LA Heat Island

The instrumental record of temperature during the last 100 yrs is somewhat contaminated by urban heat island effect. Because the temperature is monitored typically near cities, local energy use and land use changes can be imprinted on the record producing a non-representative sample.

According to a web site at LBL,

www.lbl.gov,

Californians use 250 million BTUs of energy per capita per year (Google has a great unit conversion feature: type 250 million BTU in J into google search) . Assuming that the citizens of greater LA (~ 10 million people; 5000 sq. km) behave like typical Californians, estimate ( to one significant digit) the ratio of heat generated by anthropogenic activity to that from absorption of sunlight averaged over the year. Assume the albedo of the area is 0.3 and that the atmosphere transmits 80% of the solar radiation to the surface. Note your assumptions.