“Suffering increases with each tenth of a degree of warming.” So said renowned climate scientist Katharine Hayhoe, speaking yesterday in an expert panel that Covering Climate Now and Sammy Roth of the new newsletter Climate-Colored Goggles convened in response to a widely circulated and much-discussed memo by Bill Gates, in which the Microsoft founder seemed to downplay the severity and urgency of the climate crisis.

In his memo, Gates posited that climate change “will not lead to humanity’s demise.” That’s true, Hayhoe said, but it’s also an unhelpful “straw man” argument, because scientists sounding the alarm on climate change have never argued it will lead to humanity’s extinction. Humanity’s fate amid the climate crisis is not a binary, she explains, but a question of scale: How much will humanity suffer due to climate change? And how much suffering can we prevent?

These are the questions that will fundamentally underlie proceedings at COP30, the UN climate summit that kicks off this coming Monday in Belém, Brazil. Just last week, UN Secretary General António Guterres told The Guardian and the Amazon-based outlet Sumaúma that humanity has failed to limit warming to 1.5 degrees Celsius, the goal that world leaders agreed upon in the 2015 Paris Agreement. Global average temperatures haven’t risen that far yet—today, we’re at about 1.3 degrees C of warming—but Guterres said an overshoot of the 1.5 degree C threshold has become virtually inevitable, due to countries’ routinely insufficient efforts to reduce carbon emissions. The consequences, he added, will be “devastating,” especially for the world’s most vulnerable communities.

Yet Gates, in his memo, argued that scientists’ and advocates’ focus on climate change is overstated, saying poverty and disease pose far greater threats to humanity’s quality of life. Here, Hayhoe and other panelists last night had another bone to pick with Gates. Separating these problems from climate change creates a false dichotomy, they said. In fact, climate change exacerbates challenges like poverty and hunger, and increasingly the world won’t be able to solve poverty and hunger without addressing climate change. As global heating continues unabated, “We’re talking about massive suffering,” Hayhoe said, “including loss of life, as well as livelihoods, homes, and more. And that suffering increases degree by degree.”

So, what will leaders do in Belém to arrest temperature rise and, in turn, mitigate humanity’s suffering? Guterres has vowed to protect nature—relevant especially given that the Amazon will serve as the backdrop for this year’s COP—and push back against profit-driven fossil fuel companies. Journalists in Belém and around the world will be watching to see whether countries will follow his lead.