Does Climate Change Cause Extreme Weather?

Global climate change is making weather worse over time

A large tornado rip's up the dust in the Texas pan handle
john finney photography/Moment Open/Getty Images

Climate scientists have long warned people from tying individual weather events from broad scale climate phenomenon like global climate change. Because of this, climate change deniers are often met with a rolling of eyes when they use a particularly disruptive snowstorm as evidence against global climate change.

However, increased atmospheric temperatures, warmer oceans, and melting polar ice undoubtedly have effects on weather manifestations. The links between weather and climate are difficult to make, but scientists are increasingly able to make those connections. A recent study by members of the Swiss Institute for Atmospheric and Climate Science estimated the current contribution of global warming to the rate of high precipitation and high temperature events. They found that currently 18% of heavy rain events can be attributed to global warming and that the percentage climbs to 75% for heat wave episodes. Perhaps more importantly, they found that the frequency of these extreme events will likely increase significantly if greenhouse gas emissions continue at the current high rate.

In a nutshell, people have always experienced heavy rains and heat waves, but now we experience them more often than we had for centuries, and we will see them with ever increasing frequency in the decades to come. Remarkably, while a pause has been observed in atmospheric warming since about 1999, the number of hot temperature extremes has continued to climb. 

Weather extremes are important, since they are more likely to have negative consequences than a simple increase in mean rainfall or mean temperature. For example, heat waves are routinely responsible for fatalities among the elderly, and are one of the principal urban vulnerabilities to climate change. Heat waves also worsen droughts by increasing evaporation rates and further stressing plants, as has been the case in early 2015 during California’s fourth year of drought.

The Amazon region has experienced two hundred-year droughts in just five years (one in 2005 and another in 2010), which together have generated enough greenhouse gas emissions from dying trees to cancel out the carbon absorbed by the rainforest in the first decade of the 21st century (about 1.5 billion metric tons of carbon dioxide annually, or 15 billion tons over those 10 years). Scientists estimate that the Amazon will release another 5 billion tons of carbon dioxide over the next few years as the trees killed by the 2010 drought decay. Worse, the Amazon rainforest is no longer absorbing carbon and balancing emissions as it once did, which is expected to accelerate climate change and to leave the planet even more vulnerable to its effects.

How Climate Change Is Changing the Weather

There have always been extreme weather events. What's different now is the increasing frequency of so many different kinds of extreme weather.

What we're seeing is not the end result of climate change, but the leading edge of an extreme-weather trend that will continue to worsen if we fail to act.

Although it may seem counter-intuitive that climate change can be responsible for opposites in extreme weather, such as drought and floods, climate disruption does create a variety of extreme weather conditions, often in close proximity.

So although individual weather events may be too isolated to link directly to climate change, one thing is certain: if we go on contributing to the problem and refuse to solve it, then the broad effects of climate change are not only predictable but inevitable.