Amazon rainforest is transitioning to a 'hypertropical' climate — and trees won't survive that for long

The Amazon rainforest currently has a few days or weeks of hot drought conditions per year, but researchers say this could increase to 150 days per year by 2100.

Spotify tests more personalized, AI-powered ‘Prompted Playlists’

The playlists can factor in world knowledge, go back to your listening history from day one, and be refreshed daily or weekly.

‘What to buy Dad for Christmas’: is retail ready for the AI shopping shift?

As shoppers ask ChatGPT for inspiration, brands scramble to ensure their products appeal to the bots calling the shotsConsumer test drive: can AI do your Xmas gift shopping for you?Christmas shopping – some love it, to others it’s a chore, and this year for the first time many of us will outsource the annual task of coming up with gift ideas to artificial intelligence.While traditional internet search, social media – especially TikTok and Instagram – and simply wandering a local high street will still be the main routes to presents for most this year, about a quarter of people in the UK are already using AI to find the right products, according to PricewaterhouseCoopers. Continue reading...

The best smart rings for tracking sleep and health

So, you’re thinking of buying a smart ring. Well, some good news. Picking the best of the lot is incredibly easy right now. The “bad” news is that, as far as trustworthiness and reliability, your choices are somewhat limited, as this is still a niche and emerging gadget category. Smart rings are in the middle of a resurgence. That means a lot of experimental ideas and newcomer tech brands you’ve probably never heard of. Enough competitors have cropped up that I spent the better part of last summer rocking six rings like a high-tech mafia don. While these aren’t necessarily bad products (some are pretty good), many aren’t as polished as what you’d see in more mature categories like smartwatches, headphones, and smartphones. Speaking of which, there are a few things to know about the category. Currently, these devices are primarily health trackers. Their benefit is that they’re more discreet and better suited to sleep tracking than a smartwatch. However, the vast majority don’t include smart alarms or push notifications. This makes them best suited for casual athletes or more wellness-minded people. In most cases, hardcore athletes would be better served by a smartwatch or fitness tracker, with a smart ring serving as a supplementary source of data. (But that’s quite an expensive endeavor.) Smart rings are also ill-suited for weightlifters, as they can easily scratch against equipment. With that in mind, here’s the best smart ring for most people in 2025 — and a handful of runners-up worth highlighting for the more tech-adventurous. Best smart ring for most people Oura Ring 4 The Oura Ring 4 has a new all-titanium design, improved battery life, and better accuracy thanks to a new sensor algorithm. Score: 9ProsConsMore sizesSlimmer designExpanded auto workout detectionRedesigned appBetter battery lifeSubscription required to get all featuresI still wish this had a charging case Where to Buy: $349 at Amazon $349 at Best Buy $349 at Oura Surprising no one, it’s the Oura Ring 4. I can already hear some of you shouting, “But what about the subscription!” And I agree. Even Oura’s relatively affordable $5.99 monthly fee can feel more like $100 when you consider the sheer number of apps, gadgets, and services asking for a chunk of your monthly paycheck. However, Oura is still the best in terms of hardware, size range, features offered, app, dedication to research, and experience in the field. Many of the smart rings available today follow the example set by Oura over the past decade. The upgrades from the Oura Ring Gen 3 to the Oura Ring 4 were mostly software-based, with minor hardware refinements. You can read more in my review, but the gist is a more accurate heart rate and blood oxygen algorithm, improved automatic activity detection, and an expanded range that spans size 4 to 15. The app has been redesigned to be less cluttered, and earlier this year, Oura added AI-powered meal logging and glucose tracking, the latter of which requires Oura users to purchase a Dexcom Stelo CGM ($99). Oura also launched an AI chatbot. (Of the AI chatbots in health trackers I’ve tested, this one is among the more polished implementations — though it often feels like Captain Obvious-level insights.) More recently, Oura rolled out a new feature called Health Panels, which lets you schedule a blood test at a local Quest Diagnostics location for $99. Users can then view approximately 50 biomarkers within the app related to cardiovascular and metabolic health. In addition to the metal versions introduced last year, Oura recently launched colorful ceramic versions of its fourth-gen ring, with prices starting at $499. One downside of the original metal version is that the coating can scuff or wear off with daily use. The new rings are more durable thanks to a zirconia ceramic exterior, which is harder than steel and more resistant to cracking or chipping from impact. However, the