Earth’s climate is changing, resulting in increasing temperatures and precipitation, and contributing to extreme weather and rising seas. The effects of climate change are already being observed in Delaware.
Climate change refers to long-term changes in average weather patterns that have come to define Earth’s local, regional and global climates. Impacts of climate change include sea level rise, more days of high temperatures and changes in rainfall patterns.
Climate differs from weather in that weather highlights short term conditions, such as whether it will be sunny or rainy today. Climate, by contrast, monitors atmospheric conditions over extended periods. In short, climate is what you expect – hot summers – while weather is what you get on a given day – like thunderstorms.
The Office of the Delaware State Climatologist is the principal scientific extension service for weather and climate information for Delaware. The Office resides within the Department of Geography and Spatial Sciences and the College of Earth, Ocean and Environment at the University of Delaware.
Human activities — particularly the burning of coal, natural gas and oil for energy and heat — have raised global atmospheric carbon dioxide to record levels. Over the last 150 years, carbon dioxide levels increased from 280 parts per million to 410 parts per million.
While carbon dioxide occurs naturally in the atmosphere, atmospheric levels never reached above 300 parts per million at any point in the last 800,000 years. Additionally, the yearly rate at which carbon dioxide levels are currently rising in our atmosphere is about 100 times faster than previous natural increases.
All of this affects our climate because carbon dioxide is a greenhouse gas, a type of gas with the ability to trap heat around the earth.
Greenhouse gases (GHGs) are vapors in the atmosphere that trap heat around the earth. When we use fossil fuels like coal, natural gas and oil to power our homes, businesses and vehicles, we release GHGs into the atmosphere. Humans have released a significant amount of GHGs since the mid-1800s, and this has led to rising temperatures and other changes in our earth and climate.
Greenhouse gases include carbon dioxide, methane, nitrous oxide, water vapor, tropospheric ozone and F-gases, which include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).
Carbon Dioxide (CO2) is the primary greenhouse gas contributing to recent climate change. It is absorbed and emitted naturally as part of the carbon cycle. However, human activities, such as the burning of fossil fuels and changes in land use, release significant additional amounts of CO2 into the atmosphere.
Methane (CH4) is produced through both natural and human activities, though human activities have sharply increased methane concentrations in the atmosphere through most of the 20th century. Fossil fuel production and transport, landfills and agricultural practices all emit methane.
Nitrous Oxide (N2O) is produced through natural biological processes, but human activities, such as fossil fuel combustion, wastewater treatment and agricultural practices, all emit N2O.
F-gases include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are often used in coolants, foaming agents, fire extinguishers, pesticides and aerosols. F-gases have a long atmospheric lifetime, and some of these emissions will affect the climate for many decades or centuries.
Water Vapor is the most abundant greenhouse gas and also the most important in terms of its contribution to the natural greenhouse effect, despite having a short atmospheric lifetime. Some human activities can influence local water vapor levels. However, on a global scale, the concentration of water vapor is controlled by temperature, which influences overall rates of evaporation and precipitation.
Tropospheric Ozone (O3) has a short atmospheric lifetime but is a potent greenhouse gas.
The federal Environmental Protection Agency has more information about greenhouse gases.
Because the earth is a complex system, the impacts of climate change look different depending on where you are in the world. Still, all of the known impacts — temperature increases, heat waves, more frequent and longer droughts, changes in growing seasons and precipitation patterns, more extreme weather and sea level rise, among others — can directly or indirectly affect ways of life, traditions, jobs, public health and economies.
In Delaware, the biggest impacts we are witnessing now include increased temperatures, rising sea levels and more frequent intense storms.