they wrote it for themselves. if russia stops fighting, the war ends. if ukraine stops fighting, ukraine ends. >> antony blinken has a world of trouble on his hands. the secretary of state faces dangerous tensions between china and taiwan and vladimir putin's threat to turn ukraine into a nuclear war. is there anyone in the kremlin who can tell vladimir putin no, if he decides to launch a battlefield nuclear weapon? tonight you're going to hear from a former senior staffer

inside the january 6 committee, which resumes hearings on the capitol siege wednesday. >> wait a minute. someone in the white house was calling one of the rioters on january 6 while the riot was going on? >> sure. and you know the end of that call. there are connections that need to be explored more. by acting as natural buffers, coral reefs prevent billions of dollars of damage to the u.s. each year. the state of florida, which has been hit by 18 hurricanes over the last 40 years has one of the largest barrier reaves in the world with over 90% of the living coral in the florida keys has disappeared. the situation is serious and marine biologists are trying to find ways to rescue the reefs. and part of that, believe it or not, involves meddling with the sex lives of coral.

how do coral have sex? >> i'm lesley stahl. >> i'm bill whitaker. >> i'm anderson cooper. >> i'm sharon al fonzie. >> i'm scott pelley. those stories and more tonight those stories and more tonight on "60 minutes". captioning funded by cbs .

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ukraine dominated this past week's annual gathering of the u.n. general assembly in new york attended by president biden and more than 120 world leaders. friday we met the u.s. secretary of state, antony blinken, to talk about a world of challenges and putin's nuclear threat. how concerned should americans be about the prospect of nuclear war? >> scott, we've heard a lot of irresponsible rhetoric coming out of vladimir putin, but we're focussed on making sure that we're all acting responsibly, especially when it comes to this kind of loose rhetoric. we've been very clear with the russians publicly and as well as privately, to stop the loose talk about nuclear weapons. >> privately, the united states has been in communication with the kremlin about these threats of nuclear war. >> yes. it's very important that moscow hear from us and know from us

that the consequences would be horrific and we'd made that very clear. >> you called the nuclear talk loose talk. but isn't vladimir putin telling us what he's going to do if he is backed any further into a corner? >> vladimir putin has a clear way out of the war he started, and that's to end it. if russia stops fighting, the war ends. if ukraine stops fighting, ukraine ends. >> is there anyone in the kremlin who can tell vladimir putin no if he decides to launch a battlefield nuclear weapon? >> they have a chain of command. whether it works or not, to be seen, but what i think you're pointing to is a larger challenge, and that is the achilles heel of autocracies anywhere. there is usually not anyone who has the capacity or the will to speak truth to power. and part of the reason i think

russia has gotten itself into the mess that it's in is because there is no one in the system to effectively tell putin he's doing the wrong thing. >> in our interview last week, president biden told us that he had a message for vladimir putin on the use of nuclear weapons. >> don't. don't. don't. >> he went on to say the u.s. response would be consequential. what did he mean by that? >> i'm not going to get into what the consequences would be. any use of nuclear weapons would have catastrophic effects for, of course the country using them, but for many others as well. >> if you can't give us specifics about a u.s. response, can you tell us that the administration has a plan? >> we do. >> is it a plan that would prevent world war iii? >> president biden has been determined that as we're doing everything we can to help the ukrainians defend themselves, as we're doing everything we can to rally other countries to put

pressure on russia, we're also determined that this war not expand. not get broader. >> excuse me. as we speaking to secretary blinken news broke that a u.n. investigatory commission found evidence of rape and torture of children in russian-occupied ukraine. it goes on to say it has concluded that war crimes have been committed in ukraine. what does justice look like? for ukraine? >> justice looks like accountability. accountability for those who perpetrated these war crimes, these atrocities, as well as for those who ordered them. and it's one of the reasons, scott, we're doing everything we can to support those who are trying to compile the evidence and to investigate and ultimately prosecute those

