Unit 9 Topic 3.3: The Future, Near & Far

Question 1

Climate change is a growing threat - HOW?

Answer 1

• In releasing CO2 into the atmosphere by burning fossil fuels like oil, coal and natural gas – that would have usually taken millions of years to be exposed and return to the atmosphere – we have created a shortcut in the planet’s natural carbon cycle.

Question 2

How are Carbon Dioxide Levels measured?

Answer 2

The Keeling Curve: a gauge of atmospheric CO2 levels; tracks the annual fluctuations in CO2 concentration in the northern hemisphere at Mauna Loa, Hawaii, starting in 1958

Question 3

Why does The Keeling Curve depend on Mauna Loa?

Answer 3

• Chosen due to its elevation and being far from any significant centres of human-caused CO2 production.
• “Purest” measurement

Question 4

Why does CO2 fluctuate depending on the season?

PLANT PHOTOSYNTHESIS IN THE SPRING/SUMMER

Answer 4

• When plants are in their spring/summer growth phase, plant photosynthesis (that uses CO2) predominantly outpaces respiration (that produces CO2), leading to a net removal of CO2 from the atmosphere.
• This phenomenon results in noticeably diminished CO2 concentrations in the atmosphere during these seasons.

Question 5

Why does CO2 fluctuate depending on the season?

Respiration

Answer 5

• In contrast to photosynthesis, respiration is an ongoing process that remains active year-round but takes the upper hand during the colder months when most plants are dormant and not photosynthesizing.
• This shift in dominance during the winter months results in elevated CO2 levels in the atmosphere during that period.

Question 6

How does CO2 fluctuate in the southern hemisphere?

Answer 6

• This variation also occurs in the southern hemisphere but is reversed (summer occurs during the northern hemisphere winter) in the southern hemisphere.
• The variation between summer and winter is also less pronounced as there is less land mass in the southern hemisphere and, therefore, fewer plants, causing this effect.

Question 7

How can we place the Keeling data (that CO2 levels have increased) in a broader time perspective

Answer 7

• Long atmospheric CO2 history levels can be obtained from ice cores
• Bubbles form in ice as snow is compacted, trapping a sample of the atmosphere

Question 8

What can ice core data tell us about CO2 levels relative to ice age cycles?

WHY did this occur?

Answer 8

• Ice core data has shown that there have been changes in atmospheric CO2 concentration related to ice age cycles, with lower levels of CO2 corresponding to glacial periods
• This may be caused by increased nutrient availability in the oceans and a related bloom of photosynthetic algae.
• Such blooms would cause more uptake of CO2 from the oceans, allowing more atmospheric CO2 to be drawn down from the atmosphere.
• Current CO2 levels have exceeded the natural range associated with ice age cycles.

Question 9

Why was CO2 suspected to increase around 1800, and not when the industrial revolution started (1850)?

Answer 9

• May be related to deforestation as pioneers began to spread westwards across North America, the so-called “pioneer effect.”
• Fewer trees meant less CO2 was being extracted from the atmosphere and stored in plant materials.
• By the Industrial Revolution, though, significant quantities of fossil fuels were being burned, contributing to a rise in global CO2 levels and temperature.

Question 10

HOW CAN WE DIFFERENTIATE FOSSIL FUELS FROM OTHER SOURCES?

Answer 10

• We can tell that the CO2 has come from burning fossil fuels and not other sources (like volcanic emissions) due to the 12C / 13C ratio of the CO2.
• Fossil fuels (as plants and algae produce them) also possess this enrichment, and as we burn them, the CO2 released is also enriched in 12C
• As a result, we have seen a dilution of 13CO2 in the atmosphere as more 12CO2 has been released by burning fossil fuels.

Question 11

According to NASA, the average global temperature on Earth has increased by…

In what particular year?

Answer 11

• …at least 1.1°C since 1880
• Most of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade.

Question 12

In 2008, the Stratigraphy Commission of the International Union of Geological Sciences (IUGS) received a proposal to create a new geological time unit called the…

Answer 12

• …Anthropocene, to reflect humans’ impact on the planet.

Question 13

What would the Anthropocene been classified as?

Answer 13

The Anthropocene (if erected) would have been a new epoch within the current Quaternary Period in the Cenozoic Era.

