Human impact on droughts dates back to 20th Century

Human impact on droughts dates back to 20th Century

Washington: A new study has claimed that greenhouse gases and atmospheric particles generated by human beings were affecting the worldwide drought risk as far back as the early 20th century. The study compared predicted and real-world soil moisture data to look for human influences on global drought patterns in the 20th century. Climate models predicted that a human ‘fingerprint’ —a global pattern of regional drying and wetting characteristic of the climate response to greenhouse gases — should be visible early in the 1900s and increase over time as emissions increased.

Using observational data such as precipitation and historical data reconstructed from tree rings, the researchers found that the real-world data began to align with the fingerprint within the first half of the 20th  century. The team said the study is the first to provide historical evidence connecting human-generated emissions and drought at near-global scales, lending credibility to forward-looking models that predict such a connection.

According to the research, the fingerprint is likely to grow stronger over the next few decades, potentially leading to severe human consequences. The study’s key drought indicator was the Palmer Drought Severity Index or PDSI. The PDSI provides researchers with average soil moisture over long periods of time, making it especially useful for research on climate change in the past. “We were pretty surprised that you can see this human fingerprint, this human climate change signal, emerge in the first half of the 20th century,” said Ben Cook, who co-led the study with Marvel. The story changed briefly between 1950 and 1975, as the atmosphere became cooler and wetter. —ANI


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