captioning sponsored by macneil/lehrer productions >> ifill: president obama nominated army general martin dempsey as head of the joint chiefs of staff today continuing to remake his national security team. good evening, i'm gwen ifill. >> brown: and i'm jeffrey brown. on the "newshour" tonight, the announcement came as the president took time to honor the nation's servicemen and women this memorial day. we look at the day's events and the new military leadership. >> ifill: then, we get an update on efforts to rebuild joplin, missouri, one week after a deadly tornado ripped through the city. >> brown: and judy woodruff explores what's behind the recent uptick in severe weather, not just in joplin, but across the country. >> ifill: plus, ray suarez, in rome, reports on the catholic church's approach to hiv-aids prevention. >> the vatican has ended the debate but not the controversy

over whether catholics or catholic organizations can use condoms to control the spread of aids. >> ifill: that's all ahead on tonight's "newshour." major funding for the pbs newshour has been provided by: >> during its first year, the humpback calf and its mother are almost inseparable. she lifts her calf to its first breath of air, then protects it on the long journey to their feeding grounds. one of the most important things you can do is help the next generation. at pacific life, we offer financial solutions to accomplish just that. your financial professional can tell you about pacific life-- the power to help you succeed.

>> and by the bill and melinda gates foundation. dedicated to the idea that all people deserve the chance to live a healthy productive life. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> brown: president obama today tapped the man he wants to head the nation's military establishment. he acted as the country paused to remember its war dead and as combat continued in afghanistan. the president chose memorial day to name a new leader of the nation's military, along with other top officers. >> the men and women of our armed forces are the best our nation has to offer, and they deserve nothing but the absolute

best in return. and that includes leaders who will guide them. >> brown: the pick to replace retiring admiral mike mullen, as chairman of the joint chiefs of staff, was army general martin dempsey. he's been army chief of staff for less than two months. dempsey is a veteran of nearly 40 years in the army. he's commanded troops in iraq and served as both deputy and acting commander at u.s. central command. the president also announced a new vice-chairman of the joint chiefs to replace marine general james cartwright, who is also retiring. the nominee is navy admiral james winnefeld. he's been head of the u.s. northern command and served as a nato commander and on the joint staff. >> i've selected general dempsey between them, they bring deep experience in virtually every domain-- land, air, space, sea, cyber. both of them have the respect and the trust of our troops on

the frontlines, our friends in congress, and allies and partners abroad. and both of them have my full confidence. they both have something else. for the first time, the chairman and vice chairman will have the expience of leading combat operations in the years since 9/11. >> brown: and with general dempsey moving up, the president chose general ray odierno to be the next army chief of staff. odierno is currently head of the u.s. joint forces command. he previously served three tours of duty in iraq, including as top u.s. commander. all three men-- dempsey, winnefeld and odierno-- face a series of daunting challenges, as the president made clear. >> we have much to do-- from bringing our troops home from iraq to beginning to reduce our forces in afghanistan this summer and transitioning to afghan lead; from defeating al qaeda to protecting the libyan

people. all this, even as we make difficult budget decisions while keeping our military the finest fighting force in the world. >> brown: from the challenges of the present, the president moved on to arlington national cemetery to honor the sacrifices of the past. he placed a wreath at the tomb of the unknowns. before addressing the memorial day audience... >> that's what we memorialize today. that sprit tt says send me no matter the mission; send me no matter the risk; send me no matter how great the sacrifice i'm called to make. the patriots we memorialize today gave not only all they had but all they would ever know. they gave of themselves until they had nothing more to give.

>> brown: u.s. troops stationed in afghanistan joined in honoring fallen comrades with a candlelight vigil, sunday evening in kabul. >> and we're doing what we can here, that they aren't forgotten here and the legacy of all those service members who have given the ultimate sacrifice that's what we're doing here tonight, we're here to recognize them so that they know that their legacy is remembered and not forgotten. >> brown: more than 1,400 americans have died in the fighting there since 2001. u.s. withdrawals are due to begin in july, but the pace of violence has quickened of late. four more nato soldiers died today. and in herat, a suicide bomber blew up his car outside an italian military base, killing at least four afghans and

wounding several dozen people. in addition, a nato air strike on saturday accidentally killed at least 14 women and children. >> ( translated ): about 300 meters away from our houses american forces were fighting the taliban and then an american plane appeared in the sky. i was sitting in my house when the planes started bombing. three house in our neighborhood, including my house, were bombed. >> brown: today, nato issued a formal apology for the incident. still, the outgoing chairman of the joint chiefs admiral mullen voiced hope today about the status of the afghan war. >> we've made progress in afghanistan, significant security progress in particular. i think we will continue to do so this year. i think we'll have a much better sight picture on where to go in afghanistan and in the region towards the end of this year. >> brown: general dempsey and the others nominated today will now be part of the group trying

