Scientists find a melting gun in climate impacts
ONE of the most challenging things about making climate science relatable to people who are not climate scientists is the difficulty in finding simple cause-and-effect examples that work within the time frame of the average person’s attention span. Climate science is very good at describing causes and effects on timescales of decades, but most people do not think in those terms and have perfectly good reasons for not doing so. Thus, a completely accurate conclusion, such as “increasing sea and atmospheric temperatures are causing and will cause more frequent and stronger tropical storms,” is an abstraction.
Abstractions are easy to ignore because the relevant time frame for almost all of the concerns of the average person is measured in days or weeks or months or, at most, perhaps a year or two. Information describing conditions in the year 2050 is not practically useful; information describing conditions next season or next year, however, would be. Until now, that has rarely, if ever, been possible.
That seems to have changed. In a new study published on February 28, a group of researchers from the UK’s National Oceanographic Center found definitive links between ice loss in the Arctic Ocean and unusually hot, dry summer weather in Europe, which has become a regular occurrence over the past couple years and seems to be intensifying; in the summer of 2022, for example, Britain recorded a daytime temperature of 40 degrees Celsius for the first time in history.
The study, titled “European summer weather linked to North Atlantic freshwater anomalies in preceding years,” was published in the journal Weather and Climate Dynamics and is available online.
The research gap the study sought to close was that even though it has generally taken for granted that accelerating ice loss in the Arctic is responsible for or contributes to the increased occurrence of extreme weather in midlatitude regions, the exact mechanisms behind the phenomenon were not understood. Figuring it out would, for starters, provide clearer proof of climate change effects and, more importantly, help make those effects more usefully predictable.
The Arctic region is warming faster than any other part of the Earth, and the most obvious consequence of this is accelerating ice loss. Greenland, for example, is losing about 30 million metric tons of ice per hour due to the melting of its glaciers. All of that melted freshwater flows into the ocean, changing the balance between the colder, denser fresh water and the lighter, warmer seawater (“warm” and “cold” are relative here; to you or me, all of it would still feel cold). Changing this balance alters the flow of ocean currents, which in turn alters the movement of the atmosphere above the ocean.
By mainly relying on historical weather and oceanographic data, the researchers were able to identify and describe a specific pattern. They explained, “[S]tronger freshwater anomalies are associated with a sharper sea surface temperature front between the subpolar and the subtropical North Atlantic in winter, an increased atmospheric instability above the sea surface temperature front, and a largescale atmospheric circulation that induces a northward shift in the North Atlantic Current, strengthening the sea surface temperature front. In the following summer, the lower-tropospheric winds are deflected northward along the enhanced sea surface temperature front and the European coastline, forming part of a large-scale atmospheric circulation anomaly that is associated with warmer and drier weather over Europe.”
What is particularly remarkable is that the pattern is consistent enough that predictions about weather conditions over Europe can be made for a useful time frame. If the pattern is seen in the winter, then the following summer will be hot and dry, with exactly how hot and dry being indicated by the degree of the temperature differential between the subpolar and subtropical regions of the North Atlantic. There is still a bit of variability, of course; it is implied that the predictions are only reliable down to a regional or country-sized scale.
That is still incredibly specific compared to climate change effect predictions up to this point, and more importantly, it is practical information that can be used
to prepare mitigation and response measures. The last severe European summer heat wave killed at least 60,000 people; that is the sort of problem for which the authorities and the affected populations would probably appreciate some advance warning. Likewise, the study’s basic methodology can be applied in other parts of the world, helping to improve climate and disaster mitigation and response.
Not insignificantly, the new research definitively trashes one of the more challenging arguments speciously used by climate change deniers to promote their planet-killing agenda, that being “You can’t tie specific weather events to climate change.” Well, now you can. The European study was just the start; successful research tends to inspire more of the same in short order, and so we can anticipate a progressively clearer picture of climate change impacts in close to real-time over the coming months and years.