Climate Whiplash: How water extremes affect our cities

On March 22nd, we celebrate World Water Day, a reminder of water’s essential role in sustaining life on Earth. Its importance is even clearer in the search for extraterrestrial life. Scientists often look for the presence of water when assessing whether a planet might support life. This underscores a simple truth: life cannot exist without water. If we recognize its significance in the vastness of space, we must also acknowledge the necessity of protecting this resource on Earth.

Coinciding with World Water Day, a new report highlights how climate change is disrupting the water cycle in major cities. Extreme weather events, including floods and droughts, are intensifying as wet and dry conditions become more extreme. The report reaffirms the fact that some parts of the world are getting wetter while others are drying out. South and Southeast Asia is experiencing a strong wetting trend, increasing the likelihood of extreme flooding. Meanwhile, Europe, the Middle East, and North Africa are facing a drying trend, making them increasingly susceptible to prolonged and frequent droughts. However, the report also highlights that about 20% of the world’s cities are undergoing a reversal in climate extremes. These shifts complicate climate adaptation efforts, as cities accustomed to one type of climate pattern must now prepare for the opposite.

 

The growing threat of climate whiplash

The report’s most striking finding is the increasing prevalence of what the authors call ‘climate whiplash’ – a phenomenon where extreme dry and extreme wet events occur in rapid succession. This volatility makes it exceptionally difficult for communities to prepare for and recover from weather extremes. Alarmingly, 15% of the world’s most populated cities are already experiencing these alternating extreme events, and they are spread across the globe. Considering social and infrastructure vulnerabilities, the highest climate risk is concentrated in South and Southeast Asia, as well as in North and East Africa. These regions face more extreme climate conditions and struggle with economic and infrastructural limitations that make adaptation particularly challenging.

 

Europe’s drying trend and its hidden vulnerabilities

Turning specifically to Europe, the report challenges the common perception that the continent is becoming wetter. In reality, a long-term drying trend is underway. However, this does not mean extreme flooding is no longer a concern. On the contrary, drought conditions can exacerbate flood risks when heavy rainfall occurs on dry, compacted soils. Given Europe’s relatively high level of economic development, cities generally have lower social vulnerability scores. Yet, an unexpected insight from the report is that European cities have relatively high infrastructural vulnerability compared to other high-income regions such as Australia and the United States. Many of these urban centers are relatively old, relying on aging water supply and sanitation infrastructure that may not be equipped to handle the emerging challenges of a more extreme climate.

 

The cost of inaction

The implications of these findings are clear: adapting to climate change will require significant and costly measures. Investments in water infrastructure, flood defenses, and drought preparedness will be necessary to protect communities and economies from escalating risks. Once again, this serves as a stark reminder that while climate mitigation efforts come at a cost, the cost of inaction is even greater. Failing to curb emissions today will only lead to higher adaptation expenses tomorrow, as cities are forced to confront more extreme and unpredictable climate conditions. As we mark another World Water Day, it is crucial to acknowledge that protecting our most vital resource is not just a societal imperative but an economic necessity.