to get that picture in focus. once, as expected, the u.s. senate confirms them to their new posts over the summer. for more on today's announcement on the new military leaders, we turn to celeste ward gventer. she served as deputy assistant secretary of defense in 2006 and 2007 and also had two tours in iraq as a civilian advisor. she's now at the university of texas in austin. and greg jaffe, military correspondent for "washington post." greg, let's start with you. you spent time with general dempsey, interviewed him a number of times. what should we know about him and his experience. >> he spent a tremendous amount of time in iraq both as the commander of the first armed division in baghdad where he was leading troops in 2003 and 2004. as the insurgency was really gathering steam. he did a good job. he had an army that really wasn't prepared for the kind of fight that it was taking on. i don't think he had personally prepared to fight an insurgen>> brown: that was a particularly difficult time. >> it was a particularly

difficult time. i think he proved he had the ability to learn and adjust on the fly which is an important skill in a military officer. >> brown: what would you add to that? is he a man whose views on policy are known? >> well, jeff, thank you for having me. it's a delight to be with you today. i think there's no shortage of senior military officers of late. and sometimes it's hard to get a sense of what these guys are like on a day-to-day basis but i worked with general dempsey in 2006 in iraq when he was the commander overseeing the training of iraqi police and army. what stands out to me about general dempsey is that he's a very genuine person. he's a smart person but not an ideal owing, not strongly associated with some of the main theologies currently circulating in the pentagon and in the circles. you have what people in texas perhaps call a lot of horse

sense. very common sense. very pragmatic. >> brown: i want you to both take a step back. greg, just to help us understand, why does it matter? how much does it matter who is in charge of the joint chiefs? what is their role nowadays? >> well, you know, i think it matters a lot. a guy like dempsey will be the public face of the military. on an issue like "don't ask and don't tell" and gays in the military and that repeal. adams mullen was important in seting the phone for the military. the other thing is he's the principal advisor to the president onish you ooze like afghanistan and pakistan. finally and perhaps most importantly, you know, in a time when we're cutting defense budgets it's his job to sort of mediate and lead discussions among the chiefs. the chiefs of the army, navy, air force and the commandant of the marine corps and help bring them to a consensus and bring that to the president. i think that's really important when the president is asking the military leader to do something that is relatively unpopular among them which is to make

significant cuts. >> brown: joining a team now and it's a largely new team of incoming people at defense. leon panetta in c.i.a., general petraeus. is the chair of the joint chiefs expected to just be a team player, to express his own views? what does history tell us and what do we know of this general? >> well, i think in fact part of the rationale behind tt 1986 gold-water nichols act that refined the role of the chairman was precisely to give him a larger voice in such debates. and he is the principal military advisor to the president, the national security council and the secretary of defense. i think if one reads any of the most recent accounts of significant internal debates on rye ak and afghanistan, you'd see that the chairman's voice is indeed quite influential. so he can really have a big effect on planning and on policy formulation even though he's not in the operational chain of command. >> now, greg, it was widely

reported that the president wanted someone else first. that's the outgoing vice chairman, marine general james cartwright. he fell out of favor. what happened? what do we know? >> you know, i think part of the issue with general cart rigt is he the trust of president obama. i think president obama particularly valued his advice on the issue of afghanistan where he had brought the president some options in terms of a smaller footprint in afghanistan and what the president ultimately decided upon. i think the problem with general cart rigt is that he had a somewhat strained relationship with admiral mullen, the chairman. he a somewhat strained relationship with some of the senior four stars in the pentagon. at a time when you were going to be asking the military to make some tough and unpopular decisions, you know, ear going to be managing the drawdown in afghanistan, be managing the cuts to the defense budget, i think the obama administration wanted somebody who was going to be listened to, who was

well liked among his sort of peers in the pentagon. >> brown: do you have anything to add to that celeste? it sort of goes to the question of the political role or management role of this position. >> well, i think greg is right that they needed somebody who is known for a very collegial approach and who is well liked throughout military circles. and who can work to build consensus. you know, this chairman and in fact the new chief of staff of the army, if confirmed, all have their work cut out for them. there are major problems on the horizon that the pentagon will have to confront. budgetary constraints, a drawdowns in iraq and afghanistan, you know, we're celebrating our ninth memorial day today since the u.s. has been at war since september 11. you have less than one% of the american population essentially serving in these conflict.

