Oceans – and global warming


The ocean is the Earth’s largest carbon dioxide reservoir. As CO2 levels increase in the atmosphere, they increase in the ocean, critically changing the pH and affecting marine life through ocean acidification. This process is increasing at an accelerated rate, now 10 times faster than at any other time in the past 300 million years.

At the same time, the vast majority (90 per cent) of heat from global warming ends up in the ocean. The top few metres of the ocean store as much heat as the Earth’s entire atmosphere. And since more than 70 per cent of Earth’s surface is ocean, the effects of ocean warming are extensive.

Heat stored in the ocean causes expansion, responsible for nearly one-half of global sea level rise. Record ocean temperatures were measured in 2021, followed by record sea water levels in 2022. According to the World Bank, there will be 143 million climate refugees by 2050 due to rising seas.

Coral reefs are especially vulnerable to ocean acidification and warming. They are projected to shrink 70-90 per cent at 1.5°C of warming and over 99 per cent at 2°C. The Status of Coral Reefs of the World 2020 report states 14 per cent of the world’s corals were lost between 2009 and 2018.

With the loss of Arctic Sea ice, the jet streams are slowing down and becoming erratic, greatly increasing the frequency, severity, and duration of extreme weather.

The Pacific Ocean is expected to become the biggest heat reservoir because of its large volume. Water currents will carry this ocean’s heat to the far reaches of the planet, further distressing the balance of weather patterns.
Lobster on Nova Scotia’s sea coast are migrating north to follow the colder temperatures. A Canadian study published in July 2022 showed 41 per cent of 90 fish stocks were at serious risk.

A recent global study calculated the speed of ocean warming. Using temperature sensors placed on boats, buoys, and in the ocean, thousands of measurements from around the world calculated the global ocean heat content back to 1950. With no action taken to reduce greenhouse emissions, the rate of ocean warming is projected to quadruple by 2090. By limiting global surface temperature to 2°C above the pre-industrial level, the acceleration of ocean warming will stop around 2030 (Nature Reviews Earth & Environment).

Dr. Ruth Musgrave, physicist and oceanographer at Dalhousie University, is researching ways to capitalize on the ocean’s ability to remove CO2 from the atmosphere. By adding alkalinity to seawater it enhances the ability to absorb and dissolve carbon dioxide. They hope to remove one gigaton of carbon from the atmosphere annually.

Daniel Boyce, a marine ecologist at Fisheries and Oceans Canada (DFO) is lead author of the climate risk scorecard for marine life (August 2022, Nature Climate Change). The scorecard will triage the most vulnerable fish, providing a picture of how marine life will fare in a warmer ocean. Cold-water species such as lobster are projected to lose much of their habitat. They are preparing the first-ever Climate Adaptation Framework for Fisheries, encouraging climate-smart infrastructure such as wharf designs that withstand sea-level rise.

Memorial University engineer, Dr. Baiyu (Helen) Zhang, is developing new technologies for the capture and conversion of carbon using marine algae. Based in St. John’s, her team is examining the deep North Atlantic and its essential role in the ocean carbon cycle.

Efforts to recover and protect coral reefs are paramount to ocean health. United Nations Environmental Program (UNEP) lists coral reefs as a priority ecosystem. There are numerous initiatives to support marine life and ecosystem health: Regional Seas Programme, Glowing Gone, Clean Seas, Global Fund for Coral Reefs.