There’s a difference between climate change and global warming

In the past two months, the Island’s seen more than one snowstorm or full-on blizzard, frigid temperatures that froze ponds, and wind chills that drew tears from the eyes. In this moment, climate change feels impossible. That’s because what students from kindergarten through college-level courses are told — or what they really take from a science class — is that human-induced climate change, colloquially interchanged with global warming, is a result of the greenhouse effect, when an increase in greenhouse gases in the atmosphere causes a rise in temperatures. It’s not completely illogical to take the bare-bones concept of climate change in one hand, and the several feet of snow from two snowstorms that derailed the Island in the other, and come up blank. They don’t seem to quite mesh together. And that’s because this really is a paradox, a logically contradictory situation. The Earth’s temperature is on the rise, but we can’t seem to catch a break from the snow.

But there are secondary signals of climate change. It’s not just warmer temperatures, and there is an important distinction to be made between climate change and global warming. Global warming is the rise in global temperatures, while climate change is the increase in changes in measures of climate, such as precipitation, weather, and wind patterns, over the long term. 

And though the concept of climate change goes all the way back to the 1850s, when Eunice Newton Foote, a U.S. amateur scientist or natural philosopher, tested the effect of different atmospheric gases on heat from the sun, there is a real denial of climate change and global warming, even by this country’s leaders. In fact, at the end of January, when a snowstorm battered much of the country, President Donald Trump, who recently revoked a scientific finding that climate change is a danger to public health, took to Truth Social on Jan. 23 and wrote, “Record Cold Wave expected to hit 40 States. Rarely seen anything like it before. Could the Environmental Insurrectionists please explain — WHATEVER HAPPENED TO GLOBAL WARMING???”

But this can be explained. 

The reason that last week’s blizzard — also called a nor’easter or extratropical cyclone — that dumped nearly two feet of snow on the Island and produced 70-something mph winds continues to support the idea of climate change is because warmer air can hold more water vapor. This means that up in the atmosphere, there’s more potential precipitation, which can take the form of rain, ice, hail, or snow. Warmer air is the result of the greenhouse effect and global warming, and more water vapor means more precipitation. It needs only cold Arctic air to collide with warm air from the subtropic Atlantic to manifest.

It was Foote who foreshadowed the existence of the greenhouse effect about 175 years ago, filling glass cylinders, each holding a mercury thermometer, with gases and moisture, and found that through sun exposure, temperature rose higher in moist air than dry air and was the greatest in the cylinder that contained carbon dioxide. Then, three years later, Irish scientist John Tyndall’s more sophisticated experiments showed that the Earth’s greenhouse effect is caused by water vapor and gases like carbon dioxide that absorb and emit thermal infrared energy, or heat, and change the atmosphere’s temperature. Foote, who attended the first women’s rights convention in Seneca Falls, N.Y., wasn’t recognized as a climate pioneer until the early 2010s.

What Foote and Tyndall didn’t explain through their experiment is how weather works and changes because of the greenhouse effect.

Timothy Hall, senior scientist in S&P Global’s Sustainable1 division, who previously worked for the National Aeronautics and Space Administration’s (NASA) Goddard Institute for Space Studies, said that climate change isn’t as easy as just, “Temperatures are warmer.” No, in fact, he likes to say that all weather, not just temperature, is a climate signal. “Weather sits on top of climate,” he said. His take is reminiscent of an analogy popularized by climatologist Dr. James Hansen, who also worked at Goddard, which uses a weighted, or loaded, die to show that an increase in greenhouse gases in the atmosphere increases the chance of warmer temperatures and extreme weather. It doesn’t negate the possibility of cold winters, just changes the probability.

Hall lives full-time on Martha’s Vineyard, and was here for last week’s storm. He creates hazard and risk models of extreme weather and climate for S&P, and also was a lead author on the 2017 National Climate Assessment Report. The paradoxical snow this season, he explained, is because there’s more water vapor in the atmosphere because the air is warmer. But as long as the days are cold enough, precipitation takes the form of snow. And even as the global average surface temperature of the Earth rises, there’s still variability in day-to-day and month-to-month temperatures.

Down the line, though, days won’t be so cold, and precipitation may take the form only of rain, Hall said. That may be way, way down the line, though. James Booth, an atmospheric scientist at the City College of New York, said that snowstorms are possible in the Northeast for the next 60-plus years. Manmade global warming is real, he said, but seasonal cycles still lead to cold temperatures in the winters. A blizzard doesn’t discredit the existence of climate change and global warming. In fact, the extremity supports the idea.