Quantcast
Popular

Katharine Hayhoe: Here's How Long We've Known About Climate Change

One of the biggest myths about climate science—a myth that has been deliberately fostered, for decades—is that we just don't know that much, yet.

The field is still in its infancy, people argue and a lot more is needed before coming to consensus. After all, aren't scientists always changing their minds? Just a few decades ago, they were predicting an ice age, not global warming!

Even for those of us on board with the scientific consensus that climate is changing and humans are responsible, might be hard pressed to pick a year when climate science really began. Surely before 1990, when the first Intergovernmental Panel on Climate Change assessment was published? Maybe in 1988, when Jim Hansen testified to Congress? Or in 1981, when he published his first paper on the greenhouse effect of trace gases?

Joseph Fourier (1768- 1830).

Good guesses—but all wrong. The field of climate science stretches back almost 200 years. That's right: Scientists have been studying our planet for that long.

For more than 150 years, we've known that mining coal and burning fossil fuels produces heat-trapping gases. For more than 120 years, we've been able to put numbers on exactly how much the Earth would warm if we artificially increased carbon dioxide levels in the atmosphere. And it's been more than 50 years since the President's Council of Advisors on Science and Technology formally warned a U.S. president—Lyndon B. Johnson—that building up carbon dioxide in the atmosphere would "almost certainly cause significant changes" and "could be deleterious from the point of view of human beings."

It all started in the 1820s, when a French mathematician named Joseph Fourier realized that, for the Earth to be in equilibrium with the energy it was receiving from the sun every day, it should be a lot cooler than it actually is: around 33 degrees Celsius or nearly 60 degrees Fahrenheit cooler. In fact, it should be a ball of frozen ice. But it isn't.

Eunice Foote was an amateur scientist with a lively interest in many topics, from campaigning for women's rights to filing patents for boot soles. In 1856, she wrote a paper for the annual meeting of the American Association for the Advancement of Science, reporting on her measurements of the heat-trapping properties of carbon dioxide. She even speculated that if, "at one period of [Earth's] history the air had mixed with it a larger proportion [of CO2] than at present, an increased temperature from its own action must necessarily have resulted"—in other words, if there were more carbon dioxide in the atmosphere, then it would trap more heat, and the Earth would be warmer.

All this has to do with the planet's natural atmosphere, though. How long have we known that humans can impact climate? Over in England, a scientist and professor at the Royal Institute, John Tyndall, was asking similar questions, at around the same time.

John Tyndall (1820 – 1893).

With his rigorous scientific training and access to a state-of-the-art laboratory, John laid the foundation for our modern understanding of how molecules absorb and emit radiation. He also connected the dots between human activities and heat-trapping gases.

Svante Arrhenius (1859 – 1927).

By extracting and burning coal, oil and natural gas, we're putting extra carbon into the atmosphere. And this thicker blanket traps more heat, making the planet warmer. How much warmer? In the 1890s, a Swedish chemist named Svante Arrhenius decided to calculate, by hand, the very first climate model. It took him two years to figure out how much the world would warm if humans doubled or tripled the amount of carbon in the atmosphere: and his numbers were amazingly close to what the most recent global climate models, run on powerful supercomputers, still find today.

But wait a minute. We know the climate has changed in the past, when there weren't any humans around. How do we know the planet's not just still warming after the last ice age?

During WWI, a Serbian concrete expert named Milutin Milankovic was told he could continue his studies—as long as he focused on something that had nothing at all to do with the war effort. So he thought, why don't I figure out why we had ice ages in the past?

Milutin Milankovic (1879 – 1958).

So he did. He discovered that ice ages, and the warm interglacial periods like we're in right now, are initiated by changes in the shape of the Earth's orbit around the sun and the tilt of its axis of rotation. Over time, these cycles cause the great continental ice sheets to expand and retreat.

Variations in the tilt of Earth's axis and the shape of the orbit around the sun that occur over millennia act as triggers for glacial maxima, or ice ages, and the warm periods in between.

So, does that explain what's happening right now? No, because the warming after the last ice age peaked between four to eight thousand years ago. Today, according to natural cycles, we should be gradually and slowly cooling, in preparation for the next ice age. But, thanks to all the coal, oil and gas we've burned since the Industrial Revolution, that's no longer the next event on our geological calendar. Instead, we're heading into unknown territory—unknown, that is, since the time of the dinosaurs, when there weren't any ice sheets, when the sea level was more than 300 feet higher than today and when the land where a third of the people on this planet currently live would've been under water.

