Challenging Climate Change Narratives: The Case of Sea Level Rise, By Brian Simpson

A recent study by Dutch researchers Hessel Voortman and Rob de Vos, published in the Journal of Marine Science and Engineering, has sparked significant debate by challenging the prevailing narrative that climate change is driving an accelerated rise in global sea levels. The study, which analysed over 200 tide gauge stations worldwide, found an average sea level rise of just 1.5 mm per year in 2020, equivalent to 6 inches per century, far below the 3 to 4 mm per year often cited in climate science literature and media reports. Crucially, the study found no evidence of global acceleration in sea level rise, attributing localised increases to non-climatic factors like land subsidence or geological activity. Here I examine the implications of these findings which critiques the mainstream climate narrative, and consider the broader significance for science and policy.

Voortman and de Vos's study is notable for its reliance on real-world data from tide gauge stations, spanning at least 60 years, rather than climate models or satellite imagery, which have dominated recent sea level rise estimates. Their analysis revealed that 95% of the studied locations showed no statistically significant acceleration in sea level rise, directly contradicting claims from the Intergovernmental Panel on Climate Change (IPCC) and other mainstream sources that global warming is causing seas to rise at an increasing rate. The researchers argue that the IPCC's projections for 2020 overestimated sea level rise by approximately 2 mm per year, a discrepancy they attribute to model biases rather than observed reality.

The study also highlights the influence of local, non-climatic factors in areas where sea level rise appeared elevated. For instance, phenomena like earthquakes, coastal construction, or post-glacial rebound can significantly affect local measurements, yet these are often overlooked in global climate narratives. Voortman's observation that stations showing notable rises were often near others with negligible changes further undermines the idea that CO₂-driven global warming is a universal driver of sea level rise. Instead, the findings suggest that local geological and environmental factors play a more significant role than previously acknowledged.

The mainstream climate narrative, as articulated by the IPCC and echoed by media outlets, has long emphasised that human-induced climate change, primarily through greenhouse gas emissions, is accelerating sea level rise, with dire projections of metres of rise by 2100. For example, a 2019 article in The Atlantic warned that "the oceans we know won't survive climate change," citing estimates of over 34 inches of rise by 2100. Similarly, NOAA's 2023 data claimed a doubling of the sea level rise rate from 1.4 mm per year in the 20th century to 3.6 mm per year from 2006–2015, driven by glacier and ice sheet melt. Yet Voortman and de Vos's findings challenge these claims, suggesting that such projections may be inflated by reliance on models that fail to align with empirical observations.

The discrepancy between model-based projections and tide gauge data raises questions about the reliability of climate models. Satellite imagery, introduced in the 1990s, has been a key tool for estimating global sea level rise, but Voortman argues that it may exaggerate trends by capturing short-term fluctuations, like the 1993 "trough" and 2020 "peak," rather than long-term patterns. Tide gauges, while limited in global coverage, provide a more stable, localised record that can ground-truth these broader estimates. The study's independence from external funding further bolsters its credibility, as it avoids the potential biases associated with grant-driven research aligned with climate agendas.

The findings have significant implications for both scientific inquiry and public policy. Scientifically, the study underscores the importance of empirical data over model-driven projections. Voortman's astonishment that no prior global study had compared IPCC projections with local observations, highlights a gap in the scientific process. This omission suggests a potential bias toward confirming climate change narratives rather than rigorously testing them against real-world evidence. By using data from over 200 tide gauge stations, Voortman and de Vos demonstrated the value of ground-level measurements in challenging assumptions and refining our understanding of complex systems like sea level dynamics.

For policy, the study calls into question the urgency of costly climate adaptation measures based on exaggerated sea level rise projections. Coastal infrastructure projects, such as seawalls or flood defences, often rely on IPCC estimates to justify significant investments. If the actual rate of rise is closer to 1.5 mm per year, as the study suggests, these projects may be overengineered, diverting resources from other pressing needs. Voortman, a hydraulic engineer with 30 years of experience in flood protection, emphasises the need for accurate data to inform practical engineering decisions, noting that understanding the gap between projections and observations is "crucial for practical applications."

The study also critiques the broader culture of climate alarmism, which often amplifies fears of catastrophic sea level rise to drive policy and public opinion. Media reports frequently cite extreme scenarios, such as 3 to 10 feet of rise by 2100, without acknowledging the uncertainties or variability in local conditions. This alarmism can erode public trust when predictions fail to materialise, as seen in Voortman's earlier 2023 study on the Dutch coast, which found no acceleration despite warnings to the contrary. By attributing localised rises to non-climatic factors, the new study challenges the narrative that CO₂ emissions are the primary driver, suggesting instead that natural geological processes may dominate in many regions.

However, the study is not without limitations. Its focus on tide gauge data, while valuable, excludes satellite measurements that provide broader global coverage. Critics might argue that this omission skews the findings, as tide gauges are concentrated in the Northern Hemisphere, with Latin America and Africa underrepresented. Additionally, the study's reliance on data from 2020 may not capture longer-term trends that could emerge with further warming. Nevertheless, its call for scepticism toward unverified projections aligns with the scientific principle of testing hypotheses against observable evidence.

The Voortman and de Vos study does not deny that sea levels are rising, 6 inches per century is still significant for low-lying regions, but it challenges the attribution of this rise to climate change and the claim of acceleration. Policymakers should heed this call for precision, ensuring that adaptation measures are grounded in empirical data rather than worst-case scenarios. Scientists, meanwhile, must adopt independent, data-driven research to refine models and close the gap between projections and observations.

Ultimately, the study advocates for a more nuanced approach to climate science, one that acknowledges the complexity of sea level dynamics and resists the temptation to oversimplify for political or ideological ends. By focusing on local data and questioning global assumptions, Voortman and de Vos remind us that science thrives on scrutiny, not consensus.

https://nypost.com/2025/09/04/world-news/sea-level-rise-not-caused-by-climate-change-study-claims/