pitching to keep them in it. >> ice water in their veins. focused. that is it for us at 5:00, see you back here at 6 clg. >> cbs-- 6:00. >> cbs evening news is next, and as liz said, see you at 6:00. ptioning sponsored by cbs >> ninan: earth day and the march for science. >> science makes america great! >> ninan: in cities and communities around the world, scientists take to the streets to raise awareness and defend their work from budget cuts. >> save the world! >> ninan: our dr. jon lapook is at the massive demonstration on the national mall. >> reporter: what specifically makes you worry? >> climate change is my biggest concern. >> ninan: also tonight, president trump pays an unexpected visit to the walter reed military hospital to pay tribute to america's wounded warriors. and serious cabin pressure aboard an american airlines jet. a flight attendant is grounded after a heated argument with a passenger.

>> you can't use violence with baby. just give me back my stroller, please. this is the "cbs weekend news." >> ninan: good evening. i'm reena ninan. this is our western edition. it's been 47 years since the first earth day. today, it was observed around the world with a focus on science. rallies and marches were held in more than 600 cities from new york, chicago, and washington, to london, berlin, and sydney, australia. the officially titled "march for science" was not billed as a political event, but many who marched said they were concerned about threatened cuts to research programs, especially those aimed at fighting climate change. our dr. jon lapook is at the massive march for science on the national mall. >> reporter: there was plenty of h20 on this wet, dreary day in the nation's capital. but the rain did not seem to dampen the spirit of the crowd. clinical psychologist tim truemper from salisbury, north carolina. what specifically makes you

worried? >> climate change is my bigges concern. we can't stallur progress any more in this area. >> reporter: kristin sanborn from new jersey senses a change in climate for science. >> i'm here today because i'm so upset about all the-- that science seems under attack now, facts seem under attack. >> reporter: speakers at the rally spanned many disciplines... >> some people are going to say we're politicizing science, but we're not. we're defending it. ( cheers ) >> reporter: ...and ages. >> we cannot vote, not yet. >> but we will be heard. >> but our numbers here today... >> reporter: including crowd favorites like bill nye, the science guy. >> i'm in the same place as bill! >> save the world! ( cheers ) >> reporter: the march was billed as a nonpartisan defense of science, but some strongly

attack the policies of the administration. concerns of the marchers included an 18%, $6 billion proposed cut in funding for the national institutes of health. denial of what they see as established science, such as the threat of climate change. and a changing immigration policy. foreign-born scientists fill nearly half of u.s. postdoctoral research positions. lillian knipp, kathy ely, and lucia teal live in baltimore. >> we were born in the 50s. we grew up in the 70ss. we watched progress. we were protesting back then, and we're too old for this. we should not be out here protesting about things that we won in the sphernts expaitys. >> we were at the first earth day. >> reporter: on this 48th earth day, marchers turned out in communities large and small, including this tiny contingent on the north pole. in a statement, president trump said, "my administration is committed to advancing scientific research that leads to a better understanding of our

environment and of environmental risks." and, reena, he went on to say that we should remember that rigorous science dends not on ideology but on a spirit of honest inquiry and robust debate. >> ninan: dr. jon lapook in washington, thank you. as the huge march for science crowd rallied near the white house, president trump made an unexpected visit to a military hospital today. here's errol barnett. >> reporter: president trump and first lady melania trump visited the walter reed medical center in maryland today, presenting a purple hart to sergeant first class alvaro barrientos, injured in afghanistan. >> so i heard about this, and i wanted to do it myself. >> reporter: the president's unexpected visit comes as mr. trump tries to make good on campaign promises. >> since day one, i have been fighting for the hardworking people of this country. >> reporter: in his weekly address, mr. trump highlighted his early accomplishments as he approaches 100 days in office. as a candidate, mr. trump made this contract with voters,

promising to, among other things, repeal obamacare, end illegal immigration, and pass an affordable childcare act by his 100th day. he's now feeling pressure to show what g.o.p.-controlled executive and legislative branches can deliver. on friday, trump expressed confidence that health care reform is coming after failing to get congress to repeal and replace obamacare last month. >> we'll see what happens, but health care is coming along well. >> reporter: offering no specifics, mr. trump told the associated press a tax reform proposal would be announced by "wednesday or shortly thereafter," saying it would be "bigger, i believe, than a tax cut ever." president said so-called dreamers fearing deportation should "rest easy." adding, "we are after criminals. that is our policy." today, at walter reed, president trump and the first lady also spent some time with members of the wounded warrior project.

president trump also announced what he described as a big rally to be held in pennsylvania on saturday. that will be his 100th day as commander in chief. reena. >> ninan: errol, thank you. the justice department sent warning letters to officials in several so-called sanctuary cities on friday, warning them to prove that they are complying with federal immigration laws or risk losing money. the justice department, in a separate statement, accused new york city of being "soft on crime." here's roxana saberi. >> reporter: as the trump administration threatens to crack down on sanctuary cities-- >> sanctuary jurisdictions put criminals back on the streets. >> reporter: ...local leaders are pushing back. >> it's incredibly insulting. >> reporter: that's how new york city police commissioner james o'neill described this statement by the justice department. it singled out new york as a sanctuary city that's soft on crime. >> when i read that statement by d.o.j. this afternoon, my blood began to boil.

