Deadly heatwaves, wildfires, floods, droughts and frequent severe storms and hurricanes are just some of the consequences the world is suffering today as a result of human-caused climate change.

And as bad as that sounds, it will only get worse unless we take drastic action now.

That’s the grim message in the United Nations Intergovernmental Panel on Climate Change’s latest report, in which leading experts drawing on more than 14,000 published research articles can speak with greater confidence and more specificity that every before about what is happening now and what lies ahead.

Described as “Code Red for humanity” by U.N. Secretary-General Antonio Guterres, the report makes clear that it’s no longer a question of preventing climate or reversing its effects. The effects are “widespread, rapid and intensifying,” without precedent in thousands of years. The world is getting hotter, and there’s no going back.

The report, though, is not all bad news.

It might be too late to prevent the wildfires in the western United States or heatwaves in Siberia, but small differences in global temperatures can have big differences in the kinds of impacts we face.

If we can keep global warming to 1.5 degrees Celsius over the pre-industrial era, nearly 1 billion people would suffer through life-threatening heat waves. Some plant and animal species would go extinct.

But at 2 degrees, 3 degrees or 4 degrees of warming would bring much worse consequences, including catastrophic flooding, deadly heatwaves and irreversible collapses like an ice-free Arctic or an Amazon rainforest that absorbs less carbon from the atmosphere than it releases in wildfires.

“There’s no going back from some changes in the climate system,” said Ko Barrett, a vice chair of the panel and a climate adviser at the National Oceanic and Atmospheric Administration. But aggressively cutting emissions “could really make a difference in the climate future we have ahead of us.”

The report was delivered just as the U.S. Senate was finalizing a $1 trillion bipartisan infrastructure plan, which includes some tentative steps forward in climate projects, including electric vehicle charging stations and investing in clean energy research.

An even bigger commitment would come with a $3.5 trillion budget resolution that can pass with only Democratic votes. Climate provisions in the package would use tax law to punish polluters and reward utilities that transition to renewable energy, and would finally put a price on carbon.

World leaders will gather in Scotland for the 26th U.N. Climate Change Conference, beginning Oct. 31. It will be again up to the most developed nations, like the United States, to make the commitments needed to reduce new greenhouse gas emissions.

It may be too late to prevent climate change, but we can decide how hot we want it to be.

It’s not too late to act, but time is running out.