erosion and longshore transportWhen scientists talk about climate change, they're talking about a pattern of change that's happening over many years—in other words, major changes in temperature, rainfall, snow, or wind patterns lasting for decades or longer. Climate change may result from:

One of the most important trends that scientists look at is the average temperature of the Earth, which has been increasing for many years. This is caused by increasing greenhouse gases that trap heat in our atmosphere. Rising global temperatures lead to other changes around the world, such as changes in precipitation levels, stronger hurricanes, melting glaciers, and the loss of wildlife habitats. That's because the Earth's air, water, and land are all related to one another and to the climate. This means a change in one place can lead to other changes somewhere else.

What are climate change scenarios?
Climate change is generally expected to bring unprecedented changes, but what these specific changes might be are difficult to accurately predict. A scenario is a science-based example of what might happen. Scenario planning offers a tool using many examples, so we can start to see and plan for how things might be different in the future.

How are scenarios used to determine the potential effects of climate change?
Scenarios are not forecasts or predictions. They are simply tools to help look at the big picture of a highly uncertain world and think about how things may turn out.

Uncertainty happens in everyday life
Insurance companies will tell you that it is very likely that 3 people in a group of 100 will have a car accident. They make that statement based on evaluating data collected by the insurance experts from actual observations. While this is not a certain prediction that you will be in a car accident, you recognize the risk and purchase insurance to help minimize the negative impact of a potential accident.

Similarly, scientists worldwide are telling us that climate change will impact our planet in negative ways. They make that statement based on examining data collected by actual changes observed in our environment and by looking at what happened in the past.

While they cannot predict exactly what the future will hold (and it will hold different effects in different places), they can provide plausible climate change scenarios. The description they use to indicate the likelihood of a scenario becoming reality is expressed in terms such as likelihood or confidence. Focusing on scenarios that are likely or have a high degree of confidence, we can prepare now for the future consequences and impacts of climate change.