Robert W. Christopherson Charlie Thomsen Chapter 21 Earth and the Human Denominator

Human Population Growth Figure (2010) US: 309 million

Human Impacts I: Human Impacts on the Earth in a Country P: population A: Resource consumption per person T: Production efficiency or environmental impacts per unit resource produced China: 20% world population; India: 17% of world population. US and Canada: 5% of world population, but uses twice as much energy than Europeans 7 times more than Latin Americans 10 times more than Asians 20 time more than Africans.

Human Impacts Vitousek et al. 1997, Science, 277:

Human Impacts Vitousek et al. 1997, Science, 277: Between one-third and one-half of the land surface has been transformed by human action. 2.CO2 concentration in air increase from 280ppm in 1800 to 385ppm in 2009, 37.5% increase 3.More than half of all accessible surface fresh water is in use by humanity. 4.One quarter of bird species have been driven to extinction. 5.More Nitrogen is fixed by humanity than by all natural terrestrial sources combined

Human Impacts: Land Transformation Foley et al. 2005, Sci, 309:570.

Human Impacts: Deforestation 1.Nearly A third of the world forests was cut, currently with 3.95 billion hectares, 30% of coverage. 2. Most of the deforestation happen in developing countries: The top 10 countries that lost the most forests during (FAO 2005): Brazil (3,103,000 ha/yr), Indonesia(1,871,000 ha/yr), Sudan (589,000 ha/yr), Myanmar (466,000 ha/yr), Zambia (445,000 ha/yr), Tanzania (412,000 ha/yr), Nigeria (410,000 ha/yr), D.R. Congo (319,000 ha/yr), Zimbabwe (313,000 ha/yr) Venezuela (288,000 ha/yr) Consequence: Due to forest decline, about 12.5% of the world 270,000 plant species and 75% of the world’s mammals are under threat of disappearing from the Earth for good (Salim and Ullstem 1999).

Deforestation Seen in Space

Human Impacts: Agriculture Foley et al. 2005, Sci, 309:570. Vegetation Distribution without Human Disturbance

Human Impacts: Agriculture Houghton, 1994, Biosci. 44:

Human Impacts: Agriculture Houghton, 1994, Biosci. 44: Unit: million ha/yr

Figure Every individual on the planet must be made aware of its vulnerability and of the urgent need to preserve it. No attempt to protect the environment will be successful in the long run unless ordinary people - - the California housewife, the Mexican peasant, the Soviet factory worker, the Chinese farmer -- are willing to adjust their life-styles. Our wasteful, careless ways must become a thing of the past. We must recycle more, procreate less, turn off lights, use mass transit, do a thousand things differently in our everyday lives. We owe this not only to ourselves and our children but also to the unborn generations who will one day inherit the earth.

Global Temperatures in the Future

Global Temperatures Projection Scenarios

Global Temperatures

Changes are relative to averages. Smoothed lines are decadal moving average and the shaded areas are uncertainties.

Global Temperatures

The Hokey Stick

Arctic Sea Ice Changes Figure HLC What is at stake with the rapid disappearance of arctic snow cover? What are the physical processes involved? Arctic region warms at 1.2 o C per decade, sea ice is melting 9% per decade since Due to warming spring arrives earlier (2.3days per decade). 2080: arctic land: o C summer o C winter arctic ocean: o C summer o C winter