We often call the result global warming, but it is causing a set of changes to the Earth's climate, or long-term weather patterns, that varies from place to place. Climate change encompasses not only rising average temperatures but also extreme weather events , shifting wildlife populations and habitats, rising seas , and a range of other impacts.
All of those changes are emerging as humans continue to add heat-trapping greenhouse gases to the atmosphere, changing the rhythms of climate that all living things have come to rely on. What will we do—what can we do—to slow this human-caused warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the fate of the Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.
An iceberg melts in the waters off Antarctica. Climate change has accelerated the rate of ice loss across the continent. The "greenhouse effect" is the warming that happens when certain gases in Earth's atmosphere trap heat. These gases let in light but keep heat from escaping, like the glass walls of a greenhouse, hence the name. Sunlight shines onto the Earth's surface, where the energy is absorbed and then radiate back into the atmosphere as heat.
In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into space. The more greenhouse gases concentrate in the atmosphere, the more heat gets locked up in the molecules. Scientists have known about the greenhouse effect since , when Joseph Fourier calculated that the Earth would be much colder if it had no atmosphere.
This natural greenhouse effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an average of about 60 degrees Fahrenheit 33 degrees Celsius cooler.
In , the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide , a greenhouse gas. He kicked off years of climate research that has given us a sophisticated understanding of global warming.
Levels of greenhouse gases have gone up and down over the Earth's history, but they had been fairly constant for the past few thousand years. Global average temperatures had also stayed fairly constant over that time— until the past years. Through the burning of fossil fuels and other activities that have emitted large amounts of greenhouse gases, particularly over the past few decades, humans are now enhancing the greenhouse effect and warming Earth significantly, and in ways that promise many effects , scientists warn.
Human activity isn't the only factor that affects Earth's climate. Volcanic eruptions and variations in solar radiation from sunspots, solar wind, and the Earth's position relative to the sun also play a role. Changes in solar radiation levels as well as minute particles suspended in the atmosphere from volcanic eruptions , for example, have contributed only about two percent to the recent warming effect. The balance comes from greenhouse gases and other human-caused factors, such as land use change.
The short timescale of this recent warming is singular as well. The impacts of global warming are already harming people around the world. Now climate scientists have concluded that we must limit global warming to 1.
These effects are felt by all people in one way or another but are experienced most acutely by the underprivileged, the economically marginalized, and people of color, for whom climate change is often a key driver of poverty, displacement, hunger, and social unrest. Normally this radiation would escape into space, but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter.
These heat-trapping pollutants—specifically carbon dioxide, methane, nitrous oxide, water vapor, and synthetic fluorinated gases—are known as greenhouse gases, and their impact is called the greenhouse effect.
In the United States, the largest source of greenhouse gases is transportation 29 percent , followed closely by electricity production 28 percent and industrial activity 22 percent. Curbing dangerous climate change requires very deep cuts in emissions, as well as the use of alternatives to fossil fuels worldwide.
The good news is that countries around the globe have formally committed—as part of the Paris Climate Agreement —to lower their emissions by setting new standards and crafting new policies to meet or even exceed those standards. To avoid the worst impacts of climate change, scientists tell us that we need to reduce global carbon emissions by as much as 40 percent by For that to happen, the global community must take immediate, concrete steps: to decarbonize electricity generation by equitably transitioning from fossil fuel—based production to renewable energy sources like wind and solar; to electrify our cars and trucks; and to maximize energy efficiency in our buildings, appliances, and industries.
They also said the odds of similar droughts happening in the future had roughly doubled over the past century. And in , the National Academies of Science, Engineering, and Medicine announced that we can now confidently attribute some extreme weather events, like heat waves, droughts, and heavy precipitation, directly to climate change.
In other words, global warming has the ability to turn a category 3 storm into a more dangerous category 4 storm. In fact, scientists have found that the frequency of North Atlantic hurricanes has increased since the early s, as has the number of storms that reach categories 4 and 5.
The Atlantic hurricane season included a record-breaking 30 tropical storms, 6 major hurricanes, and 13 hurricanes altogether. With increased intensity come increased damage and death. The impacts of global warming are being felt everywhere. Extreme heat waves have caused tens of thousands of deaths around the world in recent years. And in an alarming sign of events to come, Antarctica has lost nearly four trillion metric tons of ice since the s.
The rate of loss could speed up if we keep burning fossil fuels at our current pace, some experts say, causing sea levels to rise several meters in the next 50 to years and wreaking havoc on coastal communities worldwide. A: Each year scientists learn more about the consequences of global warming , and each year we also gain new evidence of its devastating impact on people and the planet. As the heat waves, droughts, and floods associated with climate change become more frequent and more intense, communities suffer and death tolls rise.
Global warming is already taking a toll on the United States. Though everyone is affected by climate change, not everyone is affected equally. Indigenous people, people of color, and the economically marginalized are typically hit the hardest. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Environmental Science. Green Science. Do you know the effects of global warming?
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