Weather vs. climate: What's the difference between the two terms?

Weather and climate are two terms you hear discussed often by the media, but sometimes the two terms can be confused.

While the terms both deal with weather, they are not the same.

While weather is the day-to-day, short-term state of the atmosphere and the conditions, climate is the average of weather conditions at a particular location over a period of 30 years or more, AccuWeather Senior Meteorologist Brett Anderson said.

Weather is instantaneous or a "snapshot" of what's going on right now. Weather is a combination of temperature, humidity, precipitation, cloud cover, visibility and wind.

A sports analogy may help to differentiate the two.

"Climate would be like an entire football season, including preseason games, regular season games, playoff games and the Super Bowl. In contrast, weather is like one or two plays going on within a game," AccuWeather Senior Meteorologist Dave Dombeck said.

There were numerous extreme natural disasters in 2017 that led many to question the role of the changing climate in these events.

"There are articles out there in the media which may mistakenly use climate change as a reason for a particular weather event," Anderson said.

It is difficult to classify weather disasters as climate disasters because there have been disasters in the past for many centuries. These previous disasters aren’t necessarily caused by climate change.

The key for scientists is to look at trends like whether there has been an increase in drought in the Southwest or an increase in big snowstorms along the East Coast.

Scientists need many years of data to come to a conclusion. Therefore, it is really hard to say that a particular event was caused by climate change, Anderson said.

"When we’re looking at climate, we’re looking at very long-term averages. The planet is warming; the United States is warming over a long period of time. That doesn’t mean it can’t get cold, like we’ve had a recent cold outbreak of weather in the Northeast," Anderson said.

For example, the bomb cyclone that pounded the Northeast at the start of January caused extreme flooding in Boston. While it is difficult to conclude that large snowstorms in the Northeast are caused by climate change, there may be a link to climate change and the flooding in Boston.

"The flooding in the Boston area was very unusual, now granted the storm arrived at high tide, but sea level is much higher now than it was 50 years ago. And so the same type of storm 30 or 40 years ago would not have resulted in as much flooding as it does today," Anderson said.

Sea level has risen due in part to the melting glaciers and the warming ocean waters resulting from climate change. Therefore, climate change likely played a role in flooding and impacts of that storm.

It is also difficult to determine whether disasters are caused by long-term climate change or if it is just cyclical.

The atmosphere goes through different cycles, such as El Niño and La Niña, which influence weather. It is a cycle that has continued for a long time, according to Dombeck.

"During certain periods of either El Niño or La Niña, and depending on where you are in the world, there can be some extreme weather and even disastrous weather that may occur because of those cycles," Dombeck said.

There needs to be an abundance of reliable information to determine if extreme weather is caused by cycles or long-term climate change.

However, there are studies that show that warming ocean water causes not necessarily more hurricanes but more intense hurricanes. There have been many strong hurricanes in recent years in the Pacific and in the Atlantic, and that may be due in part to the warming in the oceans providing more energy to these storms, according to Anderson.

Recent observations show that there has been an increase in drought, especially across regions that were already dry, such as the recent devastating and costly Southwest drought. This is likely linked to the irregular weather patterns and rising temperatures linked with climate change.

"More drought means more fire. There are more people choosing to live near the wilderness areas that are affected by these wildfires. Fires burn the land and the land gets burned. Then the rain comes in, and there are these bad mudslides like we saw in California. Climate change is certainly playing a role," Anderson said.

Likewise, climatologist and meteorologist are two different professions. While both try to project future weather conditions, they do so on very different scales using different techniques and computer models.

Weather forecasters are trying to predict the specific variables at a specific time in the relatively near future.

Meteorologists examine questions like the following: How much snow or rain is going to fall? What will the temperature be at 3:00 p.m.? When does the rain turn into ice and then snow in New York City?

A climate forecast is much different. Climatologists are trying to project temperatures over a very long period of time perhaps over a 30-year period or even a 100-year period over a much larger area.

"A lot of these climate models are forecasting the globe to warm up 2 C by the end of the century. It's much different than a weather forecast. The science has actually proven to be fairly reliable with climate models in terms of temperature projections," Anderson said.

Scientists have put out a range of forecasts saying temperature will increase anywhere from 1 to 3 C by the end of the century, for example. They’re not trying to predict rain or snow like a detailed weather forecast, according to Anderson.

Meteorologists also depend on computer models to give them guidance. However, they make projections for mainly short- or medium-term forecasts and some longer-term forecasts like a week or two or even monthly or seasonal.

Weather forecast accuracy has improved dramatically over time. For example, the recent disasters, such as Hurricane Irma, illustrate how accurate forecasts have helped to save lives during disasters. New technologies and innovations are also helping to improve the accuracy of weather forecasts and climate data.

While the accuracy of forecasts continue to improve, the accuracy of a forecast tends to decline at a steady pace the further out in time you go.

"Sometimes, meteorologists have a tough time figuring out what is going to happen short-term," Dombeck said.

"What’s that going to say about the climate models, which are way, way long-term," Dombeck said. "It is logical to think that if even the short-term models are tough to forecast, then how reliable are the models going to be out years and decades and millenniums?"

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