Unit 7 Notes Flashcards
What has human activity caused?
Global warming - global surface temperature reached 1.1 degree above 1950-1900 in 2011-2020.
What was the normal range of C02 concentration during the last 800,000 years?
Ranged from 175 to 300ppm at its’ peak, compared to 2016, where it was 402.9.
What is the Hockey Stick Graph?
Shows rapid rise in average global temperatures.
How is global warming linked to the water cycle?
Increased evaporation - warmer air holds more moisture, leads to higher humidity levels. Global warming leads to some regions experiencing increased rainfall. others may see a decrease.
How is global warming linked to carbon cycle?
Increased atmospheric carbon dioxide, ocean absorption of C02, increased ocean acidification. Enhanced photosynthesis leading to increased plant growth.
What is the relationship between increasing carbon emissions and energy budget?
Incoming energy from the sun is in the form of light energy, half of insolation reaching outer atmosphere reaches surface. As insolation passes through atmosphere, some is reflected back into space. Most insolation reaching Earth’s surface is absorbed.
How does an increase in greenhouse gases change the energy budget?
Earth received energy from sun in the form of visible light and other wavelengths. 30% of solar energy is reflected back to space by clouds, 70% is absorbed by surface.
What happens as greenhouse gas concentration rises?
Heat is more retained in the atmosphere, leading to an energy imbalance.
What are the impacts of increasing atmospheric carbon?
Changes to patterns and levels of precipitation, extreme weather events. Sea level rise, acidification of the oceans.
What has happened to the number of weather related extreme events?
Number of geophysical events stayed stable between 1980-2013. The number of weather events has grown by 4x.
What does the increase in extreme weather events suggest?
That extreme weather events are more likely to increase as a result of global warming than geophysical events.
What is the evidence that extreme weather is becoming more frequent?
More extreme rain, hotter, longer heatwaves, longer droughts, more fuel for wildfire.
What is the evidence of more extreme rain?
For every 1 degree rise in average temperature, the atmosphere holds 7% more moisture.
What is the evidence of hotter longer heatwaves?
Temperatures in Mali rose above 48 degrees during an extreme heatwave. 2022 UK heatwave.
What is the evidence of longer droughts?
Natural weather systems play a role - Drought in southern Africa in early 2024.
What is the evidence of more fuel for wildfire?
Draws more moisture out of soils and vegetation, providing fuel for fires.
What is a case study for flooding?
Boscastle - Was produced because of warm, moist air from a hurricane. 24.1mm of rain in 5 mins.
What is a case study for extreme precipitation?
2020 - Prolonged rainfall - 5th wettest winter on record. Wettest February on record.
What is a case study for Drought?
1976 - UK - Over 32 degrees for 2 weeks straight. Most areas received below 55% of usual rainfall.
What is a case study for forest fires?
2019 - Australian bushfires - Burned 18.6 Million hectares, displaced nearly 3 Billion animals.
What is an example of an extreme weather event, with atmospheric carbon?
2019-2020 Australian Bushfire. Habitat loss after deforestation, released 400 million tons of C02 into atmosphere.
What is the evidence to support the idea that more areas will experience extreme weather?
Global average temperature could increase to up to 2 degrees above pre industrial levels.
What is a feedback system?
A series of responses that change the steady state equilibrium of a system.
What is a positive feedback system?
When a series of responses increases or amplifies the initial change.
What is a negative feedback system?
When a series of responses stops or reverses the initial change.
What is an example of a positive feedback loop?
Anthropogenic activity increases carbon dioxide in the atmosphere. Atmospheric warming occurs, increasing evaporation. Warmer air can hold more water vapour.
What is an example of a negative feedback loop?
Anthropogenic activity increases carbon dioxide in the atmosphere. Atmospheric warming occurs, increasing evaporation. Warmer air can hold more water vapour. More water vapour increases cloud cover.
What is the equilibrium relationship between the water and carbon cycle?
A global temperature rise above a threshold of 1.5 degrees leads to irreversible changes. It may be impossible to return the changing climate system back to its’ original equilibrium state.
What are the examples of tipping points being reached through positive feedback loops?
Methane feedback, cryosphere feedback, marine carbon feedback, terrestrial ecosystem feedback.
How much has methane risen in the atmosphere?
250%.
What happens as methane is released, and what happens?
Released from anthropogenic sources such as fossil fuels, causes melting permafrost. As global temperature increases, permafrost melting is occurring at high latitudes in Russia and Canada.
What happens to permafrost as temperature rises?
Stores carbon in frozen organic rich soils, permafrost thaws, organic matter decomposes, methane is 25x more potent as a greenhouse gas.
What are the first three steps of the methane feedback loop?
High levels of atmospheric greenhouse gas cause global temperature to increase. Increasing temperatures cause permafrost to thaw. Thawing exposes previously frozen organic matter to decay.
What are the last two steps of the methane feedback loop?
As organic matter decays, it releases C02, and methane into the atmosphere. Atmospheric C02 and methane levels increase.
How does carbon storage and permafrost result in a feedback loop?
Carbon storage - Stores 1500 billion tons of carbon in the form of frozen organic matter. If permafrost thaws, C02 could be released into the atmosphere as C02.
How do warming temperatures and accelerated warming cause a feedback loop?
As earth warms, permafrost begins to melt. Warming could lead to a substantial increase in global average temperatures. Timing is difficult to predict.
What is Albedo?
The reflectivity of a surface.
What is the Albedo of snow and ice?
80%.
What happens to most energy from the sun which reaches snow?
It doesn’t become absorbed.
What is the positive feedback loop in the atmosphere?
Increase in atmospheric temperature, increased melting of sea ice and glaciers, reduced albedo of Earth’s surface, increased absorption of insolation.
Why are sea levels rising?
Because ice is melting, due to shrinking glaciers and ice sheets, adding water to world’s oceans.
What is another implication for the oceans of increasing atmospheric C02?
Ocean Acidification.
What is the PH of surface waters in 1990 compared to 2015?
8.115 - 8.08 in Hawaii. 8.10 to 8.08 in Bermuda.
What are the causes of Ocean acidification?
Increased C02 emissions, Absorption by Oceans, chemical reactions in seawater.
What happens to the amount of carbonate ions in seawater?
It decreased, because of increased hydrogen ions.
Why are carbonate ions also important to marine organisms?
As it means organisms could struggle to maintain shells and skeletons, leading to decreased growth rates.
Why are Oceans in areas surrounding areas more vulnerable?
They’re more efficient at absorbing C02, can experience higher rates of acidification compared to warmer ocean areas. Oceans absorb 1/4 of C02 emitted into atmosphere.
