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Why are ocean temperatures breaking records?

EcologyGlobal Warming

Level

Kara Anderson

updated May 15, 2024

UK Copywriter at Greenly

The ocean's temperatures are not just rising - they’re breaking records! April 2024 marked yet another milestone in this ongoing trend, with ocean temperatures continuing to set new records. This continues the alarming pattern from the previous year, highlighting an escalating crisis in our oceans. As sea temperatures climb higher, the repercussions extend far beyond the water's surface, affecting weather patterns, marine biodiversity, and coastal communities worldwide.

👉 This article delves into the causes and consequences of these rising temperatures, focusing on the science behind this worrying trend and what it means for our global ecosystem.

What is happening to ocean temperatures?

The world’s oceans and seas play an important role in regulating the Earth's climate. However, recent observations show that ocean temperatures are not just rising, they’re reaching levels that were previously unprecedented. April 2024 continued a trend that experts are finding increasingly concerning.

Record-breaking trends

Continuous records being smashed - Since May 4, 2023, the global sea surface temperature (SST) has consistently surpassed daily records for that specific time of year, setting new records each day!
Ongoing trend - Rising temperatures are part of a series of record-breaking temperatures observed globally. The most notable record-breaking days were the 23rd of August 2023, the 3rd of January 2024, and the 5th of January 2024, when previous temperature records were surpassed by around 0.34°C!

Geographical hotspots

Global reach - While certain regions like the North Atlantic and the Equatorial Pacific are known hotspots, recent data suggests that almost all oceanic regions are experiencing similar temperature surges.
Record regions - Particularly, the Mediterranean and Caribbean Seas have reported temperatures that are significantly higher than their long-term averages, affecting local marine ecosystems and weather patterns.

Scientific data

The rise in ocean temperatures is closely monitored by organizations like the National Oceanic Atmospheric Administration (NOAA) and the European Copernicus Institute, which provide comprehensive data and analysis. Their findings indicate that these temperature increases are consistent with predictions from climate models that incorporate human-induced global warming and natural phenomena like El Niño.

Data Sources - Utilising satellites and oceanic buoys, these institutions gather huge amounts of data that reveal how widespread and intense this warming trend is.
Model predictions - Climate models have long predicted that as global warming progresses, ocean temperatures will increase, leading to more frequent and severe marine heatwaves.

👉 This alarming trend in rising ocean temperatures underscores the urgent need to understand the driving forces behind these temperature increases and their potential impact on global climate systems.

What is behind rising ocean temperatures?

The recent spike in ocean temperatures is a complex interplay of natural variability and man-made influences. Here, we explore the primary factors contributing to these rising temperatures, providing insight as to why our oceans are warming at such alarming rates.

Natural variability

El Niño

The natural phenomenon known as El Niño significantly impacts global weather patterns and ocean temperatures. Characterized by the warming of ocean surface waters in the central and eastern tropical Pacific Ocean, El Niño events disrupt normal weather patterns and elevate global sea surface temperatures. The current cycle has been particularly strong, exacerbating the warming trend.

Ocean currents

Ocean currents, driven by wind, salinity, and Earth's rotation, distribute heat globally, moderating the Earth’s climate. These currents form a complex network that moves warm water from the tropics towards colder regions, a process central to global temperature regulation. However, disruptions in these currents (often linked to climate change) can significantly alter this dynamic.

The thermohaline circulation for example is a global conveyor belt of ocean currents, which can slow down or alter due to changes in water salinity and temperature, often caused by increased freshwater from melting ice. Such changes can prevent heat from dispersing properly, causing it to build up in certain regions and leading to warmer surface temperatures.

Shifts in currents like the Gulf Stream or the Kuroshio can also lead to regional heat rises, impacting weather patterns and potentially exacerbating marine heat waves. For example, a weakened Gulf Stream has been linked to elevated water temperatures along the U.S. East Coast, influencing hurricane activity and sea-level rise.

Solar radiation

The sun's energy output is not constant and undergoes slight variations due to the solar cycle, which lasts approximately 11 years. These variations can affect the amount of solar energy reaching the Earth. Increases in solar output can marginally raise global temperatures, including those of the oceans. While the direct impact of changes in solar radiation on ocean temperatures is relatively small, these changes can amplify the effects of greenhouse gases. When solar output peaks, it can slightly exacerbate the warming effects, especially in conjunction with elevated levels of atmospheric greenhouse gases.

Human-induced factors

Greenhouse gas emissions

Greenhouse gases such as carbon dioxide, methane, and nitrous oxide, primarily emitted from burning fossil fuels, deforestation, and industrial activities, are the fundamental drivers of global warming. When greenhouse gases accumulate in the atmosphere, they enhance the natural greenhouse effect, trapping more solar energy as heat. While the atmosphere first absorbs this heat, the Earth's oceans act as a major heat sink, absorbing over 91% of this energy. This process leads to a gradual but steady increase in ocean temperatures.

Decreased aerosol emissions

While reducing emissions of pollutants like aerosols is beneficial for air quality and the Ozone layer, aerosols have a cooling effect when present in the atmosphere because they prevent solar radiation from reaching the surface of the planet. Their reduction, particularly in regions with stricter environmental regulations, may have unintentionally contributed to global warming. One study for example concluded regulations to reduce shipping-related sulphur dioxide (SO2) emissions may increase global temperatures by as much as 0.5°C! However, it should be noted that there is still much scientific debate around this topic.

