How Does Climate Change Affect Storms?

The rash of tornadoes that came in early spring 2023, devastating parts of the U.S. South and Midwest, no doubt had many people thinking about how climate change is affecting the weather. Tornadoes seem to be happening earlier in the season than ever, and in larger numbers.

These violent storms also seem to be trending toward larger in size. Looking back to December 2021, a season not typical for tornadoes, northeast Arkansas, Tennessee, and western Kentucky were hit with tornadoes three-quarters of a mile wide with wind speeds that peaked between 158 and 206 miles per hour.

Still, the connection between more severe and unexpected tornadoes and climate change isn’t linked with high confidence — yet.

More major weather disasters

Major natural disasters have always happened. Storms, hurricanes, floods, and droughts are all part of the planet’s natural weather and climate system.

But, increasingly, natural disasters aren’t so natural. Human activity — burning fossil fuels and removing forest cover — has thrown the carbon balance out of whack. Greenhouse gases (GHGs) that civilization pumps into the atmosphere are driving increasingly dangerous weather.

Earth is experiencing more droughts, floods, more intense hurricanes, forest fires and wildfires, heavier rainfalls, rising sea levels, slowing ocean currents, and more severe winter storms and major heatwaves.

Warming oceans help fuel hurricanes

Global warming is heating up Earth’s oceans. In fact, the Intergovernmental Panel on Climate Change (IPCC) reports that oceans have absorbed more than 90 percent of the heat from global warming.

Hurricanes are now occurring in the top half of the northern hemisphere, such as Canada, because of these warmer ocean temperatures, particularly at the surface.

Historically, colder ocean surface temperatures in the north slowed down hurricanes, turning them into powerful, but nowhere near as destructive, tropical storms. Now, however, the water’s warmer temperatures don’t impede storms. In fact, warming up surface water is like revving the hurricane’s engine.

The number of tropical storms and hurricanes hasn’t increased. In fact, that number has stayed fairly uniform over the past 50 years, the IPCC reports. The intensity of tropical storms and hurricanes, however, has increased.

Scientists have confirmed that hurricanes (also called cyclones and typhoons) have grown in strength and destructive force, while also growing in the geographical areas subject to these intense storms, moving closer to the poles.

Extreme weather events from floods, to droughts, heatwaves, wildfires, and hurricanes are confirmed in the 2021 IPCC report and linked with high confidence to global warming.

The first ever hurricanes to reach as far north as Canada were in 2003 in Halifax on the east coast (2003’s Hurricane Juan was the first full-force tropical hurricane ever to hit Atlantic Canada) and in 2006 in Vancouver on the west.

Bigger storms, more damage

These bigger storms and hurricanes bring rougher coastal storms, bigger storm surges, higher water levels, taller waves, more storm damage, and flooding. Scientists also see an increased tendency of these storms that stall over one area, such as Harvey in 2017, Florence in 2018, and Dorian in 2019.

Some storm-protection barriers may not be strong enough to protect against the hurricanes that are coming, and some cities might need to reevaluate their protection. (Think New Orleans!)

For the first time, the IPCC's 2021 report confirmed a risk (at low probability) that the excess carbon dioxide that people put into the air could disrupt the carbon cycle and turn the planet’s life-support system into a vicious cycle.

Rainfall (or lack thereof)

Changes in temperature are altering evaporation and precipitation patterns, which means more rain in some places and less in others. The IPCC says these changes also mean more intense dry spells and rainstorms overall, with high-latitude areas in Europe, Russia, and Canada taking the hardest drenching.

The IPCC reports that inland mid-latitude regions — such as central Canada and inland Europe and Asia — are generally most at risk from more frequent and harsher droughts than what those areas currently experience.

Although not in those regions, the land along the Mediterranean in Europe may also experience increased droughts. Droughts and high temperatures put major stress on forests and grasslands; dry, parched vegetation is a fire waiting to happen. The soil suffers, too. Dried-out soil can release into the air the carbon that it used to store. Drought is hard on people and animals because all living things depend on water.

Global warming is also causing deserts around the world to expand. In Africa, the Sahara is getting bigger, while in China the Gobi Desert’s growth is a threat. In both places, countries are trying to arrest the increased desertification with green walls of tree planting.

The Great Green Wall in China started with tree planting in the 1970s with billions of trees planted. Although it hasn’t been entirely successful, African nations are trying to learn from mistakes in China, such as planting in all one species, and hold back the Sahara with its own Green Wall.

The IPCC reports that the duo of natural warming and human-caused warming has caused the number of dry areas around the world to double since the 1970s.

More rain, rising seas lead to flooding

Three climate change consequences lead to flooding:

• Rising sea levels
• Quicker-melting snow and glaciers
• More intense rainfall

The IPCC expects that the rising sea levels and harsher rainstorms will increase the number of floods in many places, including both flash floods (floods that happen very suddenly, often because of heavy rainfall and/or the ground is so dry it can’t quickly absorb the rain) and large-scale floods (floods that stick around for a while, caused either by prolonged rainfall or water that can’t drain away easily).

Climate change scenarios typically predict that average annual precipitation will remain nearly constant, but that areas will experience long periods of drought followed by an enormous volume of rain.

This happened in California from early January to mid-March 2023, when heavy rain caused floods in large areas of the state. There was widespread property damage and at least 22 fatalities.

Another example of flooding after drought occurred in China in summer of 2021, when as much rain fell in three days as usually falls in a year. That nation’s annual precipitation fell within days on the dry and desiccated lands. Three hundred people died. In the same summer of climate emergencies, torrential rains caused huge floods in Germany, Belgium and the Netherlands, killing 200 people.

The most likely areas to experience more flooding are high-latitude countries, such as the United Kingdom.