>> reporter: o'neill later tweeted, "even with a million more people, new york city now has one-fifth the crime of 1990 sound like we're soft on crime? a recent analysis of f.b.i. data by a progressive think tank suggested that sanctuary areas have "significantly lower" crime, possibly because illegal immigrants are less afraid to report crimes to police. on friday, the justice department also sent these letters to sanctuary jurisdictions, including neyochicago, and nevada, threatening to cut grant money if they don't cooperate with federal immigration authorities. at a border security facility in san diego, attorney general jeff sessions said the american people are tired of illegal immigration. >> we have lawful systems of immigration, and shouldn't that be enforced? >> reporter: sessions also addressed a controversial statement he had made earlier this week about a judge in hawaii who blocked the president's travel ban. >> one judge has over-ruled the

constitutional authority of the president of the united states to protect america through his executive order. >> reporter: while the president's travel ban remains on hold, the justice department has given the nine sanctuary jurisdictions that received its letters until june 30 to comply with the law. but, reena, a number of local leaders say they'll remain defiant, even at the risk of losing federal funds. >> ninan: roxana saberi, thai. an american airlines flight attendant was grounded after a heated confrontation with a passenger, and it was all caught on camera while passengers were aboarding a flight from san francisco to dallas on florida. here's carter evans. >> reporter: the video begins with a woman in tears, inconsolable. a passenger on the plane posted this video on facebook saying that moments before it was recorded, a flight attendant "violently took a stroller from a lady with her baby on my flight, hitting her and just missing the baby." as the woman sobbed, another

passenger stepped in. moments later, the flight attendant at the center of the incident returned to the plane and was quickly confronted. >> hey, bud. you do that to me, and i'll knock you flat. >> hey, you stay out of this! >> reporter: crew members tried to intervene as the verbal fight escalated. >> you don't know what the story is. >> i don't care what the story is. you almost hurt a baby. >> reporter: this flight fallout comes less than two weeks after footage of a man being dragged off a united airlines plane sparked outrage. >> this is wrong! oh, my god! >> reporter: american airlines apologized for friday's incident, saying in a statement, "what we see on this video does not reflect our values or how we care for our customers." american airlines also suspended the flight attendant involved while the incident is under investigation. reena, that passenger and her family chose to take another flight, and they were upgraded to first class. >> ninan: okay, carter evans. thank you. the murder of a police officer in paris this week by a suspected isis militant may

influence voters as they head to the polls this weekend. far-right nationalist marine le pen is among the front-runners heading into the general election. elizabeth palmer is in paris. >> reporter: love her or hate her, marine le pen is a real contender. like donald trump, she talks about patriotism, about cracking down on immigration and bringing back blue-collar jobs. but there's a big difference-- le pen's main base is among the young. sylvain hechon is 25, an activist in the town of maubeuge, a national front stronghold. he's in charge of the ground game, stuffing leaflets in mailboxes the old-fashioned way but also posting campaign news on facebook. we visited him the day before the paris shooting when he, like millions of young french people,

were preoccupied with france's economic woes. he showed us one of le pen's videos aimed squarely at millennials, who face an unemployment rate stuck at nearly 25%. why are young people attracted to the national front? "young people believe that immigrants are stealing our jobs," he tells me. "marine le pen will limit immigration, even if she has to use the military." pictures like these of waves of migrants coming ashore on european beaches resonate powerfully here in the north of france where the landscape is dotted with shuttered factories, and all that's left of the coal mines that once employed thousands are old slag heaps covered with grass. in the market town of valencienne, venus beaudechon is out spreading le pen's anti-free-trade message. "president trump put his people first," she says, "and we believe marine le pen will do that, too. defend the french."

passiotely, both in her and her agenda, but overall, she remains a controversial figure. and with only hours to go before voting starts, this race, reena, is still too close to call. >> ninan: we'll be following it all tomorrow as well. elizabeth palmer in paris, thank you. coming up, an urgent earth day warning. scientists say we're on thin ice. is like me, and you're talking to your rheumatologist about a medication... ...this is humira. this is humira helping to relieve my pain... ...and protect my joints from further damage. humira has been clinically studied for over 18 years. humira works by targeting and helping to... ...block a specific source... ...of inflammation that contributes to ra symptoms. it's proven to help relieve pain and... ...stop further joint damage in many adults. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened,

