Why is the concentration of CO2 is more in the Northern Hemisphere than the…

Answer: The higher CO2 concentration in the Northern Hemisphere is best explained by three factors: greater fossil-fuel emissions in the Northern Hemisphere, more land area in the Northern Hemisphere, and the Southern Hemisphere's larger ocean area which absorbs more CO2. Therefore, the correct choice lists those three causes.

• Greater fossil-fuel emissions in the Northern Hemisphere: Most industrial activity and population (and therefore CO2 emissions from burning fossil fuels) are concentrated in the Northern Hemisphere, directly raising its atmospheric CO2.

• More land area in the Northern Hemisphere: Greater land fraction means more terrestrial sources (respiration, land-use change) and more human activity on continents, contributing additional CO2 to the atmosphere.

• Larger ocean area in the Southern Hemisphere: Oceans take up CO2. The Southern Hemisphere’s larger ocean fraction absorbs more CO2, lowering its atmospheric concentration relative to the Northern Hemisphere.

• Limited inter-hemispheric mixing: Atmospheric exchange between hemispheres is slow enough that differences caused by uneven emissions and uptake can persist, producing the observed gradient.

• Why the 'colder Northern Hemisphere' idea is not correct: Temperature differences are not the primary driver of the hemispheric CO2 difference; the observed pattern is explained by emissions distribution, land/ocean partitioning, and atmospheric transport.