Week 3

Week 3

I've devoted more time to this week (6 or 7 hours instead of just a morning) and was pleased to score well in the test.

My responses to previous sections were entered in the comments, so here are my reflections on today's course:

1. Most important themes:

I think it's becoming very hard for the average person to avoid "connecting the dots" between extreme weather events and climate change, but I also wonder whether our growing awareness could also be in part a result of today's global 24/7 news coverage? Would we have been so aware of hurricane Sandy, or Australian heatwaves, etc. 50 years ago? For example I didn't know that the North Sea surge of 1953 killed over 1800 people in Holland.

It was interesting to see the graphics projecting future temperature & precipitation changes with different future levels of CO2. It's amazing this information is all available online!

While I knew about the carbon cycle, I wasn't aware of the significant part played by the deep ocean.

2. Difficulties:

The questions in 3.4 were all phrased in the present tense, e.g "What places on Earth have experienced the largest warming from 1980-2004? Are the areas that are experiencing the most warming..."

The charts show future projections for 2050-2074, and I wonder whether "will have experienced" and "will be experiencing" would be clearer. Or did I miss something?

3. Most interesting:

I enjoyed looking back and remembering several extreme weather events in UK during my lifetime, and relating them to where they took place, and to the storms and rainfall at the time.

4. Further research: 

I used Google and Wikipedia to find out about the Thames Barrier, and potential future flood damage in UK. Between 1983 when it was built and 2000, it was closed on average twice a year. Between 2000 and 2010 the average was 8 times a year. During every one of 11 days this past January, it was opened before the high tide, and on one occasion the tide rise high enough to spill over the river bank wall at one side of the barrier.

5. Useful websites:

The World Bank datasets are a fantastic resource with a vast amount of economic and population data by country.

Friends of the Earth - www.foe.co.uk - have good booklets and reports to support local activism.

On that note, I attended a talk last week by Polly Higgins about her campaign for Eradicating Ecocide, and urge everyone to sign up here: www.eradicatingecocide.com/wish20/

Week 2

Monday 20 January

Ancient past climate

Water & water vapour played a key role, enabling the creation of life forms but also nearly wiping them out through at least two extreme temperature swings caused by positive feedback effects. See http://www.snowballearth.org/ & http://www.bbc.co.uk/nature/ancient_earth/Snowball_Earth

BBC site noisily illustrates how extreme temperatures came about, and left evidence in rock formations.

Here is my feedback diagram:

Another course participant, Takver Takvera writes a climate change blog with a very full description of this process: http://takvera.blogspot.com.au/2014/01/exclimate-ice-albedo-feedback-mechanism.html

Recommended reading about climate records:

What are climate change records?

Met Office: http://www.metoffice.gov.uk/climate-change/guide/science/explained/observations

Rocks, ice cores and tree rings provide evidence for the state of the atmosphere at different times and locations, including temperature, amount of radiation and atmpspheric composition

How do volcanoes affect climate change?

Volcanos: http://earthobservatory.nasa.gov/Features/Aerosols/

Volcanic eruptions deposit vast amounts of dust in the atmosphere over large parts of the glove, causing increased albedo and short term reduction in temperature.

How is today’s warming different from the past?

"Natural variations" in the past several thousand years have not included the sudden rise in temperature accompanied by the similar sudden rise on atmospheric CO2 taking place over the past 100 years, and occurring even more rapidly today.

What is the role of isotopes in determining temperatures from the past?

Role of isotopes: http://www.giss.nasa.gov/research/briefs/schmidt_01/

The rate of radioactive decay of isotopes can be measured very precisely, enabling samples of rock or ice which contain an isotope to be accurately dated, which in turn dates the climate evidence contained in the samples.

How have trees been used to reconstruct different climate variIce cores: http://www.earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/ables across the world?

Tree rings: http://web.utk.edu/~grissino/principles.htm#1

The spacing and contents between the rings which grow around the tree every year, provide evidence of the amount of biological activity resulting from solar radiation, humidity and temperature during that year. Counting the rigs inwards dates each ring, or in older tree relics, carbon dating is used.

How can ice cores provide a record of atmospheric composition?

Ice cores: http://www.earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/

Snow is deposited on the ice surface each year, and its texture and chemical compositon changes in summer and winter. As each layer of snow is overlaid by another, the lower layers become compressed so that many thousands of years of ice layers may be examined by extracting a deep ice core.

400 parts per million

Two things are remarkable about CO2 reaching 400ppm:

1. No previous climate records reached this level with similar rapidity,

2. It is correlated closely with the known output of CO2 caused by extraction and burning fossil fuels during the industrial era

The last time CO2 reached similar levels was during the Pliocene period between 3.3-3.0 mya, when the average climate was 2-3 degrees C warmer and sea levels were 25 m higher. The higher temperature resulted from near-complete absence of ice, however this period was marked by overall cooling and appearance of polar ice caps. It began with extensive forestation which disappeared as the climate cooled.

Reflection:

Disappointed to achieve 9/15 in the test, having dropped 6 points on the aerosols and proxy records. I should have gone for only one answer rather then try to find all the correct answers. Instead, I scored 0, and need to study the correct ones. I believe volcanic eruption and desert dust to be aerosols, and trees rings and ice cores provide climate proxy records.

Important themes: Climate history, how it has been determined, and causes of variation
Most difficult: Multiple choice questions with more than one correct answer - can I get a correct score with just one answer? Also, video segments include lots of entertainment but I get impatient looking out for the key points.
Most interesting: What kinds of changes or events cause positive feedback loops to stabilise and then  reverse? Volcanic eruptions, asteroid impact, Milankovitch cycles
Own research: Geo-engineering by seeding water vaapour - to do
Websites: Takver Takvera's blog at http://takvera.blogspot.com.au He has a whole day ahead of me to develop his website in Melbourne, but it's very impressive even so! I'm interested to see what other course participants are producing.

Week 1

13 January

I am actually posting this in Week 2, based on notes made privately after the first session.

Summary

In Week 1, it was noted that the scientific principles of climate change began to be investigated nearly 200 years ag, and I wanted to know who first looked at these issues. I found a timeline at http://www.skepticalscience.com/cshistory.php 

While infrared radiation (heat) was described by Herschel in 1800, and Fourier described the role of earth's atmosphere in retaining heat from the sun, it wasn't until 1860 that Tyndall identified the role of CO2 in blocking the escape of heat from the earth's surface.

From previous studies, I knew about the roles of CO2, Methane and CFCs as greenhouse gases, but I wasn't so aware of the role of water vapour and Nitrous oxide. I know how clouds are formed, but need to understand more clearly how water vapour can form a positive feedback loop. The current well-documented shrinking of polar ice is an alarming positive feedback loop.

Reflection

Key Scientific principles:

Greenhouse gases absorb long wave radiations in the atmosphere, which are emitted when shortwave radiations from sun interact with biosphere, hydrosphere, cryosphere, lithosphere

Positive feedback cycles include water evaporation & ice melting, negative feedback cycles include rocks cooling

Themes

I already knew about climate vs weather, CO2 greenhouse gas, long wavelength radiation (heat) vs. short wavelength radiation (light)

Didn't know several scientific terms, water vapour as a greenhouse gas, percentages of radiation reflected & absorbed in IPCC FAQ 1.1

Researched history of climate science at http://skepticalscience.com, Fourier, Tyndall, Arrhenius et al.