Question

atmospheric carbon dioxide levels are shown below. this graph was developed by measurements that were obtained by

o direct measurements on mauna loa, hawaii, and from air bubbles trapped in ice.

o carbon isotope levels in sea floor sediments.

o measurements from undisturbed bat droppings in caves on a south pacific island.

o studies of the tissues of plants and their structures in response to differing co₂ levels.

Explanation:

The graph shows atmospheric CO₂ levels over a long period. Direct measurements on Mauna Loa (for recent times) and air bubbles in ice (for historical data) are standard methods for such data collection. Carbon isotope levels in sea - floor sediments relate more to oceanic carbon cycles rather than direct atmospheric CO₂ measurement. Bat droppings and plant tissue studies are not primary methods for long - term, broad - scale atmospheric CO₂ level determination.

Answer:

direct measurements on Mauna Loa, Hawaii, and from air bubbles trapped in ice.