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We've all heard of ways to reduce our carbon footprint: biking to work, eating less meat, recycling.

But there's another way to help the climate. A recent study from Lund University in Sweden shows that the biggest way to reduce climate change is to have fewer children.

"I knew this was a sensitive topic to bring up," says study co-author Kimberly Nicholas on NPR's Morning Edition. "Certainly it's not my place as a scientist to dictate choices for other people. But I do think it is my place to do the analysis and report it fairly."

The study concludes that four high-impact ways to reduce CO2 gas emissions include having fewer children, living without a car, avoiding airplane travel and eating a vegetarian diet.

In some places, water is dangerously scarce. In the African Sahel, generations of severe droughts have claimed millions of lives and have turned fertile pastures into swaths of desert. In Brazil, residents of the water-starved city of São Paulo have been frenetically digging homemade wells to mine fresh water, while schoolkids skip brushing their teeth as a conservation measure. And in California, devastating drought conditions in recent years idled nearly a half-million acres of crops and triggered the loss of tens of thousands of jobs.

In recent years, the best-performing artificial-intelligence systems — in areas such as autonomous driving, speech recognition, computer vision, and automatic translation — have come courtesy of software systems known as neural networks.

But neural networks take up a lot of memory and consume a lot of power, so they usually run on servers in the cloud, which receive data from desktop or mobile devices and then send back their analyses.

Robotics researchers have found a way for autonomous underwater vehicles to navigate strong currents with greater energy efficiency, which means the AUVs can gather data longer and better.

AUVs such as underwater gliders are valuable research tools limited primarily by their energy budget – every bit of battery power wasted via inefficient trajectories cuts into the time they can spend working.

Nitrogen is abundantly available in nature and forms the basis for many valuable products, both natural and artificial. This requires a reaction known as “nitrogen fixation”, whereby molecular nitrogen is split into two atoms of nitrogen that can then be connected to other elements like carbon or hydrogen. But performing nitrogen fixation to make ammonia on an industrial scale requires harsh conditions with very high temperature and pressure. EPFL scientists have now developed a uranium-based compound that allows nitrogen fixation to take place in ambient conditions. The work, published in Nature, forms a basis for the development of more efficient catalysts, while it highlights new concepts that can be expanded to metals beyond uranium.