they're tired and worn out. these will be serious problems that the pentagon will have to confront in an era of dwindling resources. >> brown: tell us a little bit more starting with you, celeste, one of of course is key decisions coming in afghanistan. >> well, of course, in july the administration is set to reduce u.s.... overall u.s. forces in afghanistan although the number is not yet firm of exactly how many u.s. forces will be reduced. i think it's interesting that we're about to have a discussion about the debt ceiling. to reflect on the fact that of the 28 billion dollars per week that the united states borrows, approximately, about $3 billion of that is to support the wars in iraq and afghanistan. it's hard to see how expenditures at this level can continue while we're trying to cut deficits. i think this is going to be a real challenge. and the pentagon is going to have to figure out how it fits into that debate. >> brown: greg, you both have mentioned the defense cut

debate here. that's gotten underway with secretary gates and others. where does general dempsey fit into that? >> as army chief which was only army chief for about two months but one of the first things as army chief was that he talked frankly about the fact that cuts were coming and the army would have to live within its means. the days of the army asking for everything it wanted and getting everything are gone. there's a sense that he knows cuts are coming. i'm not sure anyone has a plan as to what should be cut. that sources great consternation in the pentagon right now. there's not a ton of fat to cut which sounds ridiculous given the size of the pentagon budget. but i think it's largely true. >> brown: celeste, a final word. are his views on that or on, say, afghanistan on the record at all? or is this now we wait to see what role he plays in these debates? >> well, again, i think that general dempsey will play a very pragmatic role.

he'll bring a real... a very down to earth perspective. he's not going to bring a theo logical perspective to this. he's going to do what makes sense. i think his views are not entirely clear at least publicly at this point although he has emphasized the need to deal with the wars that we're in. but i think he's going to go at this with a very practical approach. >> brown: thank you both very much. >> ifill: still to come on the "newshour": facing the aftermath in joplin; the increase in violent weather and the vatican tackles h.i.v.-aids prevention. but first, the other news of the day. here's kwame holman. >> holman: government forces in yemen went on the attack today trying to recapture a town seized by islamic militants. warplanes attacked zinjibar in the south. at least 30 militants, civilians and soldiers have been killed there since friday. meanwhile, amateur video from another city taiz showed masked

men with rifles shooting from rooftops at protesters. one doctor reported at least 20 people were killed there today. the protesters have demanded that president ali abdullah saleh step down. instead, saleh increasingly has used force to crush the three- month-old uprising. protesters in syria have begun fighting back with guns and grenades. activists reported armed resistance today in two towns in the central part of the country. government troops had attacked the towns on sunday. the reports today said at least 14 people have been killed in the fighting. and, hundreds have been arrested. northern sudan warned southern sudan today to withdraw from a disputed border region, but the south refused. the standoff raised new fears of a wider conflict, with thousands of people already displaced. i spoke earlier with rebecca hamilton of the pulitzer center, who's in the southern city of juba.

rebecca hamilton, thank you for joining us. where are you now and what's happening there on the ground? >> you haveto go back to juba from several days further north up toward the north-south border of sudan. yesterday i flew over the place that the sudanese government attacked last weekend. i've been traveling in the areas where upwards of 80,000 people fled to after the attack on the town. >> reporter: what's going on with the fighting there and the talks in khartoum to try to reach a settlement? >> well, the fighting at the moment has stopped because the sudanese government has actually seized control of the town. the critical issue right now is the humanitarian one with over 80,000 people and the rainy season coming, i met displaceed this week who were taking shelter under the cover of trees in the pouring rain. these were mostly women and children. health workers are extremely concerned about disease. i spoke to a woman just this morning whose little

two-year-old son had died on the walk from the town to the place where she was. it took three days and he died of dehydration on the way. the humanitarian consequences are severe. if we see any deaths as the result of those. but in the town itself now the fighting has stopped. politically this is going to be very difficult to resolve because the position of the south is that the northern government must withdraw and right now the sudanese president bashir is continuing to say that the town is northern land and he won't withdraw. >> reporter: rebecca, how is the humanitarian aid effort going? >> it's a very difficult humanitarian aid operation. because there is a huge fuel shortage in south sudan right now. that makes transportation of relief goods very, very difficult. it's something that the south sudanese government is struggling with. it's something that the united nations is struggling with as

well. >> holman: southern sudan is due to become an independent state on july 9, after years of civil war. there was more international pressure today for libyan leader moammar qaddafi to leave office. in bulgaria, the nato secretary- general anders fogh rasmussen said: south african president jacob zuma arrived in tripoli, hoping to broker a peace deal and to persuade qaddafi to step down. the libyan leader was not among the dignitaries who greeted zuma at the airport. later, libyan state t.v. showed qaddafi meeting with zuma and his delegation. germany has announced it will close all 17 of the country's nuclear power plants by the year 2022. the decision today came on the heels of the fukushima nuclear disaster in japan in march. it marked an abrupt about-face for the center-right government. but chancellor angela merkel said it's also an opportunity.

