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Skip to 0 minutes and 0 secondsAll right. Welcome to Week 1. This is the end of the week of our online course "The Causes and Consequences of Climate Change". Together with me I have Anaïs from the University of Bergen who's a PhD student and we've been monitoring the discussion forums and there's fantastic questions coming out. And so, keep up the good work and stay active. We picked one particular question which we thought would be nice to discuss with you today in this feedback video. That relates to the Amazon and the rainforest and the fires that we've all heard about over the recent few months. So I'll leave it to Anaïs to go through some of the concepts; how that relates to the radiative forcing.

Skip to 0 minutes and 41 secondsSo I decided to start with this first effect which is related to albedo. So the albedo, it is (indicates) how much reflection (radiations) a surface sends back to space. So for example for the ice it reflects at most like 90 percent of the radiation that it gets. These are sent back to space. In the Amazon forest, it is much lower. Like 12-14%. And. And so if you remove the forest... (here we have a tree which is with this albedo and it becomes this) What will happen is that the albedo is is much lower in this second case, meaning that it reflects more solar radiation which are not used to warm the atmosphere.

Skip to 1 minute and 39 secondsIn this case the result will be a cooling (but actually a local cooling).if you deforest or if you burn the trees. So basically we think we're going from a rainforest to a savanna or maybe even worse a desert in these regions. we don't know that but there's the reflection relative to these surfaces is very different. And so this is one of the effects of deforestation.

Skip to 2 minutes and 27 secondsAnd now we can move to the second effect, maybe the one you heard about. The trees are made out of CO2 so it feeds itself with CO2.

Skip to 2 minutes and 52 secondsIt captures CO2 so it's a sink of CO2. The Amazon forest is a major sink of CO2. And also while doing that, when it captures CO2 it also absorbs H20, water, and sends it back to the atmosphere. These two gases are actually greenhouse gases... In reality the CO2 is stored in the biomass in the actual forest but when it comes to cycling CO2 it's not like it takes CO2 and produces oxygen. That's only a minor part of it. In reality it is stored in the biomass, the CO2. Now if you burn this tree or the Amazon forest, what you will do is that you will release all the CO2 to the atmosphere. So you increase the amount of greenhouse gases.

Skip to 3 minutes and 52 secondsyou have these solar radiations that are sent back to space, that we talked about before. But the solar radiations that "stay" warms the Earth and is emitted back.

Skip to 4 minutes and 14 secondsThese are thermal radiations. Then, because of the greenhouse gases, it warms the lower atmosphere ("this layer") which emits back thermal radiations... (it goes back like this). And then you have this effect again and again and the result is that you that you will see this layer because to There is less and less of the long way radiations from the surfaces emitted to space. So it's all contributing to the greenhouse effect and that's what we talk quite a bit about in the first lecture. So basically, burning forests gives more CO2 in the atmosphere and more CO2 in the atmosphere means stronger greenhouse effect. And this will happen everywhere in the planet. So you end up with a global warming.

Skip to 5 minutes and 12 secondsAnd the Amazon stores a really large amount of biomass and CO2. So if you burn all of it, it's the same as also emitting CO2 for 10 years. It's such a large number and it's a question whether it will ever come back again... Once it's gone it might be really hard to have the forest regrow. And then we have a third effect which can also be related to this local cooling (effect 1) and also to the fact that you will not have this flux of water anymore...All this perturbs the local environment and given the Amazon forest is a place of very rich biodiversity... And so You will lose it. Basically you would lose it.

Skip to 6 minutes and 5 secondsIt's also a habitat for Indigenous people. That's what we could call an ecological disaster.

Skip to 6 minutes and 19 secondsSo those are some of the consequences of what manmade changes in terms of deforestation. We very much appreciate your questions and me and Anaïs, and also Asgeir and Mari who are helping with the course, will be online and taking part, and monitoring the discussion. So if you have any questions please ask them. If you find the exercises hard during this week, don't worry. Just do the videos and read the first part of the material that comes with it. And then uh we'll pick up next week with a new topic and see if there are some questions we should summarize in a similar video. So talk to you soon!

Week 1: feedback

In this video the educators together with a PhD student from the University of Bergen discuss a central questions from this week’s lessons.

We will continuously post answers to questions through the discussion forums as well.

The video answers some of the questions you have posed and if we find that additional clarification is needed we will include this in next week’s feedback video.

© University of Bergen. Video by: UiB Learning Lab

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Causes of Climate Change

University of Bergen