Human impact on the world’s climate going back to the start of the 20th century has been detailed in a new study by the Columbia University’s Earth Institute.
The new study, which observes the patterns of drought and moisture across the world, details rising temperatures and broader human impact on water supplies.
Observations by the team include the drying soils across much of North America, central America, Eurasia and the Mediterranean. Other areas, including the Indian subcontinent, have become wetter. They say the trends will continue, with severe consequences for humans.
“We asked, does the real world look like what the models tell us to expect?” said study coauthor Benjamin Cook of the NASA Goddard Institute for Space Studies and Columbia University’s Lamont-Doherty Earth Observatory. “The answer is yes. The big thing we learned is that climate change started affecting global patterns of drought in the early 20th century. We expect this pattern to keep emerging as climate change continues.”
The new study combines computer models with long-term observations to suggest that systemic changes in what scientists call the hydroclimate are already underway across the world, and have been for some time.
They used tree rings going back 600 to 900 years to estimate soil moisture trends before human-produced greenhouse gases started rising, then compared this data with 20th-century tree rings and modern instrumental observations, to see if they could pick out drought patterns matching those predicted by computer models, amid the noise of natural yearly or decadal regional weather variations.