The climate is rapidly changing. But just how rapidly are we talking about? How “fast” is the speed of climate change—and in the grand scheme of things, how fast is too fast?
Today, nearly all scientists agree that the climate is changing because of human activity. However, there are a few people who argue that some climate change is normal and natural. But the change itself isn’t necessarily the problem: the problem is that it’s happening too fast for evolution to keep up.
In other words, it took billions of years for the world we know to form. But it could take decades for everything to change.
The Changing Environment
Since the Earth was born through a series of asteroid collisions, its surface has always been changing. First, the molten planet cooled enough for a crust to form. Known as tectonic plates, these patches of crust—which underlie the continents and seas—move slowly, only a few inches per year (about the same speed as your hair grows). When they bump into each other, the force pushes the crust upward into mountain ranges, shaping and reshaping continents. All this happens very slowly, over the course of millions of years.
(click here for a great video of the continents moving)
Of course, changes to land and sea can happen quickly, too. Think of a volcano erupting to form an island (like when Surtsey Island formed near Iceland in the 1960s), and you get the picture.
Other parts of the environment also change over time, at varying rates. For example, if a beaver dams up a river, that river might form a lake. Or mountains might get worn away by wind and rain, leaving behind valleys and plains.
The Speed of Evolution
But how fast do animals and plants change? The answer is complicated. Charles Darwin thought that evolution happens very slowly, with tiny changes over the course of many generations. In this view, it might take thousands of years—or even hundreds of thousands—for a new species to form. This theory is called gradualism.
Biologists Niles Eldredge and Stephen J. Gould thought differently. They believed that evolution happens in short spurts, an idea called punctuated equilibrium. This might take place if an animal suddenly developed a mutation (like camouflaged coloring) that was so helpful, it became common among a species in just a few generations.
Today, biologists believe in a combination of the two theories. Sometimes, evolution is slow. Other times, it is fast. The speed of change also has to do with the timespan of a generation—for humans, a single generation might last forty years. But for some bacteria, it only lasts twenty minutes. That’s one reason why bacteria evolve so much more quickly than humans.
Multiple Tempos
As it turns out, the Earth and its inhabitants change at many different rates, all at the same time. The continents reshape themselves over millions of years, volcanism forms new land instantly, species change both quickly and slowly.
Geologist Marcia Bjornerud explains, “There’s this irony to me that for years and years, geologists have been emphasizing how geologic change is slow and incremental, and I think finally the public has assimilated that idea, but now we’re also saying that actually climate change can be fast. It can happen in our lifetimes. And both of those things are true.”
Climate Change Today
The Earth has changed drastically over billions of years. It’s rearranged its continents, experienced bouts of wetness or dryness, cooled, and yes, warmed. Some people argue that the warming we’re experiencing today is just another natural cycle. The problem with that theory is this: over the last 150 years, temperatures have shot up nearly 1.2 degrees Celsius—faster than they ever have in human history.
The problem isn’t just that the environment is changing faster: it’s that animals and plants can’t keep up with the changes. Normally, a habitat would change relatively slowly, giving wildlife time to evolve. Now, there’s no time. The changing climate has catastrophic, deadly ramifications. And dead things can’t evolve.
Bjornerud observes, “The Earth has multiple tempos, and when we look back in the rock record, mass extinctions, unfortunately tend to be correlated with times where the tempo of environmental change outpaces the tempo of an evolutionary change, where the biosphere can’t keep up with the rate of environmental change, and then organisms die, and there’s kind of ecological crisis.”
The Planetary Symphony
The beat of the earth isn’t a single melody: it’s a symphony. There are many different instruments involved, each performing its own tune. In normal times, these tunes overlap in harmony. But in today’s changing climate, some instruments are racing ahead at a rate the rest of the orchestra can’t keep up with. That’s not just happenstance; climate change is fueled by human emissions of carbon dioxide.
Whether we like it or not, we are part of the orchestra—and from the looks of it, we’re playing percussion with a jackhammer.
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