Peili Wu and colleagues used climate model simulations to show how the hydrological cycle could react to changes in future amounts of carbon dioxide (CO2) in the atmosphere. They simulated the effects of a steady rise in CO2 levels to more than 1000 parts per million (ppm), followed by a decrease to pre-industrial levels of around 280 ppm.
The simulations reveal that even a dramatic reduction of CO2 would not immediately reverse long-term changes to global precipitation already stored in the system.
In fact, changes to the hydrological cycle would continue to intensify for several decades because accumulated heat in the ocean would continue to affect precipitation patterns long after global temperatures were brought back down. For instance, high-latitude regions would receive more rainfall, while the Amazon, Australia, and western Africa would become drier for decades after CO2 reductions were implemented, the researchers found.
The team points out that when considering climate mitigation strategies, the effects on precipitation need to be carefully considered. The more heat that is stored in the ocean, the greater will be the commitment to long-lasting changes to the water cycle.
The study appears in the journal Geophysical Research Letters.