How much do you know about climate change? Here's a refresher

While the great majority of Americans think climate change is happening, less than half think the global phenomenon is caused “mostly by human activities,” according to recent survey results out of Yale University.

The overwhelming consensus of scientists today is that the climate change we're experiencing now is driven almost exclusively by human activities, primarily the burning of oil, gas, coal and other fossil fuels. Yale's survey, conducted by the university's Program on Climate Change Communication, revealed a foundational gap in Americans' climate change knowledge.

The survey comes at the close of a year riddled with global, national and local extreme weather events. Between Earth reaching the hottest global temperature on record, Canada's far-reaching wildfires, and extreme flooding combined with a monthslong drought in the Chicago area, reminders of the impact of global warming have permeated everyday life in the suburbs and beyond.

As humanity looks ahead with the collective goal of preventing the world's average temperature from exceeding that of preindustrial times by more than 1.5 degrees Celsius (2.7 Fahrenheit), the Yale survey results warrant a step back to explore our understanding of what climate change is, what causes it and what we, in the suburbs as well as throughout the country, can do to slow — and even reverse — it.

To begin, here are the answers from Illinois' top climatologist, Trent Ford, to three key questions:

What are global warming and climate change?

The terms climate change and global warming are often used interchangeably, but in reality they are distinct: climate change is a result of global warming.

The latter is caused by a significantly high amount of greenhouse gases — the most impactful being carbon dioxide — in the atmosphere. As carbon dioxide increases in the atmosphere, the temperature on Earth increases, and vice versa.

This natural relationship has existed since Earth was formed, but over the last 150 years, the amount of carbon dioxide in the atmosphere has become higher than at any point in 800 millennia.

“The concentration of carbon dioxide in the atmosphere today is unprecedented in the last 800,000 years, so certainly over human history, and the rate of the increase in carbon dioxide is also unprecedented,” Ford said. “It is unequivocal that what we've seen in the last 150 years when it comes to increases in carbon dioxide concentrations is due to human activity.”

Greenhouse gasses like carbon dioxide, methane and nitrous oxide essentially act as a screen or glass that lets the sun's energy in but doesn't let all of it back out, driving up the global average temperature and resulting in global warming.

And the connection between global warming and climate changes is that when Earth's energy increases, it changes everything on Earth.

“Because the systems are so complex, and they're interacting with each other all the time — the ocean, the air, the land, the plants, the biosphere, ice — it means that we have different kinds of regional manifestations of the risk and the impact of global warming,” Ford said. “And that's called climate change.”

What is the status of climate change today?

The effects of climate change are being seen worldwide, including here in Illinois. Over the last century, the average daily temperature has increased by 1-2 degrees in most areas of the state, a 2020 study found.

“We've gotten warmer over the last 150 years, every single season, every single place in Illinois,” Ford said.

Our hotter summers mean longer and more dangerous heat waves, while our milder winters are raising cautionary flags in several areas, including agriculture and plant ecology. The state is also getting wetter, with climate change creating heavier rainfall and, conversely, prolonged dry spells in between storms.

Illinois is also putting an unusually tornado-dense year behind it. There is growing evidence tornadoes are becoming more frequent and damaging, and climatologists suspect the upward trend could be partially attributed to climate change.

“We need to make ourselves more resilient ... but ultimately, to solve the problem of climate change and the impacts that it creates, like those heavy rainfall events, we have to go back to the root cause, which is the increasing concentration of greenhouse gasses like carbon dioxide,” Ford said.

Under the most optimistic scenario, we are able to reach net zero as soon as possible, meaning we're emitting less carbon dioxide than we're taking out of the atmosphere.

But even then, global warming's impact will continue for a number of years. That's because we're facing a century and a half worth of greenhouse gasses that have built up.

“When we get beyond the end of this century, it is likely we'll see those impacts decrease if we continue to curb carbon dioxide emissions,” Ford said. “This is a long-term thing, the reason being there is staying power in the carbon dioxide. The impacts we're seeing today are the results not necessarily of the carbon dioxide that was released today, but the carbon dioxide that was released yesterday and 30 years ago and 100 years ago.”

Consequently, global surface temperatures have reached 1.1 degrees C above preindustrial times — 0.4 degrees below the 1.5 degrees goal set in 2015 by the landmark international treaty, the Paris Agreement.

What can we do?

The bad news is existing carbon reductions being made in sectors like transportation, building and energy are moving too slowly.

The good news is we have the tools in hand to mitigate and even reverse climate change — it's just a matter of policy, Ford said.

For instance, the Intergovernmental Panel on Climate Change wrote in their latest report that “deep, rapid, and sustained reductions in greenhouse gas emissions would lead to a discernible slowdown in global warming within around two decades,” adding that “there is a rapidly closing window of opportunity to secure a livable and sustainable future for all.”

“We have solutions, they just need to be implemented,” Ford said. “It's really just about the political will to get it done. Not all hope is lost. Certainly, we're not doomed by any means, but we have a lot of work to do.”

On an individual level, Ford added, the most impactful thing people can do is engage with their communities and governments on a local scale.

That's because small governments make climate decisions each day in spaces that Congress or the United Nations are not acting in, such as zoning laws, planning and development, transit design, health care systems and green space management.

People can also lead by example and take steps like reducing their food waste and energy usage, though Ford said individuals' ability to take those steps is often decided by the system they live in.

For example, driving less becomes more difficult without access to public transit, bikeable neighborhoods, or affordable homes near workplaces.

“If you don't drive your car, that's one person who's not driving their car. But if you help develop accessible and reliable public transit, think how many cars can be taken off the road from that,” Ford said. “That's where that community and political activism really comes in.”

• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.