nations)

1000's Of Medicinal Plants Being Harvested to Extinction (Australian Broadcasting Co.)

25% Of World's Conifers Threatened With Extinction (IUCN)

One in Eight Birds Face Extinction (BirdLife International)

90 Percent of Great Ape Habitats Will Be Destroyed by 2030 (United Nations)

…

The Pleistocene extinction (of the last ice age) was different from previous mass extinction events:

1. Selective disappearance of megafauna.

2. Occurred at different times on different land masses.

3. Previous ice ages did not result in similar extinctions.

Species loss across America, Europe and Australia:

100% of herbivores > 1000 kg 75% of herbivores 100-1000 kg 41% of herbivores 5-100 kg < 2% of herbivores < 5kg

1. Selective disappearance of megafauna:

2. Occurred at different times on different land masses.

Megafauna extinctions in % species lost

The extinctions coincided with the arrival of human hunters

and gatherers to continents...

Except Africa!

World Wildflife Fund estimates

Species numbers are declining on land and in aquatic systems

Source Millenium Ecosystem Assessment

The current extinction rate is orders of magnitude higher than the long-term average extinction rate.

Total Number of threatened species by continent

Source: EarthTrends 2007, using data from the IUCN Red List of Threatened Species 2007.

Anegada Ground Iguana, Virgin Islands

The cucumber tree, Yemen

Mountain GorillaCentral Africa

Ambositra Palm Madagascar

Cycas transachana, Thailand

Kirtland's Warbler

Biodiversity Hotspots

The Atlantic Coastal Rainforest of Brazil

)450 tree sp./ha. highest richness on earth(

194585.4% of Bahia

state was forest.

1960 :50% left.

1990: 6% left.1974 :25% left.

The multiple impacts of humans on biodiversity and ecosystems:

• Overexploitation of game animals.

• Purposeful setting of fire to manipulate the movement of game animals.

• Clearing of natural ecosystems for agricultural production.

• Introduction of non-native species.

• Overfishing.

• Pollution: new inputs into material cycles at a global scale (nitrogen, carbon dioxide, pesticides, …).

Causes of recorded vertebrate extinctions:

Rapid climate changes

Over-exploitationPollution

Habitat loss

Loss of biodiversitySpike 4

Human population sizeSpike 1

CO2 and othergreenhouse gases

Spike 3

ConsumptionSpike 2

Fossil fuel burning,Slash & burn of old forest

Fertilizer production

Diet and lifestyle changes of “new

consumers”