Climate Change: Causes and Evidence Part 1.

Climate Change What is the cause? How do we know? What is the Keeling Curve? How much CO 2 is in the atmosphere now? What’s the #1 GHG? What can we do?

What’s going on here?

Shifting Emphases Global Warming > Climate Change –Seasonal / Interannual > Decadal /Centennial Evidence (direct > indirect) –Observations Atmospheric, Land Surface, Ocean, Paleorecord Causes and Attribution Impacts (current and projected) – global > regional Projections (modeling) Mitigation (reducing emissions /reducing impact) Adaptation (anticipatory, autonomous, prescribed) Vulnerability and resilience

State of the Climate Global Analysis December 2010 Global Highlights The combined global land and ocean average surface temperature for December 2010 was 0.37°C (0.67°F) above the 20th century average of 12.2°C (54.0°F). This tied with 1982 and 1994 as the 17th warmest December on record. It was the coolest December since The global land surface temperature for December 2010 was 0.38°C (0.68°F) above the 20th century average of 3.7°C (38.7°F). This tied with 1994 as the 30th warmest December on record. The worldwide ocean surface temperature for December 2010 tied with 1994 and 1998 as the tenth warmest December on record, 0.36°C (0.65°F) above the 20th century average of 15.7°C (60.4°F). For the year (January–December), the combined global land and ocean surface temperature tied with 2005 as the warmest such period on record, at 0.62°C (1.12°F) above the 20th century average of 13.9°C (57.0°F) is the third warmest year- to-date on record, at 0.60°C (1.08°F) above the 20th century average. Source: National Oceanic and Atmospheric Administration, National Climatic Data CenterNational Oceanic and Atmospheric Administration, National Climatic Data Center

State of the Climate Global Analysis December 2011 Global Highlights The combined global land and ocean average surface temperature for December 2011 was 0.48°C (0.86°F) above the 20 th century average of 12.2°C (54.0°F). This tied with 1987 and 2004 as the 10 th warmest December on record. The global land surface temperature for December 2011 was 0.88°C (1.58°F) above the 20 th century average of 3.7°C (38.7°F). This tied with 1979 as the eighth warmest December on record. The worldwide ocean surface temperature for December 2011 tied with 1972 as the 16 th warmest December on record, 0.32°C (0.58°F) above the 20 th century average of 15.7°C (60.4°F). For the year (January–December), the combined global land and ocean surface temperature tied with 1997 as the 11 th warmest such period on record, at 0.51°C (0.92°F) above the 20 th century average of 13.9°C (57.0°F) and 2010 are tied for warmest year on record, at 0.64°C (1.15°F) above the 20 th century average. Source: National Oceanic and Atmospheric Administration, National Climatic Data CenterNational Oceanic and Atmospheric Administration, National Climatic Data Center

State of the Climate Global Analysis December 2010 Source: National Oceanic and Atmospheric Administration, National Climatic Data CenterNational Oceanic and Atmospheric Administration, National Climatic Data Center

State of the Climate Global Analysis December 2011 Source: National Oceanic and Atmospheric Administration, National Climatic Data CenterNational Oceanic and Atmospheric Administration, National Climatic Data Center

Mechanics, Sources, and Quantification

Global Warming and Atmospheric Constituents Radiative forcing Greenhouse gases – GWP’s Aerosols (direct and indirect) –Global dimming The Land use term Clouds

Radiative Forcing Radiative forcing is the change in the balance between radiation coming into the atmosphere and radiation going out. (+) positive radiative forcing tends on average to warm the surface of the Earth (-) negative forcing tends on average to cool the surface.  Radiative forcing of greenhouse gases are measured by the change average net radiation Watts (Wm- 2 ) at the top of the troposphere caused by the gas  Depends on radiative wavelength at which the gas absorbs, the strength of the absorption, the concentration of the gas, etc  Other forcings positive (warming), negative (cooling) Tropospheric aerosols caused by fossil fuel and biomass burning Volcanic eruptions Land cover change – albedo changes Variations in the sun’s irradiance

Greenhouse Gases (GHGs) Naturally occurring GHGs include: –water vapor, carbon dioxide, methane, nitrous oxide, and ozone. GHGs that are not naturally occurring (anthropogenic) include: – hydro-fluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6), which are generated in a variety of industrial processes. Water vapor is the most abundant greenhouse gas. However, human activities have little direct impact on its concentration in the atmosphere. In order to be able to compare how different gases contribute to the greenhouse effect, a method has been developed to estimate their global warming potentials (GWP). –GWPs depend on the capacity of greenhouse gas molecules to absorb or trap heat and the time the molecules remain in the atmosphere before being removed or broken down. –The GWP of CO2 is 1 and the GWPs of other greenhouse gases are measured relative to it. Even though CH4 and NOx have much higher GWPs than carbon dioxide, because their concentration in the atmosphere is much lower, CO2 remains the most important GHG, contributing about 60% to the enhanced greenhouse effect.

Aerosol Effects

Relative Importance of Greenhouse Gases

Measuring CO 2 Increase Before the industrial era, circa 1800, atmospheric CO2 concentration was between 275 and 280 ppmv for several thousand years (that is, between 275 and 280 molecules of CO2 for every one million molecules in the air). This we know from the composition of ancient air trapped in polar ice. Carbon dioxide has risen continuously since then, and the average value when Keeling started his measurements in 1958 was near 315 ppmv. By the year 2000 it has risen to about 367 ppmv. Today Thus, it is 40% greater than the pre-industrial era.

The Keeling Curve CO2 Flask measurements Mauna Loa Observatory, perched 3,397 meters (11,140 feet)

UMD sources of GHG emissions

CO2 Emissions Industrial and Land use What is it negative?

U.S. Carbon Emissions by Sector Source: ftp://ftp.eia.doe.gov/pub/oiaf/1605/cdrom/pdf/ggrpt/ pdf

The United States’ target: “in the range of” 17 percent below 2005 (contingent on the enactment of domestic U.S. legislation)

CO2 emissions (total) Source: Union of Concerned ScientistsUnion of Concerned Scientists

CO2 emissions (per capita) Source: Union of Concerned ScientistsUnion of Concerned Scientists

CO 2 emissions

CO 2 emissions from the burning of fossil fuel in 2009 were only 1.3% below the record 2008 figures. The global financial crisis severely affected western economies, leading to large reductions in CO 2 emissions. However, emerging economies had a strong economic performance despite the financial crisis, and recorded substantial increases in CO 2 emissions (e.g. China +8%, India +6.2%). The study also found that global CO 2 emissions from deforestation have decreased by over 25% since 2000 compared to the 1990s, mainly because of reduced CO 2 emissions from tropical deforestation. "For the first time, forest expansion in temperate latitudes has overcompensated deforestation emissions and caused a small net sink of CO 2 outside the tropics,"