responsible. >> to prosecute. you believe there should be war crime trials? >> i was in irpin. and i saw residential buildings, building block after building block, totally bombed out. this was the indiscriminate use of force. wherever the russian tide recedes, what's left in its wake is very clear evidence of war crimes and atrocities. >> the bodies i saw were not fake. >> atrocities were laid before the u.n. security council last thursday, drawing from the russian foreign minister a dubious defense. >> when sergey lavrov says that the atrocities have been staged and it is russia that is the victim, tony blinken is sitting there thinking what? >> this is "alice in wonderland." it's the world upside down. up is down, white is black. truth is false. but here's the thing, all of

these words ring totally hollow to every member on the security council. so this spewing of words is not having an effect. on the contrary. i think it just shows the total disconnect between russia and virtually the entirety of the rest of the world. >> at the moment we spoke to the secretary, russia was hurrying through what it calls elections to force these areas of ukraine's occupied east and south into the russian federation. >> these so-call the elections are a sham, period. they go in. they put in puppet governments, local governments. and then they proceed with a vote, which they'll manipulate in any event, to try to declare the territory russian territory. it is not. it will never be recognized as such. and the ukrainians have every right to take it back.

>> blinken came to our interview after meeting china's foreign minister. china has been raising pressure on the democratic island of taiwan, which, in our conversation last week, president biden pledged to defend with force. >> so unlike ukraine, to be clear, sir. u.s. forces, u.s. men and women, would defend taiwan in the event of a chinese invasion. >> yes. >> but official u.s. policy is and has been for decades to remain ambiguous about defending the island. >> china has acted increasingly aggressively when it comes to taiwan. that poses a threat to past peace and stability throughout the region. >> the foreign minister must have asked you to explain the president's remarks. >> we had a conversation about our different approaches to taiwan. and i reiterated what the president has said. and what he said clearly and consistently.

our continued adherence to the one-china policy. our determination that the differences be resolved peacefully, our insistence that peace and stability be maintained in the taiwan straits, and our deep concern that china was taking actions to try to change that status quo. that's what the issue is. >> blinken warns that turbulence in the taiwan strait would wash around the world. >> taiwan itself were anything to happen, it is where virtually all the semi conductors are made. one of the reasons we're now investing, so heavily, in our own capacity to produce semi conductors here in the united states. we design them, but the actual production is done in a handful of places and taiwan produces most of them. if that's disrupted the effect on the global economy would be devastating.

>> last week on "60 minutes," the president of iran told lesley stahl he would consider re-entering the deal on iran's weapons program. >> iran has continued to try to add extraneous issues to the negotiation that we're simply not going to say yes to. we will not accept a bad deal. the response that they've given to the last proposals put forward by our european partners have been a very significant step backwards. and so i don't see any prospects in the very near term to bring this to a conclusion. >> antony blinken is 60. one of his grandparents was born in ukraine. his stepfather survived the holocaust, and his father was u.s. ambassador. blinken has spent 30 years in policy for democrats mostly in the senate and white house. that's him in the back of the room during the strike on osama

bin laden. his philosophy on american diplomacy is robust engagement with what he calls humility and confidence. >> if we don't engage, if we're not leading, then one of two things. either someone else is. and probably not in a way that's going to advance our interests and values or no one is. and then you tend to have chaos. you get a vacuum filled with bad things before it's filled with good things, because the world does not organize itself. there's not a single big problem affecting the lives of our citizens that we can effectively solve alone, whether it's climate, covid, the effect of all these emerging technologies on our lives, we have to be working with others to try to shape all of this in a way that's actually going to make our people as well as other people a little bit more secure, a little bit more prosperous, a little bit more full of opportunity. >> given january 6th, given the fabricated controversy over the

election results. do you find that countries around the world are worried about the stability of the united states? >> it's no secret that we have challenges within our own democracy. they're playing out before the entire world. we don't sweep them under the rug. even when it's painful. so i'm able to say, to other countries that bring these up, yes, we've got our problems. but we're confronting them. we're dealing with them. you might do the same thing. >> your father was u.s. ambassador to hungary. and, as we sit here on friday afternoon, he passed away last night. and i wonder why you decided to keep such a busy schedule the day after that tragedy in your family. >> my dad was 96 years old. he was in so many ways my role model. he built a remarkable business,

