Some rather extreme weather events have occurred over the last several years. Whether it was blizzards like those in January 2016 and February 2021 or tropical systems like Isaias (2020) or Ida (2021), it's fair to ask if these events are going to be the norm. Perhaps most recently, there's been tons of smoke over the Midwest and Northeast. The most striking example occurred on June 7th as areas along the I-95 corridor in the Northeast were shrouded in orange smoke (see below). As the talk around climate change grows, more and more people are wondering if these events are still once-in-a-generation or becoming more commonplace. Therefore, we’re going to dig into the differences between weather and climate and see what conclusions we can draw.
Smoky waterfront during the daytime in Hoboken, NJ, courtesty of Meteorologist Cody Hewitt.
Weather is how the atmosphere behaves at any given moment. This includes rain, snow, cloud cover, air pressure, temperatures, flooding, lightning, and so on. These are all short-term phenomena lasting the span of a few days to even seconds. On the other hand, climate is a description of the weather over a long period of time, like months, years, and decades. The variables used for the climate are simpler, usually just temperature, total precipitation / snowfall, and wind. To put it concisely, the climate is what you can generally expect in a region on any given day (as in, I'm going to south Florida, it's likely going to be warm and humid or I'm heading to Alaska, it should be cold), and the weather is what actually happens (as in, there was a crazy thunderstorm in Florida today or it actually was milder in Alaska with a rainstorm).
Graphic via Australian Environmental Education.
The Köppen climate types attempt to classify each portion of the United States with a specific type of climate based on precipitation, temperature, and the time of year certain temperatures / precipitation patterns occur. For example, much of the southeastern United States is classified as humid subtropical, which means that warm, moist air moves in from the tropics during the summer, which makes it the wettest season. Parts of the Southwest are classified as hot desert, which features hot, arid conditions with lots of sun due to subtropical high pressure systems.
Koppen climate types via Wikipedia
So, given that weather is more of an instantaneous description and climate is more of a description of what happens on average, what does that tell us about these “freak” events that seem to happen more and more often? Well, you can’t explicitly blame climate change for any one event, as the weather literally determines the data that makes the climate. However, there are some impacts that we can associate with climate change.
Let’s use hurricanes as an example. Sea levels have risen over the last century, which will increase the impact of storm surge. Because of warmer waters, wind speeds of stronger storms will increase because there’s more heat available for the hurricanes to use to strengthen. Finally, since temperatures are warmer, the atmosphere can store more water, leading to greater precipitation totals. Most of it boils down to probability. In terms of snowstorms, as temperatures increase, it follows that the frequency of snowstorms will likely decrease over the long term (think years and decades). However, due to more water vapor available to feed into the storms, the worst storms will have a higher snowfall ceiling than those in the 50s.
Graphic via Climate Central.
So, to summarize, the weather is what’s currently happening in the atmosphere, while the climate is an average of past weather conditions. We can use the climate to predict what conditions are typically like in a region, but the weather is what occurs. Based on this, we can’t exactly blame anomalous weather events on the changing climate, but we can say that climate change raises the odds that these extreme events occur.