Mark Robbins: Understanding Ice

0:00 welcome back everybody i'm mackenzie 0:02 zowell and i'm here with the melting ice 0:04 rising seas teachout from the university 0:06 of michigan 0:06 today i'm going to be interviewing mark 0:08 robbins mark could you introduce 0:10 yourself 0:10 hi my name's mark robbins i'm a lecturer 0:14 in the earth and environmental sciences 0:15 department 0:16 at the university of michigan and my 0:18 research focus from my graduate work was 0:21 on 0:21 glacial chemistry and now some of the 0:23 things that i teach in the department 0:25 are about earth's ice ages and past 0:27 extensive ice on earth 0:29 wow awesome so can you tell me a little 0:31 bit about your field experiences i know 0:33 you've been to greenland and also the 0:35 canadian rockies 0:36 yeah so a little bit of background um 0:40 we're talking about ice in general so 0:42 glaciers have an annual cycle when it's 0:44 cold in the winter time 0:45 and they grow they accumulate a lot of 0:47 snow then in the summer they melt and 0:49 this is just an 0:50 annual cycle and so they get longer in 0:52 the winter or into the spring 0:54 and then they get shorter in the summer 0:56 and lots of researchers have looked 0:58 at what happens in that in springtime 1:01 when that melt 1:02 first starts happening and how that 1:03 water travels through the system 1:05 and not a lot of folks have looked at 1:06 what happens the reverse process as you 1:09 go from summertime 1:10 into fall so that's what i wanted to 1:12 investigate and so i had two field 1:13 seasons 1:14 i went to the canadian rockies and i was 1:17 at the athabasca glacier in the canadian 1:18 rockies 1:19 and i was there from august september 1:21 and october 1:22 and i collected melt water samples from 1:24 the front of the glacier to then look at 1:26 how the chemistry of that water 1:28 changed to then sort of work backwards 1:31 to figure out 1:32 well if the chemistry is changing what 1:34 does that mean for how that water 1:35 traveled through the system 1:37 because you can't see the path that the 1:38 water takes so i had a field season 1:41 looking at this in an alpine glacier in 1:42 the canadian rockies 1:44 and then a year later i went to southern 1:46 greenland and was stationed 1:48 at a an outlet glacier from the larger 1:50 ice sheet right at the southern tip of 1:52 the island 1:53 doing the same sort of work and i was 1:55 there august and september collecting 1:57 water samples looking at 1:58 how the chemistry of that water changed 2:00 in a more scaled up 2:02 region awesome yeah ice sheets a lot 2:06 bigger 2:08 so why is ice so important to the 2:10 climate 2:11 ice is when climate is cold 2:14 like it is today when we have ice 2:16 existing on the earth's surface 2:19 it has a really powerful feedback effect 2:21 for earth's climate 2:23 um so a big thing that factors in is the 2:25 albedo effect 2:27 and so if we compare ice to open water 2:30 just broadly speaking even if you don't 2:32 know anything about ice or anything 2:34 about 2:35 ocean systems everybody can pretty much 2:38 easily identify that ice is white or 2:41 sort of bluish 2:42 and ocean water is much darker it's you 2:44 know it's it's a dark blue kind of a 2:46 gray maybe sort of green 2:48 but either way if you put the two of 2:49 them together ice is brighter 2:51 water is darker and that has a really 2:54 big effect 2:54 with albedo which impacts earth's 2:57 climate 2:58 because as incoming light from the sun 3:01 comes in when it hits that white surface 3:03 so whether it's ice 3:05 or snow on top of the ice it reflects it 3:08 off 3:08 whereas in the ocean if you have the 3:11 ocean and you're looking at that with 3:12 that darker surface 3:13 it absorbs it more it's the sort of 3:15 thing that 3:17 may not seem initially intuitive but if 3:18 you go outside in the summertime and you 3:20 kick off your shoes and you're walking 3:22 around if you walk on 3:24 dark pavement versus light-colored 3:26 sidewalks the dark pavement feels a lot 3:28 hotter 3:29 and that's because the dark color 3:30 absorbs the energy that's coming in 3:32 and so the ocean does the same thing so 3:35 when you have ice that covers part of 3:37 the ocean or a larger extent of ice on 3:39 earth's surface 3:40 it reflects more of that incoming energy 3:43 away 3:44 and then that energy isn't um isn't 3:46 absorbed by the earth and doesn't 3:48 contribute as much 3:49 to warming whereas if you melt a lot of 3:52 the ice and you have a larger 3:53 a bigger area of ocean it can absorb 3:57 more of that incoming radiation get 3:59 warmer and 4:00 keep that heat in our earth system so 4:03 extent of ice really matters for how 4:06 that 4:06 energy is divided and parceled and 4:10 moved from kind of one part of the 4:11 system to another 4:13 yeah so just to be clear a high albedo 4:15 means that 4:16 it is a lighter surface like a white 4:18 surface yeah albedo is measured 4:21 from zero to one yeah you know zero is 4:23 no albedo one is full albedo okay 4:26 and a higher albedo is means more 4:28 reflective 4:29 so lighter in color is higher albedo 4:31 well when we were in greenland we saw 4:33 like pools of blue water on top of the 4:35 ice sheet 4:36 do you see those like when you study 4:38 glaciers have you seen them before 4:40 i saw some of those when i was in 4:41 greenland and aren't they pretty yeah 4:42 they're gorgeous 4:44 out of the window of the plane it was 4:46 really awesome to see them on the way to 4:47 summit station 4:48 did you notice how the the these 4:51 puddles or lakes on the surface were 4:54 only around the edge as you traveled 4:55 further in 4:56 there weren't as many yeah they're 4:58 they're limited so you can see like rock 