Two different scientists were studying the carbon levels of the air above a large city. They both found that the levels had increased by an average of 8% in the past decade. Scientist 1 concluded that the increase was a result of the increasing population of the city. Scientist 2 concluded that the increase was a result of an active volcano several miles from the city. Which scientist's conclusion is valid?

Scientist 1

Explanation:

The conclusion of scientists 1 is valid.

Human activities such as burning of fossil fuels, agriculture, deforestation, etc. leads to the emission of carbon in the form of carbon dioxide into the atmosphere. An increase in the population of a city will only lead to an increase in these activities and hence, an increase in the amount of carbon emitted into the atmosphere.

Also, volcanic activities leads to the production of volcanic gases which is a mixture of carbon dioxide, oxides of sulfur, nitrogen, etc.

However, an active volcano that is several miles away from the city might not be a major source of carbon in the air above a large city. The carbon dioxide produced from such volcanic activity thins out before reaching the city.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.