Climate change is long-term shifts in temperatures and weather patterns. These shifts may be natural, such as through variations in the solar cycle. But since the 1800s, human activities have been the main driver of climate change, primarily due to burning fossil fuels like coal, oil and gas.
Climate vs. Weather
Weather is short-term changes in the atmosphere – which can be that it’s raining out, or that we haven’t gotten much snow this winter.
Climate is a long-term average of weather over at least 20 to 30 years. So, while one year may have been really cold, when you look at the average change over 20-30 years, our winters are getting warmer.
One way to think about this is weather can be like the money in your pocket on any one day, but climate is your overall wealth over your lifetime - which would include your house or any other investments, any retirement savings, and any money you have in your savings accounts. Some years may have had a tighter budget than others, but your net worth shows all the ups and downs and identifies trends over time.
The Climate is Changing
In this graph each of the small white dots represents the average temperature (weather) that year, the black line shows the earth’s climate over time.
Often, you’ll hear “well it’s really cold out, so global warming is not really happening".
Using what we learned on the difference between weather and climate, we can clearly see some years are hotter and colder weather, but when looking across the timeline at climate we can see that overall, the planet is warming. For up to date tracking on global temperatures, see NASA's Global Climate Change Global Temperature page.
Our planet has a natural blanket of heat trapping gases. The sun’s energy (through solar radiation) shines down and heats the earth. Some of that heat energy bounces off or is reflected by clouds in the atmosphere, the rest warms up the earth and gives off heat energy. The natural blanket traps about half of that energy keeping the earth a temperature we can live in. Once the Earth’s surface is warm, it gives off excess energy to space as invisible infrared radiation. Essentially, this is the process that keeps our Earth’s energy in balance. If we didn’t have this blanket, there wouldn’t be life on earth – we would be a frozen planet of ice.
By digging up massive amounts of oil, coal, and gas (commonly called fossil fuels) the Earth is reabsorbing these heat-trapping gases wrapping an extra blanket around the planet that it doesn’t need. That extra blanket is trapping too much extra invisible infrared radiation (or heat), and that’s why the earth is warming.
The main greenhouse (heat-trapping) gases caused by human activity are:
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
- Fluorinated Gases (hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride and nitrogen trifluoride)
Carbon dioxide (CO2) is often the greatest focus of greenhouse gases because it is has contributed more than any other greenhouse gas and it stays in our atmosphere the longest. Although methane (CH4) may be 25 times more potent it is mostly removed from the atmosphere in 12 years, whereas carbon dioxide sticks around longer, anywhere from 300 to 1,000 years. That is why you see solutions focusing on carbon dioxide, and the term greenhouse gases and carbon used interchangeably.
Human Caused Emissions
In the past, the climate has changed from natural causes: changes in energy from the sun, massive, sustained volcanic eruptions, and predictable cycles in the Earth’s orbit that drive the ice ages and the warm periods in between have all caused the Earth to be warmer and cooler in the past.
However, since the beginning of the Industrial Era (1850), human activities, such as the burning of fossil fuels, have raised atmospheric concentrations of carbon dioxide by nearly 49%. The increase in global carbon dioxide levels from 1950 to 2022 (current) is more than what had happened naturally over a 20,000 year period. For up to date tracking on carbon dioxide levels, see NASA's Global Climate Change Carbon Dioxide page.
Source of Emissions
Looking at both the total greenhouse gas emissions by economic sector for the United States and Michigan there is a consistent trend that our emissions are coming from the fueling of our electricity, transportation, buildings, and industry.
Mitigation vs. Adaptation
In climate change work there are two types of solutions: Climate Mitigation and Climate Adaptation.
Mitigation is reducing or preventing greenhouse gases by decreasing how much energy is consumed (or energy efficiency), ensuring energy is produced from renewable sources (such as wind, solar, etc.), and finding ways to capture and store greenhouse gases (known as sequestration).
Adaptation is taking actions that reduce or prevent the harm caused by climate change and can include planning for impacts that are predicted to occur, putting processes in place to respond when anticipated changes occur, and being creative with new solutions (like businesses or energy systems) to adapt to our new normal.
While mitigation is essential to addressing climate change, adaptation is also a high priority when looking to not only maintain but enhance quality of life. For even if all human emissions of heat-trapping gases were to stop today, Earth’s temperature would continue to rise for a few decades as ocean currents bring excess heat stored in the deep ocean back to the surface. But the vast majority of future impacts can be avoided by choosing our future.