Estuaries are warming at twice the rate of the ocean

Experts at the University of Sydney have determined that estuaries are warming at twice the rate of Earth’s oceans. The investigation was focused on 166 rivers, lakes, and lagoons on the southeast coast of Australia.

According to the researchers, the accelerated impact of climate change on estuaries could adversely affect economic activity and ecological biodiversity in rivers and lakes worldwide.

“Our research shows that estuaries are particularly vulnerable to a warming environment. This is a concern not only for the marine and bird life that rely on them but the millions of people who depend on rivers, lakes and lagoons for their livelihoods around the world,” said Dr. Elliot Scanes.

The researchers predict that changes in estuarine temperature, as well as changes in salinity and acidity, will reduce the profitability of aquaculture and wild fisheries. 

Worldwide, the aquaculture industry is worth more than $243 billion a year, while the wild fisheries industry has an annual value of $152 billion. There are more than 55 million people who depend on these industries for income.

“Estuaries provide services of immense ecological and economic value,” said Professor Pauline Ross. “The rates of change observed in this study may also jeopardize the viability of coastal vegetation such as mangroves and saltmarsh in the coming decades and reduce their capacity to mitigate storm damage and sea-level rise.”

The study findings are based on more than a decade of documentation in estuaries along the entire stretch of the New South Wales coast. 

Over the course of 12 years, more than 6,200 temperature observations were taken by field officers of the NSW Department of Planning, Industry and the Environment.

The study revealed that estuaries experienced warming of about 0.2-degrees each year. On average, the estuary systems warmed by 2.16 degrees during the study period.

“This increase in temperature is an order of magnitude faster than predicted by global ocean and atmospheric models,” said Dr. Scanes.

“This is evidence that climate change has arrived in Australia; it is not a projection based on modelling, but empirical data from more than a decade of investigation.”

The study is the first of its kind to analyze the long-term warming impacts on a diverse range of estuaries.

“Our results highlight that air or ocean temperatures alone cannot be relied upon to estimate climate change in estuaries; rather, individual traits of any estuary need to be considered in the context of regional climate trends,” said Dr. Scanes. “New models will need to be developed to help predict estuarine changes.”

The study is published in the journal Nature Communications.

—

By Chrissy Sexton, Earth.com Staff Writer