Green Living Association

Climate Change Effects on Oceans

How does climate change affect oceans and marine life?

Recent studies show the 20 warmest years on record have been in the past 22 years, and the top four in the past four years. Over the past century, the average temperature of the Earth has risen by 1.8°F. Over the next one hundred years, scientists are projecting another 0.5 to 8.6°F rise in the temperature. The cause of this temperature change is human activities that have released large amounts of carbon dioxide and other greenhouse gases (such as methane, nitrous oxide and fluorinated gases) into the atmosphere. The majority of greenhouse gases come from burning fossil fuels to produce energy. Results of this global warming include rising ocean temperatures, a more acidic ocean, melting ice caps, and rising sea levels. The negative consequences of human-driven climate change will continue to accelerate with disastrous effects: sea continue to rise, inundating and eliminating nesting beaches and foraging habitat for marine wildlife; warming seas are driving ocean animals further north, leading to cold stunning and further reducing sea turtle hatchling success; and the effects of increasing ocean acidification will become more deadly to all marine life.

Turtle Island Restoration Network is committed to acting against the devastating impacts of climate change on sea turtles and other vulnerable marine species. Our specific climate change resiliency strategy is always changing, according to best available science, and is currently two-fold: we build resiliency to allow marine wildlife to withstand and recover from climate change impacts that are already occurring, and we fight back against the senseless policy and anti-environmental legislation that will hasten the effects of climate change on marine species and the entire planet. Everyone can take simple actions to reduce greenhouse gas emissions, mitigate our personal contribution to climate change, and build greater community resiliency to tackle its effects. However, it’s important to stand with TIRN and other conservation organizations to hold those most responsible for anthropogenic climate change truly accountable – governments, fossil fuel industries and lobbies, plastic manufacturers and other major corporations that benefit from the environmental injustices accepted and perpetrated under the guise of economic progress.

Oceans play a major role in climate dynamics, absorbing 93% of heat that accumulates in the Earth’s atmosphere, and a quarter of the carbon dioxide (CO2) released from fossil fuels. The impacts of climate change on our oceans include shifts in temperature, acidification, deoxygenation and changes in ocean currents.

Given their importance to the planet, it’s vital we manage the oceans in a sustainable way. Changes to the ocean mean changes to fish stocks. To manage fishing sustainably requires adapting to whatever issues climate change brings.

In the past 30 years, marine heatwaves are estimated to have increased by more than 50%. Globally, ocean temperatures are predicted to increase by 1-4°C by 2100.

These changes are impacting marine life. Sudden rises in temperature and acidification can lead to the loss of marine habitats and species. Shifting ocean currents and warming waters are changing the distribution of fish stocks and altering the structure of ecosystems.

How does climate change affect fishing?

Climate change threatens fish stocks, but also creates new opportunities for fishing.

Areas in the Tropics are predicted to see declines of up to 40% in potential seafood catch by 2050.

In contrast, areas in higher latitudes, such as the North Atlantic and North Pacific, are seeing increases in the range of some fish species.

These changes bring challenges. To continue to fish sustainably requires adopting new ways of fishing. The fishing industry and governments have found it difficult to agree how best to manage changing fish stocks, particularly if fish are moving across international boundaries or where catches need to be significantly reduced.

If climate change affects fish, can I still eat it?

Yes. Try to choose MSC labelled fish and seafood. MSC certified fisheries are well managed and more prepared for environmental changes. These fisheries follow current scientific advice to ensure they catch fish sustainably.

Wild fish is a low carbon food

Additional good news is that fishing has less impact on climate than the harvesting of other proteins. A study of greenhouse gas emissions of wild fisheries found that each kg of fish caught produces between one and five kg of carbon. By comparison, red meat production is estimated to range from 50 to 750 kg of carbon per kg of meat.

There is also evidence that sustainable fishing helps to reduce carbon emissions by increasing efficiency. For example, increased catches within Icelandic fisheries mean that fishing vessels now make shorter fishing trips, reducing their fuel use and carbon emissions as a result.

How do sustainable fisheries cope with climate change?

Sustainable fisheries that meet the MSC’s standard for sustainable fishing are well-managed and more prepared for climate change.

These fisheries have effective monitoring and management in place to reduce their impacts on the environment and only catch what is sustainable. Following advice from scientists, these fisheries have pre-agreed plans for responding to likely environmental changes.

These fisheries show that it is possible to balance economic and environmental priorities to safeguard our oceans and seafood supplies.

What happens when fisheries struggle to adapt to climate change?

As climate change can affect stocks in unexpected ways, even MSC certified fisheries can experience problems.

Here are two examples of fish stocks affected by climate change:

North East Atlantic mackerel

There has been a rapid change in Atlantic mackerel distribution since 2007.  Stocks have moved northward as sea temperatures rise.

The change in the movement of mackerel has resulted in disputes between coastal states over how to share fishery resources. With fish moving across geo-political boundaries there is a lack of agreement on how best to manage the stock.

With no result to disputes, MSC certification for North East Atlantic mackerel was suspended in March 2019. This suspension affects fisheries operating in eight countries.

The mackerel fisheries have committed to delivering an effective harvest strategy by mid-2020. The MSC is working with partners to support these efforts and encourage a resolution to the dispute.

North Sea cod

Recent declines in North Sea cod populations, have been attributed in part to changing climate. This change has resulted in fewer juvenile cod surviving to adulthood. Having fewer adult fish has made sustainable fishing of the cod stock more difficult. Because of this problem, MSC certification of North Sea cod fisheries was suspended in September 2019.

The fisheries have responded to this disappointing news by committing to measures to rebuild cod stocks over the next five years.

What else can be done to protect fish stocks?

Fisheries managers need to adopt more precautionary approaches to secure future fish stocks. But effective fisheries management also requires significant international cooperation by governments. This is a significant challenge for many countries balancing economic and environmental interests.

Some progress has been made. For example, in July 2015 delegates from Canada, Denmark (for Greenland and the Faroe Islands), Norway, Russia, and the United States signed an agreement to prevent unregulated commercial fishing in high seas of the central Arctic Ocean.

Opinion: Climate change set to drive profound change in the fishing industry