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until you know how lyrica affects you. those who have had a drug or alcohol problem may be more likely to misuse lyrica. now i have less diabetic nerve pain. ask your doctor about lyrica. >> ninan: on this earth day, scientists in alaska are sounding the alarm about rapidly melting polar ice. barry petersen has our report. >> reporter: with temperatures soaring this last winter to 50 degrees above normal, the area around the north pole is melting, and the arctic sea ice is shrinking at a rate never seen before. >> we're not talking about something that's 100 years from now. we're talking about something that's going to happen in the next decade. >> reporter: jeremy mathis is direor of arctic research for

noaa, the national oceanic and atmospheric administration. >> the arctic is warming twice as fast as other parts of the planet. >> reporter: we met mathis at utqiagvik, alaska, once called barrow, the farthest northern city in the united states, where noaa has a lonely outpost monitoring the arctic sea ice. here on the polar ice, it's not what you see but what's hidden below. the ice is thinning. it used to be nine feet thick in some areas. now it's more like three. why do i care about what's happening out there? >> we care about the arctic because it has connections to the entire northern hemisphere, to people down in the lower 48 states. >> reporter: the warming arctic is causing the jet stream to wobble across america, helping spawn massive weather events, and the number of billion-dollar events in 2017 is on track to set a record.

>> oh, man! >> reporter: and as america's weather becomes more destructive, early warnings become more critical. but scientists may lose their vital tools, like climate monitoring satellites, targeted by the trump administration. mick mulvaney is the administration's budget director. >> as to climate change, i think the president was fairly straightforward. we're not spending money on that anymore. we consider that to be a waste of your money. >> we're going to be less aware of what's coming down the road. >> reporter: john walsh is chief scientist at the international arctic research center at the university of alaska in fairbanks. >> we're basically ignoring threats to the well-being of future generations. >> reporter: in alaska, warmer temperatures are melting the permafrost. villages are literally disappearing. and scientists say alaska today is fair warning of the climate change future for the rest of america. barry petersen, cbs news,

utqiagvik, alaska. >> ninan: and still ahead, the other side of the climate change debate from a man who calls himself a "climate realist." i have spent years taking over-the-counter products for my belly pain and constipation. i've had it up to here! it's been month after month of fiber. weeks taking probiotics! days and nights of laxatives, only to have my symptoms return. (vo) if you've had enough, tell your doctor what you've tried and how long you've been at it. linzess works differently from laxatives. linzess treats adults with ibs with constipation or chronic constipation. it can help relieve your belly pain, and lets you have more frequent and complete bowel movements that are easier to pass. do not give linzess to children le than six, and it should not be given to children six less than8. it may harm them.

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♪ time to think of your future that just tastes better. with 10 times more vitamin e. and twice the omega 3s. because why have ordinary when you can have the best. only eggland's best. better taste. better nutrition. better eggs. >> ninan: they "climate realists." they reject the idea that manmade greenhouse gas emissions threaten the climate, and they think that the u.s. should stop spending tax dollars on climate-change programs. here's dean reynolds. >> reporter: scientists may worry about melting polar ice,

rising seas, or strengthening storms, but to joe bast, all of what others call warning signs of climate change are just the natural order of things. is it fair to call you climate change deniers? >> we are climate realists. the efforts to stop global warming or slow it down are way disproportional to what the science suggests would be necessary. >> reporter: from this office park near chicago, bast runs the heartland institute, a conservative think tank waging what he insists is a nonpartisan information war. >> but if you look at the opinion polls, i think the american public are on our side. they say, "okay, maybe climate is changing. maybe there's a human impact. we probably can't do anything about it. it's really expensive. we think we've wasted too much money on this already." >> reporter: besides, he says, climate change isn't necessarily a bad thing. >> cold weather kills more people than warm weather does.

