Climate change: Pace of ocean warming could quadruple by 2090, study finds

Climate change will cause the pace of ocean warming to quadruple by 2090 if greenhouse gas emissions keep rising, threatening sea life and weather patterns around the world, scientists say.

Mitigation of man-made emissions, however, would likely result in a significant reduction in the rate of ocean warming, the scientists from Auckland, Australia and the US said in the study published in Nature Reviews on Tuesday.

"Scientists use measurements of the past to help predict what the future will bring. The most important finding is: the future of the ocean is in our hands," said the experts from the Universities of Auckland and New South Wales, and Colorado's National Center of Atmospheric Research.

"However, if we don't take action, the predictions are quite dire. The rate of warming will skyrocket throughout the 21st century: by the 2090s, the rate of ocean warming is projected to be four times larger than the current level."

Greenhouse gas emission cuts in line with the Paris Agreement, however, would stop the acceleration of ocean warming by 2030, the scientists said. 

New Zealand climate scientist James Renwick, who was not involved in the study, said fish stocks were at risk if global warming wasn't mitigated.

Thinking more broadly, "If no action is taken to reduce emissions and mitigate climate change, we would be in serious trouble across the board", said Renwick, from Victoria University of Wellington.

"Water variability (flood and drought) would have increased to a point where it would be hard for the agriculture sector to cope, sea level rise would be destroying low-lying parts of Auckland and Wellington, Nelson and Timaru and all other coastal communities, heat waves would be significantly reducing crop production, etc etc etc. 

Climate change: Pace of ocean warming could quadruple by 2090, study finds
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"Hundreds of thousands of migrants from the Pacific and south Asia could be looking to come here as a result of sea level rise etc making their homelands uninhabitable."

Global food production disruption caused by climate change could also wreak havoc on the world's economy, Renwick said.

Figuring out the impact of ocean warming was important because, this year alone, the world had seen a range of climate disasters including hurricanes, heavy rain, flooding and heatwaves, the Auckland, NSW and US scientists wrote in Nature Reviews.

Ocean warming, linked to climate change, would lead to more powerful storms and other related events this century, they said.

"This study is important because it motivates us to take action to mitigate and respond to climate change. It shows what will happen if we don't take action to slow global warming.

"By the end of this century, the Pacific Ocean is expected to become the biggest heat reservoir owing to its large volume. 

"The authors were able to show that when extra heat gets into the ocean, water currents can carry that heat to the far reaches of the planet."