200 likes | 391 Views
Climate Change. Global carbon cycle (billion metric tons). Global carbon dioxide emissions and concentration. Historical and Projected Climate Change . 90% chance of temperature rise in the shaded blue area. 10% chance in the dark blue area. Source: CBO, Potential Impacts …, May 2009.
E N D
Historical and Projected Climate Change • 90% chance of temperature rise in the shaded blue area. • 10% chance in the dark blue area. Source: CBO, Potential Impacts…, May 2009.
CO2 content by fuel (1 million Btu) • 99 lbs coal (anthracite)> 227 lbs CO2 • 8 gallons gasoline> 156 lbs CO2 • 7.2 gallons diesel> 161 lbs CO2 • 971 cubic feet natural gas: > 117 lbs CO2
Greenhouse gas • Very different from conventional air pollution problems
Conventional air pollution • SO2 • Pollution impacts increased linearly when pollution increased • Pollution concentrations fell fairly quickly when emissions were reduced • Time frame a decade or less • Negative impacts could be reversed by cutting pollution • Good estimate of benefits and costs (if too low initially) • Costs and benefits affected the same generation
Climate Change • Greenhouse gas (GHG) • Pollution impacts may rise nonlinearly with increasing GHG concentrations; thresholds may exist • Pollution concentrations will fall only very slowly when emissions are reduced • Time frame several decades if not 100 years • Negative impacts may produce irreversible damages • Estimates of benefits and costs are uncertain • Costs and benefits will affect different generations
Potential Impacts of Climate Change • Link between emissions and climate • Impacts on: • Physical environment • Biological systems • Human health • Economy
Potential Impacts of Climate Change • Impacts on: • Physical environment • Temperature • Warm areas get warmer • Patterns in the U.S. shift north • Precipitation • Dry areas get drier • North gets wetter • Sea Level • Inundation of some coastal areas, more frequent 100 yr floods • Biological systems • Slower to adapt • Extinction for some species
Illustration of Changes in Averages and Extremes in Temperature and Precipitation
Potential Impacts of Climate Change • Impacts on: • Human health • More insect-borne diseases • More warm-weather deaths • More ozone events • Fewer cold-weather deaths
Potential Impacts of Climate Change • Impacts on: • Economy • Longer growing season, farmers could benefit (if water available) • West and Southwest will experience even more severe water scarcity (less snow pack, precipitation) • Less spending for heating, more for cooling • More spending for flood control along coastlines • Aggregate impacts modest, GDP will be 3% lower by 2100.
Uncertainty Reigns • Linkages: • Emissions>Concentration>Warming>PhysicaI impacts>Economic impacts • Linkages subject to very large uncertainty • Possible: • Nonlinearities • Irreversibilities
Emissions and Climate • Ongoing emissions will continue to raise atmospheric concentrations and temperatures indefinitely. • Even if emissions were cut dramatically today, average global temperature would continue to rise.
What temperature to expect? • Uncertainties make establishing a range difficult. • 20th Century, planet warmed 0.70 C relative to the Industrial Revolution • Warming is accelerating: up 0.20 C in each of the past three decades. • Stern Review: GHG concentrations could triple that of pre-industrial levels by end of century. • If this occurs, 50:50 chance of 5.00 C rise above pre-industrial level by end of 21st century.
Electricity: coal lower; wind, hydro, and natural gas higher
Market-based Policy Options • A tax on GHG emissions • A cap-and-trade system (HR 2454)