as sweet as a lollipop. that's going to do it for us. we'll see captioning sponsored by cbs >> ninan: earth day and the march for science. >> science makes america great! >> ninan: and 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. >> just give me back my stroller, please.

this is the "cbs weekend news." >> ninan: good evening. i'm reena ninan. 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 program, 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 biggest

concern. we can't stall our 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 attacked 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 clethreat of climate change. and immigration policy. knipp, kathy ely, and lucia teal. >> we were born in the 50s. we grew up in the 70ss. we were protesting back then and we're too old for this. we should not be out here protesting against things that we won in the 70s and the 80s. >> 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. are 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 depends 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 help today. here's errol barnett. >> reporter: president trump and first 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 comeses -- 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 announceed by "wednesday or shortly thwart," saying it would be "bigger, i believe, than any tax cut ever." and on immigration, the 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 they comply with federal immigration laws or risk losing money. new york staefs accused of being "soft on crime." here's kristin sanborn. >> reporter: as the trump administration threatens to crack down on sanctuary cities-- >> sanctuary jurisdictions put criminals back on the streets. >> reporter: ...local alreadies are pushing back. >> it's incredibly insulting. >> reporter: that's how 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 upon. sound like we're. soft on crime? on friday, the justice department also sent these letters to sanctuary jurisdictions, like new york, chicago, 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 made earlier this week about a judge in hawaii who blocked the president's travel ban. >> one judge has over-ruled the constitutional thfort 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 alletters until june 30 to compy with the law. but, reena, a number of local leaders say they'll remain defiant, even at the risk of losing federal funds. >> ninan: an american airlines flight attendant was grounded after a heated confrontation with a passenger and it was all caught on camera while passengers were boarding a flight on friday. here's carter evans. >> reporter: the video begins with a woman in tear, 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 comeses less than two weeks after footage of a man being dragged off a united airlines plane sparked outrage. 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 upgrade to first class. >> ninan: okay, carter evans, thank you. the murder of a police officer in paris this week by 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 tas about patriotism. about cracking down on immigration and bringing back blue-collar jobs. but there's a big difference-- lepen's main base baseis among the young. sylvain hechon is 25, an activist. 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 uwere preoccupied with france's economic woes. he showed us one of lepen's

videos aimed squarely at millennialmillennials who face n 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 sprudding lepen's anti-free trade message. "president trump put his people first and we believe marine le pen will do that, too. defend the french." marine le pen supporters believe

passionately, 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, as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening heart failure.

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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 gog happen in the next decade. >> reporter: jeremy mathis is director 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. ben tracy, cbs news, utqiagvik, alaska. >> ninan: and still ahead, the other side of the climate change debate from a man who calls

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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 effort efforts to stop globl warming or slow it down are way dispoportional 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 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 whrf 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 it's a hoax. it's a hoax. >> reporter: bast looks with approval on 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 most lie lee 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 talk 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. 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. while taking eliquis, you may bruise more easily... ...and it may take longer than usual for any bleeding to stop.

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named billy barr started taking notes on the nature around him nearly 45 years ago. john blackstone paid him a visit. >> reporter: as 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 making my own activity. >> reporter: so you would go up on the 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... >> what this does is it converts the weight of this can and the snow in it, in to the equivalent 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 track 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 held 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 the changing climate." >> 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." 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 stwors 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.

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