Our Music: on the brink

Summary

on the brink explores the vicious cycles that have brought us to the brink of a climate catastrophe and the virtuous cycles that could still pull us back from the edge. It is inspired by a series of in-depth conversations that composer Theodore Wirprud had with a team of our climate scientists beginning May, 2021.

This resources takes a closer look at the science behind the score, first briefly reminding us why warming matters, then examining the concept of vicious and virtuous cycles that are at the heart of on the brink, introducing what scientists call positive and negative climate forcing and feedback loops.

What is warming the atmosphere and why it matters

The burning of fossil fuels and resulting input of carbon dioxide (CO2) to the atmosphere, combined with other human activities that alter the natural landscape, has raised the average temperature of the Earth over the past century (Fig. 1 below).

Figure 1: Increase in average global temperatures (blue, right axis) and carbon dioxide (red, left axis) from 1850 to 2010. Global average temperature today is ~1.3 degrees C above what it was in 1850, and CO₂ is ~ 130 ppm higher than in 1850.

Scientists broadly agree that global average temperatures 2° C warmer than those in 1850 would be catastrophic to most human and natural systems – a 2° C warmer world would be one that no human has ever experienced.

What’s the big deal about a few degrees? (Where are we today?)

So, the scientific consensus is that humans must take action to keep global average temperatures no higher than 1.5° C above the global average temperature of 1850 (~15° C). To quote from the Intergovernmental Panel on Climate Change, which coordinates global collaboration to address climate change:

Every bit of warming matters, every year matters, every choice matters.

The longer we wait to effectively address the causes of climate change, the more dire the consequences for us all and future generations will be. This is partly because warming and the effects of warming can be accelerated and compounded through the functioning of the Earth system itself once it is thrown off its current equilibrium by human activity.

Vicious cycles in the climate system: Positive Climate Forcing and Positive Feedback Loops

Our planet’s oceans, lands, atmosphere, life (biosphere), and ice cover (cryosphere) are inter-connected.  For all of recorded human history, these elements of the Earth’s system have been remarkably stable and balanced, providing ideal conditions for human civilization to grow and thrive. On longer time scales, this has not always been the case. Scientists speculate that millions of years ago, the planet may even have been entirely covered in ice, the so-called “Snowball Earth” theory.  Taking it back to a timescale relevant for us, though, we recognize that humans now have the ability to affect the very balance that has allowed us to prosper.  Burning fossil fuels and changing natural landscapes to the extent we have is warming the atmosphere, setting the stage for the vicious cycles expressed musically in on the brink. This can occur via what scientists call a positive climate forcing, or changes that have a warming effect^[1]. These changes can multiply in a self-reinforcing, circular direction in what are called positive feedback loops. What does this look like? Here is one example:

^[1] USEPA

The Earth’s ice cover, known as the cryosphere, affects our climate in multiple ways, including by reflecting solar radiation back into space.  White surfaces reflect heat, whereas dark surfaces absorb it. When we burn fossil fuels, we trap heat in the atmosphere, raising the temperature. This causes ice cover to melt, exposing the darker land or ocean beneath it. With less reflective surface to reflect solar radiation back into space, the atmosphere traps more heat, leading to further warming and ice loss, which causes further warming and ice loss in a feedback loop.

It’s important to emphasize that, once these positive feedback loops are initiated, human intervention may no longer be able to slow or stop them.  This is one of the reason’s why it is critical that we act to stop the activities that contribute to climate change now.

Virtuous Cycles: Negative Feedback Loops

Feedback loops can also be “negative”, meaning that they run in a direction that reduces warming and help to keep the climate system in equilibrium. Just as with positive feedback loops, human action can set a virtuous cycle (negative feedback loop) in motion. What might this look like? Here is one possible example:

Cutting fossil fuel emissions leads to lower greenhouse gas emissions and fewer airborne particulates. This dual effect  then cascades through the Earth system, yielding both climate and human health benefits.

Notice here the “co-benefits” of moving away from fossil fuel combustion: The benefits of doing so cascade from the macro level of our climate down to the micro level of our own health. We have to remember that we are part of the Earth System, so what happens at the system level affects all of its parts, including us.

So acting today to fight climate change will not only protect our stable climate to allow future generations to thrive as we have, but it can also help to protect our own health today.

If you want to learn more about feedback loops and how they affect climate change, click here.