Why Care About Indicators for Temperature and Precipitation
Introduction
Temperature and precipitation are fundamental observations in weather analyses and useful parameters in describing the changing climate.
The temperature at a location can have wide-ranging effects on infrastructure, humans, and ecosystems. For example, increases in air temperature can lead to more intense heat waves, which can cause illness and death, especially in vulnerable populations. Annual and seasonal temperature patterns also determine the types of animals and plants that can survive in particular locations. Changes in temperature can disrupt a wide range of natural processes, particularly if these changes occur more quickly than plant and animal species can adapt.
Changes in precipitation can also have major impacts on infrastructure, humans, and ecosystems. Droughts, often caused by lack of precipitation in combination with increased evapotranspiration due to elevated temperatures, have an impact because of their effects on local water availability and overall, on water resources. When it does rain or snow, it is more likely to come as a larger event than in the past (not surprising since basic physics tells us that a warmer climate means that the atmosphere can hold more water vapor). As a result, increasing concerns about flooding are important, whether it be flash flooding after a strong precipitation event, river flooding after multiple precipitation events in a short time period (often over a larger regional area), in addition to flooding not caused by precipitation events such as coastal flooding due to tidal effects from increasing sea levels (sometimes called nuisance flooding) or due to storm surge during a hurricane or other storm.
As examples, warmer average temperatures could increase air conditioning costs and affect the spread of diseases like Lyme disease but could also improve conditions for growing some crops and decrease heating costs. More extreme variations in temperature and precipitation are a significant threat to society and to ecosystems (including impacts on biodiversity). More frequent and intense extreme heat events can increase illnesses and deaths, especially among vulnerable populations, and damage some crops. Decreases in cold events can decrease impacts on human exposure and on road infrastructure but can also affect yields for some trees and other crops. While increased precipitation can replenish water supplies and support agriculture, intense storms can damage property, cause loss of life and population displacement, and temporarily disrupt essential services such as transportation, telecommunications, energy, and water supplies. Drought can affect crop yields and availability of fresh water.
The purpose here is to examine the most relevant Earth Knowledge indicators for climate change that relate most directly to temperature and precipitation.
Indicators
Many of the Earth Knowledge indicators relate to the temperature and precipitation changes occurring throughout the world during all seasons. These temperature change indicators can themselves be useful in informing users of changing climate conditions affecting their organizations and infrastructure requirements.
Some of the Earth Knowledge indicators are aimed at looking at average, or mean, changes in temperature and/or precipitation over a range of time scales from monthly to seasonal to annual time periods. These indicators are useful as metrics for the overall changes occurring at the local scale within the overall changes occurring in the Earth’s climate. They can also show effects on the growing season, growing degree days, and other factors affecting the biosphere and food production. Changes in temperature or precipitation can also occur in some months or seasons more than in others. Other indicators look at the changes in the length of the summer and winter seasons.
The upward trend in globally averaged temperature is associated with widespread changes in weather patterns. As a result, extreme weather events such as heat waves and large storms are likely to become more frequent or more intense with human-induced climate change. As a result, Earth Knowledge has a variety of indicators relating to extremes in temperature and precipitation. These indicators look at changes in daily, monthly or seasonal maximums or minimums in temperature and at changes in the daily, monthly or seasonal amounts of precipitation as either rainfall or snowfall. Some indicators look at the changes in the number of days below or above a certain threshold in temperature or precipitation, e.g., the number of days below freezing (32°F, 0°C) or above 95°F (35°C) or 100°F (37.8°C). Other indicators evaluate the hottest or coldest temperature on a daily, monthly or seasonal basis. Some indicators examine multiple day events of high or low temperature associated with heat waves or cold waves. Changes in the number of freeze and thaw events will also be available in a future indicator release.
There are also indicators examining the changes in extremely low precipitation on a daily, monthly, seasonal or annual basis that are likely to lead to concern about drought and in extremely high precipitation on a daily, monthly, seasonal or annual basis that are likely to lead to concern about flooding. Others look at the changes in the average length of a dry period or the longest consecutive dry or wet period. Changes in precipitation intensity are also evaluated. Other indicators in coming releases will examine the number of snow days or the rain to snow ratio.
A list of the entire set of indicators for temperature and precipitation can be provided.
Sources
https://19january2025snapshot.epa.gov/climate-indicators
https://19january2025snapshot.epa.gov/climate-indicators/weather-climate
https://www.usgs.gov/faqs/what-are-some-signs-climate-change
https://oehha.ca.gov/climate-change/epic-2022/changes-climate/air-temperatures
https://essd.copernicus.org/articles/15/2295/2023/
https://www.globalchange.gov/our-work/indicators
https://climate.nasa.gov/evidence/
Note: The Earth Knowledge Perspectives (Blog) is provided for general informational purposes only and is not meant to address specific climate conditions, risks, regions or time periods or to provide recommendations for any specific uses, actions or applications. You should not rely on the material or information in this Blog as the basis for any risk assessment, or to make any business, operational or other decision.