Environmental biology 5C

evidence of climate change

• atmospheric carbon dioxide levels

• average global temperatures

• Records of changing plant communities

• Records of tree growth gained by dendrochronology

What is peat and how is it formed?

• Peat is compacted, partially decomposed plant matter.

• pollen is preserved in peat bogs

• plants can be identified from pollen

• the plants that grow depend on temp/rainfall/climate

• depth of peat indicates how many years ago plants were growing

How do tree rings indicate climate conditions?

• the study of tree rings

• each year a new ring is formed

• size of ring shows the growth of tree

• the size of ring is affected by climate

• photosynthesis is affected by climate

• the no. of rings can be used to work out a timescale

anthropogenic climate change

The atmospheric warming, and the changing climate, for which humans are thought to be responsible for

Role of co2 in the greenhouse effect

• Carbon dioxide traps heat in Earth's atmosphere

• Trees, soils, peat bogs, and oceans store carbon. When these are damaged CO2 is released, intensifying the greenhouse effect.

Sources of methane

• Released from the digestive systems of cattle, sheep, etc., increased by intensive farming.

• Organic waste decomposition (like food) emits methane.

• Mining and drilling release underground methane.

• Anaerobic bacteria in waterlogged rice paddy fields release methane.

• Global warming melts frozen ground, releasing stored methane.

How can the carbon cycle be used to reduce atmospheric CO₂ levels?

• Enhance plant growth to absorb more CO₂.

• Support marine plants and organisms that absorb CO₂ from the ocean

• Reducing disturbance of carbon pools such as soils and peat bogs to store carbon

• Limit burning of fossil fuels and biomass

Limitations of Climate Change Prediction Models

• Which emissions scenario will occur is unknown.

• Success in cutting emissions is uncertain.

• Future technologies may not work as hoped.

• Climate impacts of atmospheric gases are unpredictable.

• Sudden changes (e.g., permafrost melting) could accelerate warming.

• Non-human factors (e.g., volcanic eruptions) may affect climate.

how does climate change affect species?

• Species move towards poles or higher altitudes; may lead to competition leading to decreased biodiversity.

• Some species (e.g., plants) can't adapt quickly, risking extinction.

• Changes in rainfall disrupt species reliant on seasonal rains.

• Altered timings for plant blooming and animal reproduction; affects food availability.

• Retreating polar ice and glaciers impact water supplies and contribute to rising sea levels increasing flood risks

The temperature coefficient, Q₁₀

calculates the increase in rate of reaction when the temperature is increased by 10°C

Q₁₀ = rate at higher temperature ÷ rate at lower temperature

Natural selection process

1. mutation occurs changing alleles

2. Selection pressures affect a population increasing competition

3. Those with advantageous alleles are more likely to survive and reproduce

4. Advantageous alleles are passed to offspring

5. Advantageous alleles increase in frequency

Speciation

the development of new species from pre-existing species over time

What is allopatric speciation and how does it occur?

• Caused by geographical isolation

• No gene flow between separated populations.

• Allele frequencies change due to different selection pressures and genetic drift.

• Over time, populations evolve different phenotypes.

• If differences are great enough, populations can't interbreed, forming new species.

What is sympatric speciation and how does it occur?

• Populations remain in the same habitat but there are random changes in their alleles and become isolated due to:

  • Seasonal changes: Different mating or flowering times.

  • Mechanical changes: Physical changes prevent successful mating.

  • Behavioral changes: Differences in courtship behavior.

• No gene flow between groups, causing different allele frequencies.

• Populations evolve until they can no longer interbreed, forming new specie