The ocean has shielded us from the worst of climate change. Now it is running a fever | Karina Von Schuckmann

Marine heatwave days more than tripled in 2025 compared to the early 1990s, according to the Indicators of Global Climate Change (IGCC) report. This trend, driven by an increasing Earth energy imbalance, has pushed human-induced warming to approximately 1.37C above pre-industrial levels and accelerated sea-level rise to a record 23cm.

How are marine heatwaves impacting coastal economies?

Persistent marine heatwaves are emptying fishing grounds and bleaching coral reefs, according to the IGCC report. These events strip away kelp forests that shelter young fish, which may tip entire ecosystems past the point of recovery.

The report notes that these changes scramble ocean chemistry, including acidity and oxygen levels. For coastal communities relying on the sea for food and livelihoods, the economic harm is immediate.

Did You Know? The ocean has absorbed more than 90% of the excess heat trapped on Earth by human activity, acting as a buffer for land-based warming.

What is driving the Earth’s energy imbalance?

The IGCC report identifies the “Earth’s energy imbalance”—the gap between solar energy reaching the planet and energy radiated back into space—as the primary driver of climate change. This imbalance has more than doubled since the late 20th century.

Greenhouse gas emissions are the largest contributor to this gap. However, the report also cites the loss of reflective haze from previous air pollution and feedback loops, such as dark, heat-absorbing oceans replacing bright ice, as factors that amplify warming.

Expert Insight: Samantha Carter suggests that the simultaneous increase in energy imbalance and the closure of monitoring sites creates a dangerous strategic blind spot. Losing data at the moment indicators are “flashing red” could limit the ability of policymakers to react to accelerating environmental risks.

Why is sea-level rise accelerating in 2025?

Sea-level rise reached a new record of 23cm since 1901 in 2025, according to the IGCC report. The rate of this rise has more than doubled in recent decades.

MW2025 Day2 – Key findings of the 8th Copernicus Ocean State Report by Karina VON SCHUCKMANN – EN

This acceleration pushes floodwaters further into low-lying coastlines. It also raises the baseline for every tide and storm, increasing the risk to coastal infrastructure.

What happens to climate monitoring next?

The ability to track these changes may be compromised due to funding pressures. Last month, officials announced the scaling back of critical monitoring work.

Four of five monitoring sites across the Pacific and Atlantic are set to close, and equipment is already being removed from the water. This loss of sensor and satellite data could hinder the capacity of scientists and policymakers to measure the energy imbalance.

Frequently Asked Questions

What is the Earth’s energy imbalance?

According to the IGCC report, it is the gap between the energy reaching Earth from the sun and the energy the planet radiates back into space.

How much has human-induced warming increased?

The latest findings in the IGCC report estimate that human-induced warming has reached approximately 1.37C above pre-industrial levels.

What caused the increase in marine heatwaves?

The report attributes intensifying marine heatwaves to the Earth’s energy imbalance, fueled by greenhouse gas emissions and feedback loops like the loss of reflective ice.

How should coastal businesses adapt to the increasing frequency of marine heatwaves?