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FUTURELEARN: CLIMATE
CHANGE REFLECTION BLOG
1. What the key scientific principles that explain climate change including
the greenhouse (blanket) effect?
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Greenhouse gases/blanket effect, gases and water vapour i.e. the greenhouse
gases [methane, CO2, ozone, nitrous oxide, water vapour] prevent surface heat from
escaping and therefore warms up the Earth. This is a similar effect to that of a
greenhouse, except the greenhouse creates a warm environment by preventing air
flow, whereas the greenhouse gases trap the heat and send it back to the Earth’s
surface- more like a blanket. It is thanks to the greenhouse gases that the Earth is
warm enough to inhabit, without them it would be too cold for us to survive so we
already know that these gases do make a difference.
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Heat reflection and absorption, the albedo of the materials covering the Earth’s
surface determines how much heat radiation is retained and how much is reflected
back out and away from the surface. A surface with high albedo, such as ice, is
extremely reflective, and a low albedo surface, such as water, will absorb a lot of the
heat radiation, causing surface warming.
2. What are the key feedback mechanisms that help to explain why our
climate is able to “self-regulate”?
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Water vapour feedback (positive) in which evaporation is caused through the heating
of water, as temperatures increase the amount of evaporation increases, which
increases the amount of water molecules in the atmosphere. Those molecules then
absorb heat and re-emit it back to the surface, creating more heat, more
evaporation, more molecules, and more heat re-emitted.
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Ice albedo feedback (positive) – ice reflects a lot of heat radiation but the sea
absorbs it, which heats up the system and melts the ice which results in less
reflection so less heat is lost, system is heated up more, more melting and so the
cycle goes on.
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Stefan Boltzmann effect/Planck feedback (negative) occurs when an object such as
the Earth or a human gives off heat because they have too much, this giving off of
heat cools down the object.
The Earth uses these feedback mechanisms to self-regulate. However these feedback
mechanisms only work up to a point, and with 2 positive feedback mechanisms and only
one negative, it’s easy to see how the Earth might get overwhelmed with heat, just like
we can. Global warming = the Earth’s equivalent to hyperthermia!
3. How can our climate be conceptualised as a system containing a series
of components that interact with one another?
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The climate is a system made up of 5 components,
the atmosphere,
the hydrosphere,
the cryosphere,
the lithosphere,
the biosphere,
which are all connected as demonstrated by the water cycle
Also consider:
1. What are the most important themes you have learned this week?
This is the first time I have heard the term “blanket effect” in place of the greenhouse effect.
2. What aspect of this week did you find difficult?
The explanation of the water vapour feedback mechanism initially confused me.
3. What did you find most interesting? And why?
The idea of the blanket effect, probably because it was the first time I had heard it.
I also like the IPCC poster because it’s very informative but concise.
4. Was there something that you learned this week that prompted you to do
your own research?
Climate change has been one of my favourite topics since before doing my BSc, so I’m
always researching it, hence this course!
5. Are there any web sites or other online resource that you found
particularly useful in furthering your knowledge and understanding?
http://www.un.org/climatechange/summit/
http://www.climateconversation.wordshine.co.nz/
http://www.climategathering.org/climate-conversations-2015/
https://www.climatechange.govt.nz/science/timeline-of-change.html
http://www.global-greenhouse-warming.com/anthropogenic-climate-change.html
http://earthguide.ucsd.edu/virtualmuseum/climatechange2/07_1.shtml
http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/earth/earthsatmosphererev5.sht
ml
http://www.natureworldnews.com/articles/4963/20131119/dinosaurs-lived-in-a-low-oxygenworld-study-suggests.htm
http://wattsupwiththat.com/2010/04/26/climate-change-and-the-dinosaurs/
http://www.mfe.govt.nz/sites/default/files/media/Climate%20Change/nz-greenhouse-gasinventory-snapshot-2015.pdf
Produce a diagram illustrating the feedback mechanisms resulting in a
snowball earth.
Diagram 1
These two (positive) feedback mechanisms allowed the ice cover to expand further towards the
equator than ever before, eventually the surface was too cold due to so much radiation reflection
and so little radiation absorption, that the growing polar caps eventually met in the middle covering
the entire surface of Earth.
What are climate change records?
