Climate Change 101

Some people say climate change is caused by the sun, not by people. Scientists have examined this idea closely. The sun’s energy does change over time, and long ago, those changes sometimes made Earth warmer or cooler.

Today, scientists use satellites to measure the sun’s energy very carefully. These measurements show that since the 1970s, the sun has been giving off a little less energy, not more. If the sun were causing Earth to warm, its energy would be increasing. Because Earth is still getting warmer even while the sun’s energy is going down, the sun is not the cause of today’s warming.

It makes sense to think volcanoes could change Earth’s temperature, because big eruptions can affect the whole planet. But volcanoes usually cool the Earth, not warm it. When a volcano erupts, it sends a gas called sulfur dioxide into the air. This gas mixes with water and forms tiny particles that block some sunlight, like an umbrella around Earth.

Big eruptions, like Mount Tambora’s, occurred during recorded history and caused the planet to cool for a while afterward. We were able to measure these effects, and we know they’re not the reason we’re seeing an increase in temperature right now.

It makes sense to think that Earth’s orbit might affect climate change. Earth naturally goes through regular, repeating cycles of warming and cooling due to its orbit and tilt.

The last warm peak from these natural cycles was about 6,000 to 8,000 years ago. Right now, Earth should be slowly cooling. Instead, it is getting hotter—and much faster than expected. This shows that changes in Earth’s orbit and tilt are not causing today’s climate change.

Scientists have observed that Earth’s temperature has risen at the same time that humans began using factories, cars, and power plants. Long ago, before this heavy industry, the air had much less carbon dioxide. Scientists know this by studying ice from deep in glaciers. Scientists also study clues from rocks and fossils. Back then, there were about 280 parts of carbon dioxide in a million parts of air. Today, there are about 420 parts of carbon dioxide in a million parts of air, which is much higher.

This warming is unusual because Earth should actually be cooling a little right now. That’s because of slow changes in Earth’s path and tilt around the sun, and because the sun has been giving us slightly less energy since the 1970s. These two factors should cause an observed cooling effect, not a warming one.

Instead, Earth is warming much faster than usual. The best explanation is that people are adding extra greenhouse gases to the air. This gas acts like a blanket around the planet, trapping heat and causing Earth to warm up quickly.

Earth’s atmosphere is like a blanket around the planet. The sun is responsible for most of the energy you see on planet Earth. When sunlight reaches Earth, some of the light warms the ground and oceans. Some of that heat then tries to leave.

When the atmosphere contains more gases, such as water vapor and carbon dioxide, the blanket gets thicker. A thicker blanket holds more heat in and stops it from escaping. Greenhouse gases don’t generate heat themselves; they trap it and make it harder to escape.

Humans make this blanket even thicker when we burn fossil fuels like coal, oil, and gas. These activities add gases such as carbon dioxide and methane to the air. Because of this, more heat gets trapped, and Earth’s temperature goes up.

Climate is the average weather we expect over a long time. Weather is what happens day to day, like rain today or snow tomorrow. Even though Earth is getting warmer overall, we can still have very cold days and winters. It can still snow, and ice can still form, even in places that don’t see it very often.

Even with climate change, we can still have very cold winters. As the climate keeps warming, our winters will start to feel more like winters farther south, where it still gets cold sometimes. Snow can even fall far south, as it did in Texas in 2021. That’s why having cold weather doesn’t mean climate change isn’t real. Climate change is about long-term patterns, not just one cold day or one snowy winter.

Cities can get hotter than towns or the countryside because they have many dark surfaces, like roads and rooftops, that absorb heat from the sun. According to the Michigan Department of Environment, Great Lakes, and Energy, daytime temperatures in cities can be 1–7°F hotter than outside the city, and at night they can be 2–5°F hotter.

This extra heat can already be dangerous, especially for people without air conditioning. As the planet continues to warm due to climate change, Michigan’s cities could become even hotter and more dangerous, especially for those most at risk.

Thankfully, we can take steps to help prevent dangerous heat waves. First, we should prevent every degree of warming we can by dumping fossil fuels as quickly as possible. We can also build more green space to help reduce urban heat. This can look like trees or parks. These reflect more heat, making our cities cooler. Relying more on walkable cities also lets us have fewer parking lots, which can significantly reduce dark surfaces in cities.

Warmer temperatures can shift insect populations, leading to more mosquito- and tick-borne illnesses. Scientists have already observed an increase in tick populations in Michigan between 1996 and 2015.

Hot summer days can also make people sick from the heat, especially in large urban centers like Detroit, which are hotter than the surrounding landscape. The heat can also trap pollution near the ground, making the air harder to breathe. This can cause more asthma attacks and other breathing problems.

Climate change will change how rain falls in Michigan. Rain will come in stronger storms that can overload city systems. Many older cities in Michigan have something called a “combined sewer system.” When too much rain falls, these systems can’t handle it, and raw or partly treated sewage can end up in rivers and lakes, making the water dirty. As the climate continues to change, big rainstorms could occur more often and cause more spills into the Great Lakes.

Another problem comes from farms. Farmers use manure and fertilizers on their fields, which contain nutrients. When it rains, these nutrients can wash into rivers and lakes. In places like Lake Erie, the nutrients feed large algae blooms. Some of these blooms are toxic and can make water unsafe to drink or swim in. In 2014, people in Toledo couldn’t drink their tap water for 3 days due to a large bloom.

Warmer water can make algae grow faster, so climate change will cause these blooms to occur more often and be more dangerous.

Maple trees and maple syrup are an important part of Michigan’s natural and cultural heritage. But climate change is making it harder for maple trees to stay in Michigan. Warmer winters and late frosts can hurt the trees and reduce syrup production.

Warmer temperatures also help pests and diseases spread, making it even harder for maple trees to stay healthy.

Over the last 100 years, Michigan has seen 14% more rainfall overall and 35% more severe storms. Climate change will keep changing how and when rain falls, which can make water dirty and overload city systems.

Climate change will also lead to more intense heat waves. Cities will feel the heat the most because they have fewer trees and more dark surfaces, like roads and rooftops, that absorb sunlight.

We should do our best to stop climate change before it gets worse. Each degree of warming we prevent helps. But we can also upgrade our cities to help mitigate the effects of rising rainfall. This is known as ‘climate resiliency.’ It can look like more green space to soak up water instead of hard surfaces like concrete. It could be more solar panels all around the community to help power critical services during a blackout. These steps keep our communities safe as we experience stronger storms.