Climate scientists bring us important news about our rapidly changing world and what we might do to stave off the worst consequences of melting ice sheets, rising seas, and rapidly increasing global temperatures. But what exactly is a climate scientist, and how do they make sense of the complicated systems that rule our lives on this fragile planet? What kind of guidance can they give us about preparing for an imperiled future?


When scientists talk about the climate, they’re actually referring to several interrelated systems: the Earth’s atmosphere; land surfaces (lithosphere); oceans, rivers and lakes (hydrosphere); snow and ice (cryosphere); and the layer of the planet where life exists (biosphere). Understanding the climate requires people with backgrounds in physics, math, chemistry, geology, biology, and other scientific disciplines to analyze all these different systems and how they interact. Climate scientists tend to specialize in a particular field, but they often work in interdisciplinary teams and typically have broad working knowledge of all these systems.

“Up until 20 years ago, no one was a climate scientist—people were just meteorologists, oceanographers, ecologists, geologists, or biologists, or chemists,” says Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies. “The reason why there are now climate scientists is that we realized these things are all coupled. What happens in the ocean is not independent of what’s happening with the weather, not independent of what’s happening in forests.”


If Minneapolis is enjoying a string of February days warm enough for flip flops and t-shirts, it’s tempting to blame climate change. But that’s weather, not climate. If average temperatures in Minneapolis stay higher over a period of years, however, then we're talking climate change.

What matters to climate scientists is whether average temperatures and other conditions are changing over years and decades, and if that’s part of a larger regional or global trend. And that trend definitely exists: The past three years have been the warmest since record-keeping began in the 1880s, and 16 of the 17 warmest years on record have occurred since 2001, according to NASA.

But temperature is just one piece of an enormous climate puzzle. Climate science must also analyze many other pieces of data to unravel complicated mysteries: How does ocean warming in the tropics set off a chain reaction that affects sea ice melt in the Arctic? How quickly is melting permafrost in Siberia releasing methane into the atmosphere? To what extent is climate change driving more severe droughts and bigger hurricanes? These are among the vast constellation of questions that climate scientists explore.


The climate system has always been in a state of flux, cycling between glacial periods—ice ages—and interglacial periods during which the Earth slowly warmed again over thousands of years. But there’s something unique about what’s happening on Earth right now.

Data show that atmospheric levels of carbon dioxide (C02) are higher than they’ve been for at least 800,000 years, thanks to human-generated emissions from things like power plants and cars and the effects of deforestation. (Trees and plants are carbon "sinks"—they store enormous amounts of carbon that gets released into the atmosphere as carbon dioxide when forests are cut down and burned.) At the same time, the rate of warming in the past century has been 10 times faster than what took place between past ice ages.

Scientists know that higher concentrations of greenhouse gases (such as carbon dioxide and methane) in the past led to enormous changes on Earth. But there’s no precedent for the rate at which humans are now emitting greenhouse gases. Already global temperatures are increasing, ice sheets are melting, seas are rising and acidifying, and species are vanishing. The basic questions climate scientists are racing to understand are: How much faster might these things happen in the future, and what will this mean for life on Earth as we know it?

“The climate has always changed, but we’re seeing now rapid change, very quick, and that’s the thing that species have a hard time adapting to,” says Mark Serreze, director of the National Snow and Ice Data Center. “We’re now talking about something big happening in less than a century.”


At least a quarter of all C02 released from burning fossil fuels ends up dissolved in the ocean. That might seem like a good thing—oceans acting like a “sink” that captures carbon, much the way forests and soils do. But scientists have discovered that carbon dioxide is changing ocean chemistry by making it more acidic.

Sarah Cooley spent seven years researching ocean acidification at the Woods Hole Oceanographic Institution’s chemistry lab, including looking at how shellfish are affected when exposed to highly acidic waters. She now directs the ocean acidification program at the environmental organization Ocean Conservancy, using her expertise to advocate for scientifically rigorous state, national, and international policy and communicate the science to coastal communities whose livelihoods may hang in the balance.

Cooley can cite plenty of evidence for how acidification affects ocean life: spiny sea urchins that have trouble growing; mollusks that can’t form strong shells; oyster populations in the Pacific Northwest diminishing during periods of upwelling (when more acidic waters are pushed up to the surface). Acidification is becoming a big concern for fisheries, too, since it dramatically impacts coral reef ecosystems on which many commercial fish depend.

“Ocean acidification is happening at a rate way faster than anything ocean life has seen in its evolutionary history,” Cooley says. “Conditions are changing much faster than they are evolutionarily equipped to handle.”


Sure, most climate scientists spend a fair amount of time hunched over a computer screen in an office engaged in relatively mundane tasks like reviewing data, responding to emails, and writing grant proposals. But the concept of an office gets completely redefined during field research.

In that case, work might involve a cramped nook onboard a tiny, wave-tossed research boat navigating stormy seas, or a sweaty, mosquito-besieged tent in the middle of the rainforest. The “commute” could necessitate a snowmobile, bush plane, or a mule. Researchers must survive hungry polar bears, storms at sea, venomous snakes, and, increasingly, treacherously thin ice.

Serreze recalls a few touch-and-go situations while conducting research in the Canadian Arctic. In one instance, he and his colleagues had to beat a hasty retreat to escape an aggressive muskox family. And as warmer temperatures thin the ice, researchers must be alert to melt ponds hidden just below the snowy surface.

“You might take a snow machine out and suddenly find yourself up to your chest in ice water,” he says. “You have to be careful, but it’s so much fun, too. It’s all in the attitude of the group.”

