The Difference Between Weather and Climate

All too often the definitions of weather and climate become confused.  It can be evident in everyday life, for example if it is a particularly cool summer day in July someone might remark, “climate change doesn’t seem that bad”, or if it is a warm winter, “thanks to climate change I don’t have to shovel my drive-way”, and finally a remark from a recent London Free Press article regarding climate scientists:

“…these are the same people [climate scientists] who could not tell you what the weather will be like tomorrow or next week yet they have predicted what the Earth will be experiencing for the remainder of the century”.  ‘Feel your temperature rising? Feels more like sloppy science’, London Free Press, Saturday, September 28, 2013

In this particular excerpt, the author has confounded their definitions of weather and climate, but the two are very different.  According to NASA, weather is the behaviour of the atmosphere on a short timescale of minutes to months.  Weather is very hard to predict, as it requires knowing almost every single event occurring in the atmosphere, no matter how extreme, and is influenced by the way we interact with our environment as well as natural cyclical changes in the sun’s energy output.  As a result, weather can be quite variable.  Climate on the other hand, is “the long term pattern of weather in a particular area”.  Climate is typically described on a decadal timescale, and since it is an average of weather over a  long period of time, it allows us to determine if a year was warmer, wetter, cooler, cloudier than average.  Predicting climate can be simpler than predicting weather because with climate, extreme variations in temperature and precipitation ‘average out’.  Climate models use a lot of data to inform their predictions, and as a result, their predictions will capture the average behaviour of the atmosphere over a long time period (which is what climate scientists are aiming to predict).  Climate models are not meant to predict weather, they are meant to predict long term patterns and averages in weather for a given area.  There will inevitably be years that are cooler, hotter, drier and wetter than the climate predictions, but these are just natural variations expected for a given climate.

  So sure, climate scientists cannot tell you what the weather will be like, but they can tell you what the climate will be like, and with that, you can get a good idea of whether you will be able to wear shorts more often during winters near the end of this century.  Just remember the next time someone talks about weather and climate together: weather is short-term (i.e. this week), climate is long-term (e.g. 10 years).

Stay safe and stay informed,


3 thoughts on “The Difference Between Weather and Climate

  1. Are you able to explain why suddenly, or so it appears to me, there seem to be so many “nay sayers” in the news lately regarding scientific studies that substantiate climate change due to human interference? Could it be to calm the masses?

  2. The Intergovernmental Panel on Climate Change (IPCC) released a draft report of the physical science basis of climate change for Assessment Report 5 on Sept. 30. Since these reports summarize the state of our knowledge and predictions about climate change, and have accessible summaries for politicians and non-scientists, they garner a lot of attention on the subject. As a result, people who mistrust science, won’t accept the burden of evidence, or believe that humans can do no wrong seize the opportunity to get in the spotlight by saying something controversial (and usually wrong). In general, it seems that people are uncomfortable with change and even less comfortable with bad news, especially when they have to change their lifestyle (e.g. the obesity ‘epidemic’). Denying anthropogenic climate change can be a coping mechanism for some people.
    There are groups dedicated to providing anti-climate change sentiments to the public, however it is usually only when a large report or groundbreaking study comes about that these nay-sayers receive greater attention.

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