so on net, more people would benefit in a warmer climate. >> reporter: most climate scientists, the united nations, as well as nasa, dismiss these arguments as propaganda for fossil fuels. but bast, who is not a scientist, can count on a very powerful ally now. >> so obama's talking about all of this with the global warming and the-- a lot of ihoax. it's a hoax. >> reporter: bast looks with approvn mr. trump's decision to roll back regulations limiting greenhouse gases and to his appointments of fellow skeptics in the administration. climate change, he says, is a naturally occurring, cyclical phenomenon caused mostly by the sun, not an approaching disaster accelerated by carbon dioxide emissions caused by humans. >> there is still much to learn about-- >> reporter: the institute is now sending that message in books and videos to 300,000 public school teachers and college professors. and despite a tepid reaction to the mailings, bast believes the

tide has turned. are you winning? >> we're winning big time. 10 years from now, nobody's going to be talking about global warming. it's going to be a bad memory. >> reporter: and not a nightmare. dean reynolds, cbs news, arlington heights, illinois. >> ninan: up next, you could call him a mountain hermit, but he's kept one of the world's most complete records of climate change. change. i even accept i have a higher risk of stroke due to afib, a type of irregular heartbeat not caused by a heart valve problem. but whatever trail i take, i go for my best. so if there's something better than warfarin, i'll go for that too. eliquis. eliquis reduced the risk of stroke better than warfarin, plus had less major bleeding than warfarin. eliquis had both. don't stop taking eliquis unless your doctor tells you to, as stopping increases your risk of having a stroke. eliquis can cause serious and in rare cases fatal bleeding. don't take eliquis if you have an artificial heart valve or abnormal bleeding.

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this earth day high in the colorado rockies, where a man named billy barr started taking notes on the nature around him nearly 45 years ago. john blackstone paid him a visit. >> reporter: a springtime visit to billy barr's place is no simple journey. but it's all worth it when you discover this remote cabin deep in the woods-- it's like a snow cave here-- is home to one of the world's most valuable and unexpected troves of scientific data. >> i came out in late may, 1972. it was such a mental relief to have peace and quiet in my life. >> reporter: you came for the solitude, but you started to get a little bored. >> a bit of boredom, but a lot of it was just making my own activity. >> reporter: so you would go out and measure the snow. >> twice a day. i would first get a ruler and stick it in the snow and measure how much new snow there was. >> reporter: it wasn't just

the snow depth and when it melted. using a hand-operated system he built himself... >> and what this does is it converts the weight of this can and the snow in it into the equivalence of water. >> reporter: he also calculated how much groundwater that snow would produce when it melted. you have been doing that same thing since 1974 in this place? >> twice a day. >> reporter: when that wasn't enough to keep billy busy, he started tracking wildlife... >> precipitation, birds, mammals. >> reporter: ...and recorded it all by hand in a series of now-tattered notebooks. >> those notebooks are historic now. >> reporter: in the early 90s, scientist david inouye from the neighboring rocky mountain biological laboratory needed data for his research on wild flowers. he had heard about billy's notebooks but was shocked when he saw how comprehensive they were. >> i said, "billy, you know, those data are really relevant to how the climate is changing and how animals are responding to t changing climat" >> reporter: when you started taking your measurements, did

you have any idea that they would have any kind of long-term significance? >> no, none at all. remember, this was mid-70s, early, mid-70s. if you asked me about climate change, i would have said, "yeah, it got warm. i took my sweater off." i mean, it meant nothing to me. >> reporter: but now it means everything to the global scientific community, which has published his numbers in dozens of scientific papers. like most climate scientists, billy is concerned by what his numbers show-- temperatures are rising and snow is melting earlier each year. >> it's worrisome, obviously. it's not a good trend. will we lose water storage? will drought increase? will floods and famine increase? >> reporter: but billy leaves the answers to big questions like those to others. he's content to do his part and head out into the wilderness, where there's an infinite amount of data waiting to be collected. john blackstone, cbs news, gothic, colorado. >> ninan: and that's the cbs weekend news for this saturday.

later on cbs "48 hours." i'm reena ninan in new york. thank you for joining us. good night. this is kpix5 news. >> new at 6:00, a massive show of support for science as a crowd of 30,000 spills into the streets of san francisco. >> free speech owdosh at cal and culture vowing to showup on campus next we matter what. we have learned that mia is making a comeback as well. >> you do that to me and -- [ commotion ] >> chaos in the aisles at sfo tonight. this flight attendant has been grounded. >> i'm elizabeth cook in for julia. this plane was about to set up for dallas last night when

this happened. >> -- [ indiscernible ] [ crying ] >> reporter: the facebook video shows this mother is distraught over the way a male flight attendant grabbed her baby stroller normally left on the jet wing. witnesses say she was hit with the stroller and it came close to hitting her young child. then one man on the dallas- bound flight confronted the flight attendant. >> bud, you do that to me and i'll knock you flat. >> hey! you stay out of this! [ commotion ] >> american airlines issued a statement soon after the incident last night. we are deeply sorry for the pain we have caused this passenger and her family. the actions of our team member captioned here do not seem to show empathy, a quality nessary for customer care. in a statement, we n'know all of the facts related to a