Satellite images taken 90 years apart. During this time, these beaches have not undergone significant human intervention or reclamation.
“Climate change is not real,” “The Earth is not warming,” and “sea levels are not rising,” are common claims you find in discussions among climate change skeptics.
Sometimes they present evidence, such as the satellite image below showing Coolangatta Beach in Australia at two points in time, 1930 and 2020.
The argument from these individuals is: If sea levels are rising, then why is Coolangatta’s coastline not eroding but instead expanding over 90 years? Local authorities have confirmed that there has been virtually no human intervention or artificial reclamation at this beach.
So what is really happening?
Coolangatta Beach in Australia at two points in time, 1930 and 2020.
Beaches Expanding Despite Rising Sea Levels
According to climate change forecasts, the Earth’s temperature has increased by 1.09 degrees Celsius compared to pre-industrial times. Current sea levels are also 20 cm higher than around the mid-18th century.
The consequence of rising sea levels is that it will engulf beaches and submerge reefs. A study published in the journal Nature Climate Change last year predicted that more than one-third (37%) of the world’s beaches could disappear by 2100. In Australia alone, up to 12,000 km of sandy coastline could be lost.
However, strangely enough, a new study published in the journal Ocean & Coastal Management this year pointed to the opposite conclusion. Some coastlines in Queensland and New South Wales are actually expanding rather than eroding.
This clearly contradicts our general understanding of how climate change affects coastlines. It can even lead to confusion and become a source of “fake news” for climate change deniers and those skeptical about rising sea levels.
The expansion of Bucasia Beach in Australia from 1953 to 2020.
To investigate this phenomenon, a team of scientists at the University of Queensland used aerial imagery and satellite records to determine what exactly has been happening.
The results showed that at least 15 beaches in Queensland, stretching from the northern Cooktown to Coolangatta, have gradually expanded seaward since 1930. This phenomenon has also been observed in some countries in Africa and Southeast Asia.
While some expanding beaches in China can be explained by artificial reclamation, the beaches in Australia have seen virtually no significant human impact.
Beaches with Positive Sediment Budgets
It turns out that this is the reason for the expansion of these beaches. Scientists indicate that a beach’s expansion or erosion depends on a concept called “coastal sediment budget.”
This refers to the total amount of sand, rocks, and sediments that can move in or out of a beach over time. A positive sediment budget occurs when more sediment accumulates on the beach than erodes away. Conversely, a negative sediment budget happens when more sand is removed from the beach than is added.
Many factors influence the sediment budget or sand on beaches, not just rising sea levels.
The movement of sediment in and out is influenced by many factors, from waves, tides, to ocean currents and even just a storm. For example, in 2015, residents in Porthleven, England, woke up to find all the sand on their beach had disappeared overnight.
That was the night a strong storm swept through the southwest of their area. No one really knows where the sand went. But the entire beach suddenly returned to its original state just a day later. The sand was back.
For the expanding beaches in Queensland, such as Bucasia, they are being replenished by sediment from a nearby river. Other areas, like Suriname Beach in South America, have developed due to large rivers carrying significant amounts of silt to the coast.
Over time, a positive sediment budget will promote the expansion of coastlines, surpassing any erosion that may be caused by rising sea levels. In other words, the amount of sand reaching the beach right now still exceeds the amount lost due to climate change.
All the sand at Porthleven Beach in England was moved in and out overnight.
Boats stranded at Bucasia after the tide receded.
Not an Excuse for Complacency
However, all of this does not mean that erosion from rising sea levels is not a future threat to coastlines. Instead, we should ask a question: What will happen as forecasts indicate that sea levels will continue to rise rapidly?
The Intergovernmental Panel on Climate Change (IPCC) predicts that sea levels could be as much as 1.01 meters higher (compared to the 1995–2014 levels) by 2100, if global emissions continue unabated.
Moreover, the rate of sea level rise is accelerating. The IPCC observed that it increased by 1.3 mm per year from 1901 to 1971, 1.9 mm per year from 1971 to 2006, and 3.7 mm per year from 2006 to 2018.
Some beaches in the world are actually shrinking over the past decades.
This increase in sea level will eventually become so significant that the current positive sediment budget will no longer offset it. This will ultimately lead to erosion at beaches that are currently expanding.
Therefore, the fact that some coastlines are advancing today is not evidence that sea levels are not rising or that they cannot erode the coastline. It’s merely a fallacious argument made by climate change skeptics.
