Global Warming, explained

Raúl Sosa 9-III

Glaciers are melting, sea levels are rising, cloud forests are dying and wildfire is scrambling to keep up the pace. It has become clear that humans have caused most of the past century’s global warming by releasing heat-trapping gases as we power our modern lives. Greenhouse gas levels are higher now than at any time in the last 800,000 years.

We often call the result of 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. While many people think of global warming and climate change as synonyms, scientists use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems in part because some areas actually get cooler in the short term.

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 the climate that all living things have come to rely on.

What will and 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 hangs in the balance.

Understanding the greenhouse effect

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 radiates back into the atmosphere as heat. In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into the atmosphere. 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 1824 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 cooler.

In 1895, the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide, a greenhouse gas. He kicked off 100 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 150 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 outstanding consequences.

Aren’t temperature changes natural?

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.

But climate models that scientists use to monitor Earth’s temperatures take those factors into account. 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 unbalance comes from greenhouse gases and other human-caused factors, such as a change in land use.

The short timescale of this recent warming is singular as well. Volcanic eruptions, for example, emit particles that temporarily cool the Earth’s surface.  On the other hand, the types of global temperature fluctuations that have contributed to ice ages occur on a cycle of hundreds of thousands of years.

For thousands of years now, emissions of greenhouse gases to the atmosphere have been balanced out by greenhouse gases that are naturally absorbed. As a result, greenhouse gas concentrations and temperatures have been fairly stable, which has allowed human civilization to flourish within a consistent climate.

Now, humans have increased the amount of carbon dioxide in the atmosphere by more than a third since the Industrial Revolution. Changes that have historically taken thousands of years are now happening over the course of decades. In other words, we are killing the planet very fast.

Why does this matter?

The rapid rise in greenhouse gases is a problem because it’s changing the climate faster than some living things can adapt to. Also, a new and more unpredictable climate poses unique challenges to all life.

Historically, Earth’s climate has regularly shifted between temperatures like those we see today and temperatures cold enough to cover much of North America and Europe with ice. The difference between average global temperatures today and during those ice ages is only about 9 degrees Fahrenheit, and the swings have tended to happen slowly, over hundreds of thousands of years.

But with concentrations of greenhouse gases rising, Earth’s remaining ice sheets such as Greenland and Antarctica are starting to melt too. That extra water could raise sea levels significantly, and quickly. By 2050, sea levels are predicted to rise between one and 2.3 feet as glaciers melt.

As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme. This means more intense major storms, more rain followed by longer and drier droughts, which is a challenge for growing crops, changes in the ranges in which plants and animals can live, and loss of water supplies that have historically come from glaciers.

In conclusion, our earth is dying because humans are releasing way too many gases into the atmosphere creating a greenhouse effect. If this continues, the Earth will lose its ability to maintain life inside it and we could lose our quality of life as we know it. We have to stop producing greenhouse gases because if we don’t were looking at a dark world ahead of us. 

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