Why everywhere seems to be flooding right now

This week, there’s been yet another wave of extreme weather around the globe. North Carolina was hit with a historic amount of rain. Central and Eastern Europe have experienced some of their worst flooding in decades. And Nigeria has faced unprecedented floods following multiple days of torrential precipitation.

Individually, the disasters have been damaging; together, their severity and proximity to each other are a sobering reminder of how climate change is already impacting people around the world. Such developments are part of a broader increase in extreme weather of all kinds — droughts, extreme heat, tropical storms, and wildfires — that’s poised to continue, and escalate, in the coming years.

According to a study released this week by the Center for International Climate Research in Norway, extreme weather changes could affect as much as 70 percent of the Earth’s population in the next two decades if greater efforts aren’t taken to reduce greenhouse gas emissions, and limit global temperature increases to 1.5 degrees Celsius — or about 2.7 degrees Fahrenheit.

In the case of this week’s floods, there’s likely a clear link to climate change. While there are unique factors that fueled storms, and floods, in each of these places, higher temperatures mean the atmosphere can hold more water, which means it can also “dump” more of it, too, according to the Natural Resources Defense Council. As a result, as the Earth gets warmer, the heaviest rainfall events tend to be even more severe than they otherwise would be.

“I’m pretty comfortable making that claim that these events were at least 10 to 15 percent more intense than they would have been in terms of the amount of rain that fell in them as a result of this fairly basic effect,” UCLA climate scientist Daniel Swain told Vox, regarding rainfall in Europe and North Carolina.

While every individual storm has its own idiosyncrasies, extreme flooding events are exactly what scientists expect to see with worsening global warming: According to research by the Intergovernmental Panel on Climate Change, a body of experts convened by the United Nations, currents models reflect high confidence that the frequency and magnitude of floods are projected to increase at a global scale, with some of the most extreme changes in Asia, Central Africa, Europe, and eastern North America.

“An increase in the intensity and frequency of extreme weather events” is one of the most “visible consequences” of global warming, notes the Center for Climate and Energy Solutions. That appeared evident this week, when North Carolina, Nigeria, and Central and Eastern Europe, all thousands of miles apart, were deluged with massive amounts of rainfall in a short period of time.

One section of Carolina Beach saw 18 inches of rain in the span of 12 hours, a phenomenon the National Weather Service described as a once in a 1,000-year rainfall event.” In Vienna, Austria; Bratislava, Slovakia; and Prague, in the Czech Republic, a recent storm deposited “months worth of rain” in roughly three days, CNN reported. At least 17 people have died in Central Europe from the resulting flooding, according to the New York Times, with the death toll expected to rise further in coming days.

In Nigeria, a dam burst in the northern city of Maiduguri following multiple days of historic rains, which fueled floods that submerged 40 percent of the city and displaced hundreds of thousands of people. That event added to weeks of flooding across West and Central Africa, where more than a thousand people have died.

Although flooding is dependent on existing environmental conditions in a particular region, heavy rainfall can contribute to it, or precipitate it. And as the atmosphere gets warmer due to climate change, it can hold up to 7 percent more moisture for every 1 degree Celsius increase in temperature. That can make the rainfall from an already-intense storm even more so.

“The strongest evidence is that the warming atmosphere increases the ceiling on precipitation intensity,” said Swain. Individual variables in each of these places — including the presence of a weather event known as an “atmospheric block” in Europe — helped spur these outsize storms, but a warmer atmosphere, and its ability to produce rain, likely amplified their effects.

The flooding events of this week illustrate a phenomenon that’s poised to become more common as the world traverses a projected path of further warming. There is a window of opportunity to avoid the most catastrophic impacts of climate change if countries around the world are able to zero out greenhouse gas emissions by 2050, the goal set in the 2015 Paris climate accords. This week’s spate of extreme floods is a reminder of the global need to develop infrastructure that can be responsive to intensifying weather events, and to focus on curbing the greenhouse gas emissions contributing to climate change in the first place.

“When we see these kinds of record-breaking extreme precipitation events, that is actually a very clear and representative example of a type of event that we very much do expect to continue to increase with further warming,” Swain said.