Understanding Climate Change
Understanding Climate Change
October 2025 | Written by:听Wylie Feaster
Corresponding Author:听Jennifer Volk, Ed.D., Associate Director
91原创 Cooperative Extension
Earth鈥檚 Climate System
To understand climate change, one must first familiarize oneself with Earth鈥檚 climate system, which is comprised of the five following components:
The atmosphere contains all the gases that cover Earth, including 78% nitrogen, 21% oxygen, 0.9% argon, and 0.1% trace gases.
The cryosphere is made up of all of Earth鈥檚 surface areas that contain frozen water in the form of ice or snow, including ice sheets, ice caps, glaciers, permafrost, frozen waters, and snow-covered areas.
The hydrosphere includes all of Earth鈥檚 fresh and saline waters, both on the surface and below ground, including oceans, seas, rivers, lakes and aquifers.
The lithosphere is the solid outer part of Earth that includes the crust and upper solid mantle.
The biosphere includes all the parts of Earth that contain life, whether on land, in water, or in the air.
Each component of the climate system interacts with the others through various physical, biological, and chemical processes. For example, plants (biosphere) utilize water (hydrosphere), sunlight, and carbon dioxide (atmosphere) for photosynthesis to create energy and oxygen.
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Stability Begins With The Sun
When incoming radiation from the Sun equals the outgoing radiation emitted from all climate system components, the Earth鈥檚 climate is considered stable.
However, several constant factors impact a region鈥檚 climate, including its latitude, altitude, topography, and proximity to mountains and oceans. While locations at high latitudes receive less solar radiation, locations at lower latitudes receive more, like those near the Equator. This pattern stays true for altitude as well, since the higher up you go, the cooler it gets, which helps to explain why higher-altitude locations have climates that resemble higher-latitude locations.听
In addition to latitude and altitude, physical topographic features, like the slope of the land, can impact the amount of sunlight that the Earth鈥檚 surface absorbs. Likewise, by interfering with the movement of different air masses, mountains can influence the weather systems of surrounding areas by producing and preventing cloud formation and precipitation. Finally, oceans also play a key role in moderating the temperatures of coastal regions and the temperature differences between the land and the sea; these听variations can produce winds that result in increased storm formation.
Earth鈥檚 Atmosphere Is Like A Greenhouse
Since the end of the nineteenth century, scientists have come to understand that the Earth's natural warming occurs when gases in the atmosphere absorb and re-radiate heat from the Sun back towards Earth鈥檚 surface. Known collectively as the 鈥済reenhouse effect,鈥 due to our atmosphere鈥檚 ability to trap heat similar to the glass roof of a greenhouse, this natural phenomenon is facilitated by trace gases most commonly referred to as 鈥済reenhouse gases鈥 (GHGs) (Figure 2). Of the many different GHGs, the most important include carbon dioxide, methane, nitrous oxides, and water vapor.
As the Sun鈥檚 energy passes through the atmosphere, like light through a window, it is both absorbed and redirected in the following ways: 22.5% is reflected to space by clouds and aerosols (fine solid or liquid particles suspended in the atmosphere); 19.5% is absorbed by the atmosphere; 9% is reflected by the Earth鈥檚 surface; and 49% is absorbed by the surface. However, as the Earth鈥檚 surface begins to re-radiate the energy back out towards space, only 10% of it manages to escape to space. In comparison, the other 90% is absorbed by the GHGs in the atmosphere, thus contributing to further atmospheric warming.
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Human Influences on Climate听
Though the greenhouse effect is a natural climatic process, the concentration of GHGs in the atmosphere has significantly increased since the Industrial Revolution, a period of significant innovation and mechanization beginning in the eighteenth century. The industrial revolution transformed agrarian, rural societies into industrialized, urban ones. Since that time, global听temperatures have increased. The Intergovernmental Panel on Climate Change (IPCC), a large global group of independent scientific experts within the United Nations, concluded that atmospheric carbon dioxide levels in recent centuries have increased from 280 to 400 parts per million due to human-produced GHGs. Though several factors can cause a rise in carbon dioxide in the atmosphere, it is primarily attributed to burning fossil fuels (like oil, natural gas, and coal) for transportation, electricity production, and other industrial processes. In addition to carbon dioxide, methane and nitrous oxide concentrations in the atmosphere have increased due to various energy, agricultural, land use, and waste management practices.
Delaware鈥檚 Changing Climate
Though Delaware is the second smallest state in the U.S., it is still large enough to produce some stark climatic differences across its land area. Since Delaware is part of the Delmarva Peninsula, its climate is greatly influenced by the Atlantic Ocean and Delaware Bay to its east, and the Chesapeake Bay to its west. Additionally, with a mean elevation of only 60 feet and altitudes ranging from sea level (0 feet) at the coast to 450 feet above sea level at its highest point along the Pennsylvania border, Delaware鈥檚 status as the lowest-lying state in the nation also significantly impacts its climate. Measurements from weather stations across Delaware dating back to 1895 show that the state鈥檚 mean annual temperature has been rising at a rate of 0.2鈩 per decade, or approximately 2鈩 over the last century. As a result of this increasing temperature trend, Delaware experiences fewer nights with minimums below 32鈩 and more nights with minimums above 75鈩.
Regarding precipitation, rain patterns in Delaware remain highly variable, with no clear trends on an average annual basis. However, there does appear to be an increase in rainfall during the fall months, where statewide rainfall has been increasing at a rate of 0.27 inches per decade. Overall, trends over the historic record can be used to project how Delaware鈥檚 climate might continue to change. These types of analyses indicate that, as a state, Delaware will continue to warm and experience more frequent and intense precipitation events.
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Delaware Climate Change and Environmental Resources
Below are links to several other organizations working on better understanding, preparing for, and responding to climate change issues in Delaware.
鈥 the principal scientific extension service for weather and climate information in Delaware, located within the Department of Geography in the College of Earth, Ocean and Environment at the 91原创. Several tools and resources include:
鈥 climate data created and curated by the Office of the Delaware State Climatologist includes climate summary maps, climate normals (three-decade averages of temperature and precipitation), and precipitation frequency estimates for the state.
鈥 provides data visualizations, downloads, and general climate modeling information from the Delaware Climate Change Impact Assessment report.听
鈥 a real-time environmental service created by the Office of the Delaware State Climatologist- that provides the public with access to the latest conditions, summaries, data, and monitoring applications.
promotes and coordinates environmental monitoring efforts and provides an effective, user-friendly interface for researchers to share their findings with the public.听
鈥 an education and outreach arm of the 91原创 College of Earth, Ocean and Environment, Delaware Sea Grant helps communities use, manage, and conserve the state鈥檚 coastal resources by prioritizing resilience and fostering environmental stewardship.听
听鈥 a division of the Delaware Department of Natural Resources and Environmental Control that utilizes applied science, education, policy development and incentives to address Delaware鈥檚 climate, energy and coastal challenges.
References
Baede, A. P., Ahlonsou, E., Ding, Y., & Schimel, D. S. (2001). The climate system: an overview. Climate Change 2001: impacts, adaptation and vulnerability, 87-98.
Danielson, E., J. Levin, and E. Abrams. 1998. Meteorology, Boston: WCBMcGraw-Hill.
Delaware Climate Office. 2025. 91原创.
Delaware Environmental Monitoring & Analysis Center. 2025. 91原创.
Delaware Sea Grant. 2025. College of Earth, Ocean, and Environment, 91原创. /academics/colleges/ceoe/delaware-sea-grant/
Division of Climate, Coastal and Energy. 2025. Delaware Department of Natural Resources and Environmental Control.
Edenhofer, O., Pichs-Madruga, R., Sokona, Y., Agrawala, S., Bashmakov, I. A., Blanco, G., ... & Zwickel, T. (2014). Summary for policymakers.
Stein, T. 2019. Rising Emissions Drive Greenhouse Gas Index Increase, National Oceanic and Atmospheric Administration Research News, .
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About the Authors
Wylie Feaster, 2022 Environmental Quality Extension Scholar, 91原创
Jennifer Volk (corresponding author), Associate Director, 91原创 Cooperative Extension, Dover, DE (jennvolk@udel.edu)
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About this Publication
Original Publication Date: July 2022
Revision date(s): 2025
Reviewed by: Kevin Brinson, Assistant Research Professor and Director, Delaware Environmental Observing System and State Climatologist, 91原创, Newark, DE (2022)
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