A Changing Climate
Climate has changed in the past, slowly or quickly, due to natural events—like volcanic eruptions, changes in solar activity, and variations of Earth’s axis.
Today, the climate is changing faster than it has in 10,000 years. Why is it happening so quickly? What do the extreme weather events we experience tell us about how the climate is changing?
All About The Atmosphere
The atmosphere is an invisible “blanket” of gases that protects life on Earth by providing us the air we breath, blocking harmful ultraviolet solar radiation, and keeping Earth at a comfortable average temperature of 59°F.
Divided in five layers, the atmosphere extends from Earth’s surface to about 600 miles above ground, beyond which is outer space. It consists of nitrogen (78%), oxygen (21%), particles, and other gases. These include the heat-trapping greenhouse gases, which are responsible for the process called greenhouse effect that regulates Earth’s temperature.
- Troposphere – Also called “the lower atmosphere,” this is where the weather we experience develops and greenhouse gases are found.
- Stratosphere – This is where jet aircraft fly. Here, the abundance of ozone creates the Ozone Layer, which absorbs harmful ultraviolet radiation from the sun.
- Mesosphere – The mesosphere burns up most meteors before they fall on Earth as meteorites. The top of this layer is the coldest part of the atmosphere.
- Thermosphere – Known as the upper atmosphere, this is the thickest layer of the atmosphere. Here is where gases absorb solar rays, making it a “hot layer.”
- Exosphere – In the outermost layer of the atmosphere, satellites orbit the Earth and molecules and atoms escape into outer space.
The Greenhouse Effect
Greenhouse gases make our planet feel like the interior of a greenhouse—always warm. While 59°F might not seem that warm, without greenhouse gases Earth’s temperature would be 0°F! During the day, sunlight passes through the atmosphere, causing Earth’s surface—land and oceans—to warm up. During the night, land and oceans cool off and release that heat back in the atmosphere. Greenhouse gases trap some of the heat from Earth, keeping the atmosphere warm—and our planet, too.
Greenhouse gases occur naturally in the atmosphere. But, since the Industrial Revolution in the late 1700s, human activities have contributed large amounts of these and man-made greenhouse gases. This has strengthened the greenhouse effect, triggering today’s global warming and climate change.
Records of global surface temperature, available from the 1880s, show an increase of approximately 1.4°F since the early 20th century. While there are year-to-year fluctuations due to El Niño and other natural processes, there is a clear ongoing global warming trend associated with increased carbon dioxide (CO2) concentrations.
One or two degrees might seem a minor variation for us, but not for our planet! Scientists estimated that, to limit the effects of today’s climate change, Earth’s temperature shouldn’t increase more than 2°C (3.6°F) above preindustrial levels. However, data show we are on track to break this threshold and climates are already shifting.
In Earth’s history, carbon dioxide has fluctuated and so has temperature. But, for the past 10,000 years, our planet has experienced a relatively stable climate and carbon dioxide concentrations. Today, because of the emissions produced to fuel our daily activities since the Industrial Revolution, carbon dioxide levels are the highest humans have ever experienced. The greenhouse gases produced by burning all types of fossil fuels—coal, oil, and natural gas—are the main drivers of today’s climate change, and the exponential increase of emissions is accelerating it.
Studying The Present, Predicting The Future
Climate change is a change in global, regional, or local weather patterns. We are already seeing changes all around the world, as “extreme” weather events (from hurricanes to heavy snowfalls to droughts) are happening more frequently and with increased intensity. Individual extreme weather events can’t be attributed to climate change, but a trend of increasingly intense and frequent extreme weather may indicate changes in weather patterns and what weather events we could expect in a changed climate.
Meteorology is the study of the atmospheric processes that impact weather. Climatology is the study of climate, the factors that influence it and its impacts on the environment. Meteorologists focus on weather forecasting. They observe ongoing atmospheric processes and answer questions like “Will it rain tomorrow? Climatologists study long-term weather and trends. They study the frequency and trends of weather systems and answer questions like, “How often is this area impacted by drought and how intense has it been in the past?” Some climatologists and other climate scientists also create models to predict future climate and answer questions such as, “How much warmer will Earth be in 50 years?”
Over the last few years, Illinois has increasingly experienced extreme weather events that might indicate how climate is changing in our region, including heavy precipitation, tornadoes, snowy and cold winters, droughts, and heat waves. Based on the recent observed patterns of increased precipitation and cloudiness, climatologists expect that Illinois will experience drier summers and wetter springs, falls, and winters.
This interactive weather map shows the current temperature, wind, and other weather elements for our area. What do you notice about the current weather in Illinois? How does that compare to what typical Illinois weather is for this time of year?
James is showing us how to start a weather journal, identify clouds, and more. Dive into weather and climate with this episode of Curious By Nature below.
The Illinois State Climatologist provides weather and climate data, maps, and information for Illinois farmers, government agencies and policymakers, and all citizens. The State Climatologist also conducts research on past climate events, monitors current conditions, and studies possible future climate change acting as the state’s authoritative spokesperson on climate science. You can learn more about the changes in our state climate by checking out the Illinois State Climatologist website.