Question 14

To introduce a new geological time unit, what needs to be established/selected?

Answer 14

…a specific geographical area with sedimentary deposits that mark the base of that time period is selected as a physical reference point.

Question 15

Why did the Anthropocene Working Group of the Stratigraphy Commission select Crawford Lake in Ontario, Canada to represent the Anthropocene Epoch?

Answer 15

The lake’s sediment contains a distinctive increase in plutonium levels attributed to hydrogen bomb testing, a significant reference point chosen by the group to mark the inception of the Anthropocene in the 1950s.

Question 16

Was the Athropocene proposal successful?

Answer 16

• NO
• In March 2024, the Anthropocene Epoch proposal was voted down as (in geological terms) insufficient sediment had accumulated since the 1950s to warrant the erection of a new Epoch

Question 17

What challenges would we encounter as the planet continues to warm?

Answer 17

1. Sea level rise
2. Droughts & wildfires
3. Spread of insects & disease
4. Marine ecosystems
5. Displacement & conflict

Question 18

Sea-level rise

What challenges would we encounter as the planet continues to warm?

Answer 18

• Through melting ice caps and glaciers
• Also the thermal expansion coefficient of seawater: as the planet warms, the oceans absorb heat, causing water molecules to expand; this coefficient describes the fractional change in water volume per degree of change in temperature

Question 19

How much are sea-levels expected to rise?

What challenges would we encounter as the planet continues to warm?

Answer 19

• Between 40–70cm by 2100, depending on how much greenhouse gas is emitted.
• Does not account for any potential “catastrophic” melting scenarios involving significant components of the cryosphere, such as large parts of the ice on Greenland or Antarctica.
• 40 -70cm might not sound substantial, but the low slope of many coastal areas means around 1km or more of flooding, requiring the retreat of many coastal communities.
• The construction of barriers and dikes is one solution to this issue, but these are not applicable in every situation. Adapting to sea level may require innovative approaches, such as developing floating communities and agricultural areas

Question 20

Droughts and Wildfires

What challenges would we encounter as the planet continues to warm?

Answer 20

• Ocean evaporation will increase as temperature rises, leading to greater rainfall in some areas.
• However, this rainfall will not be evenly distributed, and some regions will experience more frequent and severe droughts.
• These droughts, in turn, increase the risk of wildfires
• This is already occurring in western North America, with areas like California and British Columbia experiencing frequent wildfire events. Drought will also impact agriculture and access to freshwater resources.

Question 21

Spread of Insects and Disease

What challenges would we encounter as the planet continues to warm?

Answer 21

• As temperatures increase, insects living in the tropics and subtropics will migrate towards the poles.
• These include pests that may impact crop production and disease-carrying insects, such as the anopheles mosquito, a vector for diseases like malaria (Figure 9).
• Currently, cold temperatures during winter limit the spread of this mosquito, but as temperatures rise and winters become milder, their range will expand.

Question 22

Marine Ecosystems

What challenges would we encounter as the planet continues to warm?

Answer 22

• As carbon dioxide is released into the atmosphere, a portion is absorbed by the oceans, causing them to become more acidic
• As the oceans become more acidic, it becomes harder for corals to secrete their calcium carbonate skeletons.

Question 23

Marine Ecosystems

Coral Bleaching + Disruption of Reefs

What challenges would we encounter as the planet continues to warm?

Answer 23

• Furthermore, rising sea temperatures, driven by global warming, can lead to coral bleaching, where corals expel their symbiotic algae that provide them with essential nutrients.

Question 24

The disruption of reefs will have severe implications for the ocean ecosystem:

Answer 24

• Reefs are hotbeds of biodiversity (sometimes called the rainforests of the oceans)
• They also provide shelter for the juveniles of many other marine species, which has broader implications for the marine ecosystem beyond reefs.

Question 25

Displacement and Conflict ## Footnote What challenges would we encounter as the planet continues to warm?

Answer 25

* Global warming effects prompting people to seek new opportunities and increase competition for dwindling resources. * This can lead to c**onflicts within and between communities and cross-border migration**, potentially straining relations between countries. Vulnerable populations are often disproportionately affected, heightening social unrest.

