IPCC Report: Climate Change is Taking a Toll on the Oceans

The second part of IPCC’s (Intergovernmental Panel on Climate Change) sixth assessment report (AR6) is out this week. Its 3675 pages incorporate a massive quantity scientific data, but it puts a special emphasis on the impacts of climate change and ways for humanity to adapt.

By a large margin, oceans are more exposed to effects of climate change than any other ecosystems. There are a number of takeaways from the report concerning the imminent threat of climate change to oceans and marine ecosystems.

In the 21st century, ocean and coastal ecosystems are projected to face conditions not seen for millenia. With increased temperatures, marine heatwaves are likely to become more frequent and severe. There will be an increase in ocean acidification and harmful algae blooms, with negative effects on marine life.

On fisheries, the catch composition and diversity of fish will change. Fishers who are unable to move, diversify and leverage technology to sustain harvests will face an existential challenge of food insecurity. Specifically, marine dependent communities, including indigenous peoples, will be at increased risk of losing cultural heritage and traditional seafood-sourced tradition.

Sea-level rise risks exposing more coastal infrastructural assets to flooding. This includes transport networks such as rail, roads and ports, and energy systems, with economic losses slowing growth of countries. The latest research shows that we are likely to see sea level rise of about one meter by the year 2100. Without climate adaptation and mitigation measures agreed by parties to the Paris Agreement, sea-level rise will continue to reshape coastlines over millennia, affecting at least 25 megacities and drowning low-lying areas where close to 1.3 billion people live.

Additionally, sea level rise and increasing severity of storms are already affecting port activity and supply chains, sometimes-disrupting trade and transport. These impacts increase food insecurity, income loss and poverty, exacerbating maritime criminal activities like illegal fishing, drug trafficking and piracy.

These economic and societal impacts propagate across national boundaries through supply chains, global markets and natural resource flows. Supply chains that rely on specialized commodities and key infrastructure can be disrupted by weather and climate extreme events. For example, climate change causes redistribution of marine fish stocks, increasing risk of transboundary management conflicts among fisheries users.

The report also depicts an emerging threat facing polar seas – the deep Arctic Ocean, the surrounding shelf seas and the Southern Ocean. They cover approximately 20 percent of the global ocean and play a significant role in absorbing carbon emissions. Unfortunately, sea ice melt-off is exposing these vulnerable polar ecosystems to human exploitation. Tourism, shipping and hydrocarbons exploration are now expanding into polar regions.

Are we approaching the so-called tipping points in the ocean? The reports answers in the affirmative. Evidence suggests that ocean tipping points are being surpassed more frequently as the climate changes.

Nevertheless, the chances of moving beyond additional tipping points in future will be minimized if we reduce greenhouse gas emissions and act to limit other human impacts on the ocean, such as overfishing and nutrient pollution.