Some impacts of climate change are direct, while others are indirect. Understanding the difference is important. It will help us 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. They include things like rising sea levels, melting ice caps, and shifting rain patterns.

Another direct impact 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 linked to climate change. A single wildfire 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 an important kind of direct impact. It means that more people are impacted by disasters and more of our money and energy must be devoted to recovery.

Some direct impacts of climate change are harder to detect. Global warming is altering many natural processes and systems, affecting plant life cycles, and increasing ocean acidification.

Ocean acidification is a change in the chemical composition of our oceans. It happens when chemicals in the water react with carbon dioxide in the atmosphere. Because of human-caused air pollution, the amount of atmospheric carbon has been increasing rapidly. Ocean acidification is causing the disappearance of coral reefs, which are all-important ecosystems for marine life.

Defining Indirect Impacts

Climate change will alter many of Earth’s natural systems and processes. Yet these are not the effects you are most likely to feel. The direct impacts of climate change will cause less obvious changes to the everyday systems we rely upon for our food, housing, and security. We call these changes indirect impacts. 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. The droughts have caused widespread crop failures and reduced freshwater availability — indirect impacts. Because food and water are harder to find, many people in the region, especially kids, don’t get enough to eat and drink, another indirect impact. This makes them weak and much more likely to come down with a disease, another indirect impact.

A single direct impact of climate change can cause many indirect impacts. Other indirect impacts include increased heat- and cold-related illnesses, breathing problems, damage to housing, and disruption to supply chains. All of these things can lead to increased costs and to people being forced to migrate. They can even lead to unrest in communities.

The different effects of climate change can interact with each other to multiply their impact on a community. For example, poor health, economic stress, and social instability caused by climate change may occur at the same time. This may lead to political conflict or a war over resources. When direct and indirect impacts come together, the results can be pretty dramatic.

But Why Differentiate?

If all these impacts are the result of climate change, why do we need to make a distinction between indirect and direct? Because these categories help us understand problems and identify solutions.

Direct impacts can easily be understood, tracked, and even predicted by climate scientists. And the way to prevent them is quite clear. To lower their chance of happening, we must lower our greenhouse gas emissions. Greenhouse gases trap heat in the upper atmosphere. Over time, this causes average global temperatures to rise. The buildup of greenhouse gases is mostly caused by burning fossil fuels like oil, coal, and natural gas, which are used for electricity, heat, and transportation. Reducing the use of fossil fuels is the major way to prevent continuing climate change.

Dealing with indirect impacts is more complicated. There are many different ways in which indirect impacts can be reduced and addressed. The solutions fall into two broad categories. First, we can reduce indirect impacts by reducing direct impacts. Second, we can adapt to climate change in various ways, meaning we can change our behavior and the way we design things. For example, we can design housing to be naturally cooler in the summer. As communities around the world face the impacts of climate change, adaptation solutions will become increasingly important. They will help us maintain our way of life while protecting human health and well-being.