There is no such thing as cold. That might sound idiotic coming from a Vermonter, but it’s true. In actuality there is only heat — and more or less of it. So to state the obvious, less heat only just feels like cold. This is not just semantics — it’s how physicists understand thermodynamics, or the movement of heat between objects, which helps describe the universe.

Heat, like water, runs downhill. It moves from where there’s more of it to where there’s less of it. Why do we care about this? Because the Earth is constantly trying to establish “thermodynamic equilibrium,” i.e. its attempt to spread heat evenly planet-wide. Ocean currents transfer heat into polar regions while large-scale atmospheric circulation also distributes heat. Luckily, equilibrium is never reached.

All these influences result in something we refer to as “climate.” Notably, Earth’s climate over the last 12,000 years since the end of the last ice age up until pre-industrial times has been extraordinarily stable and, perhaps more importantly, relatively predictable.

In the meantime, scientists, who are nothing if not fastidious and demanding of precision, do meticulously controlled research to understand how ecosystems function. They painstakingly structure experiments so as to isolate out individual cause-effect relationships while ensuring that outside mitigating factors do not influence experimental outcomes. This pinpoints cause-effect relationships as precisely as possible.

So imagine the ecological chaos that ensues as human activity pumps a colossal 43 billion tons of heat-trapping carbon dioxide into the planetary thermodynamic regime every year. This enormous amount of extra anthropogenic heat now wreaks havoc upon what used to be long-term climate stability. What humankind is faced with now is a planet-wide experiment lacking checks and verification.

CO2 is the “control knob” for Earth’s climate, with the recent series of ice ages over the last 2.8 million years exquisitely tuned to its atmospheric concentration. An 800,000-year ice core from Antarctica reveals a more detailed occurrence of five ice age episodes paired with corresponding atmospheric concentrations of CO2. During this period, CO2 concentrations dropped to 100–180 parts per million (ppm) during glacial periods and never rose above 280 ppm during warmer interglacial periods, which is where CO2 levels stood at the beginning of the fossil fuel era beginning around 1850.

With CO2 concentration now spiking at 420 ppm (and rising by 2 ppm per year), human activity has produced the equivalent, since the industrial age, to an amount of CO2 equal to the difference between “ice age” and “no ice age;” i.e. more than the amount of CO2 that lifted us out of the last ice age. We are on track to warm the Earth “more this century than between the middle of the last ice age 20,000 years ago and today.”

All that added heat supercharges the atmosphere with excess energy. And it is energy that drives weather and climate. Our planet-wide manipulation of Earth’s heat dynamics has developed into the biggest uncontrolled geophysical experiment in history, resulting in ecological consequences that are entirely unpredictable.

How bad will things get? Aside from general certainties like rising temperatures, rising sea levels, and melting ice caps, the severity and extent of most ecological consequences are difficult if not impossible to predict.

For example, we have an emerging mismatch between seasonal flowering and insect lifecycles, whose synchrony is necessary for successful pollination (which contributes one-third of the human food supply). How catastrophic will this be? No one knows.

We have enhanced plant growth due to “fertilization” from increased CO2. But is this good? Research has already shown depletion of soil nutrients due to enhanced plant growth. How much of an issue is this? No one knows for sure.

How will changes to the flow of the jet stream and other atmospheric air currents influence seasonal weather? Different researchers have different ideas. There is speculation that the Arctic Oscillation, a high-pressure airflow that keeps cold air bottled up in the far north, will break down leading to intensified polar vortex events and extreme winter conditions in the lower latitudes. How serious is this? Nobody knows.

It is understood that climate change will cause increased drought in some places and increased rainfall in others — but exactly where and how critical is uncertain. The frequency of severe weather events is increasing but how frequent and how severe these events will be is unknown. A few species can adapt to increasing temperatures although most cannot. Who will be the climate winners and who will be the losers? No one knows.

Ocean warming and acidification is already known to affect sea life; how devastating will this be to oceanic food chains? We don’t know. (Tick season all year long? Yeah, probably.) And so on. And this is not to mention the unpredictable nature of climate migration and political upheaval.

The one thing that we can speak of with certainty regarding the above catastrophes is that, given the predicted trend lines put forth as recently as 10 years ago, everything is getting much worse than originally projected.
This is worrying not because some nature lover somewhere will be unhappy to see ecosystems going haywire. It’s worrying because human welfare unquestionably depends upon proper ecosystem function as well as our ability to reliably predict how ecosystems will behave. Climate change is the biggest experiment ever conducted by the human race.  And it’s chaos out there.

Rick Weinstein, of Stowe, has a Ph.D. in Antarctic microbial ecology from Cambridge University and was a biology lecturer at the University of Tennessee for 15 years.