>> ( translated ): as a country, we think that we can become pioneers on the way to create an age of renewable energies. and we can as the first industrial nation, a big industrial nation accomplish such a turnaround to high- efficient and renewable energies, with all the chances for exports, for development, for technology and for jobs. >> holman: before the japan accident, germany had produced about one-quarter of its energy from nuclear power. it has since shut down seven of its oldest reactors. a woman who defied the kingdom's ban on women driving. she was detained may 21 after she posted video of herself behind the wheel. it was part of a campaign for a mass protest next month against the driving ban. there had been mounting international pressure to free the woman, but officials gave no reason for the decision today to let her go. saudi arabia is the only country in the rld that bars

women from driving. hackers struck pbs overnight, posting a fake story on the "newshour" website. the posting claimed rapper tupac shakur-- who died in 1996-- actually was alive, and in new zealand. the story was taken down this morning. the hackers said the attack was retaliation for a documentary about wikileaks that aired on the pbs program "frontline" last week. the executive producer of "frontline" called it a disappointing and irresponsible act. those are some of the day's major stories. now, back to gwen. >> ifill: severe weather has carved a path of destruction around the country this spring and it's apparently not over yet. the year's latest weather extreme was in full view this weekend along the bloated missouri river. the river is filled with runoff from heavy rain and record snow melt and floods now jeopardize parts of five states. the threat has officials mobilizing everything they've

got, including the national guard. in bismarck, north dakota, the army corps of engineers has been building emergency levees. >> we fully expect that all this level of protection would be in place before the higher flows come mid-month. >> ifill: and in south dakota, flows from dams have been increased to relieve pressure. >> our governments are working hard to protect public infrastructure: highways, utilities, water, sewer. and as we are able we will try to protect private property to the extent we can do so. >> ifill: but new rain is making it even tougher for people trying to save already soaked communities. >> we were doing fine until it started raining and now we're just trying to stay one step ahead of the battle and i don't think we're doing very well. >> ifill: disaster of a different kind threatened western michigan on sunday, as people in vicksburg reported tornado sightings. >> we looked over towards the

neighbor's house and you could actually see rotation, and it was down to the top of the tree level. and just as quick as we got everyone to the basement, it just broke apart. >> ifill: the storm blew down power lines and damaged houses in vicksburg. but the damage was nothing like what befell joplin, missouri just one week earlier in one of the deadliest tornadoes on record. >> how you guys doing? how are you? >> ifill: president obama spent much of sunday in joplin, seeing the devastation for himself and meeting with survivors. >> the main thing i want to communicate to the people of joplin is this is not just your tragedy, this is a national tragedy and that means there will be a national response. >> ifill: as search teams continued to work, officials confirmed more than 130 killed, and at least 29 people still unaccounted for.

and the missouri department of health and senior services has continued to work 24 hours a day to account for individuals and to expeditiously and respectfully notify next of kin when their loved ones are confirmed dead. and we will not give up until every single person is accounted for. >> ifill: >> ifill: at a sunday memorial service, missouri governor jay nixon vowed the community will persevere. >> that storm-- the likes of which we have never seen-- has brought forward a spirit of resilience the likes of which we've also never seen. >> ifill: today, american flags flew over the city's ruins for memorial day. and thousands left homeless by the disaster are still in search of permanent shelter. the federal emergency management agency fema announced the agency hopes to find rental homes within a 55-mile radius of joplin.

and, trailers like those used after hurricane katrina may be brought in if enough homes are not available. now for more about the situation in joplin and its efforts to recover, we're joined by joplin mayor, mike woolston. i talked to him earlier this afternoon. mr. mayor, thank you so much for joining us. tell me, how is the rebuilding going? >> well, we haven't quite started rebuilding just yet. you'll see behind me we do have one building going up. i think it's probably the first in the community. we're still essentially trying to dig out from under the debris. a lot of folks out this weekend cleaning up their properties. have a huge number of volunteers in town from various groups all over the country helping with that clean-up effort. so we'll continue with that for a bit before we see a substantial amount of rebuilding but we have had some announcements. our hospital that was so critically damaged they will rebuild here in town. one of the grocery stores that was flattened will rebuild here in town. we're getting some of those kinds of positive announcements. >> ifill: we've heard reports this week about the numb br of

