THE SEA is often treated as background. We look at heatwaves on land, at parched gardens, hosepipe warnings, pressure on hospitals, wildfires abroad and record temperatures in cities. But the ocean is where much of the climate story is really being written.

This week, European climate scientists reported that global sea surface temperatures outside the polar regions have hit record levels for this time of year. On June 21, data from the Copernicus Climate Change Service showed sea surface temperatures edging above the extraordinary records seen in 2023 and 2024.

That matters because the ocean is not just a passive victim of climate change. It is one of the main engines of the world’s weather.

Warmer seas put more moisture into the atmosphere. They help keep the air warmer for longer. They can add energy to storms. They can increase the risk of intense rainfall, flooding, marine heatwaves and disruption to wildlife. For coastal communities, fishing industries and anyone who depends on the sea, rising ocean heat is not an abstract statistic. It is a warning light.

The oceans absorb more than 90% of the excess heat trapped in the Earth system. That heat is mainly caused by the burning of fossil fuels such as coal, oil and gas. For decades, the seas have acted like a giant buffer, slowing the pace of warming on land. But that buffer comes at a cost.

The more heat the ocean stores, the more the whole climate system is pushed out of balance.

For Wales, this is not a distant concern. We have just seen an exceptional spell of heat. Cardiff Bute Park recorded 35.9C on June 25, setting a new Welsh June maximum temperature record. The same site also recorded an overnight minimum of 23.5C, a new record for both Wales and the UK.

Hot days are one thing. Hot nights are another. When temperatures do not fall properly overnight, people, animals, buildings and infrastructure get no chance to recover. That is when heat becomes especially dangerous for older people, young children, outdoor workers and those with health conditions.

The link between a warming ocean and weather in Wales is not simple. No single heatwave, storm or wet summer can be blamed on one measurement in the sea. Weather is always shaped by a mix of pressure systems, winds, ocean currents and natural patterns such as El Niño. But the direction of travel is becoming clearer. A warmer world loads the dice.

When the ocean surface is unusually warm, the atmosphere has more energy and more water vapour to work with. That can mean heavier downpours when rain does arrive. It can mean stronger marine heatwaves. It can affect fish, seabirds, plankton, shellfish and the wider food chain. Around our own coast, changes in sea temperature can influence where species live, how well they breed and how resilient marine habitats are to pollution, storms and disease.

This is why climate change should not only be discussed when there is a flood, a heatwave or a political row about net zero. It should be understood as a steady reshaping of the conditions we live with.

For Pembrokeshire, Carmarthenshire and Ceredigion, the sea is part of daily life. It supports tourism, fishing, ferry routes, wildlife, beaches, ports and coastal communities. Warmer seas may sound pleasant to some visitors, but they come with risks: more stress on marine ecosystems, changing fish patterns, increased coastal vulnerability and greater pressure on already stretched public services during extreme weather. There is also a danger that record-breaking weather becomes normalised.

The 2023 ocean temperature records shocked scientists. Then came 2024. Now those levels have been passed again. Each new record can make the previous one feel less remarkable, but the lesson should be the opposite. Records falling year after year are not a sign that we are adapting comfortably. They are a sign that the baseline is shifting.

The ocean has been buying humanity time. It has absorbed vast quantities of heat that would otherwise have warmed the land and atmosphere even faster. But the heat has not disappeared. It is in the system. It affects currents, storms, sea levels, ice melt and marine life. What happens at sea eventually comes back to shore.

There are still practical choices to make. Cutting emissions matters. Protecting saltmarshes, seagrass and coastal habitats matters. Planning for hotter summers and heavier rainfall matters. Supporting farmers, fishers, councils and emergency services to adapt matters. So does taking everyday heat risk seriously, especially for vulnerable people.

Climate change is sometimes presented as a future threat. But this week’s ocean temperature record is another reminder that it is already here, already measurable and already affecting the world around us.

The sea is speaking. The question is whether we are listening.

PLAID CYMRU has renewed calls for the Crown Estate to be devolved to Wales after figures showed income linked to Wales rising from £8.7 million to £210 million in five years.