5:00 and then as you travel into the ice then 5:01 you get this kind of band 5:03 of ponds of with these really beautiful 5:06 blue 5:06 lakes yeah and then as you travel 5:08 further in there aren't any anymore 5:10 and those are their transitory features 5:13 um then they really are 5:14 lakes or ponds and they accumulate melt 5:17 from the surface of the ice as the ice 5:19 melts with incoming solar radiation 5:21 it makes kind of streams and rivers on 5:23 the surface of the ice which you 5:24 probably 5:25 saw yeah uh leading into these these 5:27 ponds 5:28 and so they they hold the water there 5:30 but it's not a stable configuration 5:32 because if you have you know if i had 5:34 ice cubes in my glass of water 5:35 the ice floats right yeah so ice is less 5:38 dense than liquid water 5:40 so if we have on the edge of the ice 5:41 sheet all this liquid water that's 5:43 pooled up on top of the ice 5:45 it can't stay there forever because it 5:47 wants to go down because it's denser 5:49 than the ice that's around 5:50 so those those lakes exist and then they 5:53 catastrophically drain like the whole 5:54 thing can empty 5:55 within a span of days that's crazy 5:58 yeah i think the other day i saw um some 6:01 sort of headline that 6:02 some climate activists had swam in one 6:04 of those glacial lakes and i was like 6:06 ah that's so dangerous i wonder if they 6:08 really 6:09 if they know how dangerous those are um 6:12 so are there differences between 6:14 ice found in glaciers like in the 6:16 rockies and the ice in greenland 6:18 sort of mostly age okay so all ice 6:21 on earth exists or originates as snow 6:25 and i i joke in some of my classes how 6:27 do you make a glacier 6:29 you have to snow more than you melt yeah 6:31 that's it that's what it comes down to 6:33 and if it snows a lot more than it melts 6:35 you can grow a glacier faster 6:37 if it snows only a little bit more than 6:38 it melts you're going to grow it very 6:39 slowly 6:40 but you have to snow more than it melts 6:42 and so once that snow 6:44 falls it's a couple year process for 6:46 that snow to turn into ice 6:48 and it happens due to the the weight and 6:50 the pressure of 6:52 subsequent layers of snow that fall on 6:54 top so if you get your first layer of 6:56 snow that's just 6:57 pretty snow crystals and then you pile a 6:59 lot more on top of it 7:00 and over time that weight compacts the 7:02 snow and it transitions and 7:04 metamorphoses into glacial ice and so 7:07 how that process happens and the rate at 7:09 which that process happens 7:11 depends on how much moisture is in the 7:12 snow and how much it snows 7:14 but the overall process is going to 7:15 happen whether you're looking at alpine 7:17 glaciers in the canadian rockies 7:19 or outlet glaciers from the greenland 7:20 ice sheet but the big difference between 7:22 the two is the size 7:23 right because greenland is a very large 7:25 ice sheet and so as that snow 7:28 or as that snow falls and the ice 7:29 accumulates and the ice forms and grows 7:32 it kind of it's kind of like pancake 7:34 batter right like you pile it up in the 7:35 middle 7:36 and then it flows out to the side and so 7:39 as it flows 7:40 out the ice that's at the edges that if 7:42 you go to an outlet glacier 7:44 like i was at in greenland the age of 7:46 that ice is going to be much older 7:47 because it formed a long time ago and it 7:49 traveled 7:50 further whereas if you go to a smaller 7:52 glacier like in the canadian rockies for 7:54 example 7:55 that ice it's just it's just it's a the 7:57 magnitude is smaller so 7:58 it's not as old because it traveled from 8:00 where it accumulated 8:02 out to the toe of the glacier and then 8:04 it melts yeah 8:05 so it's younger ice but overall the 8:07 process to make them is very similar 8:09 yeah i've heard a lot that some glaciers 8:11 are growing while others are shrinking 8:13 and with climate change it would 8:15 seem like everything should be shrinking 8:16 right so why is there 8:18 this difference it comes back to the 8:20 same line it has to snow more than it 8:22 melts 8:23 and so if you any any glacier if you 8:26 increase the amount of snow 8:27 that falls on it then you can grow more 8:31 ice 8:31 and so as the earth is warming because 8:34 that is happening 8:34 climate is changing and the earth is 8:36 warming which is why most are shrinking 8:37 you're correct 8:38 but air masses are changing and some air 8:41 can carry as air warms 8:43 it's capable of carrying more water 8:46 right now it's really cold outside the 8:48 air feels really dry yeah when you walk 8:50 outside in the summer 8:51 and it's hot oftentimes the air feels 8:53 really wet and heavy 8:55 warm air can hold more water and so 8:58 as as the earth is warming as air masses 9:01 are changing 9:02 they can carry more water and so 9:03 sometimes that water 9:05 in the air in the clouds gets routed 9:07 over glaciers and so it snows more 9:10 and so if you have a place where it is 9:12 snowing more due to these changing 9:14 atmospheric 9:15 conditions you can actually have that 9:17 glacier grow 9:18 it's not going to grow indefinitely this 9:19 is this is not a 9:21 ongoing forever and ever process because 9:23 it's still gonna melt 9:25 but if that shift happens so that it 9:27 snows more than it melts 9:28 yeah you're gonna have a glacier that's 9:30 growing even though most are shrinking 9:32 and earth is warming 9:33 all right well thank you so much for 9:35 being here and for answering all of my 9:36 questions 9:37 you're welcome all right everybody 9:40 thanks again for tuning in this has been 9:42 um melting ice rising seas 9:44 i'm mackenzie zowell and i hope that you 9:47 guys are enjoying the teach out so far