Climate change Flashcards
(47 cards)
Global average temperatures have increased by about…
1 degree Celsius (1.8 degrees Fahrenheit) since the late 19th century.
The rate of warming has accelerated in recent decades…
the five warmest years on record all occurring since 2010.
The oceans have absorbed much of this heat…
The top 700 meters (2,300 feet) of ocean warming by about 0.4 degrees Celsius (0.7 degrees Fahrenheit) since 1969.
Arctic sea ice has decreased by…
about 13% per decade since 1979.
Sea levels have risen by…
About 8 inches since 1880.
Palaeoclimatic indicators
Ice cores
Palynology
Fossils
Foraminifera
Paintings / novels
Past weather records
Ice cores; What they do, Pros / Cons.
Snow settles on the surface, oxygen and carbon from the atmosphere within the snow become compressed when a new layer forms, again and again until these layers are preserved in the ice sheet.
O18 and 016 oxygen isotopes can be examined; 018 evaporates from ocean at higher temperatures. Therefore if a core layer has more 018, it indicates a warmer year.
In addition, the amount of co2 present in the ice can indicate how warm the climate was in such period.
Pros:
Can be used to see past temperatures of up to 800,000 years ago in antarctica
Cons:
Can be difficult to distinguish the ice core layers when examining older samples, as the pressure causes regelation in the ice which distorts layers.
Also expensive to do.
May not be indicative of the global climate, and more just the area where they were drilled from.
Micro fossils
By examining micro fossils found in ocean sediment samples, the climate at the time can be deduced through 2 ways:
O16 / O18 oxygen isotope ratio in the fossil
Type / species of fossil, as only certain species can survive in certain temperatures, due to foraminifera being highly sensitive to climatic changes.
Dated using radio carbon dating techniques; Oldest microfossils on Earth around 3.5 billion years old, however, less than 100 million years old to actually work out past temp.
Cons:
Very hard to identify if old due to breaking up over time
Can move location due to currents.
Paintings / books / other media
Paintings / novels can be used to depict what past temperatures were like, such as Charles Dickens a Christmas carol which took place during the victorian era during the little ice age in the uk, which lasted approx from 1300 to 1850. This therefore shows how it can be used to indicate past temps, as there is vivid detail on how the thames used to freeze and people would ice skate / winter markets.
Cons:
Quantitative, can be bias / up to interpretation, not accurate
Palynology
The amount of pollen found in sediment deposits, such as peats and bogs, can indicate past climates;
For example, they can show:
Type of species pollen was from, which indicates temp, as plants can only survive in certain temps
Also show the amount of pollen, as higher amounts of pollen found which are dated to a certain year indicate that it was a warmer year and more plants bloomed.
Cons:
Like micro-fossils, pollen samples can be moved around due to a variety of factors such as landslides, tectonic movement, washed away during rainfall etc. Also not as accurate as other proxies.
Internal forcing mechanisms:
Tectonic plate movement / ocean currents changing
Volcanic eruptions
Greenhouse gases
external forcing mechanisms
Milankovitch cycles
Sunspots
How can tectonic plate movement cause climate change?
Creation on the Panama Isthmus about 3 million years ago had a profound impact on the Earth’s climate. The isthmus blocked the flow of water between the Pacific / Atlantic, forming the gulf stream, which is a warm ocean current that flows from the Gulf of Mexico up the Eastern coast of the US.
Before the isthmus, currents could flow between both oceans via the central american seaway, which cooled the climate. After this was blocked, the gulf stream warmed the earth by approx. 2/3*C
How can volcanic erection cause climate change
The average temperature in the Northern Hemisphere was about 0.2 degrees Celsius cooler than average during the months following the eruption of Eyjafjallajokull.
Due to the increased albedo of the ash clouds.
Eccentricity
Eccentricity: The Earth’s orbit around the Sun is not perfectly circular, but rather it is slightly elliptical. This means that the Earth’s distance from the Sun varies throughout the year. The eccentricity of the Earth’s orbit changes over time, with periods of high eccentricity (when the Earth’s orbit is more elliptical) and periods of low eccentricity (when the Earth’s orbit is more circular). The eccentricity of the Earth’s orbit has a cycle of about 100,000 years.
Obliquity
Obliquity: The Earth’s axis is tilted relative to its orbital plane. This tilt is what causes the seasons. The Earth’s obliquity changes over time, with periods of high obliquity (when the Earth’s axis is more tilted) and periods of low obliquity (when the Earth’s axis is less tilted). The obliquity of the Earth’s axis has a cycle of about 41,000 years.
Precession
Precession: The Earth’s axis precesses, or wobbles, like a spinning top. This precession is caused by the gravitational pull of the Sun and the Moon. The Earth’s precession has a cycle of about 26,000 years.
Sunspots
Sunspots are areas of intense magnetic activity on the surface of the sun. Sunspots release higher amounts of solar radiation.
Cycle lasts around 11 years, with the peak and minimum of this short term cycle not effecting temp. significantly (0.1% of solar radiation variation)
However, over centuries sunspot activity can effect the global temperature to a higher effect; e.g. The maunder minimum which caused colder winters and lower global avg. temps from 1650-1720 due to less sunspot activity according to scientists.
Reasons for the Anthropocene (anthropogenic climate change)
Population increases - increases in carbon footprints worldwide
Land use changes - forestry being cut down and used for farming, which increases methane + co2
Energy demand - due to globalisation + new technologies + population increase, more energy is required than before, resulting in the burning of coal / natural gases.
GHG contribution case study countries
AC = UK
EDC = China
AC GHG contribution statistics
The UK remained dependent on coal as its main energy source for much of the twentieth century. Although coal production peaked in 1916 (137 million tonnes), as late as 1961 output was still more than 120 million tonnes.
UK’s CO emissions peaked in 1971. Since then, annual emissions have fallen by around one-third.
There are several reasons for this:
The shift away from coal as the primary fuel to cheaper natural gas.
The development of nuclear power stations (particularly in the 1970s and 1980s) and renewable sources of energy since the 1990s.
Improvements in energy conservation through more energy-efficient homes, offices and factories.
International obligations and legally binding reductions in carbon emissions.
In 2014 alone, uk emissions fell by approx. 9%
80% reduction in co2 emissions by 2050
EDC GHG contribution statistics
1990: China emitted 2.7 billion tons of carbon dioxide equivalent (CO2e).
2000: China emitted 4.3 billion tons of CO2e.
2010: China emitted 9.8 billion tons of CO2e.
2020: China emitted 14.5 billion tons of CO2e.
The government has pledged to peak emissions by 2030 and achieve net-zero emissions by 2060.
Differing opinions on climate change
Media:
Some say media causes hysteria
Additionally, media can often find it hard to understand scientific research / methodology around CC
Such as Fox news etc
Lobbying:
Some parties have vested interest in keeping CC a conspiracy, such as energy companies, which donate to keep policy in their favour. For example, in 2019, the API spend $15 million on lobbying.
Impacts of climate change
Ecosystems disrupted (marine / terrestrial)
Diseases spread
Extreme weather events
Food scarcity
