NASA find evidence that shows humans influence on planet drought can be traced as far back as the start of the 20th century, and continues to get stronger over time.
Researchers suggest the impact of greenhouse gas emissions would’ve started to affect drought and precipitation patterns back in 1900. While that’s based on extrapolated data, the same model matches up with real-world data from the mid-20th century onwards.
Scientists report that the situation is getting worse the human “fingerprint” on the wet and dry cycles of our planet is getting ever-more noticeable.
One important part of the team’s calculations was the Palmer Drought Severity Index, or PDSI, which estimates average summer soil moisture over many years via data like wind speed and rainfall.
The researchers also went back through ‘drought atlases‘, which use the thickness of tree rings to assess precipitation drought for a particular year.
The data showed that greenhouse gas emissions from the very earliest point of the 20th century were probably having a significant effect on temperatures and rainfall across the globe.
Researchers are surprised that you can see human fingerprint, this human climate change signal, emerge in the first half of the 20th century.
What we do know is that these same models are predicting more frequent and more severe droughts in the future, as temperatures rise and that’s likely to lead to food and water shortages, impacts on health, and increased global conflict.
“Climate change is not just a future problem,” says Cook. “This shows it’s already affecting global patterns of drought, hydroclimate, trends, variability it’s happening now. And we expect these trends to continue, as long as we keep warming the world.”