CLIMATE An Abrupt Climate Change Scenario and Its Implications for United States National Security (Pentagon Report, 2003). Global warming “should be elevated beyond a scientific debate to a US national security concern... future wars will be fought over the issue of survival rather than religion, ideology or national honour.” "Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems." IPCC, 5th intergovernmental report - 2014 Understanding climate matters….

I. Large Scale Determinants A. Solar Radiation CLIMATE I. Large Scale Determinants A. Solar Radiation 1. Average Radiation Budget - Solar Constant = 2 calories/cm2/min - 50% is reflected, absorbed, reradiated (Most ultraviolet light is reflected/absorbed) by the atmosphere - on average, 1 cal/cm2/min strikes earth. (but this varies dramatically, as we will see…)

- 50% is reflected, absorbed, reradiated (Most ultraviolet light is reflected/absorbed) Difference between red and yellow is incoming radiation absorbed by atmosphere

YAY OZONE! CO2 fills ‘window’ in H2O absorbance ABSORBANCE Greenhouse effect

A. Solar Radiation 1. Average Radiation Budget 2. Local Radiation Budget – Angle of incidence (latitude and season) Goes through more atmosphere Less energystrikes/unit area (since it is spread over more area) 3) More is reflected off surface; a lower percentage of what strikes/unit area is absorbed

A. Solar Radiation 1. Average Radiation Budget 2. Local Radiation Budget – Angle of incidence (latitude and season)

B. Effects on Atmospheric Circulation LOW ENERGY LOW ENERGY HIGH ENERGY

HIGH ENERGY LOW ENERGY

As air rises: - decrease pressure - increase volume - decrease energy/unit volume - decrease temperature

As air rises: - decrease pressure - increase volume - decrease energy/unit volume - decrease temperature “Adiabatic cooling” Decrease temp, increase tendancy of water vapor to condense

PV = nRT As air rises: - decrease pressure - increase volume - decrease energy/unit volume - decrease temperature “Adiabatic cooling” Decrease temp, increase tendancy of water vapor to condense PV = nRT

As dry cold air falls: - increase pressure - decrease volume - increase energy/unit volume - increase temperature “Adiabatic warming”

30oN 30oS As dry cold air falls: - increase pressure - decrease volume - increase energy/unit volume - increase temperature “Adiabatic warming” 30oN Increase temp of this dry air, evaporate water off surface 30oS

30oN 30oS HOT, DRY, DESERTS TROPICAL RAINS at solar equator

30 N 30 S

Latitude of solar equator drive seasonal rainy seasons in tropics

Three cycles in each hemisphere: Hadley temperate (Ferrel), polar

Transfer of energy from equator to poles (“Why are global warming’s greatest effects at the poles, not in raising the temperature of the tropics?)

C. The Coriolis Effect - Pattern of air movement along the surface of the earth…

C. The Coriolis Effect Pattern of air movement along the surface of the earth… - conservation of momentum east - speed relative to Earth changes (treadmill analogy)

C. The Coriolis Effect

D. Effects on Ocean Circulation

E. Long-Term Effects 1. ENSO (El Nino Southern Oscillation)

E. Long-Term Effects 1. ENSO (El Nino Southern Oscillation) “upwelling” of cold, nutrient-rich water from depth feeds coastal productivity of fish “upwelling” stops, fish populations (and fisheries) crash

E. Long-Term Effects 1. ENSO (El Nino Southern Oscillation)

E. Long-Term Effects 2. Younger Dryas - Dramatic cooling of northern Europe 11,000-13,000 years ago, correlating with the melting of the Laurentian Ice Sheet in North America. - Fresh water formed a lens on surface; deflecting Gulf Stream to the east at a much lower latitude, starving Europe of the heat transferred by the Gulf Stream.

F. Difficulties in Modeling Global Climate 1. Positive Feedback Loops

F. Difficulties in Modeling Global Climate 1. Positive Feedback Loops

F. Difficulties in Modeling Global Climate 1. Negative Feedback Loops