Ocean surface acidity is rising

• The green on the graph shows that ocean Ph has dropped.
• This is the same as saying that acidity has risen.
• The straight green line shows how ocean surface Ph has dropped between 1990 and 2009, i.e., how acidity has risen.
• The straight green line is the “line of best fit” for the zigzag green line, the Ph data.
• The zigzag green line joins Hawaii’s annual seawater Ph levels.
• The zigzag red line shows the movement of carbon dioxide in the atmosphere.

This graph comes from “Skeptical Science”:
Ocean Acidification: Global Warming’s Evil Twin

---

---

Global warming’s twin evil

Ocean acidity is increasing because, as levels of CO₂  in our atmosphere increase, our oceans absorb more CO2, increasing the amount of carbonic acid in the oceans.

The high level of CO₂ in our atmosphere brings (1) increasing global temperatures, but it also brings (2) another danger, increasing acidity in our oceans.  This acidity is destructive and is why ocean acidification is global warming’s twin evil.

---

Increased acidification: Very dangerous

Increased acidity makes it harder for creatures like plankton to build their shells. It also makes it harder for corals to build their skeletons. At higher acid levels, these shells and skeletons become weaker and can even dissolve.

This acidity could lead to radical changes in ocean life. For example, if plankton populations drop, this hits a critical food chain: food for krill and whales. Such fundamental changes in the ocean could impact millions of people who depend on the sea for food and resources.

“If we continue to add carbon dioxide at current rates … by the end of this century … [we may have] an ocean more acidic than any seen for the past 20 million years. … A more acidic ocean won’t destroy all marine life in the sea, but the rise in seawater acidity of 30 percent that we have already seen is already affecting some ocean organisms like corals and zooplankton. Smithsonian Institute & US National Museum of Natural History

It is not sustainable for ocean acidity to keep on increasing like this.

---

The red line in the graph: CO₂ Levels

The graph shows in red how CO₂ Levels have changed from about 1958 to 2009.

• The red saw-tooth line shows the movement of CO2 levels in air from Mauna Loa, Hawaii, in parts per million by volume (ppmv). You can see CO₂ levels:
  • dropping each northern hemisphere summer, when photosynthesis in the forests of Eurasia draws down large amounts of CO₂, and
  • rising each northern winter when human burning again dominates.
• The black straight line is the CO₂ trend line since 1990. It is increasing over time.

---

Other References

• Ocean Acidification: The Big Global Warming Story: ABC TV: Catalyst
• Ocean: NASA
• Climate Change Seeps into the Sea: NASA: 2008

---

Related pages on this site

A 3-minute pitch for Australia becoming a renewable energy superpower.

---

Updated 10 Jan 2019. Checked 6 Jan 2023.