The Unseen Threat: How a Weakening Jet Stream Is Reshaping Travel in the Mediterranean

Written By Roger Hyde

This week, as the heat finally breaks in Mallorca, the accompanying storm clouds provides a stark reminder for the climate volatility we now face.

This is a part of the world that has always known summer heat. But as a resident of Mallorca one of the original European sunshine vacation destinations, I can tell you that what we are experiencing now goes far beyond the traditional notion of a hot summer.

It is a new reality of prolonged, intense heatwaves and stifling 'tropical nights', a trend that is becoming a regular fixture in our calendars. The prolonged heat of this magnitude is absolutely unprecedented in my decades of witnessing these changes firsthand. My work has taken me to every corner of the Mediterranean region over decades, and I have witnessed these changes directly. What concerns me most is the rapid acceleration we are seeing in recent years.

404 Noir co-founder Roger Hyde beating the heat this week with dusk and night mountain climbing to beat the heat in the Tramuntana Mountains of Mallorca. Photo thanks to Braden Mayfield.

This is a wake-up call for the travel industry. The very cause of these heatwaves, a weakening subtropical jet stream, is profoundly reshaping tourism in the Mediterranean, a region that is a global climate change hotspot, heating faster than other continents. I believe we in the travel sector have a responsibility to confront this risk.

My latest article dives into this new reality, using real-world examples and data to ask the obvious, yet unasked, questions about a problem that is not being anticipated, prepared for, or acknowledged.

The Scientific Cause: How a Weakening Jet Stream Fuels Our Heatwaves

While we often think of heatwaves as localized events, the latest climate science reveals a deeper, more systemic cause. Research now links these intense Mediterranean heatwaves to a fundamental change in our global weather systems: a weakening and shifting subtropical jet stream.

This powerful atmospheric current is a fast-flowing "river of air" in the upper atmosphere, and it's powered by the temperature difference between the cold Arctic and the warmer equator. It's what the pilot sometimes mentioned making flights from London to New York considerably quicker heading east than west.

(This video from the UK Government Meteorological Office gives a great general explanation.)

This weakening is a direct and unnatural consequence of global warming, driven largely by the fact that the Arctic is warming significantly faster than the rest of the planet - a phenomenon known as Arctic amplification. This reduces the previously more predictable and defined temperature difference that powers the jet stream, causing it to become more erratic, sluggish, and wavy. It's buckling, or at least wobbling.

This "wobbling" effect allows large, high-pressure systems (like the subtropical ridge between 20' and 40' latitudes) to become "stuck" over a particular region, causing prolonged heatwaves. In the case of the Mediterranean, this creates a destructive feedback loop:

  • Less Wind & Higher Sea Temperatures: The stagnant, high-pressure system leads to a significant decrease in winds. This allows the sun's heat to warm the sea surface more effectively, leading to a significant and unnerving rise in sea temperatures.

  • Hotter Air: This hotter sea then acts as a thermal battery, raising the air temperature above it, which in turn intensifies the heatwave and prevents the nocturnal cooling that humans and ecosystems need to recover. Natural processes cannot keep up with these unnatural changes.

The result is not just a few hot days; it's a new climate reality that poses a direct, immediate threat to the tourism industry in the Mediterranean and beyond. Understanding this scientific cause is the first step to building a resilient travel strategy.

Based on Copernicus Satellite Marine Service (CMEMS) data, showing sea surface anomalies for the Western Mediterranean in late June 2025.

From Scientific Cause to Operational Risk

This scientific reality has profound, on-the-ground implications for everyaspect of travel. We are not just seeing a problem, we are experiencing its consequences:

  • Global Events & Disruption: The same weakening jet stream that is fueling Mediterranean heatwaves is also linked to other unprecedented weather events globally. In recent weeks on my own news feed I've seen prolonged, record-breaking heat in the UK, a sudden and intense desert storm at the Burning Man festival, and massive, persistent flooding in Pakistan. These are not isolated incidents, they are all symptoms of the same systemic climate volatility.

  • Human Health: Thousands of heat-related deaths and public workers collapsing in Spain this summer are a stark reminder that heat is a safety hazard. This is a risk for both visitors and locals.

  • Economic Viability: With the rise of "coolcations," as reported by Condé Nast, travelers are already shifting their booking patterns to avoid the Mediterranean heat, threatening a major economic pillar of the region.

  • Unchecked Growth Paradox: All of this is being fueled by an increasing supply and demand for cheap flights to these same destinations, despite all talk of sustainability from the aviation and tourism industries. We are witnessing an industry that is actively pursuing growth by relying on a method of travel — the burning of fossil fuels — that is helping to destroy the very planet it relies on and claims to protect.

    Pioneering a Path Forward: From Ignorance to Proactive Strategy

This problem doesn't have an easy answer, but my decades of experience suggest that true sustainability demands a deeper look. At 404 NOIR, we believe the next frontier for responsible premier travel lies in advocating for a 'less is better' philosophy—prioritizing quality, ethical integrity, and genuine climate responsibility over unchecked growth.

This requires:

  • Honest Dialogue: We must engage in honest dialogue by connecting the scientific cause of these heatwaves to their devastating consequences.

  • Resilience by Design: Proactively integrating climate risk into safety assessments, logistics, and planning, ensuring our operations are resilient to a hotter, more volatile world.

  • New Economic Models: Exploring and implementing innovative business models that prioritize local well-being and long-term viability, while actually reducing GHG emissions. This includes taking a serious look at Scope 3 downstream emissions, recognizing that a company or destination cannot claim climate responsibility or sustainability without also accounting for and mitigating the emissions from their clients' flights and other travel in their value chain.

The challenges of a warming planet are real, but they also present an opportunity for courageous leadership. How can we, as an industry, move from being a source of these problems to being a genuine part of the solution?

Join the Conversation

This conversation is vital. Are these disruptions and increasing climate instability and unlivable conditions inevitable? How are you and your organization preparing for the new reality of climate-driven disruptions? There is lots to discuss.

References

A compilation of the URLs and a brief description of the sources that were used to inform and support the content of this article.

Sources for Climate Science & Heatwave Dynamics:

Sources for Social & Economic Context:

Roger Hyde
Next

From 'Cool Banks' to 'Net Zero': Is the Tourism Industry Prepared for the Mediterranean's New Climate Reality?