Glaciers and global warming

Glaciers and global warming

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This task is about glaciers and global warming.

Question 1Change answer

The debate
Some people say glaciers worldwide are getting smaller and that this is a sign that global warming really is happening. But some glaciers, such as Franz Josef in New Zealand, have got bigger in the past.
So other people say this proves global warming is not happening!
a) To make an informed decision about something it is important to gather enough evidence. Use each piece of information about glaciers in the table below to write a question you would need to ask about Franz Josef before you could make an informed decision about whether its recent changes are evidence either for or against global warming.
Fact
Question
i) There are many glaciers in the South Island and elsewhere in the world. Is Franz Josef changing in the same way as other glaciers?
ii) Glaciers in steep, narrow valleys are less affected by small overall temperature changes than wider glaciers.
iii) Some glaciers have a layer of rubble on top. It makes them look dirty but also acts like a cooling layer of insulation that traps the cold.
iv) Changes to glaciers are related to weather that happened several years ago.
v) Glaciers have always gone through periods of retreat (shrinking) and advance (growing).

Question 1Change answer

b)  Why is it important to think about more than one piece of evidence before you make up your mind about something?
Task administration: 
This task can be completed with pencil and paper or online.
Copyright: 

Image source: User: Dramatic, wikipedia.org | CC-BY-SA 3.0
Level:
5
Curriculum info: 
Science, Knowledge, Planet Earth
Keywords: 
global warming, climate change, glaciers, evidence, systems thinking
Description of task: 
Students formulate questions about glaciers and climate change to show awareness that informed opinions are based on inter-related aspects of evidence rather than individual instances.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask. 
 
Capability: Use evidence
This resource provides opportunities to discuss the reasoning skills involved in selecting combinations of data to provide evidence.
Science capabilities: 
Use evidence
Answers/responses: 
  Y10 (08/2006)
a) ii) Broad question: 
What shape is the Franz Josef glacier?

More specific question: 
Does the Franz Josef glacier flow down a wide or a narrow valley? 

 difficult
 
iii) Specific question: 
Does the Franz Josef glacier have a layer of rubble on top?		 moderate
iv) Broad question: 
What sorts of weather patterns are common in the Franz Josef area? 

More specific question: 
Was the weather unusually cold in the Franz Josef area several years ago?

 difficult
v) Broad question:
How has the Franz Josef glacier changed over time?
What is Franz Josefs history of shrinking and growth?
Is Franz Josef just in its growth phase?

More specific question: 
Is the overall trend for the Franz Josef glacier to be gaining or losing its ice volume?

 difficult
b) Franz Josef being recently in retreat is not enough on its own to justify the opinion that global warming is or is not happening. The pattern at any one moment in time may not represent the long-term trend. In addition, each glacier has specific features (e.g., its shape and physical features such as moraine cover) and contexts (e.g., its location and typical weather patterns) that contribute to its behaviour. These cannot be generalised to all glaciers.

Student responses to this question fell into several different types:

"Both sides of the story"; taking all relevant aspects into account and possibly changing your mind:
  • Because one piece of evidence could have been influenced by other factors. If there are many pieces of evidence saying the same thing it is more likely they are true.
 41% of
responses
"More is better"; a general sense that more pieces of evidence are a good thing without saying why:

  • Because you need all the facts before you judge.
  • Because you need to see the whole picture.
 14% of
responses
Use of terms related to scientific ways of investigating (e.g., fair test; getting proof, looking for outliers, greater accuracy, developing new theories, seeking alternative explanations etc.)

  • So you have all the evidence – a fair test.
  • Because it might just be a coincidence that this thing has happened. You need   a lot of proof before you can confirm anything.
 7% of
responses
Opinion-based decisions; while these might acknowledge there could be two sides to a story, the emphasis seemed to be on persuading others to your point of view rather than deciding with reference to all the evidence to hand. Some students saw knowing more as a useful cover for ignorance:
  • Because different evidence is told by people with different opinions and you must hear everyones opinion before making up your mind otherwise it's biast [sic].
  • Because it helps you. Instead of just one thing, you can have 3-4 things to say.
  • More evidence means there is a more likely chance for both sides to win.
  • So if it doesn't work you can use the other [evidence].
 7% of
responses
Local conditions: a few responses were specific to the glacier context.
  • Because different glaciers behave in different ways.
 2% of
responses
One of these answers showed how lack of contextual knowledge about glaciers can make it difficult to meaningfully complete the task.
  • Because if you wanted to move a glacier to a cooler place to keep it colder it might say in another fact that they can't survive when they are moved!!
No response, or an answer that did not address question.
 21% of
students
Teaching and learning: 
To find out more about New Zealand glaciers growing from 1983 and 2008, read Explaining New Zealand’s “unusual” growing glaciers.
Diagnostic and formative information: 

Glaciers as complex systems
It was apparent that some students have little understanding of what glaciers are, or how they change over time. This item draws on systems thinking, although this is not especially apparent in the item itself. The table below summarises factors we considered when shaping it.