one of the leading investment banks in this country over many years. he led a life of dignity, of decency, of modesty that is something i've very much aspired to. and so i guess i thought that honoring everything that he shared with me, the best way to do that was to continue doing my job. >> that job, for the foreseeable future, will be consumed with a question that has defeated generations of diplomats. how to keep a small war in europe from igniting the world. are there any talks currently that we may not have heard about? >> there are no talks because russia has not demonstrated any willingness in this moment to engage in meaningful discussions. if and when that changes, we will do everything we can to support a diplomatic process. >> is vladimir putin losing this war? >> he's already lost in terms of

what he was trying to achieve. because keep in mind, what he said very clearly from the start is his objective was to erase ukraine's identity as an independent country. that has already failed. ukrainians are fighting for their own land. they're fighting for their own country. the russians are not. and these russian soldiers who are being thrown into this conflict, often not knowing where they're going or what they're doing, this is not something that they want to be fighting for. the ukrainians are fighting for their own future, they're fighting for their own land. they're fighting for their own lives.

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which resumes public hearings on the capitol siege wednesday. members of the committee aren't happy that denver riggleman, an experienced officer and former republican congressman is talking to "60 minutes" about the work he did for them, nor are they thrilled he's writ and book about his time on the committee called "the breach". riggleman has a history of swimming against the tide. once a member of the ultra conservative house freedom caucus, he was endorsed twice by then-president trump. but after hearing what denver riggleman has to say tonight, it's unlikely the former president will be buying his book. did it hit you at one point that this is way bigger than it appeared in the beginning? >> absolutely. you get a real ah-ha moment when you see that the white house switchboard had connected to a rioter's phone while it's happening. that's a pretty big ah-ha moment. you get an ah-ha --

>> wait a minute. someone in the white house was calling one of the rioters while the riot was going on? >> on january 6, absolutely. >> and you know who both ends of that call. >> i only know one end of that call. i don't know the white house end, which i believe is more important. but the american people need to know that there are connections that need to be explored more. >> as senior technical advisor for the january 6 committee, denver riggleman, an ex-military intelligence officer ran a data-driven operation, pursuing phone records and other digital clues tied to the attack on the capitol. >> from my perspective, if the white house, even if it's a short call and a connected call, who is actually making that phone call. >> is there a simple innocent explanation for that? >> was it an accidental call? and the white house just misdialed rioter on that day, on january 6? probably not. >> denver riggleman told us he uncovered a lot of disquieting information for the committee.

>> do you swear or affirm under penalty of perjury -- >> republican vice chair, liz cheney recommended the former conservative congressman for the staff, partly for his political experience but mostly for his technical expertise. >> i think liz and some of the other people recognize he does know how congress works, how the political system works. he was in the freedom caucus but has a background in data intelligence. >> he ran his own data analysis firm. >> mr. chairman. >> when the january 6 committee came calling, he assembled a small squad of data miners and analysts like he had in the military to comb through 20 million line of data. social media records, phone texts, anything and everything leading up to january 6.

>> a way that had never had been done before with millions of lines of data and create a graph that shows how these groups actually intermingled. >> you were able to identify six centers of gravity? >> yeah, there's six pretty big centers of gravity or six groups that we looked at, and really it came down to trump team, trump family, rally goers, unaffiliated doj-charged defendants, proud boys and oath keepers and others who are alternate electors and things like that. so when you have those six groups of people you can start looking at the connections between them. >> once he started connecting the dots this complex graph emerged. each thick line represents tens of thousands of calls and contacts among and between the groups. zoom in to see the details. these are calls and texts from just one person of interest. multiply that hundreds of times, and you end up with this graph riggleman calls "the monster". >> we don't have text content. but what we do have is how long they talked, when they talked.

that is very important. and really does suggest that there was much more coordination than the american public can even imagine. when it came to january 6th. >> for example. the data revealed five calls in the weeks before january 6 between the white house and this woman. a stop the steal activist named bianca garcia. the committee received this video from the evening of january 5th. she was part of a clandestine meeting with the heads of the proud boys and oath keepers. the paramilitary groups. that would breach the capitol the next day. >> and, you know, when you have the white house switchboard and certain other cell phone numbers connected to bianca, that is a link that needs to be investigated. the thread that needs to be pulled. identifying all the white house numbers and why we have certain specific people, why they were talking to the white house.

