The science of climate change, explained

Photo Illustration by Andrea D'Aquino
Photo Illustration by Andrea D'Aquino

How do we know climate change is really happening?

Climate change is often cast as a prediction made by complicated computer models. But the scientific basis for climate change is much broader, and models are actually only one part of it (and, for what it’s worth, they’re surprisingly accurate).

For more than a century, scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up just a small fraction of the atmosphere but exert outsized control on Earth’s climate by trapping some of the planet’s heat before it escapes into space. This greenhouse effect is important: It’s why a planet so far from the sun has liquid water and life!

However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. Ever since, human activities have been heating the planet.

We know this is true thanks to an overwhelming body of evidence that begins with temperature measurements taken at weather stations and on ships starting in the mid-1800s. Later, scientists began tracking surface temperatures with satellites and looking for clues about climate change in geologic records. Together, these data all tell the same story: Earth is getting hotter.

Source: NASA Goddard Institute for Space Studies | By Veronica Penney
Source: NASA Goddard Institute for Space Studies | By Veronica Penney

Average global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, since 1880, with the greatest changes happening in the late 20th century. Land areas have warmed more than the sea surface and the Arctic has warmed the most — by more than 4 degrees Fahrenheit just since the 1960s. Temperature extremes have also shifted. In the United States, daily record highs now outnumber record lows two-to-one.

We also know that climate change is happening because we see the effects everywhere. Ice sheets and glaciers are shrinking while sea levels are rising. Arctic sea ice is disappearing. In the spring, snow melts sooner and plants flower earlier. Animals are moving to higher elevations and latitudes to find cooler conditions. And droughts, floods and wildfires have all gotten more extreme. Models predicted many of these changes, but observations show they are now coming to pass.

How bad are the effects of climate change going to be?

It depends on how aggressively we act to address climate change. If we continue with business as usual, by the end of the century, it will be too hot to go outside during heat waves in the Middle East and South AsiaDroughts will grip Central America, the Mediterranean, and southern Africa. And many island nations and low-lying areas, from Texas to Bangladesh, will be overtaken by rising seas.

Conversely, climate change could bring welcome warming and extended growing seasons to the upper Midwest, Canada, the Nordic countries and Russia. Farther north, however, the loss of snow, ice and permafrost will upend the traditions of Indigenous peoples and threaten infrastructure.

What will it cost to do something about climate change, versus doing nothing?

One of the most common arguments against taking aggressive action to combat climate change is that doing so will kill jobs and cripple the economy. But that implies that there’s an alternative in which we pay nothing for climate change. And unfortunately, there isn’t.

In reality, not tackling climate change will cost a lot and will cause enormous human suffering and ecological damage, while transitioning to a greener economy would benefit many people and ecosystems around the world.

Tools & Resources


🌎 Klima

Effective, immediate, simple climate action in the palm of your hand.

When doing your part to reduce climate change, it can be hard to know where to begin. That’s why Klima creates a personal estimate of the greenhouse gases you’re generating—and suggests concrete ways to offset that.Who it’s for: Anyone who’s curious about their personal impact on the environment. Klima asks a few specifics about your lifestyle—for example, how many miles you drive a year, how big your home is, and how often you shop. Using those numbers, the app tells you how much you would need to donate to carbon-offsetting projects to cancel out your carbon footprint.

What sets it apart: Contribute right in the app to up to three causes—like tree planting, solar power, and providing clean-fuel cookstoves to people around the world who need them—and see exactly how much CO2 your donations are offsetting.Don’t miss: Because offsetting alone won’t stop climate change, the app also suggests ways to reduce your carbon footprint. A personalized checklist tells you how going vegan, driving less, or cutting back on shopping can reduce your overall impact on the environment.

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📖 52 Weeks of UX is a discourse on the process of designing for real people, an old project from product designer Joshua Porter and Josh Brewer which ended in 2011 but contains some amazing writings, articles with great insights and information.

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— That’s it for this edition. See you with the next one.