Scientists now know that increases in atmospheric carbon dioxide levels warm the climate. Changes in global surface temperature induce many secondary modifications, such as changes in clouds, moisture in the atmosphere and temperature distribution. All of these influence the processes that control rain and snowfall and they can alter precipitation. Climate models indicate that precipitation around the world will increase by roughly 2–3% per degree Celsius of global surface-temperature change.
However, it's not quite as simple as that. The latest research is showing that precipitation can also respond directly to the atmospheric heating caused by increases in carbon dioxide. This direct reaction occurs much faster than the precipitation modifications caused by global climate change because global change is relatively slow; it depends on how quickly the oceans warm – something that can take decades to centuries. The fast atmospheric response, on the other hand, occurs within just a few days and seems to suppress precipitation. Climate models indicate that when carbon dioxide levels are increasing, the global precipitation response to surface-temperature change is suppressed by roughly 1% per degree Celsius of global surface warming.
This means that climate-mitigation strategies that aim to stabilize atmospheric carbon dioxide levels would lead to a more intense precipitation change per degree Celsius of global warming, with an associated increase in precipitation for years to come. Future research should focus on evaluating how precipitation responds to many different climate-change mechanisms, as well as understanding how these responses manifest themselves in different regions.