>> specific white house records are kept secret to protect every administration. but in his book "the breach", he pushed hard to have those numbers identified. >> i was very, very aggressive, about these link connections, getting those white house numbers. >> did you express those concerns to the committee at the time? >> yes. >> what was the response? >> the response was go forth and do the best you can with the resources we have. >> riggleman requested $3.2 million but only received a fraction of that. they burrowed into the data, the mother lode dropped into their laps, not just phone records but more than 2,000 actual texts to and from mark meadows, former president trump's chief of staff. there were numbers, but no names. so riggleman told us his team made a giant spreadsheet, painstakingly identifying the people behind each number.

and when they did, they were privy to the real time thoughts of trump family members. former cabinet secretaries. members of congress, conspiracy mongers, even a supreme court justice's wife. >> you've called the texts from president trump's chief of staff, mark meadows, the crown jewels. why? >> it was a road map. you know. it showed actually the evolution of the beginning arguments from alternate electors all the way through rally planning, all the way to day of. it showed conspiracy theories, the saturation of qanon. >> how did you get them? >> he gave them up. >> do you think it was a mistake in. >> if you go back to the simplest explanation i think he wanted to give up some of his text messages. this is a caveat. i don't know if we got them all. but what we got is pretty valuable. >> you say they provide proof of

a comprehensive plot at all levels of government to overturn the election. >> irrefutable. early in the text messages, they were talking about alternate electors as soon as november 5th or november 6th. >> right off the bat, come on. >> right off the bat. >> first mention of january 6 was two days after the election. donald trump jr. wrote the white house chief of staff, this is what we need to do, and laid out a rambling scheme to seek alternate electors, a plot the department of justice is investigating. we get trump electors, he wrote in part. it gets kicked to congress 6 january, 2021. once again he concludes, trump wins. many other texts were of bizarre election conspiracies. chinese plots to install idt bi seize voting machines as part of god's plan. even a call from republican lawmakers for president trump to declare martial law and stay in power.

from the sheer number of texts, it seems almost half the world had mark meadows' phone number. >> it shows you an administration completely eaten up with a digital virus called qanon and conspiracy theories and apocalyptic messianic buffoonery. it's a look into the psyche of the republican party today. >> people in the republican party would say you're an opponent. you're the opposition. of course you're going to say this. >> i would tell them this. i'm not their enemy. i'm just a guy trying to tell you that the data doesn't support that the election was stolen. >> when we first started here -- >> denver riggleman iii is a proud son from virginia. he told us his family never questioned going to church on voting republican. >> i'm an appalachian boy, man. >> in 2013, he settled here in

50 greene acres of the blue ridge mountains outside charlottesville where he helped his wife pursue her dream of opening a distillery. it smells delicious. >> you want to eat the air. >> it was kristine's bourbon that got him into politics. frustrated with high liquor taxes and government red tape, he made an unsuccessful run for governor in 2017. soon, a seat opened up in virginia's conservative fifth congressional district. he ran, and to his surprise, he won. and in 2018 found himself in the seat once held by james madison. >> the accidental congressman i called myself. >> a republican with a libertarian bent, he joined the freedom caucus, the most conservative wing of the party. he voted with president trump 92% of the time, but says his loyalty was questioned, because he'd sometimes reach across the aisle to work with democrats.

kristine told us the beginning of the end was when denver decided to officiate the wedding of two gay campaign workers. >> so you were this staunch conservative. and you officiate a same-sex wedding. >> yeah. kristine's there, you know, honey, you might have the shortest political career in the history of virginia. i said it will blow over in two weeks. >> what happened? >> it didn't blow over. >> no, it was brutal. >> what did you think of how he reacted to the criticism? >> i think he stood his ground, and he doesn't regret doing it. >> he told us he also doesn't regret calling white supremacists cultural parasites after they marched on charlottesville. >> qanon and the conspiracy theories it promotes -- >> or denouncing qanon from the floor of congress. >> they were saying that because the gay wedding i was trying to change the sexual orientation of children. that really is a qanon-based conspiracy theory.

