Climate is determined by the long-term pattern of oceanic and atmospheric conditions at a location. Climate is described by statistics, such as means and extremes of temperature, precipitation, and other variables, and by the intensity, frequency, and duration of weather events. Over Earth's history, indications of climate change have been recorded in fossils and ice core samples. At one extreme, climate change can result in extended periods of heat and drought; at the other, extensive glaciation. Currently, our planet's global surface temperature is rising. This change is linked to human activities that increase the amount of greenhouse gases (e.g., carbon dioxide and methane) in the atmosphere. It is important to understand climatic processes because they have the potential to affect environmental conditions.
You may change your wardrobe with the seasons, grabbing a heavy coat in winter, while wearing only a light t-shirt in summer. Although ecosystems, plants, and animals cannot adjust their attire quite so easily, they have evolved to make changes that help them survive seasonal conditions caused by the rotation of the Earth around the sun.
Impacts from climate change are happening now. These impacts extend well beyond an increase in temperature, affecting ecosystems and communities in the United States and around the world. Things that we depend upon and value — water, energy, transportation, wildlife, agriculture, ecosystems, and human health — are experiencing the effects of a changing climate.
Some say that climate is what you expect and weather is what you get. More formally, climate is the long-term average of temperature, precipitation, and other weather variables at a given location. Every 30 years, climate scientists calculate new averages. The normal high and low temperatures reported on your local weather forecast come from these 30-year averages. Although climate describes conditions in the atmosphere (hot/cold, wet/dry), these conditions are influenced by the ocean, land, sun, and atmospheric chemistry. NOAA monitors these factors to understand and predict changes to local or global climate.