Climate Change Attributions
Firefighter battling fires on Rhodes, 7-24-23 (Greek City Times)
Because of the diverse atmospheric interactions between environmental factors including clouds, winds, dust, and the ocean it has been difficult to attribute the impacts of climate change to a given extreme weather event. Within the past decade, a new area of field emerged, Attribution Science, to help resolve this complexity and provide predictions of probability.
According to the Climate School at Colombia University, this attribution question could not have been answered ten years ago. Now, linking climate change to extreme weather is easier due to the World Weather Attribution (WWA) initiative. The new organization analyses an extreme weather event just after it happens determining the contribution of climate change to its severity. Attribution science calculates the likelihood of a specific event happening today and compares that probability to how it might have unfolded in a world that had not been affected by heat-trapping greenhouse gases. Attribution science determines, not if climate change caused an extreme event, but rather if the event were more severe, more likely to occur, and if so by how much.
WWA investigators first determine how frequently a certain magnitude of an event might occur based on the historical data. Extreme weather is more accurately analyzed when long-term observational records exist that can be replicated by computer models. In many regions, weather data exists for many years that can used for climate models. Events connected to temperature, like heat waves and droughts, provide the most certainty in the simulations. Modelers prefers data that began to be collected in the 20th Century and, preferably, in the 19th. The more data that is available, the better the predictions that can be developed.
The new organization just calculated the climate change impacts for the latest extreme weather now affecting Europe, North America, and China and released their attribution report. From massive fires in Greece, to extreme heatwaves in the western United States and northern China, the Summer of 2023 will not be soon forgotten. According to the WWA's assessment: the role of climate change in these events is 'overwhelming'.
Their entire report is now available but some of the key findings were underscored in the summary:
- North America, Europe, and China have experienced increasingly frequent heatwaves as a result of climate warming. An event like the current one is expected once in 15 years in the US/Mexico region; once every 10 years in Southern Europe; and once every 5 years in China;
- Without climate change, these heat events would have been extremely rare. In China it would have been about a 1 in 250 year event while the maximum heat like July 2023 would have been virtually impossible to occur in the US/Mexico region and Southern Europe;
- Unless the world rapidly stops burning fossil fuels, these events will become even more common and the world will experience heatwaves that are even hotter and longer-lasting.
If such dire predictions were not enough for concerted actions to reduce atmospheric pollution, expand renewable energy, and build resilience into architecture, a multi-year study by a Danish research team monitoring ice melting on Greenland adds another dimension to the impacts of climate change. Some of the graphics are technical but the 'bottom line' remains that coastal zones from the mid-Atlantic states, to Florida, and the Gulf of Mexico can expect some major re-alignments and North America was the only continent mentioned by the Danes. WHB