people without homes. what steps are being taken to find places for them to live. >> we're working with fema to find housing for everyone. someone asked me earlier if fema will bring in mobile units. i'm not sure exactly what the eventual outcome will be, but we're willing to visit with fema and consider just about any option. they're looking primarily at a radius of about within 50 miles of town. so given the number of folks that need housing, we may have to house a few of those folks in the outlying towns a few miles away from here. we hope to keep those people here because this is home. >> ifill: are there any concerns about the idea of bringing in mobile units like they had after katrina, these trailers when you're in a tornado zone? >> sure. some concerns. i guess on the surface what would we do with all those when they left or do they belong to fema? do they belong to the occupants? do they belong to the city? a lot of the details like that i don't have any information. as i said i think we're trying to look at any option that

would take care of our citizens because that is our primary focus. >> ifill: you had a residential visit yesterday. how do those kinds of visits-- or do they-- help with either the actual rebuilding itself in terms of resources coming from washington or is it the sense of the mood of the people of joplin? >> i think it was a bit of the sense of the mood of the people though. i think our folks are fairly resilient. i think spirits were as high as could be expected in the days immediately after the storm. the president's visit draws attention to the area. we had had quite a lot of attention prior to that. we've had promises from government at every level that we would have the cooperation we needed, that they were here for the long term, and that they would not be leaving us just as soon as the media lost interest in us. and the president reaffirmed that. i was very pleased to hear that. he publicly announced in his remarks that they would be here long term and provide us with the help we needed. very reassuring for me and i think for our citizens. >> ifill: it is great to hear

about the resiliency of the people in joplin. what do you do as a community leader about rebuilding the local economy which has been quite stricken by this as well as the local infrastructure? >> well, we try to help our citizens and homes. of course that's probably the top priority. we're also concerned about our business owners. we have a pretty substantial number of our businesses that were damaged or destroyed. we're hoping to provide them some assistance as well. we're encouraging everyone, whether you just be a homeowner or a tenant or a business owner, to register with fema. that's critically important. the sooner the better so you can basically get in line and it will be a fairly lengthy line. we're encouraging people to register with fema and take advantage of that kind of assistance. my understanding is fema will direct people to whatever resource might best help them given their particular concerns. >> ifill: you mentioned at the top of this that the hospital announced it's going to rebuild in joplin. what about the schools? the school system? i know that the high school took a big hit.

>> the high school was... it's my understanding that it is a total loss. they had a high school age technical school where they learned heating culinary arts. that was totally destroyed. we had one elementary that was totally destroyed. the public school district announced i believe it was thursday morning that ounof our newer middle school about a year old had serious damage. they would use the same contractors that built that facility to rebuild it. the same contractors, same everything, same blueprints. my understanding is they have already started on that. the school district has announced that they will hold summer school and classes will open on schedule in august. >> ifill: as you begin to think about what has happened in just this last week, the good news and the not so good news which the city has had to deal with, what would you say are the biggest challenges awaiting you now in the next several weeks and months, maybe years? >> i would guess just getting through the process. we recognize this is going to be a long process.

it's difficult right now to project how long it will be before we get back to, quote unquote, normal, if we ever do get back there. i guess what strikes me is the amount of effort and time that it will take working through the various government programs and bureaucracy, the paperwork, to make sure that we do things right. to take care of our citizens. every decision that we make from the very beginning of this has been made with the perspective of what's in the best interest of our citizens. that will always be our number one focus when we're making decisions is what's best for our community. >> ifill: mr. mayor, a price tag on any of this yet? >> the numbers we have are real rough, gwen. they vary widely. as we get through the process a little further, i expect that those will be narrowed down and refined to a more definitive number. at this point i'd be hesitant to guess at something because on my part it would be just a guess.

it's still in the process of trying to assess all the damage. once we get dug out a little bit further and get a better idea of what remains of some buildings if they're salvageable or not we'll probably have a better number. at this point i would be reluctant to put a price tag on it. >> ifill: thank you so much for joining us, mr. mayor. >> thank you. >> brown: the storm in joplin was preceded by a series of tornadoes this spring that has brought devastation to the south and midwest. all together, it's been the deadliest season since 1953 with more than 520 people killed so far. all of this has led to many questions about what's happening this year. judy woodruff explores the science. >> woodruff: so how unusual are the tornadoes and other weather we've been seeing in the u.s. this spring and what might explain it? for that, we turn to two weather specialists. jeff masters is co-founder and director of meteorologist of the weather underground, a weather-tracking website.

