REFLECTION WEEK 2

WEEK 2

One challenge more.

This was a really fascinating week, I'm amazed by the complexity of the topic. Personally, I have found the concept of 'snowball earth' very interesting, I have never heard of this before therefore, I required further reading which I thoroughly enjoyed doing.

All the new information of this week have been harder to comprehend however I have enjoyed looking for more information about paleoclimatology, volcanoes, isotopes and more inetresting  topics. But, I think that the most important thing I learnt this week is that the past could give us answers for the future.

I'm really enjoyed this course!!!

PLIOCENE vs TODAY

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. What could explain the changes?


The last time atmospheric CO2 was at 400ppm, humans didn't exist. It was during the ancient Pliocene era, tree million years ago. If we compare the temperatures in that periode with the tempertatures today, we can observe great diferences:

• In the Piocene the global average temperatures were 3 to 4 ºC warmer than today and the polar temperatures were 10ºC warmer too.
• In the Pliocene the Artic was ice free and the sea level was between 5 and 40 meters higher.

However, the most important diference is that in the Pliocene a higher concentration of CO2 would have been entirely down to natural earth processes. Nowadays, the increase of CO2 levels has been happening much more rapidly today than it did during que Pliocene epoch because of the industrialization, the human activities, burning fosil fuels and other process have changed the amount of greenhouse gases emitted into the atmosphere. Therefore we will progressively continue see climate changes over the next years.



Sources:

http://www.esrl.noaa.gov/gmd/ccgg/trends/weekly.html
https://en.wikipedia.org/wiki/Pliocene
https://scripps.ucsd.edu/programs/keelingcurve/2013/12/03/what-does-400-ppm-look-like/
http://www.skepticalscience.com/pliocene-snapshot.html

RECENT PAST CLIMATE CHANGE

What are climate change records?

To understand the world's climate and how it was changed, there are many measurements that scientist have to evaluate.

An obstacle in evaluating past climate change is the fact that a lot of observations are not complete. Climate observations were mainly limited to weather situations and ships, and included measurements made near the land or ocean surface. 

In recent years things have improved, ballon soundings have been widespread over the land, satellites have covered all world and there has been an increase in sub-surface monitoring.

But there are no records of measurements bafore 1600s so scientifics have to use other types of information to investigate further back. These kind of data are called indirect or proxy measurements.

They use the tree-rings to determinate the chages in temperature and precipitation. A tree grows and it adds a new ring around its waistline each year so climate conditions have influence in the tree-ring widths.

The ice-cores have accumulated from snowfall over many millennia so, ice cores can tell to scientifics about temperature, precipitation, volcanic activity and wind patterns.

Coral reefs can be used to obtain measurements about temperature and sea-level changes. Corals build their hard skeletons form calcium carbonate. The calcium carbonate contains isotopes of oxygen that can be used to determine the temperature of the water in wich the coras grews.

Finally, scientist can use the polen grains to identify the type of plant from which they came and identify at what time the sediment, where the pollen laid, was deposited.

Sources:  http://www.ncdc.noaa.gov/news/what-are-proxy-data

How volcanos have influence in climate change?

During this week we have seen that the gases and dust particles thrown into the atmosphere during volcanic eruptions have influences on climate.

Volcanic ash or dust released into the atmosphere during an eruption shade sunlight and cause temporary cooling. Larger particles let sunlight in but do not let heat radiation from the Earth’s surface out, and the result is a warmer Earth. Small ash particles form a dark cloud in the troposphere that block some of the incoming energy from the Sun and the Earth cools. Most of these particles fall out of the atmosphere within rain a few hours or days after an eruption. But the smallest particles of dust get into the stratosphere and are able to travel vast distances, often worldwide. These tiny particles are so light that they can stay in the stratosphere for months, blocking sunlight and causing cooling over large areas of the Earth.

Another component has influence in the climate change. Often, erupting volcanoes emit sulfur dioxide into the atmosphere. The sulfur dioxide moves into the stratosphere and combines with water to form sulfuric acid aerosols. The sulfuric acid makes a haze of tiny droplets in the stratosphere that reflects incoming solar radiation, causing cooling of the Earth’s surface. The aerosols can stay in the stratosphere for up to three years, moved around by winds and causing significant cooling worldwide. Eventually, the droplets grow large enough to fall to Earth.

