Caltech Science Exchange / Topics / Sustainability / Climate Change Effects

What Are the Effects of Climate Change?

NASA’s Global Climate Change website provides the public with accurate and timely news and information about Earth’s changing climate, along with current data and visualizations, presented from the unique perspective of one of the world’s leading climate research agencies. The website is produced by a team at the Jet Propulsion Laboratory, which Caltech manages for NASA.

Global climate change has already had observable effects on the environment, many of which were predicted by scientists: loss of sea ice, accelerated sea level rise, and longer, more intense heat waves.

The Intergovernmental Panel on Climate Change (IPCC), a United Nations organization that includes 195 member countries and thousands of independent scientific experts, says that some of the harms caused by Earth's changing climate are irreversible, such as species extinction. However, the IPCC also reports with high confidence that a 60 percent reduction of greenhouse gases by 2035 would noticeably slow down global warming to 2.5 degrees Fahrenheit over the next two decades.

Small temperature rise, big impact

Earth's average temperature has increased about 2 degrees Fahrenheit during the 20th century. Small changes in Earth's temperature correspond to enormous changes in the environment. For example, at the end of the last ice age, when the northeast United States was covered by more than 3,000 feet of ice, average temperatures were only 5 to 9 degrees cooler than today.

Scientists have high confidence that global temperatures will continue to rise for decades to come, largely because of greenhouse gases produced by human activities.

In its March 2023 Synthesis Report on climate data, the IPCC forecasted with medium confidence a temperature rise of 5.8 degrees Fahrenheit by the end of the century if no further action is taken to mitigate global warming. In that scenario, today's children would be likely to experience a fivefold increase in extreme weather events such as floods, tropical cyclones, and droughts by the time they reach their 80s.

Significant changes in the environment can fundamentally affect human survival by making it more difficult to access food and water. Currently, more than 3 billion people live in regions that are highly vulnerable to the impact of climate change, according to the IPCC. Parts of the world most threatened—including the Arctic, Africa, and Central and South America—have contributed the least to these conditions.

According to the Third and Fourth National Climate Assessment reports and other recent updates, some of the long-term effects of global climate change in the United States include: