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The world may already have crossed a series of climate tipping points, according to a stark warning from scientists. This risk is “an existential threat to civilisation”, they say, meaning “we are in a state of planetary emergency”.

Tipping points are reached when particular impacts of global heating become unstoppable, such as the runaway loss of ice sheets or forests. In the past, extreme heating of 5C was thought necessary to pass tipping points, but the latest evidence suggests this could happen between 1C and 2C.

The planet has already heated by 1C and the temperature is certain to rise further, due to past emissions and because greenhouse gas levels are still rising^[1]. The scientists further warn that one tipping point, such as the release of methane from thawing permafrost, may fuel others, leading to a cascade.

The researchers, writing in a commentary article in the journal Nature^[2], acknowledge that the complex science of tipping points means great uncertainty remains. But they say the potential damage from the tipping points is so big and the time to act so short, that “to err on the side of danger is not a responsible option”. They call for urgent international action.

“A saving grace is that the rate at which damage accumulates from tipping could still be under our control to some extent,” they write. “The stability and resilience of our planet is in peril. International action – not just words – must reflect this.”

Prof Tim Lenton at the University of Exeter, the lead author of the article, said: “We might already have crossed the threshold for a cascade of interrelated tipping points. The simple version is the schoolkids [striking for climate action] are right: we are seeing potentially irreversible changes in the climate system under way, or very close.”

“As a scientist, I just want to tell it how it is,” he said. “It is not trying to be alarmist, but trying to treat the whole climate change problem as a risk management problem. It is what I consider the common sense way.”

Phil Williamson at the University of East Anglia, who did not contribute to the article, said: “The prognosis by Tim Lenton and colleagues is, unfortunately, fully plausible: that we might have already lost control of the Earth’s climate.”

The new article comes as the UN warns action is very far^[4] from stopping global temperature rise, with the world currently on track for 3C-4C^[5]. The commentary lists nine tipping points that may have been activated.

“We have this alarming evidence that part of the west Antarctic ice sheet may be in irreversible retreat^[6],” said Lenton. “All the signals are that it is.” A similar situation appears to be occurring at the Wilkes basin in east Antarctica^[7]. The collapse of these ice sheets would eventually raise sea level by many metres.

The massive Greenland ice sheet^[8] was melting at an accelerating rate^[9], the scientists said, while Arctic sea ice is shrinking fast^[10]. “Permafrost across the Arctic is beginning to irreversibly thaw and release carbon dioxide and methane,” they said.

The Gulf Stream current in the Atlantic, which warms Europe, has also slowed by 15% since the mid-^[11]20th century^[12]. “That is just about in the range of natural variability, but it is also hard to rule out that it is part of a longer downturn,” Lenton said.

The scientists report that 17% of the Amazon rainforest has been lost since 1970. The tipping point, where loss of forest leads to it drying out, could lie in the range 20%-40%, they said. In temperate forests, especially in North America, heating has triggered more fires and pest outbreaks, potentially turning some regions from a sink for carbon to a source. In the tropics, corals are predicted to be wiped out by 2C^[13] of heating.

A cascade of tipping points could occur because, for example, the melting of Arctic sea ice amplifies heating by exposing dark ocean that absorbs more sunlight. That may increase the melting of Greenland ice and permafrost areas. “Multiple risks can interact, with one change reinforcing another, and with warming of just a degree or two sufficient to result in dramatic cascading effects,” said Williamson.

Prof Martin Siegert, at Imperial College London, said: “The new work is valuable. They are being a little speculative, but maybe you need to be.” He pointed out that the extremely rapid rate at which CO2^[14] was being pumped into the atmosphere^[15] was unlikely to have ever occurred on Earth before. “It may mean that tipping points can occur in unexpected ways as there is no geological precedent for this rate of CO2 change.”

The article reports that preliminary results from the latest climate models suggest global heating will be greater than expected, increasing the risk of tipping points. Prof Piers Forster, at the University of Leeds, disagreed on that point. However, he added: “I completely endorse their call for action. Although possibly low probability, the risks they identify are real.”

Lenton said action would still have real benefits, by slowing the impacts and giving more time for people to adapt. He said: “This article is not meant to be a counsel of despair. If we want to avoid the worst of these bad climate tipping points, we need to activate some positive social and economic tipping points [such as renewable energy] towards what should ultimately be a happier, flourishing, sustainable future for the generations to come.”

Unified junior middleweight world titlist Julian "J Rock" Williams is going home to Philadelphia to make his first title defense.

Williams will defend his two 154-pound belts against Jeison Rosario ‎in the main event of a Premier Boxing Champions card on Jan. 18 (Fox, 8 p.m. ET) at Temple University's Liacouras Center, PBC announced on Wednesday.

‎In the co-feature, rising junior lightweight prospect Chris Colbert will fight former world titlist Jezreel Corrales in a 10-round bout.

In his second shot at a world title, ‎Williams traveled to Jarrett Hurd's home area in Fairfax, Virginia, in May and won a unanimous decision^[1], taking the belts in an action-packed contender for fight of the year.

They were initially supposed to meet in a fall rematch, but Hurd ultimately decided not to go through with the fight.

That pushed Williams (27-1-1, 16 KOs), 29,‎ back to January against Rosario.

‎"There's no better way for him to follow that up than by defending his titles in front of his hometown fans in Philadelphia," said TGB Promotions president Tom Brown, whose company is promoting the card. "The great fight fans in Philadelphia are in for fireworks because Jeison Rosario hits hard and he comes to pull off the spectacular upset, and he only needs one punch to do so."

‎Williams will be fighting in Philadelphia for the first time in nine years.

"This is going to be great having a homecoming fight back in Philadelphia," Williams said. "I'm excited for the crowd that'll be at the Liacouras Center and to be back fighting on Fox. I haven't fought in Philadelphia since 2011, so I can't wait to get back in the ring in front of all my people.

"Rosario is a good fighter and I'm very familiar with him. I know he packs a solid punch and that he's been on a tear ever since his lone loss to Nathaniel Gallimore. So he'll be a stiff test for me, but I'm prepared to win. Most of all, I'm just excited to defend my titles and as a unified champion in front of my hometown crowd."

‎The Miami-based Dominican Republic native Rosario (19-1-1, 13 KOs), 24, will take an eight-fight unbeaten streak into his first world title fight.

"I'm very thankful and excited for this opportunity," Rosario said. "I'm going to take advantage of it. I plan to bring these titles back to the Dominican Republic by knockout, but if I have to go 12 rounds, I'm ready. I learned a lot from my first defeat, and it will never happen again. I also want to thank PBC, my promoter Sampson Boxing and my manager Caesar Mercedes for putting me in this position. I can't wait to make the most of it."

Colbert (13-0, 5 KOs), 23, of Brooklyn, New York, is one of boxing's top prospects. He's coming off a sensational one-punch knockout of Miguel Beltran Jr. in the first round in September.

"This is the stage that I've been waiting for," Colbert said. "It's time to show out. I'm going to show the world what the hype behind me is all about and prove that I'm a soon-to-be champion of the world. All I know about Corrales is that he's a former champion who's going to bring his A-game, but I'm looking to get him out of there. I'm excited to be back in Philly and I'm definitely going to have my crew and fans coming down from New York to show support."

Corrales (23-3, 9 KOs), 28, of Panama, will look to rebound after a split-decision defeat to Ladarius Miller in July.

"Colbert is a good fighter but he's not ready for what I can do in the ring," Corrales said. "I'm going to show that I'm still one of the best in the division. This is a great opportunity to prove that."

SAN DIEGO (KUSI) – Chuck Yeager is a former United States Air Force officer, flying ace and record-setting test pilot.

In 1947, he became the first pilot confirmed to have exceeded the speed of sound in level flight. Yeager’s career began in World War II as a private in the United States Army Air Forces.

KUSI’s Dave Scott takes a closer look at Yeager’s career and legacy in this World of Wonder.

Roughly half of all pregnancies^[1] worldwide aren’t planned. We can attribute this, at least partially, to the fact that half the species (ahem, women) bears most of the birth control burden. If men had access to a long-lasting contraception, researchers have projected, the rate of unplanned pregnancies would tumble^[2].

Now, Indian scientists claim they are getting closer to giving men such an option. Officials at the Indian Council of Medical Research say they’ve successfully completed clinical testing of the world’s first injectable male contraceptive, the Hindustan Times^[3] reported.

“The product is ready, with only regulatory approvals pending with [India’s drug regulator],” Radhey Shyam Sharma, a New Delhi reproductive biologist who leads the research, told the newspaper. “The product can safely be called the world’s first male contraceptive.”

If that were true, it would mean India has found one of the holy grails of reproductive medicine — overcoming the biological and regulatory challenges^[4] that have thwarted past attempts to bring a new male birth control to market. (For more on those, and other promising male birth control options, see here^[5].)

The product is a nonsurgical vasectomy called RISUG^[6], which stands for “reversible inhibition of sperm under guidance,” and it’s effectively an injection in men’s penises. If that sounds like something no man would ever agree to, let me explain.

With RISUG, doctors inject a polymer gel into the vas deferens, the tube that transports sperm and semen out of the penis, under local anesthesia. This is intended to block sperm, and therefore, the chances that a man impregnates a woman, with effects that can last for 13 years, Sharma told the Hindustan Times.

In some ways, it’s similar to a vasectomy, a surgery that involves cutting or tying the vas deferens to stop sperm from entering the urethra and getting passed along to a female partner. But reversing a vasectomy requires more surgery, and the RISUG treatment can reportedly be reversed simply with another shot that breaks down the gel and could cost as little as $10^[7].

RISUG’s potential has been highlighted by the media for years. In 2015, Vice^[8] called it “the perfect male birth control. ... It’s affordable, minimally invasive, and fully reversible—and it’s the most effective, non-permanent way of preventing pregnancy (from the sperm side) the world has ever seen, according to studies so far.”

A 2017 Bloomberg^[9] feature on the efforts to develop it suggested that it would get approval by Indian regulators that year. “The procedure is 98 percent effective at preventing pregnancy — about the same as condoms^[10] if they are used every time — and has no major side effects,” Bloomberg said.

But however promising RISUG may seem, and however much the world needs a new form of male birth control, some researchers are skeptical. And a closer look at the most recent phase three clinical trial of the treatment in India suggests there’s good reason to be cautious.

A new RISUG trial raises more questions than answers

Sharma recently published the results of the clinical trial^[11] on RISUG in the Indian Journal of Medical Research, and it tells a slightly more complicated story than what he’s been telling the press. The study involved 139 men under the age of 41 who were living with their wives and had at least two children each. The men were given a single dose of RISUG and then followed up by doctors for six months. Their wives were also monitored to find out if they became pregnant. Note: This is a small, short-term study.

Importantly, the partners of the 133 men in the trial who got the shot didn’t get pregnant despite having unprotected sex.

But while the researchers recorded no severe side effects, they did note that “mild scrotal enlargement” was common, as was scrotal pain and nodules at the injection site. These issues resolved within the six-month study period — but two men experienced ongoing “fluid collection” around their scrotums.

The short-term swelling and discomfort may be acceptable to men and regulators, since it resolved quickly, said Michael Skinner^[12], a reproductive biologist who studies male contraceptives at Washington State University. But the continued fluid buildup two men experienced is more concerning, and we’d need a longer-term trial to understand the impact of this response.

Even more curious, six of the men in the trial couldn’t tolerate a complete dose of RISUG “either because of leakage from the syringe or because of vas counter punctures,” the study’s authors wrote. The 133 men who did tolerate the shot only stopped releasing sperm between one and six months after the procedure, meaning the injection took a while to kick in. And while the partners of those men didn’t become pregnant, it’s not clear whether the sperm-fighting effects will last — and whether they will outweigh the potential harms of RISUG, since, again, the study was too small and short term to say for sure.

To reach the US market, regulators would need studies involving thousands of participants, explained Stephanie Page^[13], a professor of medicine at the University of Washington. The RISUG developer would also need to show that the treatment is as safe and effective as currently available birth control options.

But that might be difficult, Page said. “[RISUG] is a non-scalpel vasectomy that fails in six of 139 men. That isn’t great compared to vasectomy. And the ‘[switch] on rate’ is longer than a regular vasectomy, which is usually one month.”

A Berkeley, California-based non-profit called the Parsemus Foundation has licensed the RISUG technology in the US. And the related product they’ve developed, Vasalgel^[14], is only in the preclinical phase of testing. According to Parsemus, the results from animal studies — on rabbits^[15] and monkeys^[16] — are promising. But there’s no human trial scheduled yet. So despite the hype^[17], it’s also far from being approved for the market.

Even so, the Hindustan Times report said, it could be a matter of months before the product hits the Indian market.

We need more data to understand the effects of penis injection birth control

Before this new RISUG clinical trial was published, researchers have been raising concerns about the treatment. In 2014, researchers in India penned a commentary in the Indian Journal of Medical Research^[18] on RISUG’s promise and perils. “RISUG has surely created a new concept of contraception with great feasibility and long lasting sterility,” they wrote. “Unfortunately, the advancement of this injectable polymer is slow, the clinical trials are not providing enough robust conclusions.” (The lead author on that paper did not respond to Vox’s request for comment, nor did Sharma.)

A 2018 paper^[19] by researchers at the University of Virginia School similarly raised concerns about RISUG’s safety. They cited earlier stage clinical trials and studies in animals that showed RISUG may damage sperm and tissues in the male reproductive organs. “To date,” they also noted, “there has been no data reported on reversibility of RISUG in humans.” So only animal trials have demonstrated the product’s potential to be reversed.

Skinner^[20], the reproductive biologist, echoed these concerns. “I have not seen any large clinical trails yet, nor studies on reversibility in humans, so [we] will need to wait and see how useful it becomes,” he told Vox. “It could replace need for vasectomy in future, and if reversible [be] useful for contraception. The key is some large scale trials for utility and reversibility in humans.”

So for now, it’s probably best to ignore the hype until the slow grind of science yields clearer answers about RISUG.

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