Climate data is the 30 year averages of global weather. A climate change record is a compilation of
information regarding the climate’s patterns and changes. The most common type of record today is data
collection, which goes back to the 1700’s (exact year varies depending on location), however observation
stations methods of data collection only became uniform in 1914. Often Met Office refers to the “record”,
meaning the data collected between today and 1914. Atmospheric temperatures are collected from various
satellites, while surface temperatures are collected from thermometers and weather stations positioned on
numerous buoys and ships. There is a lot of contention around how reliable the post 1914 data is, and this
contributes largely to the climate change debate.
To obtain information about climate prior to any kind of monitoring, we use proxies, such as the isotopes
that are preserved within core samples, sediment compositions and deposits within those sediments. Tree
rings, ice cores, ocean and lake sediments can provide much climate change data, as can coral and pollen.
Less scientific but helpful none the less, are written historical records such as fishermen’s log books,
personal diaries (particularly those of gardeners and travellers!).
How do volcanoes affect climate change?
Initially after an eruption there will likely be a decrease in global temperatures due to the smoke and ash
blocking the sun’s radiation, as well are particulate matter reflecting radiation back into the atmosphere.
However, an eruption releases a large amount of carbon dioxide into the Earth’s atmosphere, essentially
wrapping it up in a blanket and preventing heat from escaping. The Earth’s surface will then experience an
increase in temperature.
How is today’s warming different from the past?
The warming occurring in recent times differs from that of the past because it is not predictable and cannot
be explained away by natural events.
What is the role of isotopes in determining temperatures from the past?
Isotopes are versions of an atom or an element that have the same number of protons, but different
numbers of neutrons. Ascertaining the ratios of the isotopes present within a core sample (usually an ice
core or sediment core) can provide information regarding the atmospheric gases and temperatures at the
time of the isotopes becoming “locked” into the sediment or ice.
How have trees been used to reconstruct different climate variables across the world?
The grow rings present within a core sample of a tree trunk shows us the rate of growth of the tree during a
certain period. From that growth rate we can gathering information regarding the (weather) conditions
experienced by that tree. Cross referencing with neighbouring trees provides more accurate information.
How can ice cores provide a record of atmospheric composition?
Oxygen isotopes become locked in ice cores, the ratios of which vary depending on temperatures.
Understanding past climate changes can be key to understanding the state of the climate in
the future. On May 9, 2013, carbon dioxide levels in the atmosphere reached the level of 400
parts per million (ppm). The last time the Earth experienced this level of carbon dioxide was
in the Pliocene about three to five million years ago. Investigate what the temperatures
were during this time period and compare them to today. Using your knowledge from the
course so far, what could explain the changes?
The Pliocene was a warmer time with higher sea temperatures, presumably there was greater volcanic activity
creating a larger CO2 output thickening the blanket which produced higher surface temps, as well as the ocean
absorbing more of it thus causing the level to rise. I'm guessing the CO2 output then was too extreme for Earth
to self-regulate as well as it is can today?
2.8 Reflect
What are the most important themes you have learned this week?
The most important themes this week have been the feedback mechanisms discussed in
week 1, but put into the context of the Earth’s climate history, and understanding how we
have in fact had higher temperatures and higher CO2 levels in the past but that doesn’t
make what we’re experiencing in modern times, less concerning.
What aspect of this week did you find difficult?
Trawling through opinion to find fact. Many sources discount historical climate data as being
inaccurate or insufficient, while others consider it to be perfectly reliable. This disagreement makes
for some rather conflicting research!
What did you find most interesting? And why?
I consider the Earth’s self-regulation to be an interesting topic, particularly in terms of “then” (i.e.
when CO2 and temps were higher) compared with now, because understanding that seems pretty
vital in understanding the climate change we are experiencing now, and deciding whether to be in
camp climate action or camp climate denier.
Was there something that you learned this week that prompted you to do your own
research?
2.5 calls for one question to be answered, but I’ve tried to answer all six and I look forward to
doing all of the recommended reading and expanding on them all when I have finished playing
catch up!
I’m also keen to do more research on the Pliocene and expanding on my response to the explain
the changes section.
Are there any web sites or other online resource that you found particularly useful in
furthering your knowledge and understanding?
Unfortunately I have only had a chance to look at the ones provided in this course at this stage.