Historical departure from annual global mean surface temperature average (1961-1990), showing that warming after the last glacial maximum peaked between 8,000 and 4,000 years ago.

Yes, it's been warmer before and it's been colder. But human civilization is not built to deal with the changes we are making to this planet, the only one we have. That's why we care about a changing climate.

This essay originally appeared at The Equation, a blog of the Union of Concerned Scientists.


Show Comments ()
Sponsored

World's First Collapsible, Reusable Straw Fits Right On Your Keychain

Straws suck—literally and figuratively. Americans throw away 500 million of these single-use plastics everyday day, clogging landfills, polluting oceans and causing harm to aquatic creatures.

And while reusable straws made of bamboo or metal already exist on the market, the Santa Fe-based team at FinalStraw have invented the world's first collapsible, reusable straw you can conveniently attach to your keychain so you won't forget to bring your own when you're on the go.

Keep reading... Show less
Health
The 2018 London Marathon dropped air pollution on one street along its route by 89 percent. Kleon3 / Wikimedia / CC BY-SA 4.0

London Marathon Leads to 89% Drop in Air Pollution

Global Action Plan, a non-profit organization dedicated to tackling "throw away culture" and the impact it has on humans and the planet, discovered an unexpected health benefit to running marathons.

Keep reading... Show less
Popular
March For The Ocean

Why It’s Time We March for the Ocean

By Sylvia Earle & David Helvarg

We've recently seen the remarkable capacity of youth to mobilize and to inspire us with a message of change in their march against gun violence. Theirs is also a generation equipped with technologies not just to connect to each other but to better understand our blue planet in ways unimaginable even a generation ago. These include satellite tagging and following of migratory species such as whales, sharks and tuna and accessing the deep ocean with both autonomous robots and human occupied submersibles that allow us to dive into the history of our Earth.

Keep reading... Show less

Study Reveals Dangerous Antarctic Feedback Loop

A new study of the melting patterns of glaciers in Antarctica provides real-world evidence for one of the more troubling model-based climate change predictions, The Washington Post reported Monday.

The study, published April 18 in Science Advances, found that fresh water melting off of glaciers in some regions of Antarctica caused a layer of cold, fresh water to float above warmer, saltier water, both slowing ocean circulation and melting lower parts of the ice sheets.

Keep reading... Show less
Sponsored
Renewable Energy
GE's Haliade-X 12-megawatt offshore wind turbine

World's Largest Offshore Wind Turbine Can Power 16,000 Homes

The world's largest and most powerful offshore wind turbine will test its wings at an innovative facility in northeast England.

The 12-megawatt Haliade-X, developed by GE Renewable Energy, stands 853 feet tall, or about three times the height of the Flat Iron building in New York City. Its massive rotor diameter of 722 feet is roughly the tower height of San Francisco's Golden Gate Bridge above water.

Keep reading... Show less
Water overflowing the Oroville dam spillover in 2017. William Croyle, California Department of Water Resources

Climate Change Could Increase 'Whiplash' Between Wet and Dry Years in California, Leading to More Disasters

California has had a rough eight years. From 2010 to 2016, it endured the worst drought in its recorded history. Then, massive rainfall in 2016 and 2017 forced 18,000 Californians to evacuate their homes as the emergency spillway of the Oroville Dam was threatened due to erosion. Summer 2017 also saw the worst wildfire in the state's history.

But research published in Nature Climate Change Monday found that, if humans don't act to halt climate change, California's recent sequence of catastrophes could become the new normal.

Keep reading... Show less
Sponsored
Pixabay

Will Scientists Develop a Zero-Waste Cell Phone?

By Marlene Cimons

How often do you swap out your old smartphone for a new one? Every two or three years? Every year? Today, phone companies make it easy with deals to trade in your old phone for the newest version. But those discarded phones are becoming a huge source of waste, with many components ending up in landfills or incinerators.

When a cell phone gets tossed, only a few materials get recycled, mostly useful metals like gold, silver, copper and palladium, which can be used in manufacturing other products. But other materials—especially fiberglass and resins—which make up the bulk of cell phones' circuit boards, often end up at sites where they can leak dangerous chemicals into our groundwater, soil and air.

Keep reading... Show less
Health
formulanone / Flickr / CC BY-SA 2.0

Federal Court: Reinstate Fines for Gas Guzzlers

By Andrea Germanos

A federal court on Monday stopped another of the Trump administration's attacks on clean air—its indefinite delay of stricter penalties for automakers producing vehicle fleets that don't meet fuel efficiency standards.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!