Factor Advance (or slower retreat) is more likely when Rapid retreat is more likely when
Geography Glaciers that start at higher altitudes are likely to stay colder for longer. Glaciers that flow into lakes melt more quickly if the lake gets warmer.
How steeply the glacier falls Steep, shorter glaciers "flow" more rapidly as gravity pulls the ice towards the sea. Longer flatter glaciers flow more slowly.
Surface area exposed to sun Steep narrow valleys have relatively less ice exposed on the surface. Broad, flatter glaciers have more ice exposed to the sun's rays.
Amount of rubble on surface of glacier Layers of stone and gravel insulate the ice and slow down melting. Clean ice on glacier surface melts more quickly than ice covered in a layer of rubble.
Change in weather patterns in the area* Continual cold and stormy weather causes a build up of snow and ice at the head (top) of the glacier. Warmer weather results in smaller winter snowfalls, so less new ice forms.
Weather in the recent past New Zealand's glaciers are affected by what happened several years ago in that area. This is because it takes time for ice to form from snow and flow into the glacier from the mountain head.
Shape of valley Both advance and retreat happen more quickly when the glacier is in a steep, narrow valley than when the glacier is broad and wide.
Natural cycles Even when global conditions are relatively stable glaciers tend to show cycles of advance and retreat. Each cycle is about 11 years long.

* The West Coast glaciers are unusual in their exposure to westerly winds and higher rates of precipitation (snow and rain) than glaciers on the eastern side of the Southern Alps.
El Nino weather patterns caused a particularly cold late-winter/early summer in 2004. For more information see: http://www.niwascience.co.nz/pubs/mr/archive/2005-08-30-1

Developing thinking as a key competency

It is important that students develop the skills of critical literacy so that they are able to make informed decisions framed by the processes and values of science. Part a) asked students to shape critical questions that turned a general science idea into a question specific to one situation. This is an important part of using established science ideas when investigating any complex question or issue. For this reason it could be seen as an important skill for democratic participation in decision-making, which most teachers would see as an important reason for learning science. However the task seemed unfamiliar to most students. Many identified this as the hardest part of the question set and the non-response rate was high – more so in some schools than in others. (The differences between schools were very marked for this item.)

Some students, mainly females, completed the task successfully but complained that it made them feel "dumb" because they didn't know what to do. Others responded that they hadn't learned about this topic and so didn't know the "facts" to give. Unfamiliar types of questions and skills are unsettling at first and the overall pattern of responses suggests that students need lots of practice to become more fluent at asking critical questions of this type.

One teacher scaffolded the task for his students by showing them how to complete item ii). He commented that this was a more straightforward example than the one we gave (we agree – we are learning more about how to structure such tasks too). Doing the next example had helped his students get started. You could consider editing the task to make the first response item the given example. Cut and paste student task into word processing program. See Changing an assessment resource.
Next steps: 

Gaining "meta-knowledge" about thinking
Gaining the language to be able to "think about thinking" is an important aspect of developing this key competency. Students' responses suggest there is an opportunity here to highlight different types of questions, and the purposes for which they are appropriately used. The item required students to ask a specific question from a general pattern.

Other types of questions posed by students were:  

Questions to find information or explanations
Some students wrote questions of the type that is familiar to them from traditional school work.

  • Why have some glaciers got rubble on top?
  • How long does it take for the weather to affect the glaciers?

These types of questions often revealed interesting misconceptions:

  • Do glaciers change in size relative to there [sic] distance from the sun?
  • How do glaciers protect themselves from the sun?

Investigative questions
Some students seemed to think a "fair testing" type of question was called for:

  • By how much does a rubble layer slow down melting?
Adversarial questions
A few students wrote "rebuttal" type questions of the sort that might be used in a debate or court of law. They seemed to see this as a combative exercise, rather than one of attempting to establish an overall picture of the relationship between parts and events in a complex system.

  • Does appearance not matter? Rubble can be the preserver of our glaciers.
  • Hot air rises. Wouldn't it affect the steep ones more?
  • Is it scientifically proven that rubble insulates glaciers? Has it been measured?

Pattern-seeking questions
A few students shaped questions that captured the essence of the relevant factor by extrapolating from Franz Josef to glaciers in general. Examples are:

  • Does the age and global position of Franz Josef simply mean that it is in advance while others are in retreat?
  • Are other glaciers exposed to same/similar weather conditions increasing as well?

Some students got the general idea but did not shape sufficiently specific questions. Examples are:

  • Where is Franz Josef situated?
  • What was the weather like in New Zealand several years ago?

Use of evidence in making a case
If you use this item as a group discussion activity, consider giving students examples of the types of responses that can be made to question b). They could analyse their own responses to see which type(s) they fall into. They could further discuss the adequacy of each type of response.

http://www.metservice.co.nz/default/index.php?pkey=190512&ckey=192955

https://www.wgtn.ac.nz/news/2017/02/explaining-new-zealands-unusual-growing-glaciers

Ministry of Education (2005). Connected 2. Wellington: Learning Media. (This resource is freely available to primary schools.) It contains an article that compares changes in glaciers and lava flows over time. The teachers' notes outline an Internet search activity that could help students become more aware of the places where glaciers are found, their names and general geographic features.