>> but his independence riled the republican base. he lost his seat in 2020 to a republican further to his right. do you consider yourself a republican today? >> no. no. i left the republican party i'm an independent. i don't want to call it independent. i'm unaffiliated. i'm just me. >> now this unaffiliated ex-congressman had a skill set that caught the attention of the january 6 committee. he joined the staff in august of last year. riggleman's data team was first to identify a telephone number in meadows' texts belonging to ginni thomas. she texted links tied to qanon, including this won, saying the biden crime family and ballot fraud co-conspirators are being arrested and detained and will be living in barges off

guantanamo bay to face military tribunals for sedition. she added, i hope this is true. what did you think of those texts? >> actually, as far as academically, it was hellaciously insightful. >> in what way? >> about how the conspiracy theories and this digital virus had really metastasized in the gop. >> you make it sound like an infection. >> it is an infecton. but ginni thomas specifically, someone who has access to the president and married to a supreme court justice pushing that sort of nonsense to the chief of staff to the president, that should be an eye-opener for everybody. >> riggleman left the committee last april. he told us one reason. they wouldn't subpoena ginni thomas. they provided "60 minutes" a statement that says in part, mr. riggleman had limited knowledge of the investigation. he departed prior to our most important investigative work.

the committee has run down all the leads that arose from his work. last week, ginny thomas agreed to be interviewed. what riggleman said he learned from texts from mark meadows, at "60 minutes" overtime.com, sponsored pfizer. dancing crew. trip for two. nail the final interview. buy or lease? masterpiece. inside joke. artichoke. game with doug. brand new mug. come here, kid. gimme a hug. the more you want to do, the more we want to do. boosters designed for covid-19 variants are now available. brought to you by pfizer & biontech.

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kevin: i've fought wildfires for twenty years. is advice worth talking about. here's the reality we face every day. this is a crisis. we need more firefighters, more equipment, better forest management to prevent wildfires and reduce toxic smoke. and we need to reduce the tailpipe emissions that are driving changes to our climate. that's why cal fire firefighters, the american lung association, and the california democratic party support prop 30. prevent fires. cut emissions. and cleaner air. yes on 30. as hurricane fiona left a swath of destruction across the caribbean and north atlantic this week, it was a reminder of the devastating power of storms.

one of the best existing sources of protection from waves and floods is dying off. by serving as natural buffers, coral reaefs prevent billions o dollars of damage. the state of florida, which has been hit by 18 hurricanes over the last 40 years has one of the largest barrier reefs in the world. but nearly 90% of the living coral in the florida keys has disappeared during that time. the situation's so serious that marine biologists have stepped up their efforts to find innovative ways to try to rescue the reefs. and that's what our story tonight is about. it involves strange underwater farms, the u.s. department of defense and more than we ever thought we'd need to know about the sex lives of coral. we left miami behind us and headed two miles off the coast with marine biologist andrew baker and diego lerman. they're old friends and colleagues, professors at the

university of miami who've seen first hand how the reefs have changed. >> they've seen a lot of die out because of water quality and pollution. and climate change. florida keys probably leads the way in terms of the sheer a coral that has been lost. >> that's why in this spot in the ocean, the university of miami has built something you'd normally visit on land to buy a tree or rose bush. a nursery. >> this is our coral nursery. just like on land. you grow your corals, prune them and put them somewhere else on a natural reef. >> don't forget to close your breathing valve. >> the water was murky and the current strong as we went to take a look. a nurse shark checked us out but quickly lost interest. corals are often confused with rocks or plants, but they're actually colonies of tiny animals called polyps who build

the reefs and protect the shores. after a short swim we came to an area with 40 of these tree-like structures. hanging from them like christmas ornaments are pieces of living coral that have been pruned from healthy colonies all over florida. their position close to the surface so they get lots of sun light and nutrients and occasionally cleaned of micro algae that can damage them. andrew baker explained. >> a great advantage of these nurseries is they allow us to grow coral tissue very quickly. they grow faster in these trees than they do on the reefs. >> many of the corals growing here are important and threatened. every diver knows you're not supposed to touch coral, so it was odd to be handed a clipper and told to start cutting off pieces. we brought the stag horn coral i cut to an area nearby called rainbow reef that the professor and his team began replanting two and a half years ago.

