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  • Hi. It's Mr. Andersen and welcome to biology video essentials 51. This is on

  • ecosystems and how ecosystems can be impacted by changes in their environment. This right

  • here is a picture of some contrails that are created. Contrail are created when jets fly

  • over an area. Pollutants coming from the combustion of the jet fuel will actual have water vapor

  • adhere to it. And so you get the creation of a man-made cloud. And you can see how many

  • of these contrails are created. This is a satellite image over Nova Scotia. And these

  • are all the contrails that are created in a typical day. And so we're actually making

  • clouds. Now what do those clouds do? Clouds will actually hold heat in. And so in Montana,

  • when it's going to be a clear night I know that in the winter especially like now, it's

  • going to get really, really cold at night. Because the clouds aren't going to hold in

  • that heat. And so how could we ever study how much of an impact are we having on the

  • weather? Well we'd have to have a time when there are no jets flying. And when would that

  • happen? Well it's only happened really once. After 9/11 we shut down jet traffic in the

  • United States for a 3 day period. And so scientists were able to observe that three day period

  • and compare it to the days proceeding it, days after that. And we were able to find

  • that we had roughly a 1 degree Celsius change on the weather. Just during that one day period.

  • And weather remember over a long term is called climate. And so we can impact ecosystems just

  • by changing the climate. So basically in this podcast I'm going to talk about how ecosystems

  • can be impacted by changes in their environment. Some of those are human changes. And of course

  • I'm going to talk about global warming or climate change. We could also have geologic

  • changes. An example I'll give you is continental drift. And then finally we could have meteorological

  • changes. Meteorological just simply means weather changes. And so an example I'll talk

  • about is el Nino. Or warming of the oceans and how that's actually impacting ecosystems

  • on our planet. So let's start with global warming. This is a famous map. It basically

  • compares the average temperature from 1950 to 1981. So a 30 year period to the ten year

  • period that we're just finishing. And basically anything on the map that's red means that

  • it got warmer. Anything on the map that's blue, which I can find a little bit down here,

  • means it got cooler. And then the grey areas means we didn't get much data from that. And

  • so you can see that there's a huge warming over the last decade compared to the 50s to

  • 1980. And so basically there's no credible scientist out there that's saying that there's

  • not global warming. And there's no credible scientist out there who's saying humans aren't

  • having an impact on that. And so a couple of examples of feedback loops, because that's

  • again one of our major themes, this would be in the permafrost. So as permafrost starts

  • to melt it gives off a methane gas. Methane gas is a really good green house gas. And

  • so that's going to increase the temperature through the green house effect. Which is going

  • to warm the permafrost. Which is going to create more methane gas. And so you know we

  • call that a positive feedback loop. Now some of that heat is going to dissipate from the

  • arctic. And so this is not really a localized phenomena. But it is going to increase global

  • warming. That's why were going to see an increase over the next 100 years. One that's more global

  • would be the increase that we're seeing in water vapor. And so this is from 1980 to 2004.

  • This is just looking at the amount of water vapor in the atmosphere. And you can see that

  • we're seeing an increase in the amount of water vapor. What is that H20 going to do

  • in the atmosphere? Well, it's going to increase the temperature. It's going to increase the

  • temperature which creates more water vapor which is going to increase the temperature.

  • And so basically our temperature is being increased by changes that we're having on

  • our planet. Because it's not just weather, excuse me, it's not just water and methane,

  • it's going to be carbon dioxide that we're putting into the atmosphere. And other green

  • house gases that are increasing the temperature. And it'll take awhile for that to actually

  • take off. And we're starting to experience that right now. How much of an impact is it

  • going to have on ecosystems? Well it's first of all going to effect ecosystems that are

  • more susceptible to changes in temperature. And so this is data that I got from the intergovernmental

  • panel on climate change. So it's basically almost 200 countries take all their data.

  • They compile it together. And they're looking at how changes in the temperature are going

  • to effect our planet. Now they're not necessarily looking at ecosystems. But that's a part of

  • the study that they did. And basically what they predicted is if we see 1/2 of a degree

  • of Celsius change over the next 100 years, we're going to have damage to the coral reefs

  • and the arctic ecosystems. Now of course we're going to impact the arctic ecosystems more

  • than those closer we'll say to the equator, because any warming is going to change that

  • climate there. And so it's going to impact species that have evolved to live in a cold

  • area. An example could be like the polar bears. Now coral reefs are damaged in a different

  • way. Let me click to the next slide. If we see a 1 degree change, all the coral reefs

  • will become bleached. So basically a coral is made up of two things. You have a coral

  • which is essentially an animal. And then you have an algae that lives mutualistically with

  • them. And so basically the coral will extrude that algae so they become bleached. And they

  • can't use the photosynthetic features of the algae anymore. And so it's a defense mechanism

  • to changes in the temperature. That's why they will be impacted. But if we see a 1 degree

  • change they're predicting we'll see 10% of the global ecosystems will be transformed.

  • And so basically what's going to happen is as we increase temperature, it's going to

  • get warmer and warmer and warmer. And so it's going to impact these areas near the arctic

  • more than those areas near the equator as we warm up the temperature. Now it's happening

  • so quickly that species who normally could evolve to changes like that aren't able to

  • evolve quickly enough. And so they're going to be impacted by that. So if we get a 2 degree

  • change over the next 100 years we'll see mass mortality in the coral reefs. 1/6 of all ecosystems

  • will be transformed. Then this is where it gets a little bit scary. A fourth of all species

  • will be committed to extinction. It doesn't mean that they necessarily will go extinct,

  • but they will be headed down a pathway of extinction. And so what is extinction? It

  • means when all the organisms of a specific species are gone from our planet. The opposite

  • of that is an extant species is one that's around today. And so just a 2 degree change

  • could have huge impacts on that. And they predicted a 3 degree change could get a third

  • of all species on our planet going extinct. And so when you hear numbers about this being

  • the greatest extinction that we've ever had, this man-made extinction, it's because we

  • are getting changes in the temperature. And those global changes in the temperature are

  • going to impact ecosystems and thereby impact species in that area. They also predict that

  • half of all nature preserves ail be unable to meet their conservation objectives. So

  • this is Pelican Island, one of the first national refuges that we have in the United States.

