Ocean Acidification Is Already Harming The Great Barrier Reef's Growth

Ocean Acidification Is Already Harming The Great Barrier Reef's Growth

Corals grow better in the more alkaline ocean conditions that existed in pre-industrial times.

A new experiment on the Great Barrier Reef has shown, for the first time, that ocean acidification is already harming the growth of coral reefs in their natural setting.

As our research published in Nature today shows, the reduction in seawater pH – caused by carbon dioxide from human activities such as burning fossil fuels – is making it more difficult for corals to build and maintain their skeletons.

We and our colleagues, led by Rebecca Albright and Ken Calderia from the Carnegie Institution for Science in Stanford, California, carried out the first experimental manipulation of seawater chemistry in a natural coral reef ecosystem. Previous climate change studies on coral reefs have been done either in the laboratory or in closed-system tanks on the reef.

Coral reefs are particularly vulnerable to ocean acidification because calcium carbonate, the mineral building blocks of their skeletons, dissolves easily in acid. Below a certain pH, this dissolution is predicted to outweigh the accumulation of new calcium carbonate that allows reefs to grow and to recover from erosion processes such as storms.

Previous studies have shown large-scale declines in coral reefs over recent decades. Rates of reef calcification were 40% lower in 2008-09 than in 1975-76.

However, it was hard to pinpoint exactly how much of the decline was due to acidification, and how much was caused by other human-induced stresses such as ocean warming, pollution and overfishing. Understanding this is essential to predicting how coral reefs may fare in the face of continued global climate change.

To answer this question, we manipulated the pH of seawater flowing over a reef flat at One Tree Island in the southern Great Barrier Reef. By adding sodium hydroxide (an alkali), we brought the reef’s pH closer to levels estimated for pre-industrial times, based on estimates of atmospheric carbon dioxide from that era. In doing so, we pushed the reef “back in time”, to find out how fast it would have been growing before human-induced acidification began.

It was clear from our results that reef calcification was around 7% higher under pre-industrial conditions than those experienced today.

Most other ocean acidification experiments manipulate seawater conditions based on the low pH levels predicted for coming decades, to understand the potential effects of future ocean conditions. But we have shown that present-day conditions are already taking their toll on corals.

As Albright explains:

Our work provides the first strong evidence from experiments on a natural ecosystem that ocean acidification is already causing reefs to grow more slowly than they did 100 years ago. Ocean acidification is already taking its toll on coral reef communities. This is no longer a fear for the future; it is the reality of today.

With greenhouse gas emissions continuing to rise, our results suggest a bleak future for coral reefs over the coming decades, with reduced calcification and increased dissolution. This is particularly concerning in light of the major coral bleaching events observed globally over the past few years amid prolonged high sea surface temperatures. The mixed effects of ocean warming and acidification, as well as other human-induced and natural stressors, pose serious threats to the ecosystems we know today.

Increasing the alkalinity of ocean water around coral reefs has been proposed as a geoengineering measure to save shallow marine ecosystems. Our results suggest that this could be effective in isolated areas, but implementing such measures at large scales would be almost impossible.

As our colleague Ken Caldeira has pointed out, the only real and lasting solution is to make deep, rapid cuts in our carbon dioxide emissions. Otherwise the next century could be one without coral reefs.

About The Authors

Kennedy Wolfe, PhD Candidate, University of Sydney. His is a researcher at the University of Sydney, Australia, investigating the impacts of human activities on the Great Barrier Reef.

Maria Byrne is Professor of Marine and Developmental Biology at the University of Sydney. For 12 years she was the director of One Tree Island Research Station, the University’s facility on the Great Barrier Reef.

Appeared On The Conversation

Related Book:

{amazonWS:searchindex=Books;keywords=great barrier reef;maxresults=3}

Sorry, there has been a problem fetching the results. You can try refreshing the page. Reload this page
English Afrikaans Arabic Chinese (Simplified) Chinese (Traditional) Dutch Filipino French German Hindi Indonesian Italian Japanese Korean Malay Persian Portuguese Russian Spanish Swahili Swedish Thai Turkish Urdu Vietnamese

LATEST VIDEOS

Jay Inslee Tells Hayes That He Wants To Gut The Filibuster To Fight Climate Change
by MSNBC
Washington Governor Jay Inslee is running for president on the single issue of climate change and argues that doing…
Causes and Effects of Climate Change
by National Geographic
What causes climate change (also known as global warming)? And what are the effects of climate change? Learn the human…
Extreme Weather and Global Warming
by NASA Goddard
Is the frequency of extreme weather events a sign that global warming is gaining pace and exceeding predictions? Bill…
Thanks to Climate Change, Wet Winters No Match for Drier California Summers
by KPIX CBS SF Bay Area
If the emerald-green hills around Northern California have you thinking recent rains have put a damper on the fire…
Climate Change Is Not One Issue
by MSNBC
"Climate change is not one issue," said David Wallace-Wells, author of "The Uninhabitable Earth," but is…
The Heat: Climate change
by CGTN America
Images gathered by NASA show an increase in foliage in China and India. The greening effect is mainly due to ambitious…
No company is doing enough to combat climate change: Jeremy Grantham
by CNBC Television
Jeremy Grantham, co-founder of GMO, on climate change and what needs to be done to combat it.
Power Plants Are POISONING Groundwater All Over America
by The Ring of Fire
According to a new report, 90% of coal-fired power plants across the country have completely contaminated the…

LATEST ARTICLES

Default Image
Climate change denial is evil, says Mary Robinson
by Damian Carrington Environment editor
The denial of climate change is not just ignorant, but “malign and evil”, according to Mary Robinson, because it denies…
McConnell to Put Green New Deal to Test Vote in First of Many Showcases
McConnell to Put Green New Deal to Test Vote in First of Many Showcases
by Global Warming & Climate Change
But climate change is not “extremely out of the mainstream.” Concern about climate change in the United States is the…
Why Housing Policy Is Climate Policy
Why Housing Policy Is Climate Policy
by Global Warming & Climate Change
Low-density, single-family-home zoning is effectively a ban on economically diverse communities.
Default Image
Come on, UK weather forecasters – tell it like it is on climate change
by Adam Corner
They have a national reach that most climate campaigners would die for. They are familiar and respected experts on the…
Green New Deal: 6 places already reducing emissions from buildings
Green New Deal: 6 places already reducing emissions from buildings
by David Roberts
One of the elements of the Green New Deal resolution that has caused the most consternation among critics on the right…
Default Image
UK environmentalists target Barclays in fossil fuels campaign
by Matthew Taylor
A UK-wide campaign is being launched to persuade one of the country’s biggest high street banks to stop investing…
Oceanic carbon uptake could falter
Oceanic carbon uptake could falter
by Tim Radford
What does oceanic carbon uptake achieve? Greenhouse gas that sinks below the waves slows global warming a little and…
Britain (Yes, Rainy Britain) Could Run Short of Water by 2050, Official Says
Britain (Yes, Rainy Britain) Could Run Short of Water by 2050, Official Says
by Global Warming & Climate Change
“Climate change plus growth equals an existential threat,” Mr. Bevan said. To avoid severe water shortages, he added,…