catherine heyho is a professor and climate scientist at texas tech university. she was a member of the review team that studied the work of the u.n. panel on climate change. we thank you both for being with us. jeff masters, let me begin with you. you've been studying meteorology for over 30 years. just how much more severe are the storms and tornadoes we've been seeing this year than in the past? >> we've never seen a year like this before. it started off in mid april on the 14th we had a swarm of tornadoes hit the south and then the southeast. over a three-day period we had 162 tornadoes. that was an all-time record for most tornadoes in a tornado outbreak. we've only ever seen one outbreak similar back in 1974 we had 148 tornadoes in one outbreak. that outbreak was followed two weeks later by the most incredible outbreak we've ever seen: 362 tornadoes in a four- day span including the tuscaloosa birmingham tornado

which was probably the most damaging tornado of all time. more than double the previous record which was set just two weeks before that. on top of this these storms dump tremendous amounts of rainfall. the heaviest rains ever recorded in april over the ohio and mississippi valleys which helped contribute to the mississippi river floods we're seeing. and then after those two outbreaks... i'm sorry, go ahead, judy. >> woodruff: i was going to say you're saying there's been a string of these severe incidents. the death toll higher than it's been in a very long time. is there a consensus among meteorologists about why this is happening? >> as far as the death toll goes we just got unlucky. we do see incredibly violent tornadoes fairly regularly, every few years we see an ef-5 tornado with 200 miles an hour winds. but if one of those storms happens to track over a populated area, then we see some of these incredible death tolls. >> woodruff: catherine, let me bring you in here. there's been a lot of question about... questioning about

whether the severe weather, these records that are set have a connection to climate change. how do you see that as somebody who has studied climate change? >> whenever we see a season like we're having right now, it's a natural part of being human to say, is there a pattern to it? and so, of course, that's what we're asking right now. is there a pattern to all of the weird weather that we've been seeing this spring? unfortunately at least for those of us who want a pattern immediately, we can't tie any one event or even one season to climate change. climate is the average statistics of weather over at least 30 years. but what we can do is we can add this season to the books and we can start looking at whether we see any trend in heavy rainfall events, in drought, and in tornadoes. when we do that, we do see trends in some things. we see trends in heat wave frequency and severity in many places around the world. we also see increases in heavy rainfall events across the

entire u.s. especially in the midwest and the northeast. but when we look at the tornado records we don't see any conclusive trends in tornado numbers or severity yet. so we don't know if, as jeff said himself, if this is a fluke this year or if it's the beginning of a new trend. it's too early to say. >> woodruff: jeff masters, what about that possible connection to climate change. is it too early to say? >> well, absolutely. we have a problem with the tornado record. it's very hard to measure tornadoes. we can't put wind measurement instruments into them so we have to indirectly further say if they hit a building and knock it down you say this tornado probably will 200 miles an hour end. very tough to measure and very tough to figure out if tornadoes are changing with time. our measurements only go back about 60 years which isn't long enough to see if there's a climate trend or not. >> woodruff: what about all the flooding we've seen in the midwest, the south, the mississippi river. and that entire basin.

a connection there? questions are also being raised about that. you know, the warm air, excess moisture. possible connection to climate change or not? >> again, we can't tell what's happening in the mississippi basin specifically to climate change. one event or one region is not enough. but we can look around the whole u.s., and we can look around the whole world. when we do that, we see that we have experienced a significant increase in heavy rainfall events that often do lead to flooding. this is happening not just here in the u.s. but around the world. not only that, but that increase has been connected quite deaf definitely to climate change. in other words, we would not be seeing an increase as big as we have over the last 50, 100 years if it was not for climate change. >> woodruff: draw that line for us. what is the connection. >> as it gets warmer, the air can hold more water vapor so whenever a storm comes through there's more water available

to that storm. whether it's rainfall in the summer or even snowfall in the winter. we're also seeing shifts in our weather patterns and circulation patterns. some places that are already quite dry are getting dryer. other places that are already quite wet are getting wetter. some places can experience increases in heavy rainfall and droughts at the same time. because if a lot of the water vapor comes down in a few storms then you have a longer dry period in between before you get the next one. >> woodruff: jeff masters, as somebody again who watches this closely, what would you add to that? and what are you most curious about as you look at these patterns of severe storms and unusually heavy flooding? >> with flooding, the thing to think about is that, yes, precipitation has increased by 5% or more over the last 50 years in the u.s., but the flood heights are getting higher not just because of higher precipitation. they're also getting higher because of humans causing changes to flood plains. we're draining more flood

plains. we're putting more water behind levees. we're engineering the levy system so that we can improve-and-a-half... navigation. those little improvements cause thed flood heights to go higher. we need to give the rivers room to expand. we need to have more of the safeguards where you can let the river out through some of these spill ways like we've had to do this year. that was a very smart idea to open these three spill ways that helped the mississippi go out and not be at such high flood levels. we need to give the river more room. we have to stop developing our flood plains and putting people in harm's way. >> woodruff: on that note we thank you both. jeff masters and catherine heyhoe. we appreciate it. >> you're welcome. >> thank you, judy. >> ifill: the catholic church reaffirms its stand on the use of condoms in the fight against h.i.v./aids. ray suarez and our global health unit report from rome.