he showed me how to use a special type of cement to attach the newly-cut pieces of coral to the reef. it's more important to make sure the corals don't get killed off by the same forces that killed their predecessors. water pollution, disease and a phenomenon called bleaching in which coral can lose their color and die because of rising ocean temperatures caused by climate change. >> we need to make sure that the corals we put out are not going to be the next victims for the next bleaching episode. or the next stressor that comes along. >> you're trying to accelerate the process of natural selection, find the coral which are hardier and can survive in higher temperatures. >> that's exactly right. >> to do that, professor baker and scientists from the shedd aquarium in chicago are using a technique to allow them to determine the survivability of coral in a few hours on a boat anchored above the nursery.

when we arrived, researchers were putting samples of elk horn coral just brought to the surface into these converted party coolers, containing increasingly warm water to see which varieties would do best in higher temperatures. ross cunning is a research biologist with the shedd aquarium. >> just like all of us are different genetic individuals, all of these different genetic strains will vary natural in heat tolerance. >> just because it's all elk horn coral does not mean it's all the same genetically. >> right. that's exactly what we want to get at. differentiation among elk horn corals and use thetorestation pg more on the reef. >> scientists are also trying to breed the most heat and disease-resistant coral together. it's called selective breeding.

liv williamson is a biologist at the university of miami. her lab is filled with vats of frozen coral sperm. so this is coral sperm. >> this is coral sperm that has been kept at these really, really low temperatures now for a year or more. >> her work is similar to that of domestic animal breeders. she and her team mix the sperm with carefully chosen coral eggs to create offspring that will be more likely to survive disease and rising ocean temperatures. >> i never thought i would ask this question, but how do coral have sex? >> so the idea is that all the different colonies on a reef are using cues from the environment to make sure they release their eggs and sperm all at once so they're able to mix with the spawn of other colonies. >> sex life of coral is nothing to write home about. most spawn only once or twice a year after a full moon. so scientists have to be ready to capture the sperm and eggs at the exact right moment. >> we use very fine mesh nets with a jar at the op. and they slowly float their way up into the jar, and all we have to do is cap off the jar and

take it with us. it literally looks like being in a snow globe under water. it's amazing. it's totally incredible to be able to see it. >> this is where williamson raises what she calls the coral babies that she's bred. the blue light mimics sunlight filtering through the water helping them grow. >> this coral baby you're holding right now is actually the offspring of a coral colony here in miami that we think is resistant to disease. >> so you know the history of these polyps. >> yeah. in many cases i collected them as eggs or sperm or put them together to fertilize them. have been there really since birth if you will. >> do you feel like warm and cuddly toward coral? >> i really do. >> it's not something that -- >> they don't seem too warm and cuddly. i show coral baby pictures to people and they usually don't want to see them. >> today they're growing slowly on small ceramic plates, but they may someday be growing in

under water nurseries and repopulating reefs. >> this one's? >> almost a year old. they grow really slowly. that's part of the problem with the conservation. while we're losing some of the big, old colonies, some are thousands or hundreds of years old. they've taken so long to grow replacing them isn't easy. >> but with less coral serving as a natural buffer, many communities need protection right away from the increasingly powerful storms that have been battering their shores. one way researchers hope to restore coral and provide more immediate protection along the coast is to create hybrid reefs. this is a small scale prototype. the honeycomb structures on the bottom would be made of concrete and are designed to absorb wave energy immediately. the corals on top would provide more and more protection as they grow. >> when the waves break, they throw up a lot of spray. >> inside this simulator at the

