Regardless of where you live, you’ve probably witnessed the effects of climate change. Was it a huge forest fire in the western state where you live? Was it a Great Lakes rain bomb? Or a severe hurricane on the Gulf Coast? Was it the sky turning gray with ash in New York or Chicago, Illinois?

Or maybe you haven’t been affected personally by some huge event, but you’ve noticed things changing subtly: the price of food going up, or the cost of insurance on your family’s house, or just the intensity of the heat in your neighborhood in summer.

Climate change is already impacting us all—especially when it comes to economics and health—but not everyone experiences it in the same way. The impact varies based on location, income, social networks, and many other factors.

Some of these impacts are the direct result of climate change on natural systems. But others are indirect. They’re the result of how climate change interacts with human systems and activities. This may not seem like a big difference, but distinguishing between direct and indirect impacts is helpful. In fact, it’s crucial if we’re going to understand how climate change works and what can be done to reduce its impacts.

Defining Direct Impacts

Let’s start with direct impacts. Direct impacts are measurable changes in Earth’s natural systems caused directly by warming temperatures. These are likely the impacts you think of first, such as rising sea levels, melting ice caps, and shifting rain patterns.

Another set of direct impacts is the increased likelihood—and often severity—of some naturally occurring events, such as floods, storms, and wildfires. Not every natural disaster can be clearly attributed to climate change. A single wildfire, for example, might have happened whether the world was heating up or not. However, climate change makes the chance of that wildfire happening much greater. It also makes it more likely that the wildfire will be severe. This increased likelihood and severity of natural disasters is a very important kind of direct impact because even a small increase in the number and severity of natural disasters can mean that many more people are impacted by disasters and that more of our money and energy must be devoted to recovery.

Direct impacts of climate change can be more subtle, though. Global warming is altering many natural processes and systems, causing changes in plant life cycles and increasing ocean acidification.

Ocean acidification is a change in the chemical composition of our oceans due to chemical reactions with atmospheric carbon. At the same time, these direct impacts may be less noticeable, but they’re still significant. For example, ocean acidification slows the development of coral reefs and is a driver in the disappearance of these vital ecosystems.

Defining Indirect Impacts

Clearly, climate change will alter many of Earth’s natural systems and processes. Yet these are not the effects that you are most likely to feel. Rather, the direct impacts of climate change will cause more subtle changes to the everyday systems we rely upon for our food, housing, and security. We call these changes indirect impacts because they are the result of climate change interacting with our human systems.

Picture this: Climate change has increased the frequency and length of droughts in a region (a direct impact). In turn, these droughts have caused multiple crop failures and reduced freshwater availability, which has compromised the region’s food and water systems (all indirect impacts). But the effects don’t stop there. As a result of stressed food and water systems, people in the region, especially kids, have become malnourished and dehydrated (another indirect impact). This then makes them more susceptible to disease, including water-borne diseases, which are more common in areas where water is being pulled from less clean sources (another indirect impact).

As you can see, a single direct impact of climate change can easily result in many indirect impacts. Other types of indirect impacts of climate change include increased heat- and cold-related illnesses, respiratory problems, challenges to mental health, damage to infrastructure and housing, disruption to supply chains, the displacement and migration of people, increased costs, political conflict and even instability and unrest in communities.

What’s worse, the different results of climate change can interact with each other to multiply their effects on a community. For example, poor health, economic stress, and social instability caused by climate change might combine to cause a political conflict or war over resources. Or a single coastal community might find itself experiencing poor water quality, physical health issues, and damaged infrastructure at the same time due to a combination of sea-level rise, periodic flooding, and a recent tropical storm. When direct and indirect impacts come together, the results can be pretty dramatic.

But Why Differentiate?

But if all these impacts are the result of climate change, why do we need to differentiate between indirect and direct? Because these categories can help us understand the problems and identify different solutions for each one.

Direct impacts can easily be understood, tracked, and even predicted by climate scientists through climate models. The only major variable left in these models is how much and at what rate we humans mitigate our emissions. Otherwise, understanding direct impacts is quite clear. To lower the chance of direct impacts, we must lower our emissions.

Indirect impacts, on the other hand, depend much more on human response on multiple fronts. Our actions in preparing for and adapting to climate change can dramatically reduce these indirect impacts for particular communities. We can do this by carefully deciding where money and energy are invested, how political bodies come together, how innovations are distributed, and much more. Consequently, understanding indirect impacts is much more complicated.

It’s not just a matter of understanding the problem, though. To reduce direct impacts, humans must focus on climate change mitigation to reduce greenhouse gas emissions as quickly as possible. There are few other meaningful ways to reduce the direct impacts of climate change. However, indirect impacts can be reduced and addressed on multiple fronts. We can reduce indirect impacts by reducing direct impacts through climate change mitigation and by creating more resilient and adaptive human systems through climate change adaptation. As communities around the world face the impacts of climate change, adaptation solutions will become increasingly important in maintaining our human systems, networks, and communities while protecting human health and well-being.