Weather vs. Climate: How Do They Differ?2 min read
People often try to dispute or confirm climate change due to a single weather event. There are big differences between what we call “weather” and “climate”. Weather refers to short-term changes in the atmosphere, and climate refers to the weather over a very long period.1
The normal temperatures that the market weather vendors use are averages of temperatures over a 10- or a 30-year period. The 30-year normal is updated by the National Atmospheric and Oceanic Administration (NOAA) every 10 years, while the 10-year normal is the running average. The natural gas market tends to use a shorter timeframe, a five-year average, when estimating withdrawals or injections.
Climate data can tell someone what they can expect during a given time of year. Usually there is cold and snowy weather across the Midwest from December through February, while the Southeast tends to be hot and humid during the summer months. While descriptions of a location’s climate can tell someone what to expect, it does not provide any specific details about what the weather will be on a given day.1 There could be a very warm day across the Midwest during the winter months and a cool/dry day across the Southeast during the summer months.
While descriptions of a location’s climate can tell someone what to expect, it does not provide any specific details about what the weather will be on a given day.
The recent cold outbreak and subsequent warm-up across the Midwest may be used as a point to either prove or disprove climate change. While global climate change has been linked to increased temperature volatility, this one volatile event cannot prove or disprove climate change. This event was purely a weather event; however, the frequency of such volatile events has been increasing over the past several decades. This long-term uptick in volatility can be linked to climate change since the period is quite long.
Climate change does not mean that it will never be cold again.2 There will still be wintry weather conditions despite a warming planet. Climate change tells us that warm days may be a little warmer and cold days may be a little less cold. Days of record cold temperatures are still expected, however a lot of small warmer changes over a long timescale (decades) can ultimately add up to something more substantial. For example, the current 10-year normal is quite a bit warmer than the current 30-year normal. In fact, experts at the World Meteorological Organization (WMO) concur that 2011-2020 was the warmest decade on record.3
The WMO concurs that 2011-2020 was the warmest decade on record.4
The starkest difference is seen during the summer months. For example, in 2019, the current 30-year normal (1981-2010) for population-weighted cooling degree-days (PWCDDs) was 881, while the 10-year normal (2009-2018) was 962. To put this into context, if this summer had come in right at the 10-year normal of 962 PWCDDs, it would be the 8th hottest summer since 1950. If this summer came in right at the 30-year normal of 881, it would be the 31st hottest summer since 1950.
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