  • And all of these are going to be impacted by changes in temperature. And the reason

  • why is that species simply can't evolve quickly enough to changes that are 3 degree changes

  • over 100 year period. And so those are going to be man-made changes. But there have also

  • been global changes not caused by man over time. One great example of that would be continental

  • drift. All the continents on our planet, remember, used to be organized into one super continent

  • called Pangea. Pangea broke apart into two subcontinents. We had, this is Gondwanaland

  • or Gondwana. And then we had Laurasia in the north. And so basically when they figured

  • this out, they looked at fossils and where fossils were found. And so we had fossils,

  • not only did the continents fit together, but those continents had fossils that would

  • move throughout all of them. So it was a good way to show, scientists show, that the continents

  • had actually drifted apart. But basically that drifting has caused biogeographical changes,

  • or changes in the life that are living on those planets. And so we can look at where

  • species are found. And we can predict how those ecosystems had changed over time. Or

  • we can at least go back and look through the evidence and figure out what happened over

  • time. Example could be in the mammals or the marsupial mammals. So basically there are

  • three types of mammals. You've got the egg-laying mammals. An example would be the platypus.

  • You have the marsupial mammals. Example would be like the kangaroo. And then you have the

  • placental mammals. Which is essentially everything that you think of as a mammal. And so if you

  • think about where are the marsupials found on our planet, well almost all of the marsupials

  • you can think of are found Australia. So Koala Bear is an example of that. But we also have

  • marsupials in South America. And we have one marsupial in North America. This is the possum.

  • And so how did marsupials get where they were? Well basically what happened is we had marsupials

  • in Gondwana. So we had them in Antarctica. We had them in Australia, and we had some

  • of them in South America. Scientists don't think we had movement into Africa at all.

  • So we had marsupials that are all across here. And so basically as those continents drifted,

  • Antarctica got so cold that the ecosystem changes so much that all the marsupials died

  • off there. We had the marsupials here in Australia that were adrift. So we didn't have the placental

  • mammals there. And then we had those in South America. Now South America eventually drifted

  • into North America. And we had the movement of some of those marsupial mammals into North

  • America, but mostly we had the movement of all the placental mammals down. So we had

  • this battle of the mammals. And so basically as continents drift about, they're going to

  • change their climate. And thereby they're going to change the ecosystems that they have.

  • Now the last and the third type is how meteorological changes can actually impact ecosystems. And

  • so this is el Nino. El Nino happens somewhere between every two to seven years. It kind

  • of centers around 5 years. And basically what'll happen is you'll have a warming of these waters

  • in the Pacific. So along the coast of South America. So you get a warming in this area.

  • And then it'll kind of go away. And then we have la Nina. And then we'll have el Nino.

  • And so we have these changes of the temperatures. And so basically that's going to impact the

  • ecosystems during those time periods. And so this is a marine iguana. It's really cool

  • kind of an animal. Basically what it'll do is it'll sit on land and it'll get warmed

  • up. They live the Galapagos Islands which are going to be right down here. You could

  • imagine in the middle of el Nino. And so basically what they do is they will feed on algae underwater.

  • So they swim down under the water. They feed on algae. They come back up to the surface.

  • They are cold blooded so they have to warm up their bodies so they can digest that food.

  • Then they go down again. Get algae. Really cool looking creature. Look kind of prehistoric.

  • But basically what happens to them during el Nino is that most of the land will actually

  • do well, because we're going to warm up the temperature. We get more precipitation. So

  • a lot of the plants are going to do well. But the algae that live under water are going

  • to be impacted by that increase. So what does that do? Well there is less algae. Now the

  • marine iguanas, when they go down, aren't going to find as much algae. And so they're

  • going to be impacted by that. Or the ecosystem will be impacted by that. And so scientists

  • found that you see a 20% decrease in the length of iguanas during an el Nino period. Now why

  • is that? Well there are two reasons. Number one is that they'll actually shrink their

  • body in response to el Nino. So their bones will actually get shorter. Which is crazy.

  • If you think about what if I were to get 20% shorter when it gets just a little bit warmer?

  • And so there's a stress hormone that's released that actually making their bones short. Which

  • is pretty cool. But there's also selection going on. In other words if your a big marine

  • iguana, you're going to have to dive deeper to find algae. You're going to have to come

  • back on land. It's going to take you longer for your body to warm up. So you can actually

  • digest the food so you can go back down again. And so now we see selective pressure on the

  • larger marine iguanas. And so we're going to see a movement towards smaller body size.

  • And so again, just simple changes in the temperature can have huge impacts on an ecosystem. And

  • even though we might think we're having small impacts on our climate, humans are having

  • great impacts on our climate which is going to kind of feedback out of control over the

  • next hundred years. And we're going to see changes in the environment. But hopefully

  • we can mediate some of that just through eduction. And so I hope that's helpful. }

Hi. It's Mr. Andersen and welcome to biology video essentials 51. This is on

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生態系の変化 (Ecosystem Change)

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    Jan に公開 2021 年 01 月 14 日