People, planet, and the path ahead

How climate influences weather: six questions

Visitors to Central Park pass a flowering rhododendron on Feb. 28 in New York. Some scientists say spring may be record early in about half the nation in 2017. Mark Lennihan/AP

From extreme rains in some places to early spring in others, weather events prompt questions about what role climate change may be playing.

1. Does climate change cause extreme weather events?

Not really, in a pure sense. But think of climate as the broad forces and patterns in the air and oceans that set the parameters for the weather – the everyday variations in things such as wind and precipitation. When climate changes, it affects the weather, including the intensity and frequency of some extreme weather events.

For years scientists have cautioned people against confusing climate with weather, and climate-change doubters remind us that blizzards and hurricanes occurred long before industrialization increased the amount of carbon dioxide in the atmosphere.

Instead of, “Was X event caused by climate change?” meteorology professor David Titley at the Pennsylvania State University says “A better way to frame it is, ‘what’s the new frequency for this type of event?’ Or, ‘how often or how severe will these sorts of events be in the future?’ ”

​So, for example, some researchers say their models suggest climate change is making extreme rainfall cycles (as well as periods of drought) more likely in California​. Rising average temperatures are also making heat waves more common globally, including in months like February when you wouldn't traditionally expect them in northern latitudes.

The conclusions scientists draw are inevitably estimates, not firm cause-effect equations. But many believe their ability to tease out the role that climate change probably played in certain weather events has increased dramatically, as has their understanding of how global warming translates into regional weather trends.

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