>> reporter: throughout the spring, pilgrims and tourists from around the world have poured into the vatican, drawn by the beatification of pope john paul ii, putting him on the road to sainthood just six years after his death. also heading to vatican city over the weekend, theologians, health officials, and researchers for a meeting about the treatme of h.i.v. and aids. the church is one of the biggest providers of h.i.v./aids care in the world with more than 117,000 health facilities worldwide. the conference was convened amidst ongoing controversy about the catholic church's opposition to using condoms to control the spread of aids. aids groups around the world, had hoped the church would use the conference to announce a major reversal of its position. the answer turned out to be a resounding no. over the past two years, pope benedict the sixteenth has issued statements open to conflicting interpretation that

encouraged some to think the church was taking a more nuanced position on condom use in h.i.v./prevention. >> i don't think there was any confusion about what he meant. >> reporter: but father michael czerny, a key health official for the church, says the pope continues to believe that condoms don't help prevent aids. >> he mentioned one of the solutions that people tend to line up behind. or they tend to promote, and he pointed out it was not the solution people think it is. >> reporter: but aids advocates were encouraged last fall when the pope seemed to indicate a softening of his position during a book interview. "there may be a basis in the case of some individuals, as perhaps when a male prostitute uses a condom, where this can be the first step in the direction of a moralization, a first assumption of responsibility." jon o'brien, who heads catholics for choice, was not at the

conference this week, but still maintained that the pope's comments had signaled a new thinking at the vatican. >> the statement by the pope was a victory for common sense and for reason and it was a sign from what we hoped from pope benedict that he would be a listening pope. >> reporter: the pope himself did not attend the conference, but sent his secretary of state. most of those attending spoke in support of the church's teaching, but there was some disagreement. michel sidibe is the head of un aids which strongly endorss the use of condoms as a prevention strategy. >> i welcome pope benedict's recent clarification of the use of condoms for h.i.v. prevention. this is very important. >> reporter: monsignor jean- marie mpendawatu musivi was one of the conference organizers.

>> ( translated ): i think we should read everything in the whole speech that the pope made, because if you just extrapolate a few sentences then these few sentences will not give you the whole meaning of the discourse of the pope. therefore, you have to go into details and read the entire passage in order to understand the real meaning. >> reporter: meaning, in short, that the pope's statement did not change policy. catholics, and catholic agencies, would not use condoms as part of an aids prevention strategy. sean callahan is with u.s. based catholic relief services, which works with governments and n.g.o.s combating aids throughout the developing world. >> as a catholic organization we don't support the use of condoms and we don't promote it. what we focus on his havior change. the problem you see with condoms is not only the utilization of them, but can they be utilized well, are they there all the time, and things of that nature and that is one of the reasons why the church is against it besides other church teachings. >> reporter: in just a few decades the condom has moved

whispered over, kept behind pharmacists counters, to a near ubiquitous thing for sale in a from something hard to get, its sale limited by law in some places, for sale in a street-corner vending machine around the corner from st peters basilica. condoms, along with testing, have been the cornerstones of aids prevention efforts around the world. but even as the graveyards of sub-saharan africa continue to fill up. new infections continue. 1,000 a day in south africa. edward green has the perspective of an aids researcher, not a theologian and he says the numbers bear out the pope's position. >> certainly in africa in the years since 1988 we've seen that greater condom use is not associated with lower h.i.v. infection rates. so, yes, they've been oversold. people who do use condoms tend to have a false sense of security and take greater risks than they would take if they were not using condoms at all. >> reporter: a man i spoke with

outside johannesburg in 2009 showed the lack of acceptance of condom use in africa. >> me, as a man, i have to sleep with another woman, and on the other side i have an original woman. >> reporter: if there's a risk of infection why don't they stop? >> they won't stop. >> reporter: until they die? >> until they die because they don't believe in condoms. they are living a true african. i won't use a condom. >> reporter: kevin dowling is a catholic bishop who wasn't invited to the vatican conference. we spoke with him last week as he met patients outside his rural clinic. >> we do not distribute condoms, dowling has been on the front- lines of the h.i.v./aids epidemic for nearly 20 years, and runs one of the largest aids

treatment programs in south africa. >> we do not distribute condoms, we give people the information they need to make an informed decision in conscience about what they are going to do in their lives. >> reporter: bishop dowling sees what he calls the injustice and degradation of transactional sex, or survival sex, among the poorest women, and says there's protection in condom use. >> the option to abstain from sex before marriage, the option to be faithful to a single partner within marriage just does not obtain in these situations. that is where the issue of a condom, not for contraceptive purposes, but to prevent the transmission of a death-dealing virus comes into play. >> reporter: again and again church leaders stressed behavior change: chastity outside marriage, and fidelity within marriage. >> ( translated ): we have to educate on chastity. we have to strengthen families.

