Climate change: what could possibly go wrong?

Credit: pixabay

Explain the basics of the blanket effect 

It's like this. The greenhouse effect is like Manchester United, an unrivalled explanation of how CO2 emissions warm the planet. Then along comes a noisy neighbour, which explains the process even better, and buys up all the best players/feedbacks.

The greenhouse effect is a flawed description of how the Earth is warming, because a sealed greenhouse doesn't let much warm air out or cool air in. That's how it stay warm. The blanket effect is a way of describing the effect greenhouse gases are having on the Earth and its atmosphere. The Earth is warmed by heat from the Sun. Some of this heat is radiated back into space; however, the blankets of greenhouse gases prevent some of this heat radiation, and cause it to be reabsorbed, warming the Earth.

Describe one positive and one negative feedback mechanism in the climate system 

A positive feedback is like this: climate change sceptic Donald Trump is elected president of the US. He promotes policies that increase both global warming and the number of climate sceptics. This makes people less likely to make behavioural changes that limit global warming. Coal and fracked gas production increase, thus warming the planet further.

A negative feedback is like this: climate change sceptic Donald Trump is elected president of the US. He promotes policies that increase global warming. This results in sea level rises, severe weather events, and a melt in the permafrost. The melting permafrost opens up new opportunities for hydrocarbon exploitation in Russia. However, a 3,000-year-old virus is also released from the permafrost, decimating the global human population and greatly reducing anthropogenic greenhouse gas emissions, resulting in a cooling planet and the permafrost resealing over.

Or perhaps it's more like this: A positive feedback mechanism in the climate system is ice albedo. The release of CO2 causes the planet to warm. This reduces ice cover in the polar regions. Reduced ice cover means a lower albedo, that is, less solar radiation is reflected back into the atmosphere from the earth's surface. This increases warming, which decreases ice cover.

A negative feedback mechanism in the climate system is silicate weathering. When it is warmer, it rains more. This increased rainfall weathers rocks, causing soil and stones to fall into the oceans. In the oceans, this weathered material connects with CO2 that has been absorbed by and dissolved into the oceans. This binds the CO2, preventing it from being released. Taking CO2 out of the atmosphere has a cooling effect, reducing rainfall, this reducing silicate weathering. A negative feedback loop enables the Earth to keep its temperature balanced.
Source: https://www.scisnack.com/2015/08/04/why-negative-feedback-is-good-for-the-climate/

Put contemporary climate change into the context of past, natural variability

'Aint nothing new under the sun,' King Solomon moaned in Ecclesiastes, and when it comes to a changing climate, the grumpy monarch was right. Climate change is not a modern phenomenon, and the Earth has previously experienced cycles of cooling and warming.

So what's all the fuss about then? Well, previous cycles of climate change have taken place over much greater periods of time (hundreds of thousands of years); the speed of change in the Earth's temperature over the past 200 years is unprecedented. Slower change has allowed the Earth to adapt, and feedbacks to kick into place. The current level of CO2 in the atmosphere is problematic because it is putting unusual stress on the Earth's natural ability to absorb CO2 and cool itself.

Review the evidence for human-induced climate change 

Since about 1750, the energy reaching the Earth from the sun has remained largely constant. However, the global average temperatures of the land and the sea have risen dramatically. Therefore, there must be an alternative explanation. As part of industrialisation, much of the world has been burning fossil fuels, releasing carbon that would otherwise have been released over a much greater timescale, if at all. This CO2, and other greenhouse gases, are adding layers to the blanket of gases around the Earth, letting less heat escape.
Sources: https://www.skepticalscience.com/empirical-evidence-for-global-warming.htm and https://climate.nasa.gov/evidence/ (two sources among many. Seriously, climate deniers, time to come up with a new excuse)

Explore the impacts of climate change on the cryosphere 

It's not called the cryosphere because of all those heart-rending pictures of polar bears floating around on pieces of ice so small you could stir them into your G&T; the cryosphere is the really, really, cold bits of the Earth, like Alaska, Antarctica and Theresa May's heart.

It is in the cryosphere that some of the effects of global warming are most apparent. Global warming is causing all of the following, to a greater or lesser degree: melting glaciers, shrinking sea ice and sea ice forming later in the year and for shorter periods of time, reduced albedo. The positive feedback of albedo means smaller ice sheets could accelerate global warming, resulting in melting of land ice, including the permafrost. Melting of the permafrost could provide another positive feedback because of the levels of methane stored in the frozen soils.
Source: https://serc.carleton.edu/eslabs/cryosphere/5b.html

Evaluate the vulnerability of the oceans to ‘the other carbon dioxide problem’ 

The oceans have absorbed much of the CO2 that has been released, both naturally and anthropogenically. This has been largely positive, because it has curtailed warming on the land, protecting us from some global warming.

However, the higher levels of CO2 have resulted in ocean acidification - climate change's noisy, troublesome and extremely irritating little brother, who is, basically, getting high on hydrogen ions and spoiling the party for everyone.

Carbon dioxide links with water and carbonate in the water to produce bicarbonate, reducing the availability of calcium carbonate in the water. This is having startling effects on marine life: marine creatures with shells or skeletons are finding it harder to get the calcium carbonate they need to form properly (so Nemo's probably OK but Sebastian, the amusing lobster from Little Mermaid, is in trouble). This is likely to have have ramifications higher up the food chain, including for human fish consumption.
Sources: https://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F; https://www.eartheclipse.com/environment/causes-effects-solutions-of-ocean-acidification.html; http://www.epoca-project.eu/index.php/what-is-ocean-acidification.html

Discuss how scientists model future climate scenarios 

Scientists use a variety of methods - ice cores, tree rings, pollen, sediments and corals - to investigate what the climate was doing in the recent and distant past. To build climate models, climatologists feed data from known climate inputs (such as water vapour, sun radiation, CO2 levels) and run them using historical data. This enables them to see whether the modelling is a reliable prediction of future climate.

The unknown in this area is human activity. The number of humans there are and how much fossil fuel they burn will greatly determine the climate.

Reflect on the role humans are playing in changing the Earth system 

Higgledy piggledy
Gorging on fossil fuels
Making us hotter than
We rightly should be

Much of the warmth is caused
Anthropogenically
Which basically means
That the problem is me

Update: Nya Murray on the climate change course has compiled a much more comprehensive list of useful climate change links so thanks very much to her. 

Some of the links I've found useful on this course: 

• http://www.enviropedia.org.uk/ 
• http://anthropocene.info/tipping-elements.php 
• https://www.youtube.com/watch?v=Lgh3Obf4LeA 
• https://www.sciencealert.com/this-map-shows-the-parts-of-the-world-most-vulnerable-to-climate-change 
• http://www.climatehotmap.org/ 
• https://www.carbonbrief.org 
• http://www.un.org/sustainabledevelopment/takeaction/ 
• https://www.metoffice.gov.uk/climate-guide 
• https://theconversation.com/uk/topics/climate-change-27
• https://www.theguardian.com/environment/climate-change
• https://www.nasa.gov/topics/earth/index.html