trade-off is that the ceramic version is both thicker and heavier, so it may not be as comfortable to wear over extended periods. I’ve been long-term testing three iterations of the Oura Ring since 2018. Accuracy, design, and comfort have improved with each generation. The company continues to communicate research and scientific developments clearly and frequently. Third-party retail options have expanded, and I’ve seen investment pour into Oura. In an emerging category, these things matter. A lot. While I believe some of Oura’s newer competitors do some things better or have more creative ideas, Oura is the one I continually recommend for its combination of reliability, accuracy, and experience. Read my full Oura Ring 4 review. Honorable mentions If subscriptions are an absolute dealbreaker, you’ll find zero protest here. In that case, here are the best alternatives to the Oura Ring. Samsung Galaxy Ring Score: 7ProsConsExcellent hardwareLong battery lifeSlim, lightweight designNo subscriptionAndroid onlyBetter if used with Samsung productsAccuracy is a mixed bag Where to Buy: $399.99 $249.99 at Amazon $399.99 $249.99 at Best Buy $399.99 $279.99 at Samsung The $400 Samsung Galaxy Ring nails the hardware. Its charging case is more elegant than the Oura Ring’s, and I prefer the slightly concave design for comfort. It also has the second widest size range. If you’re already all-in on a Samsung Galaxy Watch 8 or Ultra, you get the added benefit of extended battery life. If you have the latest Galaxy Z Flip 7 or Z Fold 7, Samsung also has gesture controls for the ring so you can control the camera. There are a lot of interesting ecosystem-centric ideas that Samsung has for its Galaxy Ring, but while there’s no subscription (yet), it’ll cost you a pretty penny to unlock the ring’s full potential. Without discounts, we’re talking about $1,800 to nearly $3,000 for the phone, watch, and ring. The Galaxy Ring is also a first-gen device with some first-gen quirks, too. Samsung is still catching up with sleep tracking accuracy, and its Galaxy AI-powered health features are rather hit or miss. Ultrahuman Ring Air Where to Buy: $349 at Best Buy $349 $279 at Walmart I’m also keen on the $350 Ultrahuman Ring Air. It gave the Oura Ring an honest run for its money when I tested six smart rings at once last year. It’s not quite as good with accuracy, but it’s on par with comfort and design. The app has much more of a fitness focus than wellness. Instead of a subscription, it has “PowerPlugs.” You can think of them as add-on features. Some are free, like smart alarms and cycle tracking. Others will come with an additional fee, like a planned atrial fibrillation detection PowerPlug and a cardio adaptability metric, which currently costs $24 a year. RingConn Gen 2 Air Where to Buy: $199 at Amazon $199 at RingConn Lastly, I’ve been testing the RingConn Gen 2 Air, a slimmer, entry-level version of its Gen 2 ring. At $200, it’s the most affordable smart ring I’ve tested but looks and feels a lot nicer than the original RingConn I tested last summer. I had issues with the RingConn’s squarish shape, but it’s much less noticeable this time around and more comfortable. It’s broadly accurate, and the app goes heavy on AI, to middling effect. It has great battery life. I’ve gotten around eight to nine days on a single charge — far better than any other smart ring I’ve tested. What’s coming next Sandbar, a company founded by former Meta employees, recently announced plans for the AI-powered Stream Ring, which you can preorder now ahead of its tentative release in the summer of 2026. The new smart ring will be available in silver for $249 and gold for $349; both are made of aluminum and feature a black resin band interior, along with an exterior button that users can press to capture voice notes. Additionally, the Stream Ring supports a personalized AI chatbot and promises “all-day battery life.” Pebble is getting into the smart ring game with the Index 01, which is available for preorder for $75 ahead of its March 2026 debut. Instead of focusing on health and wellness tracking, though, the ring is designed to capture voice notes, set timers and alarms, and create reminders. Whatever you record is sent to the Pebble app for iOS or Android, where you can see a feed of the audio and transcriptions you’ve collected. Pebble says the Index 01’s battery can last a couple of years; however, it can’t be recharged, so once it’s dead, that’s it. Update, December 10th: Updated to reflect current pricing / availability and details about the new Pebble Index 01 and ceramic Oura Ring 4. Brandon Russell also contributed to this post.

Behind the Scenes With Historical Advisers to Ken Burns’ The American Revolution

Three experts discuss their behind-the-scenes experience as historical advisers to the new The American Revolution series.

Meta’s New A.I. Superstars Are Chafing Against the Rest of the Company

An us-versus-them mentality has emerged between Meta’s top artificial intelligence team and longtime lieutenants to Mark Zuckerberg.

LIVE: President Trump takes questions in the White House: ABC News Live

24/7 coverage of breaking news and live events