global warming what is it? what’s causing it? what are the solutions?
TRANSCRIPT
Global Warming• What is it?
• What’s causing it?• What are the solutions?
Greenhouse effect
CO2: one of the main heat-trapping gases.
Its concentration in the atmosphere, past 250 yrs.
Past 10,000 yrs
CO2 concentration: 400,000 yrs--4 ice ages.Read graph from right to left.Recent increase unprecedented, NOT a natural cycle.
Present interglacialperiod
2010, 2005, 1998: tied as hottest years on record.
2001-2010: hottest decade on record.
It’s getting warmer
Global warming is here now!• The number of severe hurricanes has increased by 80% during past 30 yrs.• Droughts in Texas, western states. • Decrease in migratory birds, due to warmer winters in northern states. • Increase in tree mortality, Western U.S. • pH of ocean is dropping due to CO2; affects corals, shellfish.• Range shifts of MANY biological species.• Forest fires are increasing, as predicted.• Prolonged dry spells.• Reduced snowpack. • More rain, more extreme rain.• Polar bear now “endangered.” • Bacterial “blooms” in waters.• ETC!
Glacier National Park,Montana, is melting.
1850: 150 named glaciers.
2007: 26. 2030: 0 expected
S Cascade Glacier, Washington, 1928, 1979, 2003.
Alaska
Austria
Arctic melt extent, 1979 and 2003
Expected to be ice-free in summer by 2030.
Recentlly: Melting has accelerated. “Arctic ice could be in an abrupt, irreversible decline.” Are we approaching a tipping point?
Reflectivity feedback could have serious consequences for Greenland.
Greenland ice is melting
Greenland melt extent
James Hansen, NASA’s chief climatologist, GW expert:
Earth could pass a “tipping point” during next 10 to 20 yrs that would initiate irreversible melting of the Greenland and W Antarctic ice caps, raising sea levels by 50 feet over the next few centuries and “produce a new planet.”
We could see 10-ft rises by the end of this century.
Is this what you want for your
grandchildren?
It’s a moral issue!
What’s causing the warming?When we look at the patterns of global changes (temps, ice, rainfall, etc.) …..
…we find that natural sources cannot explain it, but human-emissions of
greenhouse gases do.
Intergovernmental Panel on Climate Change (IPCC): •“Unequivocal” that climate is warming, •“Very likely” that human activities are major driver.
The cause: mostly fossil fuels
Carbon in atmosphere
IPCC Report: A conservative document
• Spons by U.N. & World Meteorological Org
• ~3000 scientists compile the 6-yr reports
• Based on tens of thousands of peer-reviewed scientific papers published in hundreds of scientific journals
• Results arrived at by consensus
The major U.S. carbon polluters:
Electric Power 41%
3/4 from coal
Transportation 33%
3/4 from cars and trucks
COAL
• 1 plant = 1 million cars
SOLUTIONS:• Energy efficiency & alternative energy sources
• Carbon capture & storage! (~50% price incr)
• Congress could mandate CCS
CARS
• 55 mpg by 2020 (hybrids today)
• Plug-in hybrids, attached to renewable electricity
• Gasoline tax of several $ per gallon
• “Externalities” of driving: $12 per gallon!
• 6 tons of CO2 / yr,
3 X car’s weight!
SOLUTIONS:
The Solutions:
Reduce CO2 emissions: Efficiency (use less) Renewables (solar, wind)
Nuclear powerCarbon capture and storage
More broadly: Preserve, replant forestsLimit population growth
The best choice: Energy efficiency!
Bicycling
Pedestrian zones,pedestrian streets
Light rail for NW Arkansas!
Renewables: Wind
Photovoltaics
Solar-thermal electricity
Active solar heating
Passive (or direct)
solar
Geothermal energyFor electricity: For heating & cooling:
Biofuels
biofuels from grasses…
… and agri waste
From corn today: bad idea! With research:
Also: Nuclear power
• No greenhouse gases !
• Serious drawbacks (proliferation etc.)
• MUCH safer than fossil fuels.
China, India
20 leading climate scientists published a paper in Nature in
Sep 2009:
• Our present 390 ppm atm CO2 concentration is already unsustainable and dangerous.
• We need to move it back to 350 ppm asap, in order to hold the temp increase to 2oC.
James Hansen, NASA’s cilmatologist
Paul CrutzenNobel Prize, Chem.
What’s needed:
• 60% global emissions reduction by 2050.
• Converge on 1.5 tons / person-yr
• India: emits 1 ton / person-yr today
• US: emits 20 tons / person-yr
--must reduce by 90%
• Europe: reduce by 80%.
• But emissions are increasing, not decreasing!
THANK YOU!
Website: physics.uark.edu/hobson
We’re all in this together!