Cooley knows from experience how good teammates can forge close bonds. She met her husband while on a research vessel that traveled from Florida to the central North Atlantic to the northern coast of South America, and says working in close quarters with colleagues for months strips away all pretense. “If you can stand someone after seeing the worst of them and smelling their seawater-soaked shoes for 50 days, you’ve probably got a solid basis for relationship.”


Climate modeling, a sub-specialty of climate science, may not come with the glory afforded, say, a researcher who evades poisonous snakes to retrieve tree ring specimens in the Amazon. But modelers’ work is essential. They employ mathematical equations based on laws of physics and chemistry, and feed enormous quantities of complex data into supercomputers to illuminate how the Earth’s systems interact to influence climate.

In the past half-century, climate models have become ever more complex. They can incorporate information about specific physical and chemical processes—how ice reflects sunlight, how quickly a cloud forms, how water passes through leaves—to simulate real-world effects. They can predict how a big external force, such as a volcanic eruption, impacts temperature, rainfall, and wind. Recently, models suggested that the West Antarctic Ice Sheet may melt much faster than previously believed, potentially leading to catastrophic sea level rise by the end of this century.

But even the best models can’t capture everything. “No model is as complicated as the real world,” says Schmidt, a climate modeler himself. What’s important, he adds, is that models are skillful: They get us ever closer to what’s actually going on in the system.


During the 19th century, the world was just becoming aware of past ice ages, and scientists were trying to understand what had caused these long periods of cooling and warming. Serious air pollution caused by the coal-fired Industrial Revolution was an increasing cause for concern, but we were only beginning to understand the impacts of fossil fuels on our atmosphere. In 1861, Irish physicist John Tyndall showed how water vapor and atmospheric gases, such as methane and carbon dioxide, trapped heat in Earth’s atmosphere. By the end of the century, other scientists, like Swedish chemist Svante Arrhenius, had started to recognize the burning of fossil fuels as a factor in this “greenhouse effect.”

But it was an amateur—a British steam engineer named Guy Stewart Callendar—who in the 1930s began systematically documenting rising global temperatures and connecting this to rising levels of greenhouse gases.

At first, Callendar’s findings were mostly disregarded. Then World War II and the Cold War prompted more government funding for atmospheric science and technology, and early computer models validated his conclusions. Starting in the late 1950s, official measurements taken in Antarctica and atop Mauna Loa in Hawaii began showing unequivocally that concentrations of C02, the most prevalent greenhouse gas, were rising.


Hannes Grobe/AWI via Wikimedia Commons // CC BY 3.0

Scientists need to understand climate patterns over thousands and millions of years. Data from modern technology like satellites and high-tech instruments only go back a few decades; weather records from ships can fill in some of the blanks going back another hundred years or so, and other historic records can peer a little deeper into the past. But for the long-term view, you need paleoclimatology. This branch of climate science uses clues from the natural environment—things like coral, tree rings, ice cores, and fossils—to reconstruct how Earth’s climate has changed over eons.

One important tool for paleoclimatologists is a sediment core, extracted from the ocean floor or lake beds. These sediment samples contain layer upon layer of dust, pollen, minerals, shells, and other particles. They hold information about air and water temperature, ocean currents, winds, and the chemical composition of sea water at different points in geologic time.

An incredible amount of data is also trapped in ice, including air bubbles, dust, volcanic ash, and soot from forest fires. From ice cores extracted in polar regions, scientists can actually get year-by-year snapshots of atmospheric gases, air and water temperature, and past episodes of massive ice sheet melt. Patterns in such data—higher sea levels or global temperatures during periods when the Earth's atmosphere contained high carbon dioxide concentrations similar to today, for example—may be useful in understanding what we face in a rapidly warming world.


Jim White, who directs the Institute of Arctic and Alpine Research at the University of Colorado Boulder, has made many trips to Greenland in his career as a paleoclimatologist. He says that back in the 1950s and ’60s (before his time as a researcher), scientific expeditions were brought to Greenland by ship: “They’d get dropped off and told, ‘We’ll see you in two months.’”

As transportation options like airplanes and helicopters became more widely used, travel and communication got easier. But scientific teams are still at the mercy of the weather. Even in summertime, supply flights can be delayed for days or weeks because of extreme weather conditions.

“We have to have a lot of Plan Bs,” White says. “The summer I was getting married, I told my wife-to-be that I may get stuck up there. She thought I was kidding. Later she realized it really could have happened.”

But there’s an upside to spending weeks camping in frigid weather while extracting ice cores from a mile and a half deep in a glacier: “It’s almost impossible to gain weight,” White says. “You’re breathing negative 30-degree air, your body is fighting to stay warm, and so you burn calories and you can eat like a horse.”


Teaching university students about climate, White says he’s reminded on a daily basis of the fact that he thinks about time differently than most. “When I talk with my students about timeframes of interest, theirs may be Thursday night. But I have multiple ones because of what I do. I’m trained to think in tens of thousands of years. And I think quite a bit about the next 50, 100, 200 years.”

White says he and his international colleagues spend time on research expeditions talking about their children and grandchildren, pondering how the world can get beyond short-term thinking in order to be better prepared for the enormous global changes that will affect future generations.

“Human beings are capable of altering the planet long before we’re capable of understanding the ramifications of that," he says. "We say we love our kids, but do we show it? We will never deal with climate change until we learn to value our children and grandchildren at the 50-year timescale.”

All photos via iStock except where noted.