Week 2 questions part 1

I am attempting to answer all six questions posed this week because I find the extra reading and investigation of the subject truly fascinating. Here are the first 2...

What are climate change records?

There are many different ways in which data from climate has been recorded. In the modern past it has been with the use of satellites and advanced weather stations taking data from the atmosphere in balloons, or from below the surface of the ocean. The provide world-wide coverage. Going further back in the last century the data was recorded in weather stations that provided limited geographical coverage. If we go back more than 100 years there are very few, isolated records. Beyond a couple of hundred years ago the data record collected by people starts to peter out. We therefore need to turn to proxy records. These come from a wealth of sources. From the studies of tree rings, ice cores, coral reefs and sediment layers, to name some of the main ones. Data collected from these are not as accurate as data collected directly.
However, when the results are overlapped and compared a record of the climate in Earth’s past and how it has changed emerges, from 100’s of years (tree-rings) to hundreds of 100’s (ice cores) to millions (sediment layers) before present.


How do volcanoes affect climate change?

The constant shifting of the Earth’s tectonic plates produces volcanic eruptions in some parts of the world. When these occur vast clouds of ash are emitted into the atmosphere, along with other aerosols. One case study is that of the eruption of the Laki fissure system in 1784. Benjamin Franklin recorded that the following months were much cooler than expected across Europe and inferred that the volcanic eruption could be the cause. Records show that temperature across the Northern Hemisphere that year dropped by about 1 degree, which had severe impacts across the area in the form of food shortages and famine. So how did this eruption cause such a dramatic cooling effect? The aerosols and gasses emitted from the eruption form sulphates in the atmosphere. Sulphate aerosols can settle high in the atmosphere and remain there for months or even years. These aerosols are considered ‘light’ which means that they have a high albedo level and are very effective at reflecting radiation from the sun back into space, cooling the surface below. A good diagram of the overall interactions and effects of a volcanic eruption can be found in the paper “Volcanic eruptions and climate” by Alan Robock. See below, or HERE for a link to the full article.

Refs: 

http://www.aos.wisc.edu/~aos915/Robock_2000.pdf

http://www.scientificamerican.com/article/how-do-volcanoes-affect-w/

http://www.cru.uea.ac.uk/documents/421974/1295957/Info+sheet+%2313.pdf/8f7e9115-8a35-4ec2-b45d-f3ba36524a44

Week 1 Reflections

 The course has recommended I have a good old think about what has been covered in each week. A good idea to make sure what I have learned doesn’t trickle out of my brain straight away. They have kindly provided some prompt questions which I have copied below, along with my thoughts…

1. What are the key scientific principles that explain climate change including the greenhouse (blanket) effect?

Firstly I learned that the “greenhouse” effect is not actually a very accurate way of describing what is happening here. Greenhouses keep their heat in by preventing the circulation of air and the loss of heat through convection. What’s happening around the planet is more accurately equated to the effect a blanket has in preventing heat loss through insulation. Key gasses present in the atmosphere act like a blanket trapping heat in. These gases are water vapour, methane, ozone and nitrous oxide. Of course we need this effect. It’s what makes the Earth a suitable temperature to support life. Otherwise it would be a rather chilly 30 degrees colder than it is.

The climate is regulated by the Earth through the system of absorption and reflection of heat radiation produced by the sun (more in point 2).

The Met Office studies the climate of an area over the course of about 30 years. It is this timescale that is the predominant difference between climate and weather.

2. What are the key feedback mechanisms that help to explain why our climate is able to “self-regulate”?

The three main feedback loops are

a.    Water vapour. An important greenhouse gas, this feedback loop is one that most people will be familiar with from articles relating to climate change and the melting of the polar ice caps. Radiation from the sun hits the surface of water bodies on the Earth. The heat causes evaporation, creating molecules of water vapour in the atmosphere. These in turn absorb radiation from the sun and re-emit some back down to the Earth’s surface, causing more evaporation, and so the loop continues.

b.    Ice albedo. This feedback loop is one that most people will be familiar with from articles relating to climate change and the melting of the polar ice caps. As with the above loop, radiation hits the Earth’s surface and is absorbed by water bodies, but reflected by the ice sheets. If the system warms up, the ice starts melting and therefore reducing in area, concurrently increasing the surface area of the more reflective water. More heat is absorbed, more ice melts and the feedback loop continues.

c.    Radiation. As heat is released from a single body it cools. It therefore has less heat to omit, but as it does so cools further, diminishing in this feedback loop.

A and b are examples of positive feedback, where the overall effect is an amplifying one. In these cases leading to increasing temperatures. C is a negative feedback loop, where the temperature continues to decrease as radiation is emitted. This combination of positive and negative loops helps the Earth to self-regulate. The danger is if something changes this balance, giving one of the effects greater influence.

3. How can our climate be conceptualised as a system containing a series of components that interact with one another?

The course uses the water cycle as an example of a system in which something exists in different states and is constantly shifting. A system most people are at least loosely familiar with. The water cycle is affected by such things as heat radiation, surface vegetation and physical things such as mountains. The climate can be an extended version of this system.

The five “spheres” that make up the climate system are

a.    The atmosphere (the air)

b.    The hydrosphere (all water bodies)

c.    The biosphere (the living organisms)

d.    The cryosphere (ice sheets and glaciers etc)

e.    The lithosphere (the Earth’s crust)

These five systems combine to make the climate system as a whole. All interacting with each other.

The course also asked me to consider some other points and details I’ve learnt in the content of week one. In here I have to add the new vocabulary. Albedo is a new word for me. But it is attributed to a familiar concept. It refers to the absorption rate/reflectivity of different surfaces on the Earth. So, for example, ice has a low albedo. It is highly reflective. Water, on the other hand has a high albedo. It absorbs radiation from the sun. As discussed in point 2 above.

From a zoologists view point I am looking forward to learning more about the biotic factors involved in climate change.

I have had a quick look around the internet and the New Scientist has a good round-up of different aspects of climate change. It’s a few years old now, but not enough to matter! Find it here.

Day 1

So here it starts. For the next 8 weeks I will be studying a course through the University of Exeter and Future Learn called Climate Change: Challenges and Solutions. It's an interesting topic and I'm looking forward to the next few weeks of learning and participating in the discussions.