The party says the increase, described as a rise of around 2,300 per cent, shows that Welsh natural resources are generating huge sums while communities in Wales see little direct benefit.

The Crown Estate manages much of the seabed around Wales, England and Northern Ireland, including areas leased for offshore wind developments. Its profits are paid to the UK Treasury, rather than being retained directly in Wales.

Plaid Cymru’s Ceredigion-Penfro branch said: “Crown Estate profits are up 2,300% but Welsh communities see no benefit.”

The issue has become increasingly topical as Pembrokeshire and the wider west Wales coast are being promoted as key locations for the next generation of floating offshore wind in the Celtic Sea.

Supporters of devolution argue that Wales should have control over the revenue generated from its coastline, seabed and natural resources, with profits reinvested in local infrastructure, ports, skills, transport and public services.

They also point to Scotland, where the Crown Estate has already been devolved. In Scotland, revenue from Crown Estate assets is managed north of the border and contributes to Scottish public finances.

Plaid Cymru says Wales should be treated in the same way.

The party argues that, as offshore wind expands, Wales risks seeing major energy infrastructure developed around its coastline while the financial rewards continue to flow to Westminster.

The Crown Estate has benefited significantly from offshore wind leasing in recent years. Across the UK, the estate has reported profits of more than £1 billion for a third consecutive year, with offshore wind continuing to play a major role in its income.

In Wales, the political argument is sharpened by the scale of potential development in the Celtic Sea.

Ports such as Milford Haven and Port Talbot are expected to play a major role in supporting floating offshore wind, with politicians and industry leaders saying the sector could bring thousands of jobs and major investment.

However, campaigners say Wales must secure more than construction work and supply-chain promises. They argue that long-term control of Crown Estate revenues would allow Wales to build a lasting national benefit from renewable energy.

The UK Government has previously resisted calls to devolve the Crown Estate in Wales. Ministers have argued that Crown Estate profits are returned to the Treasury and used for public spending across the UK.

Opponents of devolution also say Wales already receives funding through the wider UK funding settlement, and that changing the Crown Estate model could add complexity at a time when major energy projects need certainty.

But calls for change have continued to grow, particularly as the value of offshore wind leases has increased.

For Plaid Cymru, the issue is now being framed as a question of fairness.

The party says Wales is being asked to host nationally important renewable energy infrastructure while having limited control over the income generated from its own natural resources.

With the Senedd election approaching, the future of the Crown Estate is likely to remain a major political dividing line.

For campaigners, the argument is simple: if Welsh waters are helping to generate hundreds of millions of pounds, Welsh communities should see the benefit.

For the UK Government, the current system keeps Crown Estate revenue within the UK-wide public finances.

The debate now turns on whether Wales should continue under that arrangement, or follow Scotland in taking control of Crown Estate assets for itself.

VISITORS to Welsh beaches have been warned not to touch unusual blue sea creatures which have washed ashore along parts of the coastline.

Hundreds of velella velella, commonly known as by-the-wind sailors, have been reported on beaches in Anglesey, Gwynedd and Tenby.

The small, bright blue marine creatures are free-floating hydrozoans and are related to Portuguese man o’ war, sea anemones and corals.

They get their name from a small sail-like structure on their body, which catches the wind and carries them across the surface of the sea.

One was spotted on Tenby South Beach on Tuesday (Jun 16), where beachgoer Maxine Allinson described it as “fantastic” and “like a crystal”.

Marine experts say the creatures are often seen after changes in currents or stormy weather, which can push large numbers ashore at the same time.

Although they are much smaller and less dangerous than Portuguese man o’ war, they do have stinging cells.

Their sting is usually mild, but people are being advised not to pick them up, especially as contact with the face, lips or sensitive skin could cause pain or tingling.

Experts also warn that the stinging cells can remain active even after the creatures appear to be dead on the beach.

The advice is to admire them from a safe distance and leave them where they are.

Caption: Maxine Allinson spotted a velella velella on Tenby South beach Tuesday