One of the world’s most famous climate scientists has just calculated the financial burden that tomorrow’s young citizens will face to keep the globe at a habitable temperature and contain global warming and climate change—a $535 trillion bill.

Of course, if humans started to reduce greenhouse gas emissions by six percent a year right now, the end of the century challenge would be to take 150 billion tonnes from the atmosphere, and most of this could be achieved simply by better forest and agricultural management, according to a new study in the journal Earth System Dynamics.

The study, authored by researchers from the U.S., France, China, the UK and Australia, rests on two arguments.

Slow start

One is that although the world’s nations vowed in Paris in 2015 to contain global warming by 2100 to “well below” 2°C relative to the average global temperatures for most of the planet’s history since the last Ice Age, concerted international action has been slow to start. One nation—the U.S.—has already announced that it will withdraw from the Paris agreement.

The other argument is that, even if humans do in the decades to come rise to the challenge, it could be too late: by then greenhouse gas concentrations could have reached a level in the atmosphere that would in the long run condemn the world to sea level rises of several meters, and a succession of economic and humanitarian disasters.