Question 26

Renewable energy resources

Answer 26

1. Hydroelectricity 2. Wind Power 3. Solar Power

Question 27

Hydroelectricity ## Footnote Renewable energy resources

Answer 27

* Hydropower, or hydroelectric power, is **a renewable energy source that generates electricity by harnessing the energy of *flowing or falling water to drive turbines.*** * A clean, renewable resource that has been used for many years globally

Question 28

Disadvantages of hydroelectricity - Habitat Disruption: ## Footnote Renewable energy resources

Answer 28

The construction of dams and reservoirs can disrupt local ecosystems and destroy habitats for aquatic life and wildlife

Question 29

Disadvantages of hydroelectricity - Sedimentation ## Footnote Renewable energy resources

Answer 29

Dams can trap sediments, preventing them from flowing downstream. This can lead to downstream erosion and disrupt sediment-dependent ecosystems

Question 30

Disadvantages of hydroelectricity - Land Submersion ## Footnote Renewable energy resources

Answer 30

* Large reservoirs created by dam construction can submerge vast areas of land, displacing communities and causing cultural and environmental disruptions. * In addition, it may result in a loss of valuable agricultural land

Question 31

Disadvantages of hydroelectricity - Initial Construction Costs ## Footnote Renewable energy resources

Answer 31

Building large-scale hydropower facilities with high upfront costs can be capital-intensive

Question 32

Windpower - disadvantages ## Footnote Renewable energy resources

Answer 32

A renewable and environmentally friendly source of energy, but also has several disadvantages: * **Intermittency**: Wind is not constant; can make wind power unreliable as a sole source of energy. * **Energy storage requirements:** To address intermittency, wind power often requires energy storage solutions like batteries, which can be expensive and have limited capacity. * **Land and space requirements:** can lead to habitat disruption and competition with other land uses, such as agriculture or wildlife conservation.

Question 33

Solar Power ## Footnote Renewable energy resources

Answer 33

* These panels can be deployed on a large scale in the form of solar farms or locally attached to existing buildings that contribute to the local electricity grid. * Ivanpah Solar Project has been tested; As the water heats up (from reflecting mirrors) and transforms into steam, it propels turbines to generate electricity.

Question 34

Solar power drawbacks

Answer 34

* It **relies on relatively bright weather conditions**, though modern solar panels rely less on full sunshine and can generate electricity in somewhat dull conditions. * Additionally, solar energy storage remains as challenging as it is for wind power systems.

Question 35

Nuclear Sources of Energy

Answer 35

* Nuclear Fusion * Nuclear fission

Question 36

Nuclear Fission ## Footnote Nuclear Sources of Energy

Answer 36

* the process where **the nucleus of a heavy atom**, like uranium-235 or plutonium-239, **is bombarded by a neutron**, causing it to split into smaller atoms and release additional neutrons * This results in a loss of mass, converted into energy following Einstein's famous equation, E=mc²

Question 37

Disadvantages of nuclear energy: ## Footnote Nuclear Sources of Energy

Answer 37

* **High Initial Costs**: substantial capital investment and time; high costs can deter countries and investors from pursuing nuclear energy projects. * **Limited Fuel Resources**: some **nuclear fuels**, such as enriched uranium, are finite resources, and *their availability depends on mining*. There are concerns about potential uranium shortages in the near future. * **Security Risks**: materials used in nuclear reactors, such as enriched uranium or plutonium, **can be attractive targets for theft or misuse in the context of nuclear weapons proliferation**. Security measures to safeguard these materials are crucial. * **Radioactive Waste**: production of radioactive waste. Managing and storing radioactive waste securely presents technical and safety challenges.

Question 38

Nuclear Fusion ## Footnote Nuclear Sources of Energy

Answer 38

* Unlike *nuclear fission, which involves splitting heavy atomic nuclei*, **fusion combines light atomic nuclei**, typically isotopes of hydrogen, deuterium and tritium. * **Fusion ultimately creates an atom of helium and a mass loss**, which, like nuclear fission, is **converted into energy**. This process is similar to the reaction that powers the sun and other stars

Question 39

What are the benefits if practical nuclear fusion is achieved? ## Footnote Nuclear Sources of Energy

Answer 39

* If practical nuclear fusion can be achieved, it will **allow for sustainable, safe, and abundant power generation without significant radioactive waste production** (compared to fission) or greenhouse gas emissions. * Fusion **requires very high temperatures and pressures to fuse the positively changed hydrogen nuclei**

Question 40

The Tectonic Future - what do the atlantic/pacific oceans look like?

