Driving out misinformation with blankets, feedback loops and albedos

As week 1 is coming to an end, I realised how misinformed I am about climate change.

When I think about climate change, coral reefs, acid rain, greenhouse gases, less water, milder winters, CO2 bad, renewable energy, fossil fuels, public transport, less cars, plastic, consumerism and governments are a few of the ideas that come to mind but I have to admit that I don’t really know how these elements interact with each other. Sure I have a vague notion about certain dynamics, for example, that burning fossil fuels emit CO2 into the atmosphere, which contribute to increasing the temperature of the Earth. But why and how does this happen?

To really understand the science and facts surrounding climate change is my main motivation for this MOOC.

The Páramo ecosystem in South America: it plays an important role in supporting water regulation and flood control. Located 3,200 and 4,200 meters above sea level along the Andean Mountains, it is home to many endemic species, like the ones seen in the picture called ‘frailejones’. Climate change and human activity (crop and animal agriculture) threaten the existence of páramos.

Week 1 was certainly a good start on this path away from confusion, and it had a funny start too. I hope I was not the only one who giggled when professor Tim Lenton, Chair in Climate Change at the University of Exeter, appeared wrapped in a blanket on a warm summer day.

Screenshot 2015-01-16 11.10.07

The blanket metaphor: a layer of gases act as a blanket warming the Earth’s surface. The most important gas is water vapour along with carbon dioxide, carbon monoxide, methane, nitrous oxide amongst others. Find the full list by clicking on the image.

The message was conveyed and it was an effective strategy – I don’t think I’ll forget it: what prevents heat from leaving and helps keep the Earth’s surface warm is the air trapped inside this blanket made out of greenhouse gases.

I was particularly surprised when I learned that water vapour is the most important greenhouse gas, more important than carbon dioxide in fact. Wait, but why? Why does water vapour play such a strong role?

As we saw in a later video, when more water evaporates, more water vapour is suspended in the atmosphere which leads to more heat being trapped inside the blanket causing a further temperature increase and therefore, more water evaporates. This is called a positive feedback loop and it is estimated to contribute to the blanket effect as twice as much than CO2 alone.

Screenshot 2015-01-16 11.18.29

The water feedback loop: higher temperature results in more water evaporation which in turn contributes to a more powerful blanket trapping even more heat and further increasing temperature. Click on the image for a more detailed IPCC explanation.

This week I also learned a new word: albedo. I hadn’t thought about how the ratio of sunlight reflected back into the atmosphere depended on the Earth’s surface, and as soon as I gave it a few seconds of thought, it made a lot of sense: “wearing sunblock when skiing is very important.” So having surfaces with high albedo helps by reflecting sunlight back into space and surfaces with low albedo absorb sunlight and warm the Earth even more. Oh! So here’s another positive feedback loop: ice has a high albedo (it can reflect as much as 0.9 of incoming sunlight) and as it melts with warmer oceans, which have a low albedo (reflecting only 0.07 to 0.10 of radiation received), there are less of these high reflecting surfaces and therefore, temperature increases.

I did read in the comments that I wasn’t alone in being excited about learning more about albedos. Here is a straightforward map showing Earth’s albedo for November 2014, if you click on it you’ll be directed to an interactive version (in another tab, don’t worry this one won’t close).

Albedo is the ratio between the amount of light a surface reflects and receives. The dark blue regions are surfaces with low albedos and the lighter ones are surfaces with high albedos. The ratio ranges from 0 (no light reflected) to 1 (all light reflected) Source: NASA.

There are a couple of more things to note about albedos: because light has different wavelengths, it makes sense that some surfaces have different albedos depending on the wavelength and also, a surface’s albedo changes depending on the angle of incoming sunlight.

Although forests have a general low albedo, they have a high albedo for green light which they reflect back and a low albedo for the wavelengths they absorb for photosynthesis 

Although green forests have a general low albedo, they have a high albedo for green light which they reflect back and a low albedo for red and blue wavelengths which they absorb for photosynthesis. Click on the image for the source.

After reading other participant’s comments on the discussion board, it seems the video explaining the difference between climate and weather was effective. I wrote about this difference:

“Weather is pulling out my umbrella because it started raining. Climate is having to adopt different farming techniques because of different rainfall patterns.”

I wrote this because a family farmer from Colombia who has lived all her life in the same region and recalls how different the soil, water streams and rainfall patterns are from when she was a child.

So although this post is getting lengthy, I have something I would like to share with you. If you have 5 minutes and 27 seconds, I encourage you to listen to this urgent broadcast by Amy Goodman host of Democracy Now! She draws a frighteningly accurate parallel between big tobacco and fossil fuel companies and how they actively create and spread confusion, misinformation and doubt in order to stop regulation and carry out their business as usual.

It speaks to me because as I said at the beginning of this post, I am not uninformed about climate change, I am misinformed which is worse! But I’m really happy about the progress made this week. I’m very surprised by the amount of participants being active and engaging in the discussion boards either taking a risk and asking a question or helping out others with answers and resources.

See you next week and I hope you find the feedback video for this week helpful. We asked professor Lenton about Planck’s feedback, clouds, angles and albedo, and about the Earth as an entire self-regulating system.

Thank you for reading!




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