Ocean is Primed For Harmful El Niños, Say Corals
The El Niños are coming. A new study has found that the ocean is warming steadily, establishing conditions for rushes of harmful and nutrient-starved waters in the Pacific Ocean in the near-future.
A study recently published in the journal Paleoceanography details how coral sampling along a remote island in Kiribati helped researchers from the United States, Australia, and Canada build a record of ocean temperatures and salinity that covers about 60 years worth of change and El Niños.
The data revealed a distinct pattern that suggests that El Niños are closely tied to instances of changing extreme weather.
"During an El Niño event warm waters to the north of Australia move eastward, taking their rainfall with them," Helen McGregor from The Australian National University said in a statement. "This changes the pattern of Australia's rainfall and droughts significantly."
These events also impact ocean life, in which nutrient-rich cold water is flushed away by a flood of uncharacteristically warm water in the Pacific. This can harm essential sea life like corals, which, though tropical, can be stressed by sudden temperature spikes.
However, it's not like these events are unnatural. El Niños occur irregularly every two to seven years, and are the product of shifting air and ocean currents.
To study these shifts, the team focused on differences in sea temperatures that generate the circulating winds known as the Walker Circulation, which drive the trade winds that bring moisture across the Pacific Ocean to the north of Australia.
The Kiribati coral samples were taken from Porites coral just along where the Walker Circulation flows.
"This coral quietly laid down an excellent record of the ocean conditions at that location," explained McGregor.
"The trend is unmistakable," added lead-author Jessica Carilli. "The ocean is primed for more El Niño events."
And, if what the coral is telling them is right, the researchers expect these events to come sooner rather than later.