we have to work on change in sexual behavior. chastity is joyous. were promiscuity not endemic, h.i.v. would not be an epidemic. >> reporter: catholic church officials also strongly condemned the tendency for poor people to get poorer medical care around the world, especially those suffering with aids. and repeatedly stressed the promise of aids drugs, anti- retrovirals, in stopping the spread of the disease. but catholic leaders have daunting advice for married couples with one infected partner: long-term celibacy within marriage. >> ( translated ): the key issue is that the couple should refrain from risky behaviors. they should abstain from sexual intercourse because this is risky for them. and the church is very, very, close, very near to these families to help them achieve this goal. >> reporter: on the day of the vatican conference, catholics for choice ran an ad in one of italy's most influential newspapers "il corriere della sera." it thanked the pope for saying

condoms can prevent the spread of h.i.v., and continued in part, "we believe in god, we believe in caring for each other. we believe condoms save lives." groups like catholics for choice will be disappointed by the church's strong re-statement of long-standing prohibition of condoms, under any circumstances. but despite the disagreements, governments still need the resources and expertise of the catholic church, they will not turn away what is still vital, lifesaving help over condom policy. >> ifill: again, the major developments of the day: president obama nominated army general martin dempsey to be chairman of the joint chiefs of staff. the announcement came as americans honored the nation's war dead on memorial day. government troops in yemen tried to recapture a town from

militants, while protesters in syria fought security forces with guns and grenades. and flooding on the missouri river and its tributaries threatened towns across montana and the dakotas. and to kwame holman for what's on the "newshour" online. hackers posted a fake story on the newshour website. it claimed that a man who died in 1996 was actually alive. the story was taken down this morning. the hacker said it was in retaliation for a documentary about wikileaks that aired on the pbs program front line last week. both the front line website and the newshour's were attacked. the executive producer of front line called it a disappointing and irresponsible act. >> brown: before we go, on this memorial day: here's an encore from poet wyatt prunty.

we first ran his poem "the returning dead" in march of 2006. it was his response to the "newshour's" honor roll of service personnel killed in iraq and afghanistan. >> my name is wyatt prunty. i served in the navy in vietnam. i was a nearsighted gunnery officer and i don't think i hurt anyone. that was a difficult for many. difficult for some of us because while we disagreed with the war itself we believed we could not refuse to serve. years later i starteded this writers' conference. and i now live and write here in tennessee. my wife and i have watched the newshour since its beginning. which means we have had a good, long marriage. for three years we have studied the faces of soldiers from all regions and backgrounds in america. they're the ones the newshour

has broadcast as its honor roll. but i'm going to read as a response to those lost yet so permanently set people whose lives are our gift. the poem is called "the returning dead." each night i make a drink and wait for them. they have become the day's concluding news. installments from a world without anthems or children, unfocusing eyes, a question that repeatedly rejects my easy terms. they're ones who believed and acted in the narrow and select ways handed them while ordinary lives ran on without interruption or bad pictures. as though nothing had changed. change is the one unanswerable question of these faces. the world can rearrange itself repeatedly, but these remain

the same: silent in everything they lack. that's what they've come to. in places with names like afghanistan, iraq. this is the way it happens. the words are old: mother, father, home. and the will of a river etched out of the landscape history refines to myth. the tv blanks between segments but every static face defines itself. holds stubbornly its private scene, fixed publicly. as we are led back to that little negative whose lack is each of us. staring the staring dead, leaning, sometimes like grief itself and then straightening back.

>> brown: and now, tonight's honor roll. as always we add the names as their deaths are made official and photographs become available. here, in silence, are nine more.

>> ifill: and that's the "newshour" for tonight. on tuesday, we'll look at the conflict heating up between north and south sudan. i'm gwen ifill. >> brown: and i'm jeffrey brown. we'll see you on-line and again here tomorrow evening. thank you and good night. major funding for the pbs newshour has been provided by: >> okay, listen. somebody has got to get serious. >> i think... >> we need renewable energy. >> ...renewable energy is vital to our planet. >> you hear about alternatives, right? wind, solar, algae. >> i think it's got to work on a big scale. and i think it's got to be affordable. >> so, where are they? >> it has to work in the real world. at chevron, we're investing millions in solar and biofuel technology to make it work. >> we've got to get on this now. >> right now.

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