The Greenhouse Effect and its Hazards

The activity is focused on the reading of the book by Houghton, J. Global warming: The complete briefing (Cambridge: Cambridge University Press, 2015) 5th edition. Chapters 1 and 2, pp.1–33.

By reading this chapters, the professors make us develop our own knowledge on climate change and greenhouse effect specifically by answering a list of questions which I will adres here below.

            What major climate anomalies and episodic events occurred in 1998?  

Reading through the first chapter of the above mentioned book as well as a couple of online resources (Earth Temperature in 1998 Is Reported at Record High, by William K. Stevens in the NYT or Did global warming stop in 1998? by Rebecca Lindsey in climate.gov) I discover the events of 1998.

As explained very well by the NYT article, the average temperature globally in 1998 has been the highest ever measured since people began to measure it, with an average of 4.62 degrees F (12.57 degrees C). Interesting as well to notice that the United Nations, said 1998 would be the 20th year in a row that the globe's surface has been warmer than its recent long-term average.

The cause of this event have been attributed by scientists to El Nino, the extensive pool of warm water that develops from time to time in the tropical Pacific, and therefore it predicted correctly a cooling down of the temperatures in the years past 1998. Moreover, this also resulted in an unprecedented peak in extreme rainfalls during the year 1998 in Kenya and Somalia, record rainfalls in California as well as a drought in Indonesia (overall the world experienced a high increase in tropical cyclones).

            What environmental hazards are associated with climate change and who is most affected?  

Environmental hazards are geological phenomenon caused by the change in climate, among these floods, droughts, sea level rise, and increasing number of tropical cyclones.

The first obvious effect of an environmental hazard is the geological one to the flora and fauna of the region where the event occured.
Second effect is the socio economic one which is very much dependent on the political region: a first world economy will be much faster and easier recovered than a third world one, both in financial and economical sense as well as in the humanitarian one.

            How do volcanic eruptions affect temperature extremes?  

Very interestingly so, the release of ash particles (extremely small rock particles) and sulfuric dioxide which mix with water particles into the stratosphere and atmosphere creates a large volcanic cloud which blocks the sunlight from reaching the earth and therefore cooling the temperature.

            What are adaptation and mitigation?  

In approaching some possible actions to resolve or slow down the effects of climate change, we can go in two directions.

We can either move towards ADAPTATION, which by definition it has an impact on the already visible effects which we adapted already to in order to decrease the contingencies.

On the other hand, we can approach a MITIGATION effect, which as a contrary has a more long-term strategy to it in order to try and decrease our emissions of greenhouse gases and therefore alter the whole course of climate change from its roots.

            What is the greenhouse effect?

Step one: The sun emits radiations which touch the earth surface and warm it up, about 84% of this remains on the planet, the rest is reflected back to space or scattered around.

Step two: As a response, the earth must emit itself some thermal radiation to counterbalance this energy, during the night for example this cooling effect is experienced visibly by frosting. The amount of thermal temperature the earth emits depends on its temperature - the warmer it is, the more radiation it emits.

Step three: The gases which make up the atmosphere, nitrogen and oxygen, do not absorb any thermal radiation. It is the water vapour, carbon dioxide and some other minor gases present in the atmosphere in much smaller quantities acting as a protective blanket for the living beings on the earth surface (causing a difference of 20 to 30°C) and warming them up. This is the natural greenhouse effect.

            What is the ‘runaway’ greenhouse effect?

On a planet like Venus, where only 1 to 2 % of the sunlight reaches the surface, it could be imagined that the average temperature is quite low. On the contrary, because of the very thick absorbing atmosphere of carbon dioxide present around the planet, little of the thermal radiation from the sun can get out.

The history of the formation of such an effect comes from the primordial release of the gases interior to the planet, specifically water vapor, a very powerful greenhouse gas, this would cause the temperature to rise and therefore evaporate more and more water creating more and more gas exhausting all the water resources of the planet and leaving only a thick cloud of greenhouse gases.

Why did the same not happen on Earth, a planet of similar seize?

The reason is very simple: Venus is located closer to the sun than the earth. The starting temperature of venus is much higher than the one of the sun.

References:

Houghton, J. Global warming: The complete briefing (Cambridge: Cambridge University Press, 2015) 5th edition. Chapters 1 and 2, pp.1–33

https://scied.ucar.edu/learning-zone/how-climate-works/how-volcanoes-influence-climate#:~:text=The%20gases%20and%20dust%20particles,the%20characteristics%20of%20the%20eruption

https://www.usgs.gov/faqs/do-volcanoes-affect-weather

https://www.nytimes.com/1998/12/18/us/earth-temperature-in-1998-is-reported-at-record-high.html

https://www.climate.gov/news-features/climate-qa/did-global-warming-stop-1998#:~:text=No%2C%20but%20thanks%20to%20natural,decades%20leading%20up%20to%20it.