This study investigates the factors contributing to drought conditions in Eurasia, distinguishing between natural variability and climate change. Utilizing the Great Eurasian Drought Atlas (GEDA) and tree ring data, researchers analyzed historical droughts to find that modern conditions are primarily driven by global temperature increases, with varying impacts across different regions in Europe and Asia.
Determining the causes of changing drought conditions globally entails a complex analysis between natural hydroclimatic variability and climate change influences. Researchers utilize sophisticated computer models to replicate past climate variations, enabling the identification of unprecedented drought conditions. However, these models may present biases, potentially undermining the reliability of drought assessments in certain areas.
Tree ring data, which reflect natural climate variability by demonstrating growth patterns corresponding to warmer or wetter years versus drier or colder ones, provide an invaluable supplementary method to these model-based analyses. In a study focused on drought conditions across Europe and Asia, Marvel et al. employed tree ring measurements to create the Great Eurasian Drought Atlas (GEDA), incorporating records from thousands of trees dating from 1000 to 2020 CE.
The researchers categorized the GEDA data according to regions identified in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report and analyzed tree ring data from 1000 to 1849 CE to estimate preindustrial averages of the Palmer Drought Severity Index (PDSI). This analysis aimed to ascertain if existing preindustrial drought variations could explain modern drought conditions from 1850 to 2020.
The findings indicated that the contemporary shifts in the PDSI across numerous regions are better attributed to rising global temperatures rather than solely natural variability. Specifically, regions such as eastern Europe, the Mediterranean, and Arctic Russia are experiencing increased dryness, while northern Europe, east central Asia, and Tibet are displaying trends toward increased moisture.
While the researchers acknowledge that tree ring growth can be influenced by non-climatic factors, they assert that these influences did not substantially affect their results. The GEDA database predominantly comprises data from strategically selected locations and tree species where climate remains the paramount factor determining growth patterns.
This study highlights the distinct impact of climate change on drought conditions in Eurasia, indicating that the majority of modern drought severity is influenced by rising temperatures rather than natural variability. It further emphasizes the utility of tree ring measurements as effective proxies for assessing historical climate patterns in drought research.
Original Source: eos.org