Cumulative effect

These factors do not operate in isolation but interact in ways that amplify their effects. For example, the warming caused by greenhouse gases may increase the duration and intensity of El Niño events, which further raises ocean temperatures. Additionally, the heat absorbed by the oceans leads to further climate changes, such as the intensification of marine heat waves, which have become more frequent and severe as global temperatures rise.

What does the research say about the future of ocean temperatures?

To predict future climate conditions and understand the current state of ocean warming, scientists rely on a combination of observations and models. These tools help to understand the dynamics of ocean temperatures and provide insights into future trends, helping us to better predict and mitigate the impacts of rising ocean temperatures.

Observational data

Satellite monitoring - Advanced satellite technology provides comprehensive data on sea surface temperatures across the globe. These satellites monitor infrared radiation emitted from the ocean's surface, allowing scientists to detect temperature changes over time and space with remarkable accuracy.
Ocean buoys and Argo floats - A network of thousands of floating buoys and robotic floats, measure temperature, salinity, and currents throughout the ocean depths. This data is crucial for understanding how heat is distributed vertically within the oceans and how this affects surface temperatures.

Climate models

General circulation models (GCMs) - These models simulate the Earth's atmosphere and oceans and are fundamental in predicting future climate conditions. GCMs use mathematical equations to represent physical processes, providing scenarios based on varying levels of greenhouse gas emissions.
Coupled Model Intercomparison Project (CMIP) - As part of the International Panel on Climate Change (IPCC) assessments, CMIP brings together results from multiple climate models to improve predictions. These results have consistently shown that as greenhouse gas concentrations increase, so will global and ocean temperatures.

Predictions and projections

Based on current emission trajectories, climate models predict that ocean temperatures will continue to rise. The degree of warming is directly tied to future greenhouse gas emissions, with higher emissions leading to more significant warming.

Models have also helped identify regions most at risk of extreme warming, guiding targeted climate adaptation and mitigation efforts. For example, tropical and polar regions are projected to experience the fastest rates of ocean warming.

Understanding these trends through scientific models and observations is crucial for effective policy-making and public awareness. They not only illustrate the dire need for immediate action to reduce greenhouse gas emissions but also help in planning adaptation strategies to protect ecosystems and communities from the negative effects of ocean warming.

What are the impacts of rising ocean temperatures?

The rising ocean temperatures are not just a concern for marine biodiversity. they have cascading effects on global climate systems, weather patterns, and human communities.

Impact on marine ecosystems

Coral bleaching - Warmer waters stress corals, leading to bleaching, where corals lose the algae that give them color and life. This not only affects the corals themselves but also the creatures that rely on coral reefs for habitat, ultimately impacting biodiversity and fishery resources.
Altered marine life distribution - As ocean temperatures rise, marine species are shifting poleward in search of cooler waters. This migration affects food chains and fishing patterns, disrupting ecosystems and the economies that depend on them.

Influence on climate and weather

Intensification of storms - Warmer ocean surfaces fuel more powerful tropical storms and hurricanes. As the water warms, it evaporates more rapidly, providing more energy to storms, which can lead to increased storm intensity and more frequent extreme weather events.
Sea level rise - The expansion of seawater as it warms and the increased melting of ice sheets and glaciers contribute to rising sea levels. This not only poses a threat to coastal areas due to flooding but also affects tidal systems and erosion patterns, potentially displacing millions of people worldwide.

Effects on our communities

Threats to food security - Many global populations depend on fish and other marine species for protein. Changes in the distribution of these species can lead to food shortages and loss of livelihoods, particularly for communities that rely heavily on fishing.
Economic impacts - The tourism industry, especially in regions known for their natural beauty and biodiversity like coral reefs, faces significant challenges as these attractions are degraded or lost. Additionally, the infrastructure damage from increased storm severity can lead to financial losses.

Global health concerns

Spread of diseases - Warmer waters can facilitate the spread of waterborne pathogens and diseases. For example, increased sea surface temperatures are linked to the expansion of Vibrio bacteria, which can cause illnesses in humans.
Heat-related illnesses - As temperatures rise, heat stress and related illnesses become more common, not only affecting those in tropical regions but increasingly in areas previously not used to such conditions.

Long-term global implications

Irreversible changes - Some changes to ocean systems may be irreversible (referred to as climate tipping points). This includes deep ocean warming and the resulting changes in ocean currents, which can alter global climate patterns beyond our current understanding or predictions.
Feedback loops - Warmer oceans absorb less CO2, decreasing the ocean's ability to buffer against climate change. This reduction can lead to a feedback loop where reduced absorption capacity leads to higher atmospheric CO2 levels, further accelerating global warming.

Looking forward

The record-breaking rise in ocean temperatures highlights a broader environmental crisis: global warming. To prevent further damage and stabilize our planet's climate systems, we must address the root causes of global warming - particularly greenhouse gas emissions. These emissions, primarily from burning fossil fuels, deforestation, and industrial activities, trap heat in our atmosphere, with significant amounts being absorbed by our oceans. Reducing these emissions is not just a matter of policy but a necessity for survival, demanding immediate and sustained global action.

Moreover, the role of international cooperation cannot be overstated. Climate change and its impacts on ocean temperatures know no borders. Effective management and mitigation of ocean warming require a united approach, involving the sharing of technology, scientific research, and resources. Collaborative international efforts must be strengthened to enforce and enhance agreements like the Paris Agreement, aiming for ambitious targets that align with scientific recommendations to limit global temperature rise.

By prioritizing strategies that integrate emissions mitigation and adaptation to changes, we can safeguard marine ecosystems and human communities, ensuring a sustainable future for generations to come.

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