Question

scientists can directly measure the amount of co₂ in the atmosphere today. researchers at the mauna loa observatory in hawaii have been doing this since the 1950s. to determine what the atmospheric concentrations of co₂ were before they could be directly measured, scientists measure the gases inside ancient air bubbles trapped in polar ice. this graph shows data collected at the mauna loa observatory combined with data taken from ice drilled from deep below antarctica. carbon dioxide concentrations over the past 400,000 years complete the sentence. according to the graph, carbon dioxide concentration has — over the past 20,000 years. stayed about the same roughly doubled roughly tripled

Explanation:

Step1: Analyze the graph trend

Observe the graph of \(CO_2\) concentration over time.

Step2: Determine the change over 20,000 years

Compare the \(CO_2\) concentration at the start (around 100,000 BCE) and now (today). The concentration has increased significantly.

Answer:

roughly doubled