Chapter 3: Climate Change and the

Energy Transition

• “Ever since civilization began, each generation has left the next a planet similar to the one it inherited. Our generation may be the first to abandon that tradition.”

Evidence of Climate Change

• Earth’s average temperature has risen 0.6°C since 1970

• Projected to rise by up to 6°C by the end of the century

• Sea level rose 7 inches in the 20th century• Projected to rise 3 to 6 feet by the the end

of the century

Causes of Warming

• Greenhouse gases:• CO2 = 63%• Methane = 18%• Nitrous oxide = 6%• Other gases = 13%

Atmospheric Brown Clouds

Sources of Carbon

• Electricity generation, heating, transportation and industry

• Only about 5 million tons are absorbed by oceans, soil and vegatation, the rest remains in atmosphere

• In 2008:• 7.9 billion tons emitted by burning of fossil fuels• 1.5 billion tons emitted by deforestation• Total of 9.4 billion tons

Sources of Methane• Mostly human caused through agriculture• Landfills• Thawing of permafrost• Arctic soil contains more carbon than currently

resides in the atmosphere• Problem: permafrost is melting

Sources of Atmospheric Brown Clouds

• Soot particles from burning coal, diesel fuel and wood

• Affect climate in 3 ways:1) Intercept sunlight, heating upper atmosphere2) Reflect sunlight, lowering earth’s surface

temperature3) When deposited, darken surfaces and accelerate

melting

Particular concern over Tibetan Plateau, Himilayas, Sierra Nevadas

Effects of Climate Change

• Diminish crop yields lower food production• Melt mountain glaciers feeding rivers• Generate more destructive storms• Increase severity of floods• Intensify drought• Cause more frequent/destructive wildfires• Alter ecosystems worldwide loss of species

Melting ice, Rising seas

• Rapid shrinking of the Earth’s 2 largest ice sheets• Greenland, potential to raise sea level by 23 ft• West Anarctica, potential to raise by 16 ft

The Arctic Region• Arctic is warming 2x faster than the rest of the planet• In surrounding regions (Alaska, western Canada,

eastern Russia) winter temperatures have risen 3-4°C over last half century

• 1979-2006, summer sea ice shrinkage accelerated to 9.1%/decade

• 2007 (record melt year), sea ice shrank to an area some 20% smaller than the previous melt record in 2005

• Multiyear sea ice is not recovering in winter

Albedo Effect• Self – reinforcing trend, accelerating melt• Typically, when sunlight strikes sea ice, 30%

is absorbed and 70% is reflected back• As ice melts, sunlight hits darker surface of

water and 94% is absorbed and only 6% is reflected back

Greenland

• April 2004-April 2006, lost ice 2.5x faster than in preceding two years

• Ice melt seeps through cracks in glacier, lubricating surface between glacier and rock accelerating glacial flow and calving

• Huge masses of ice falling into sea are causing minor earthquakes

NASA Satellite Data

• 2007 – ice shelves shrank by 24 square miles

• 2008 – ice shelves shrank by 71 square miles