What is climate change?
Climate is usually defined as the "average weather" in a place. It includes patterns of temperature, precipitation (rain or snow), humidity, wind and seasons. Climate patterns play a fundamental role in shaping natural ecosystems, and the human economies and cultures that depend on them. But the climate we’ve come to expect is not what it used to be, because the past is no longer a reliable predictor of the future. Our climate is rapidly changing with disruptive impacts, and that change is progressing faster than any seen in the last 2,000 years.
According to the report, Preparing for a Changing Climate, rising levels of carbon dioxide and other heat-trapping gases in the atmosphere have warmed the Earth and are causing wide-ranging impacts, including rising sea levels; melting snow and ice; more extreme heat events, fires and drought; and more extreme storms, rainfall and floods. Scientists project that these trends will continue and in some cases accelerate, posing significant risks to human health, our forests, agriculture, freshwater supplies, coastlines, and other natural resources that are vital to Washington state’s economy, environment, and our quality of life.
Because so many systems are tied to climate, a change in climate can affect many related aspects of where and how people, plants and animals live, such as food production, availability and use of water, and health risks. For example, a change in the usual timing of rains or temperatures can affect when plants bloom and set fruit, when insects hatch or when streams are their fullest. This can affect historically synchronized pollination of crops, food for migrating birds, spawning of fish, water supplies for drinking and irrigation, forest health, and more.
Some short-term climate variation is normal, but longer-term trends now indicate a changing climate.
Our state and societies around the globe need to reduce human-caused greenhouse gas emissions to avoid worsening climate impacts and reduce the risk of creating changes beyond our ability to respond and adapt. Washington state is addressing this challenge and has adopted policies to reduce energy use, limit greenhouse gas emissions, and build a clean energy economy. Some changes in climate — and impacts on our state — are unavoidable, even if we reduce greenhouse gas emissions today. But we can take more actions to reduce progressively worsening impacts.
How is weather different from climate?
Weather can change from hour-to-hour, day-to-day, and season-to-season. It may rain for an hour and then become sunny and clear. Weather is what we hear about on the news or weather report. It includes wind, temperature, humidity, atmospheric pressure, cloudiness, sunshine and precipitation (rain or snow).
Climate is the average weather for a particular region over a long time period. Climate describes the total of all weather occurring over a long period of years in a given place. This includes average weather conditions, regular weather seasons (winter, spring, summer, and fall), and special weather events (like tornadoes and floods). Climate tells us what it's usually like in the place where you live. Historically, San Diego is known to have a mild climate, New Orleans a humid climate, Buffalo a snowy climate, and Seattle a rainy climate.
A simple way of remembering the difference is that 'climate' is what you expect (cool, wet winters) and 'weather' is what you get (a foggy morning with afternoon sunshine).
Are climate change and global warming the same thing?
Not exactly, but they’re closely related and some people use the terms interchangeably. Global warming causes climates to change. "Global warming" refers to rising global temperatures, while “climate change” includes other more specific kinds of changes, too. Warmer global temperatures in the atmosphere and oceans leads to climate changes affecting rainfall patterns, arctic ice (and the northern jet stream that drives our weather), frequency and intensity of storms and droughts, growing seasons, humidity, melting polar and glacial ice, and sea level.
Also, while “global warming” is planet-wide, “climate change” can refer to changes at the global, continental, regional and local levels. Even though a warming trend is global, different areas around the world will experience different specific changes in their climates, which will have unique impacts on local plants, animals and people. A few areas might even get cooler rather than warmer, and extreme weather events can include snowstorms as well as heat waves.
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