university of miami's rosensteen school, professor brian house and his team can create the equivalent of a category 5 hurricane with winds up to 155 miles per hour. >> i'll turn on the paddle and you'll see it really change a lot. like they start hitting those like right now, boom, right? >> wow. oh, my god. >> you can see the waves are breaking over that structure. >> the simulator can test how well different structures and types of coral absorb wave energy and prevent damage on land. >> category 5. >> wow. university miami is developing this for darpa, the pentagon's agency. the defense department is looking ways to protect its many military base along the coast, like tindallid which got

damaged by hurricane michael. they plan to give the university of miami up to $20 million to build a hybrid reef off the coast of florida within the next five years. what role does coral play in that as opposed to just a man made honeycomb structure? >> depending on the types of waves and things, you can have as much as 60% dissipation of wave energy by having course on top of the structure. they add friction to the surface. >> this isn't just a man made structure static because of the coral. it would expand and continue to grow. >> that's one of the real exciting things about this. it's essentially self-healingif if it gets impacted by a storm it can grow back. >> they will provide the coral with specific goals in mind. they have very ambitious goals for you. >> they do, and i think that reflects the scale of the problem to be honest. we know for example coral reefs are going to be facing increasing warming temperatures.

so here's a project asking us to determine what corals will experience. >> so they're saying within five years, they want to you be able to find coral that can resist a 2-degree centigrade rise of temperatures in the ocean? >> that's right. >> were you surprised darpa was interested in your work? >> it was the first agency to come forward and say hey, you guys, as a community why don't you think big. >> darpa also awarded >> darpa also awarded contracts to rutgers, to use oysters rather than coral. and to the university hawaii creating a different configuration of coral and other materials. and darpa isn't the only government agency taking action.

the national oceanianic and atmospheric association. there are many potential obstacles to restoring coral reefs as diego lerman and his team learned after 2017. >> it was major setback. we lost 90% of all of the corals that we had been growing for a decade. >> wow. >> it was a huge loss. but we also rebuilt very quickly. >> there's not much anyone can do about a major hurricane. but perhaps the biggest criticism of restoring reefs or creating hybrid ones is that it's not possible to do this on the scale that's needed. >> thank you. >> you got it, man. >> there are some people who think this is like spitting into the ocean. that this is not going to be enough to counteract climate change. >> we get that all the time. but if we don't address this challenge in the meantime while we deal with the larger societal problems we won't have any coral reefs left by the time we get this other problem under

control. >> without a meaningful reduction of carbon gases to address climate change, will you be able to rescue the reeveesfs >> absolutely not. the mantra is we are buying time. >> the intergovernmental panel thinks 99% of the coral reefs could be lost in the next 30 years. that's a pretty dire assessment. >> that's right. so coral reefs are on their way to being the first global ecosystem that will lose as a result of climate change. so we have no time to lose.

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the last minute of "60 minutes" is sponsored by united health care. get medicare with more. tonight, an update on a story we first reported last november about a growing number of aviation companies racing to develop a new generation of supersonic passenger jets.

one of them, the american startup company, boom, and its founder blake shoal had already created a test plane when we visited the factory. >> this is it? >> that's it. >> oh, wow. turning that test plane into a passenger transport called overture as we said in our story, was a long shot. >> and we're working with rolls-royce on a custom engine that will power overture. >> you're working with rolls-royce. this engine does not exist yet? >> it is a lightly customized engine. part of that is rolls-royce's work where they are turning design knobs. >> this month, the odds for success grew longer when rolls-royce withdrew from the partnership and left boom actively searching for another engine maker. i'm bill whitaker. we'll be back next week with another edition of "60 minutes." when it was time to sign up for a medicare plan... mom didn't know which way to turn. but thanks to the right plan promise from unitedhealthcare

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under the leftover alliance, but taylor, monte, and turner all carved their own unique path to finale night. and tonight, one of them will be crowned the winner and take home the $750,000 grand prize. welcome to the live two-hour season finale of "big brother." [ cheers and applause ] >> previously on "big brother" -- early in the game, the powerful leftovers alliance was born. >> i say it's time for the leftovers to take over. >> and week after week, they took out their targets. >> amira,