Decades of Warming

Though hindsight isn’t quite 2020 yet, climate change has left plenty to remember over the past 10 years. This release covers warming temperatures by the decade, with clear trends at the local, national, and global scales.

Extreme Temperature Change: Air Temperatures

Average air temperatures are rising. Climate change has already increased average temperatures enough to shift seasons — spring comes earlier and fall frosts arrive later. While average global air temperatures are warming, historical data also reflects that we are also experiencing more extreme temperature change.

Extreme Temperature Change: Water Temperatures

As average air temperatures rise, so do the average water temperatures of our oceans, lakes and rivers, affecting ecosystems and species that depend on them.

Shorter Cold Snaps and Warming Winters

Rising temperatures sometimes seem most noticeable during periods of extreme heat such as summer heat waves. However, for much of the U.S., winter is the fastest warming season. Cold weather still occurs in a warming climate but, on average, winters are not as cold as they used to be and cold snaps that do happen are becoming shorter and less frequent.

The Science of Modern Climate Change

Modern climate change differs from natural climate change — also known as geologic climate change — because it is caused by humans and is occurring much faster than geologic climate change. Modern climate change is primarily driven by the effects of greenhouse gases, and is directly linked with human activities.

Urban Heat Island Effect

The “urban heat island effect” (UHIE) describes the phenomena where temperatures in densely populated cities can be significantly higher than in surrounding areas.

Why a Half-degree Temperature Rise is a Big Deal

A jump from 1.5 to 2 degrees—a third more of an increase—raises projected impacts by about that same fraction, and this is a big deal. Heat waves would last around a third longer, rain storms would be about a third more intense, the increase in sea level would be approximately that much higher and the percentage of tropical coral reefs at risk of severe degradation would be roughly that much greater.