20th August 2026
The view from the Caithness coast raises a perfectly reasonable question about one of the most discussed consequences of climate change
Walk along almost any part of the Caithness coastline and there is something rather strange about the debate over rising sea levels.
We are repeatedly told that the world's oceans are rising. Yet if you stand on the shore at Wick, Thurso, Dunnet or elsewhere around Caithness, it is difficult to see any obvious evidence of the sea steadily advancing inland.
The sea still appears to be where it has always been. Beaches remain beaches, rocks remain rocks and the familiar high-water marks are still broadly where local people remember them.
So if sea levels really are rising, why can't we see it?
The answer is that sea-level rise is real, but the way it happens is considerably more complicated than the phrase "the sea is rising" might suggest.
The first thing to understand is the scale involved. Global sea level is changing by only a few millimetres a year. That is an amount far too small for the human eye to detect on a coastline. A high tide can move the water level by metres, while waves, wind, atmospheric pressure and storms can move water even further.
Against those movements, a few millimetres a year simply disappear into the daily noise of the sea.
There is, however, something particularly interesting about Caithness because we don't have to rely solely on global measurements. Scotland has tide gauges around its coastline, including one at Wick, and the measurements tell us something rather different from the impression we might get from simply looking at the shore.
The Scottish Marine Assessment reports that the Wick tide gauge recorded a mean sea-level trend of 15.7 millimetres per decade between 1988 and 2018. That equates to approximately 1.6 millimetres a year over that particular period.
That is measurable scientifically, but almost impossible to detect visually.
Over ten years, 1.6 millimetres a year would amount to roughly 1.6 centimetres. Even after half a century, it would amount to only around eight centimetres if the rate remained unchanged.
That begins to explain the apparent contradiction between what the scientists say and what local people see.
But there is another important factor.
When we talk about sea-level rise, we tend to imagine that the land beneath our feet is completely stationary. It isn't.
Scotland is still responding to the enormous weight of ice that covered much of the country during the last Ice Age. When that ice melted, the land that had been depressed by its weight began to rise again. This process, known as glacial isostatic adjustment or post-glacial rebound, continues today.
NatureScot explains that central parts of Scotland are still rising, although the present uplift is relatively modest. In some areas it can be as much as 0.6 millimetres a year. At the same time, coastal waters around the UK are rising by up to about 2 millimetres a year. The result is that Scotland is now experiencing a net relative sea-level rise.
This is an important distinction.
What matters to someone standing on the Caithness coast isn't simply how much the ocean is rising globally. What matters is the relative movement between the land and the sea.
If the land is rising while the sea is rising, the difference between the two is smaller than it would be if the land were stationary.
This also explains why sea-level trends can vary considerably around Scotland. The Scottish Marine Assessment says that observed sea-level trends vary greatly around the Scottish coast, mainly because different parts of the land are moving at different rates relative to the sea.
There is therefore no single "Scottish sea-level rise" that applies equally to every beach, harbour and rocky headland.
And there is another reason why simply looking at the shoreline can be misleading.
A coastline isn't a fixed line.
Beaches gain and lose sand. Gravel is moved by waves. Dunes migrate. Storms can remove enormous quantities of material in a matter of hours, while calmer periods can put some of it back.
A rocky coastline may barely change position for decades, while a sandy beach nearby can alter dramatically.
That means that coastal erosion isn't the same thing as sea-level rise.
Indeed, a rising sea does not necessarily mean that every beach will visibly retreat by a corresponding amount.
What scientists are particularly interested in is what happens when rising sea levels combine with other forces.
Consider a major storm.
Suppose a severe storm produces an exceptionally high water level along the Caithness coast. If the underlying average sea level is several centimetres higher than it was decades earlier, the storm is starting from a higher base.
The difference may not be noticeable on an ordinary Tuesday afternoon.
But during an extreme event, those extra centimetres can matter.
That is why the future risk associated with sea-level rise is not necessarily that we will suddenly look out of the window one morning and discover that the sea has moved dramatically inland.
The more realistic concern is that events that were previously rare may become more damaging.
SEPA's future flood mapping explicitly takes projected increases in mean sea level into account. It warns that rising sea levels will increase the risk of flooding from the sea, while recognising that the impact varies considerably from one part of Scotland to another.
SEPA's guidance also points out that relative sea-level rise is only one component of future coastal flood risk. Storm surges, waves and future storm conditions also matter.
That is particularly relevant to Caithness.
A calm sea on a summer day tells us remarkably little about what the same coastline might experience during an exceptional Atlantic storm.
There is also an important lesson here about how we interpret climate statistics.
A statement such as "sea levels are rising" is scientifically correct, but it can create an impression of something that is happening much faster and more visibly than it actually is.
The sea is not rising like water being poured into a bath.
It is a slow change in the average level of a huge and constantly moving system. Tides rise and fall. Waves come and go. Atmospheric pressure changes. Storm surges temporarily raise the water level. Coastal sediments move. And the land itself is moving.
The underlying trend can therefore be almost invisible to someone standing on the beach.
Yet the fact that we cannot see it does not mean that it isn't happening.
There is another fascinating point in the Scottish evidence. Historical tide-gauge records show that sea levels have risen at Scottish measurement sites over the periods for which records are available, although the rates differ considerably from place to place.
And the concern for the future isn't simply about what has happened over the last few decades.
SEPA's current guidance for flood-risk assessment incorporates projected sea-level changes through to 2100 and beyond. It also says that sea-level rise is expected to increase the rate of coastal erosion.
That brings us back to the original question.
If sea levels are rising, why can't I see it?
Because the change is currently too small, too slow and too easily masked by the enormous natural movements of the sea for the human eye to detect.
But there is an important qualification.
You might not be able to see sea-level rise directly, but you could eventually see its consequences.
Those consequences could include more frequent coastal flooding during extreme tides and storms, greater pressure on vulnerable coastal infrastructure and increased erosion in susceptible areas.
And that distinction is perhaps the most important one for people living in a coastal part of Scotland.
We shouldn't expect to walk along a Caithness beach and suddenly discover that the sea has moved noticeably closer.
The question is more subtle.
Has the starting point for the next big storm changed?
The tide gauge at Wick suggests that it has.
And that is perhaps why the best evidence of a changing sea isn't necessarily something we can see with our eyes. It is something that instruments have been quietly recording for decades.
For Caithness, the story is not one of a sea dramatically swallowing the coastline. It is a much slower story of ocean levels changing, land continuing to move, and the balance between the two gradually shifting.
The sea may look exactly the same when we look at it tomorrow.
But that doesn't necessarily mean that it is behaving exactly as it did when our parents or grandparents looked at the same shoreline.