Since the late 1950s, Charles David Keeling and other researchers at the Mauna Loa Observatory on the island of Hawaii have recorded information on the concentration of carbon dioxide in our atmosphere. This data is recorded in the famed "Keeling Curve." As you may recall from the Keeling Curve, atmospheric carbon dioxide levels have steadily risen since the 1950s.

Oceanic carbon dioxide levels have risen alongside atmospheric levels, with a lag of several years. This lag occurs because it takes time for carbon dioxide concentrations in the atmosphere and ocean to reach equilibrium after an increase in atmospheric carbon dioxide.

In addition to this gaseous data, a similar research team has been recording ocean surface pH since the late 1980s at Station ALOHA, north of the island of Hawaii.

Open up the Graphing Ocean Acidification learning tool to interact with this data. Plot the data and use the slope tool to find the slope of the trend in atmospheric carbon dioxide concentration from 1988-2009. Next find the slope of proxy pH from 1988-2009. Answer the following questions before moving on:

• How do the slopes of atmospheric carbon dioxide concentration and surface ocean pH compare?
• Do the two slopes appear to be correlated