Lesson 3 - Climate change

what does anthropogenic climate change mean?

climate change caused by human activity

What two gasses have the biggest impact on the greenhouse effect?

carbon dioxide and water vapour

Why is too much methane problematic?

Methane oxidises in the atmosphere which produces CO₂ and water

How do greenhouse gasses cause global warming (explain in terms of wavelength of radiation)?

Short wave length radiation from the sun passes through the ozone layer and is absorbed by the earth. The short wavelengths are converted into longer wavelengths (IR). IR is given off by the earth. Parts of the IR is escapes into space, Most get trapped on earth by greenhouse gasses and heat is re-emitted onto earth's surface.

What is the issue with this graph?

Too simplistic. Not all peaks in global temperature correlate with higher CO₂ levels.

What other factors could cause an increase in average global temperature?

sunspots and variation of the earth's orbit.

What are some consequences of global warming?

Climate change higher temp. = more evaporation of water = extreme rainfall. Changes in wind + ocean currents = more hurricanes Rising seawater melting of polar ice caps loss of habitats loss of arctic and coastal habitats changes in biotic factors temperate animals moving to previously arctic conditions —> more competition —> disruption of food chains.

How are rising CO₂ levels affecting the formation of coral reefs?

CO₂ dissolves in water and forms H₂CO₃ (carbonic acid). The molecule easily dissociates into H⁺ and HCO⁻. The H⁺ makes the water acidic (ocean acidification). This increase the solubility of calcium carbonate so less CaCO₃. Exoskeletons will dissolve so they become less resilient.

what impacts does melting ice have on a polar bear's ability to survive?

longer swimming distances loss of hunting grounds habitat fragmentation → isolate bear populations → less genetic diversity

What is the positive feedback cycle of global warming in terms of sea ice?

Increase in temperature → snow + ice melts → Darker surfaces are revealed → albedo reduced → increased absorption of radiation → accelerates temp. and melting of snow.

what is peat?

an accumulation of partially decayed organic matter.

What conditions does peat form in?

waterlogged (very wet) + acidic

Why is peat important?

sequesters carbon has a net cooling effect on the climate slows the flow of water, cleaning it naturally and reducing flood risk

What is the positive feedback cycle of global warming in terms of peat?

rise in temperature → more microbial activities → accelerated decomposition of organic matter → releases a lot of carbon dioxide + methane → further increase in temp.

what are three approaches to increasing carbon sequestration?

afforestation
restoration of peat-forming wetlands
forest regeneration

what is afforestation?

plant trees where there are no trees.

What is forest regeneration?

allowing trees to naturally regrow by itself

what are some pros of afforestation?

Fast Carbon Sequestration Biodiversity Benefits Economic Opportunities (timber production)

what are some cons of afforestation?

conflicts with agriculture and urban development

Expensive to establish + maintain

right species of trees must be used otherwise it may outcompete local trees

what are some pros of forest regeneration?

cost-effective
local trees species

what are some cons of forest regeneration?

takes time and must implement rules to not disturb the growth of trees

What are some pros of restoration of peat forming wetlands?

reduces flooding Biodiversity and Habitat Restoration carbon sequestration

what are some cons of restoration of peat forming wetlands?

Slow Sequestration Rates funding and resources

What impacts does climate change have on ocean currents and upwelling?

Rising temperatures and melting ice alter water density and salinity, disrupting ocean circulation. Warmer surface waters hinder upwelling.

what is upwelling?

he process by which deep, cold, nutrient-rich water rises to the surface of the ocean.

what is phenology?

The study of the timing of biological events

what are some examples of biological events?

Migration Egg laying

What are the effects of climate change on spruce bark beetles?

higher temperatures → two life cycles are more like to occur (most of the time 1 or 2 life cycles) → more competition for food + damage to trees

How does climate change lead to evolution?

climate change introduces new selection pressures so can drive evolution by natural selection.

How has the tawny owls evolved due to climate change?

less snow so frequency of brown owls has increased compared to grey owls.