In 2005, physicists David Frame and Miles Allen were headed to a scientific conference in Exeter, England. According to Frame, they were “playing around” with climate models in preparation for their presentation.

At that time, most research centered on stabilizing the concentration of greenhouse gases in the atmosphere to avert severe climate change. However, scientists faced challenges in predicting how much the planet would warm if these concentrations reached specific levels.

Frame and Allen approached the issue from a different angle. Instead of focusing on atmospheric concentrations, they examined emissions. They wondered what would happen if humanity ceased emitting anthropogenic carbon dioxide. Using a climate model on a train, they found that global temperatures reached a new stable level. In other words, global warming would halt if humanity achieved “net-zero” carbon dioxide emissions. Frame recalled, “It was pretty cool to sit on the train and see these numbers for the first time and think, ‘Wow, this is a big deal.’

This groundbreaking presentation and the subsequent Nature paper published in 2009 reshaped the thinking within the climate science community. Prior to the net-zero concept, it was generally accepted that humans could emit around 2.5 gigatons annually (approximately 6% of current global emissions) while still stabilizing global temperatures. However, it became clear that to stabilize the climate, emissions must reach net zero, balanced by equivalent removals from the atmosphere.

The global consensus surrounding the need to achieve net zero CO2 emissions rapidly gained traction, culminating in a landmark conclusion in the 2014 Intergovernmental Panel on Climate Change (IPCC) report. The subsequent question was about timing: when must we reach net zero? At the 2015 Paris Agreement, nations committed to limiting temperature increases as close to 1.5°C as feasible, aiming for net-zero emissions by around mid-century.

Almost immediately, governments worldwide faced immense pressure to establish net-zero targets. Hundreds of companies joined the movement, recognizing the economic opportunities presented by the transition to clean energy. This “net-zero fever” has led to some dubious commitments that excessively rely on using global forests and wetlands to absorb human pollution. Nevertheless, this shift has altered the course of this century: approximately 75% of global emissions are now encompassed by net-zero pledges, and projections for global warming throughout this century have decreased from around 3.7–4.8°C to 2.4–2.6°C under existing climate commitments.Read more here.

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