¥Past 200 years human activities via fossil
fuel consumption and land-use changes have
increased all greenhouse gases ->+ ~0.8¡C (1.4¡F)
¥CO2 once in atmosphere causes climate change for ~1000 years
(retention time)
¥Key example of positive feedback-> +1¡C (1.8¡F) change in
atmospheric temperature caused by CO2 will stimulate
water vapor increase causing another +1¡C
(1.8¡F) temperature increase (positive feedback)
¥Some aerosols (solid-vapor or liquid
droplets-vapor mixture) in atmosphere and some clouds
scatter sunlight offsetting warming to some degree, not all aerosols and not
all clouds scatter sunlight (or equally scatter)
¥Currently cars, trucks and buses are the
greatest contributors to atmospheric warming
¥34 billion tons of carbon dioxide released
into atmosphere annually from industrialization
and deforestation