Science with a Passion; Life and Death on a Remote Pacific Reef

March 1, 2018

A robust crowd of citizens, scientists, and climate-curious individuals were on hand to hear Dr. Kim Cobb deliver the keynote address at the 2018 Climate Change Symposium on Thursday, February 22, 2018. The annual event hosted by the Nelson Institute poses the question of how global climate change will affect the ways in which we live and interact with the world.

Dr. Cobb’s extensive experience studying oceanographic climate models of El Niño events and coral reefs as a professor of Earth & Atmospheric Sciences at the Georgia Institute of Technology made her the ideal choice for the annual event hosted by the Nelson Institute that poses the question of how global climate change will affect the ways in which we live and interact with the world.

Much of Cobb's work focused on one specific reef, the Kiritimati Island reef, which is also the largest coral atoll in the world. The goal of her studies is to understand how oceans were affected by past El Niño-Southern Oscillation (ENSO) events and construct a model of past ocean climates. Her work began in 1997 when she found this research site and she has returned to the reef nearly every year since.

The ENSO cycle contains two phases: El Niño and La Niña periods, which are more generally known as the warm phase and cold phases of ENSO. During these phases, ocean temperatures will either warm the average temperature in El Niño years, or cool down during La Niña years. These patterns occur somewhat irregularly, however, scientists have learned how to better predict when an ENSO event may occur.

In order to collect data, Cobb drills for coral samples in reefs and uses radioactive isotope dating techniques to measure the age of the coral she's collected. The Kiritimati Island reef site offered much key data which helped her model past ocean climate environments. This data even offered insight into how this coral site would react to future climatic events, like the 2015 El Nino event, which completely destroyed her research site.

"This is what I've been waiting for my whole life. It was like my calibration dream come true, except it didn't turn out that way," Cobb said.

As the temperatures rose from the El Niño event that year, she observed a nearly complete coral bleaching at her site. Coral bleaching occurs when temperatures are very warm over a long period of time, in which Cobb said the corals will expel the algae that lives inside their tissue and go into a period of dormancy and starvation. She said the temperatures observed during the 2015 El Niño year were particularly troublesome.

As Cobb watched the temperatures remain high, the results were clear: basically the entire reef was dead. Up to 90 percent of the corals in her site were either dead or had experienced permanent damage due to bleaching.

Cobb said coral reefs are sensitive habitants and it will take decades for the site to recover.

"How bittersweet it was to wait for the big El Niño for decades, and then it comes and it wipes out my research site that I've painstakingly been learning about and on for 20 years, wiping out the very archive I've used to study this subject."

This blow to her research landed her on the front page of major media outlets to sound off the alarm of the major damage done to some of the largest coral reefs in the world. Cobb hasn't lost hope and believes scientists can use their voice to communicate beyond the data and take responsibility in their local communities to create small-scale change. These community level changes, she says, may ultimately save us.

"We need all hands on deck for this moment," Cobb said. "Everybody has to find their voice."

This year's symposium was hosted in collaboration with the Department of Geography, Department of Geoscience, Center for Climatic Research, and the Center for Sustainability and the Global Environment.

Photo: Dr. Cobb (left) and tech  Jordan Watson drilling a Porites coral core on Fanning Island (4N, 160W). They recovered ~60 yrs of growth in a 3-ft-long core. Photogaphy: Zafer Kizilkaya.