Answer 40

* Currently, **the width of the Atlantic is increasing at the expense of the Pacific Ocean**. * Many of the Pacific Ocean plates are being subducted around its margins. * Extensive passive tectonic margins characterize the Atlantic Ocean. * In addition, the continents today are fairly fragmented.

Question 41

By 50 million years (5) ## Footnote The Tectonic Future

Answer 41

* The Atlantic will be much **wider** than it is today. * Still, subduction is predicted to have initiated along the east coasts of North and South America, the western Atlantic Trench. * In addition, **Africa will have collided with Europe**, closing the Mediterranean and creating a new mountain range, the Mediterranean Mountains. * By this time, **Australia would have collided with SE Asia** * Transform boundary on the west coast of North America would have moved California towards Alaska.

Question 42

By 150 million years ## Footnote The Tectonic Future

Answer 42

* The Atlantic will have been **shrinking** for some time, and much of the mid-Atlantic ridge will likely have been largely subducted below the east coast of North and South America. * Antarctica is predicted to have collided with the landmass comprised of Australia and SE Asia.

Question 43

250 million years ## Footnote The Tectonic Future

Answer 43

* **The lithospheric plates below the Atlantic Ocean would have mainly been subducted**, once again uniting most continents into a single landmass that Scotese named **"Pangea Ultima."** * In his model, Scotese suggests the possibility of an inland sea, but predicting details this far into the future is difficult.

Question 44

As we move further into the distant future, our biosphere may encounter challenges from our sun. | THE SUN'S CORE ## Footnote The Distant Future - Increasing Solar Luminosity

Answer 44

* **The sun transforms hydrogen into helium**, with the 'missing' **5 million tons being converted into energy**. * This **outward flow of energy from the core is what prevents the sun from collapsing under its own gravity.** (like gravitational equilibrium) * The sun's core is isolated from the outer layers, **preventing the addition of new hydrogen and the removal of helium produced through fusion.** * As helium accumulates at the core's center, its gravitational compression releases energy. This energy is generated in increasing amounts as more helium accumulates, causing the sun to become progressively hotter and brighter.

Question 45

Scientists predict that in approximately 600 million years...

Answer 45

the sun's increased heat could lead to a significant increase in silicate weathering.

Question 46

Silicate weathering & future CO2 levels

Answer 46

* Silicate weathering is a natural process that removes CO2 from the atmosphere by weathering rocks * **This process may have become so accelerated that it could deplete atmospheric** CO2 to a level where a significant group of plants, called the C3 plants, will struggle to photosynthesize

Question 47

In approximately 1 billion years, what will the sun do to earth's surface?

Answer 47

* Earth's surface temperatures **could become so high due to the sun's warming that the *oceans completely evaporate*.** * As for Venus, this could cause a runaway greenhouse effect. * In addition, today, water introduced into the mantle via subduction is thought to help reduce mantle viscosity and allow subduction processes to occur. * Once all the oceans have evaporated, plate tectonics might eventually cease.

Question 48

About 5.5 billion years from today - RED GIANT

Answer 48

* The Sun's core will **exhaust all of its hydrogen fuel**, and **fusion reactions will halt**. * Despite this, the core continues to undergo compression, generating substantial heat. * When this happens, the temperature of the hydrogen surrounding the core becomes sufficient to initiate fusion, forming a shell of fusion around the core. * The combined energy from the core compression and the fusion shell around it heat the gases in the sun's outer layers, causing them to expand. * This expansion will also cause a change in the Sun's colour; a reddish hue due to lower heat radiation per square centimetre.

Question 49

The Sun will pass through several expansion and contraction phases, shedding much of its outer layers into space - will fusion continue?

Answer 49

* No * All fusion processes will ultimately cease, leaving behind a slowly cooling core called a white dwarf star by around 7.7 Billion years from now.