The tracer starts with the project’s expected CO2 emissions, often taken from the developer’s own environmental‑assessment submission, and estimates how much that amount will raise global temperature.

Next, the tool consults peer‑reviewed scientific literature to turn the temperature increase into specific real‑world impacts such as coral‑reef loss, reduced food production, job losses, heat‑related deaths, glacier melt and poverty.

For the proposed Bay du Nord offshore oil project, the tracer calculates that 188 megatonnes of CO2 released over 20 years would add about 0.00008 °C to global temperatures.

That modest warming, the tool says, would expose roughly 111,000 more people to unprecedented heat, cause 25 extra heat‑related deaths in Europe, melt 4.6 km² of glacier ice, eliminate about 2,100 jobs and push around 9,800 people into extreme poverty.

"We can now link the emissions associated with individual fossil‑fuel projects to the amount of warming that they contribute to the planet, and then a direct line to specific impacts from that warming," said Sarah Perkins‑Kirkpatrick, a climate science professor at the Australian National University.

By converting abstract emission figures into concrete outcomes, the tracer gives governments, regulators, courts and the public a clear picture of the true cost of new fossil‑fuel projects.

The tracer proves that a single project’s emissions can be turned into concrete numbers – extra heat, glacier loss, deaths and poverty – making the “drop in the ocean” defence hard to keep.