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Impact of Climate Change on High Seas.

Author: Natalia Vasnier

Published: 25/09/2023

On Wednesday the 20th of September 2023, a historical treaty was officially signed between nearly seventy countries at the United Nations to protect 30% of international high seas by 2030. Following 15 years of discussions, the UN successfully sealed the Treaty to protect High Seas in June 2023. This comes as a result of repeated appeals by environmental NGOs to find a immediate solution to protect vital maritime ecosystems. This is the first time that so many countries have come together and unite in the face of climate protection. Even if this historic treaty was signed it will take some time for all countries to ratify the treaty under their own domestic process.

Seas and oceans represent 95% of the world's surface, yet only 1% of high seas are under protection.

High seas

Only 39% of oceans are under national jurisdiction, as they are part of Exclusive Economic Zones. EEZ are maritime continental zones they extend 370 kilometres beyond a nation’s territorial sea zone. This means that the country has jurisdiction over the living and non-living resources in those areas. Beyond this area are the international waters also known as high seas. Even if they are located beyond national jurisdiction, high seas are not lawless, any activity happening in those waters must abide by Maritime Law.

This stipulates that no country owns high seas, it is a global common. However, this leads to a wider problem, if no one owns it, who takes care of it?

Only 1.2% of high seas are protected, all marine life outside these zones are unprotected and victims of shipping traffics, climate change and overfishing. The new Treaty seeks to safeguard and recuperate marine nature attacked by overfishing activities.

Ocean temperatures

This treaty comes at a critical time in the fight against climate change. The 2023 summer recorded the highest temperature levels, with heat waves in Europe leading to ravaging wildfires in Canada and Greece. Data from the Copernicus Climate Change Service reveals that the month of July 2023 was the hottest one yet. This not only impacts land temperatures, but this also leads to unusually high sea surface temperatures. Since April 2023, the average daily sea surface temperatures constantly broke records. The ocean is known as the planet’s greatest carbon sink, as it absorbs excess heat from the atmosphere. Oceans holds 50 times more carbon than the atmosphere and carbon can be stored in the ocean's depths for centuries.

Waters around Western Europe and West Africa are 0.9°C higher than the normal temperature level. It is important to understand the impact a variation of 1°C in temperature can have on the planet. Climate specialists explain that the earth constantly looks to keep and equilibrium, and when temperatures rise above the normal level the planet compensates for this with extreme weathers. Hurricanes are described as the most efficient way to compensate for the rise in temperatures. Some say that the planet will always have a way to survive, I believe that they might be right. Scientists state that if countries do not find a radical strategy to curb global emissions, there will be an increase in 10% of extreme weather in high seas in the following years.

Protecting high seas

Disappearing maritime ecosystems

Maritime ecosystems are not only disturbed by temperatures levels but also by fishing companies. Scientists estimate that nearly 10% of global marine species are at risk of extinction, because of pollution and overfishing. Around 41% species are threatened by climate change, estimated by the IUCN. The unsustainable fishing of local wildlife creates additional stress on local communities who are losing vital food supplies. The UN Treaty will put a limit on the amount of fishing that can take place in the protected zones, and the routes of shipping lanes. Deep sea mining is another activity which will be restricted by this agreements. Activists have raised awareness about the negative impact of mining on maritime wildlife, and it's disruption to breeding grounds.

The impact of high sea surface temperatures as no surprise impact maritime ecosystems and coastal communities. Rising temperatures leads to a loss of marine life and biodiversity, coral reefs around the world have been decreasing and disappearing. If there is to be a global 2°C increase, it would mean that there would be a 100% loss of coral reefs. This would be an irreversible damage. Around half of the world's population depends on the sea for their day-to-day life food sources. Moreover, rising temperatures leads to an acidification of waters due to the higher concentration of carbon dioxide being dissolved into oceans. This phenomenon is life threating for coral reefs. If they get destroyed so are the homes of local wildlife and fish. Therefore, searching for new habitats wildlife is starting to move in northern regions, where waters are cooler.

Threat of extreme weather on shipping

Rising sea levels will not only impact ecosystems and maritime wildlife, but also the shipping industry at large. As temperatures rises so does the probability of extreme weathers. Travelling in rough waters and potentially life threating storms could cost a lot to the billion-dollar industry. As mentioned, the planet compensates for rising temperatures by creating extreme weather events to distribute temperature across the globe. Hurricanes, cyclones, snowstorms leads some ships to lose vital cargo. While others struggle passing through canals, recently there have been some tensions surrounding the Panama Canal. Indeed, early this year that Panama Canal Authority restricted the number of daily passage of ships following an intense period of drought. To put it into perspective for one ship to pass through the canal 200m litres of water needs to be supplied. With the main water source experiencing the lowest water levels seen in decades, Panama and the shipping industry are experiencing a very difficult period. Therefore, higher sea temperatures and levels will lead to inevitable repercussions on national economies who are thoroughly involved in the shipping industry.


Greenpeace has been fighting for many years for countries to sign a Treaty that would create a protected sanctuary of high seas. They call for a Treaty that would create a sanctuary in the high seas that would prevent destructive fishing activities and deep-sea mining which menaces the fragile sea floors. Environmental activists globally, have been protesting and marching to raise awareness of the impact of climate change on Oceans. As world leaders gather for the UN’s general assembly in September 2023, thousands set to the streets of New York to call for government action on global warming. This march was supported by over 700 climate organisations. This issue is not only of concern for local coastal communities, and activists but also for governments as higher sea temperatures has wider repercussions on the economy.

Hope for the Planet

This treaty is described as a success for multilateralism following the union of dozens of countries including the US and China in coming together for a greater good. The new High Sea Treaty meets all the demands of Greenpeace, by protecting maritime wildlife from overexploitation. This treaty is an ode of hope for the future of the planet. It comes at the time when local Indigenous communities in Brazil won a legal battle for land demarcation in the Supreme Court. Earlier this year, France rose taxes on flights to pay for trains, in an effort to promote its national railway system. Along the same lines, India, Germany and Poland started to install solar panels to produce renewable energy to power their trains. All these activities at the national and international level create hope for the planet and show to some extent radical actions taken by governments to deter climate change.

By Natalia Vasnier.


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