It is abundantly clear how human-driven climate change has contributed to the deadly flooding we've seen of late in Spain and elsewhere, writes Prof Conor Murphy of the Geography Department and MU's Climate Research Centre, ICARUS.

    The news and images emerging from the recent floods in Spain are both devastating and shocking. Our thoughts are with those who have lost loved ones, homes and livelihoods.

    The full extent of the impacts will not be known for some time and are certain to be long lasting.

    While weather extremes will happen, it now abundantly clear that climate change is increasing their ferocity. Ongoing formal 'attribution' studies will no doubt quantify the increased risks of such extremes due to climate change, but we don’t need such studies to see that the fingerprints of human driven climate change have contributed in multiple ways to the extent of devastation in Spain. Here are three incriminating pieces of evidence:

    Mediterranean sea surface temperatures

    We saw record-high water temperatures across the Mediterranean this past summer. More than 90% of the additional heat from greenhouse gases has been absorbed by the oceans. Aside from the damage this has caused to local ecosystems, such elevated water temperatures provide the heat energy that fuels extreme weather events. Warmer waters contribute more moisture to the atmosphere, feeding storms and creating unstable atmospheric conditions. These elevated sea surface temperatures played a key role in the devastating flooding in central Europe in September and amplified the extreme rainfall totals witnessed in Spain.

    A warmer atmosphere

    A warmer atmosphere holds more moisture, leading to more intense rainfall events. 2023 was the hottest year on record globally by a large margin, but 2024 is on track to surpass it. We are on the cusp of global average temperatures being 1.5°C above pre-industrial levels—a critical threshold in global efforts to reduce greenhouse gas emissions.

    A warming Arctic

    This point is more controversial and still contested by scientists, but there's a saying that "what happens in the Arctic doesn't stay in the Arctic". The Arctic region is warming faster than any other area on the planet. Some scientists maintain that Arctic warming is weakening the mid-latitude jet stream—the high-altitude ribbon of air that often directs storms over regions like Ireland—and causing it to become more wavy. When this happens, extreme weather conditions can be blocked or stalled over the same location.

    We've seen stalled low-pressure systems cause dramatic flooding in central Europe and Spain in the last two months alone. Such stalling leads to huge rainfall amounts in affected regions, giving rise to what we might call mega-floods.

    During the Spanish floods, a low-pressure system got trapped in place over the Iberian Peninsula, drawing in warm, moist air over the exceptionally hot Mediterranean. In eastern Spain, particularly the Valencia region, local topography and hydrology contributed to creating the perfect storm. This region has upland areas that force air to rise further, amplifying instability and rainfall extremes.

    The landscape, characterised by thin soils and steep slopes, causes heavy rainfall to run off rapidly. With some areas recording over 400mm of rainfall in less than six to eight hours, downstream settlements were inundated. These landscapes are also likely denuded of natural vegetation, further accelerating the rainfall-runoff response.

    While the impacts of these devastating floods are still unfolding, they are likely to reverberate locally and beyond for many months. The impacts of flooding do not end when the waters recede. They have long-term impacts on health and wellbeing.

    As we confront climate change–amplified extremes, it is becoming increasingly obvious that impacts flow across borders. We live in a highly interconnected world, and the devastation of key agricultural regions in Spain is likely to impact the availability and price of foodstuffs over the coming months. As a small, open economy heavily reliant on imports, exports, and supply chains, Ireland is highly exposed to such transboundary climate risks.

    We are certainly not immune to climate change in Ireland and we are also vulnerable. The fingerprint of climate change has been revealed in studies of the Midleton flood associated with Storm Babet in October 2023. It's the same familiar story: the storm drew additional moisture and energy from the climate-warmed Atlantic, while the heavy rainfall that triggered the floods was made considerably worse by the enhanced water-holding capacity of a warmer atmosphere. This signal of climate change has been shown in many of our long-term rainfall records.

    If the devastation from the Spanish floods doesn't ignite more aggressive climate action, what will? But how many even remember the devastation of the central European floods a few short weeks ago, where many lost their lives and tens of thousands were evacuated? Or the staggering human toll of excessive summer heat in Europe in 2022, which resulted in over 60,000 heat-related deaths.

    These events are just a prelude to the future. In a world that's 3°C warmer than pre-industrial, such extremes wouldn't just be twice as bad (we are almost halfway there) — they could be dramatically more severe. Climate change is accelerating before our eyes. It is imperative that we act now, not just to mitigate its progression but to prepare for its inevitable impacts. The time for half-measures is over: we must confront this crisis head-on to safeguard our future.

    This piece originally appeared on RTÉ Brainstorm