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

http://volcano.oregonstate.edu/how-do-volcanoes-affect-atmosphere-and-climate
http://scied.ucar.edu/shortcontent/how-volcanoes-influence-climate


How is today’s warming different from the past?

The Earth’s climate changed due to natural causes in the past. Most often, global climate has changed because of variations in sunlight, the effect of volcanic eruptions, variations in the Earth's orbit and fluctuations in the energy that the sun emits. 

These natural causes have influence today but too small compared to human activity. For example, although volcanoes continue to emit carbon dioxide, the amount of carbon dioxide is extremely small compared to human emission because the world population is a little over a trillion today which implies that carbon dioxide emissions have considerably increased.

Sources: http://earthobservatory.nasa.gov/Features/GlobalWarming/page3.php


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

The carbonate is the key to know about past temperatures. Originally, carbote is dissolved in the oceans and it forms the shell of a little sea animal, the foraminifera. Studying the shell of this animal through the carbonate that forms it, scientifics can discover how temperatures have changed.

Carbonate contains oxygen, whose atoms exist in two naturally-occurring stable isotopes, ¹⁸O and ¹⁶O.The ratio of these two isotopes in the shells tells us about past temperatures.

The variability of ¹⁸O in the ocean determinates the temperature. This way, when water evaporates in warm climates, the molecules of ¹⁶O tends to evaporate first, so it has more ¹⁸O in places where lots of water evaporates and less where it rains a lot.
¹⁸O isotope is the first to back down into the oceans in form of precipitation, therefore shells have high levels of this isotope.

Changes in climate that alter the global patterns of evaporation or precipitation can therefore cause changes to the background δ¹⁸O ratio.  

Sources: http://www.giss.nasa.gov/research/briefs/schmidt_01/


How have trees been used to reconstruct different climate variables across the world?

Dendrochronology or tree-ring dating is the method of scientific dating based on the analysis of tree ring growth patterns. Tree rings vary in width denpendent on fast or slow growth patterns during warm or cold periods. the density of cells reflects on the growth patterns (low density results in thin rings, high density produces thick rings). Tree could also have diseases or additional enrichment, which result in the varying growth patterns also.

Tree-rings can provide continuous yearly paleoclimatic records for regions or periods of time with no instrumental climate data. However, different species respond to different climate parameters. Scientifics have to consider when dating trees that most trees are not old enough, so the records do not date back as far as other sources of climate data. This is when crossdating is important to identify similar growth patterns across many trees and make a longer timeline of climate data.This way, increasing the amount of trees utilised to study, the best crossdating results can be obtained.

Sources:
http://web.utk.edu/~grissino/principles.htm#1
http://www.windows2universe.org/earth/climate/CDcourses_treerings.html
https://www.ncdc.noaa.gov/news/picture-climate-how-can-we-learn-tree-rings

How can ice cores provide a record of atmospheric composition?

The most important property of ice cores is that they are a direct archive of past atmospheric gasses. Air is trapped at the base of the firn layer, and when the compacted snow turns to ice, the air is trapped in bubbles.The air bubbles are extracted by melting, crushing or grating the ice in a vacuum.This method provides detailed records of carbon dioxide, methane and nitrous oxide going back over 650,000 years

Also, it is possible to discern past air temperatures from ice cores. This can be related directly to concentrations of carbon dioxide, methane and other greenhouse gasses preserved in the ice. The ratio of oxygen isotopes in the snow reveals temperature, though in this case, the ratio tells how cold the air was at the time the snow fell. In snow, colder temperatures result in higher concentrations of light oxygen.

Sources:
http://www.antarcticglaciers.org/glaciers-and-climate/ice-cores/ice-core-basics/
http://www.earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/

PAST CLIMATE CHANGE

When we think about climate change it's easy to wonder what happened in the past. This week we are going to learn more about how our climate has changed over the last 4.5 billion years.

The Earth's climate has changed many times before. There have been times when most of the planet was covered in ice, and there have also been much warmer periods. Over at least the last years, temperatures and carbon dioxide levels in the atmosphere have increased and decreased in a cyclical pattern.

