It's 8:52 AM and 86 Degrees Fahrenheit (30 Celsius) Where I Live in Southern California

My husband just came back from a morning outing with our four-month-old. "How was the botanic garden? I ask him.

"It was okay. It was just too hot, he tells me. I didn't expect us to spend so much of our son's first summer cooped up inside, hiding from the heat.

As I write this, an extreme heat warning for my area is glaring at me from my phone, effective for at least the next three days. "Dangerously hot conditions with high temperatures up to 110 [degrees Fahrenheit] expected, my weather app warns me. "Stay in an air-conditioned room, stay out of the sun.

It's the sort of warning more kids are growing up with as global average temperatures climb. Around the world, 560 million children under the age of 10 are experiencing at least one additional month of heat stress each year as a result of climate change, according to a new study published in the journal Science Advances. "I hope that this increases public awareness that climate change is a problem that is already happening today, that's already affecting us, says Rosa Pietroiusti, lead author of the study and a PhD researcher at Vrije Universiteit Brussel.

"It's affecting the health of the most vulnerable. Pietroiusti's team used an international standard for moderate heat stress, days when taking protective measures like rest breaks are recommended to prevent heat-related illness. The threshold is set at a WetBulb Globe Temperature of 28 degrees Celsius (82.4 F), a measure that takes heat, humidity, wind speed, and cloud cover into account.

Thanks to advances in climate attribution science, they were able to assess the number of days crossing that threshold and how many of those heat stress days were added by climate change. They found that children are disproportionately exposed to dangerous heat, as compared to older age categories. Climate change has led to at least one additional month of heat stress for 43 percent of all kids in the 0-9 age group — 560 million little ones.

That's nearly triple the number of people aged 60-69 exposed to the same amount of climate-induced heat stress. That's due to even more socio-political inequity at a global scale; the highest increases in heat stress due to human-caused climate change take place in countries in the Global South that have contributed least to the fossil fuel pollution raising temperatures. These countries have younger populations, and they also tend to have less access to air conditioning or infrastructure designed to withstand extreme weather events.

And if countries blow past the targets they agreed upon in the Paris climate accord, the number of children under the age of 10 that are exposed to an extra month of heat stress rises to 650 million with just 2 degrees Celsius of global warming, the new study finds. And yet it's a leading cause of weather related deaths globally, according to the World Health Organization. Heat stress can lead to dehydration, heat stroke, and eventually organ failure.

Babies and kids are even more susceptible than most adults. Their small bodies have a higher surface area-to-body mass ratio that makes it easier for them to overheat. Think of a small ice cube melting in the sun compared to a big block of ice.

Babies' sweat glands are still developing, making it even harder for them to regulate their body temperature. They're totally dependent on adults to take life-saving precautions, like staying hydrated. Heat-related illness is preventable as long as a kid can find a place to stay cool.

And we can stop summers from getting even hotter than they already are today by turning to energy sources like solar and wind that don't emit planet-heating pollution. There are already plenty of ways the heat makes being a new mom even harder than it needs to be. The American Academy of Pediatrics recommends that parents avoid taking babies outside for long stretches whenever the 'feels like' temperature reaches higher than 90 degrees Fahrenheit (32.2 Celsius).