To understand this cyclical pattern the BBC has published a series of documentaries on snowball Earth. Link or Youtube

Snowball Earth describes the coldest climate inmaginable. In the distant past the Earth froze over from pole to pole. 

But, how could it be possible?

We know that our climate is controlled by some feedbacks and cycles, particulary in this case, the ice albedo feedback, the water cycle and the carbon dioxide cycle. 

 

ICE ALBEDO FEEDBACK

These cycles can be summarised in this diagram which explain the process of the snowball Earth theory:

 

Amazingly, the Earth is capable of selfregulating, with a series of mechanisms that work together and surprisingly gases like carbon dioxide played a powerful role in governing global climate.

Further information in these links;
Snowball Earth
http://www.bbc.co.uk/nature/ancient_earth/Snowball_Earth
https://www.youtube.com/watch?v=Dv0e-zGGgjQ 
http://globalwarmingsimplified.weebly.com/ 

MINDMAP

It'sreally important to think about how organize your ideas because a good organisation can make easier to undertand a topic.


I have found some interesting pages that allow me to elaborate a MIND MAP online.

You can export your mind map as .pdf file .png file, print it or save it.


mindmapfree.com/

https://www.mindmup.com/


You are probably wondering what a mind map is so, a mind map is a diagram used to visually organize information. A mind map is often created around a single concept, written in the center of a blank landscape page, to which associated representations of ideas such as images, words and parts of words are added. Major ideas are connected directly to the central concept, and other ideas branch out from those.

 


For me It's a extraordinary way to organize my ideas about the topic I have been studing.

I created this two mind maps about the topics studied this first week of the course. I hope they will be useful for you.

REFLECTION

At the end of the firs week of this course I test my knoledge of the key principle of climate change and the climate system. It was not difficult to answer the questions and I was certainly got that completely right.

We can reflect on these key questions:

• What are the key scientific principles that explain climate change including the greenhouse (blanket) effect?
• What are the key feedback mechanisms that help to explain why our climate is able to “self-regulate”?
• How can our climate be conceptualised as a system containing a series of components that interact with one another?

Also consider:

• What are the most important themes you have learned this week?
• What aspect of this week did you find difficult?
• What did you find most interesting? And why?
• Was there something that you learned this week that prompted you to do your own research?

In my opinion, this week was really interesting. The NASA's article was really useful to understand how the Earth is covered with a blanket which is in fact made up of greenhouse gases, of which water vapour is one of the most important. What attracted my attention was the idea of the interaction of the different feefback (positive and negative) mechanisms whereby the climate system is able to self-regulate.

Finally, I just want to say that I love to learn new things and this is a new challenge for me because english is not my mother tongue so, some of the different issues were a bit difficult for me to understand at first, but It encourages me to do my best.

Looking forward to next week.

THE CLIMATE SYSTEM, FEEDBACKS, CYCLES AND SELF-REGULATION

Our climate is a system that it is controlled by positive and negative feedbacks as well as natural cycles.

As a system, we can distinguish 5 key components ( the atmosphere, hydrosphere, biosphere, cryosphere and lithosphere ). These components intetract between them through a series of cycles that link every component to another.

 

There are a lot of natural cycles, but a good example is the water cycle.In the picture below you can observe how it works.

To determine the climate state of the Earth is needed to undesrtand the feedbacks that operate in the climate system. There are 3 key feedbacks, water vapour feedback, ice albedo feedback and the radiation feedback.

The water vapor feedback is a positive feedback (in a mathematical way) and has three components: temperature, evaporation and water vapour. If we incresase the temperature, the evaporation increases.

The ice albedo feedback has a significant influence on the climate. The ice reflects so much solar radiation back to the atmosphere because it has a high albedo. On the other hand, the ocean tends to absorb more that it reflects because it has a low albedo, for this reason the ocean is heating. This means that the warming of the ocean will melt the sea ice.

The last feedback is the radiation feedback, it is a good example of negative feedback. It works by cooling an object when the temperature is rising. All objects give off radiation, but the warmer a body is the more radiation it gives off.

To sump up, climate can be conceived as a system that involves different components. The mixture of positive and negative feedbacks cooperates to a self-regulation of the climate system.