Climate Topic 2: Climate Change

Changes in earth’s orbit and tilt, Occurences in sunspots & large-scale volcanic eruptions

When the earth’s orbit is the most elliptic, more radiation reaches earth at its closest approach to the sun compared to its furthest. This cycle occurs over 100 000 years

Tilt increases —> seasons become more extreme with hemispheres tilted towards the sun receiving more radiation and higher temperatures in summer and lower radiation & temperatures in the winter when tilited away from the sun. This cycle occurs over 41000 years

Higher sunspot activity leads to higher amounts of solar radiation as the sunspots with lower temperatures cause areas around it to radiate more energy from the sun leading to higher temperatures on earth.

A volcanic eruption releases high amounts of dust, ash & sulfur dioxide into the atmosphere. These particles spread around the low atmospheric area and absorb and reflect more solar radiation back into space, reducing temperatures temporarily

Factors relating to, or resulting from actions of people

It describes the natural process by which the greenhouse gases in the Earth’s atmosphere trap longwave radiation emitted from the earth’s surface

Increased anthropogenic activities since 1850, causing the concentration of atmospheric greenhouse gases to increase

Burning of fossil fuels & changing land use for argiculture, industries and urbanisation

Burning of fossil fuels like coal, oil and natural gas produces large amounts of carbon dioxide

The large-scale removal of trees results in less of them absorbing carbon dioxide through photosynthesis. Any carbon stored by the trees is also released back into the atmosphere when they are cut

Fossil fuels are burned to produce energy for farm machinery, livestock rearing and natural decomposition release methane, nitrogen in chemical fertilisers being converted to nitrous oxide

Increase in atmospheric temperature & increase in ocean surface temperatures

Community of organisms on land

Warm surface water moves from the equator to the poles due to winds. The water then cools, becomes denser and sinks, spreading along the bottom of the ocean, forming cool subsurface flows, eventually rising back to the surface

Water at the surface gains heat due to rising atmospheric temperatures, becoming less dense. This reduces the sinking of it, thereby slowing down the flow of water

Areas with surface water experience higher precipitation and flooding due to warmer air that can hold more water vapour while at dry areas, warmer air increases evaporation causing water bodies and soils to dry out and less moisture in the air leading to more droughts

When ocean temperatures increase, the algae living on corals are rejected since they produce harmful oxygen radicals. When they leave, the corals turn white and are more likely to die due to lack of nutrients. Fish living in coral reefs lose their habitats and food source so they also face population decline, affecting food chains

Increase in carbon dioxide causes oceans to absorb excessive amounts of $CO_2$ which forms carbonic acid in oceans. This acid dissolves calcium carbonate which is needed by aquatic organisms such as corals, mussels and oysters to form their skeletons and shells

It reduces the sinking of water at the poles, so warm surface waters mixes less with cooler, deeper water. Near-surface aquatic life like phytoplankton are therefore cutoff from nutrients below, affecting their numbers and the food source of animals which fed on them

Warming oceans cause aquatic species to migrate polewards into deeper cooler waters, decreasing biodiversity in equatorial regions with the opposite happening in poleward ones.

Warming atmospheres cause plants and animals to migrate to higher latitudes & altitudes where it’s cooler increasing their biodiversity. The mix of prey, predators & competitors in the terrestrial ecosystem also change, disrupting food webs and thus they face extinction

About 170 species of birds tracked in North America have expanded their range northwards. by 50km on average during the past 4 decades

In Australia, wallabies are migrating to higher altitudes. They found herbfields in mountains a suitable source of food but their overgrazing threatens to reduce these herbfields to grassy lawns. Other species that depend on these herbfields will face greater competition and higher rate of extinction

Plants are more vulnerable as they are not able to migrate so due to lack of water, they will wither and die. They are also more vulnerable to diseases and insect attacks. Animals will be forced to relocate, in search of water, food & habitat due to habitat & food supply loss. Some may not be able to adapt and become extinct

It can result in landslides which destroy habitats as plants are uprooted. Unusually large amounts of water may overflow into riverbanks & cause floods. Soil erosion can also happen, removing nutrients needed by plants to grow well.

CC leads to higher temperatures, making heatwaves more intense and frequent, causing people to suffer from heat stroke, have difficulty breathing, or even die. Soil moisture is also depleted, causing widespread crop failure, resulting in food shortages

Warmer atmospheric temperatures increase evaporation, reducing surface water and drying out soil & vegetation. Shortage of clean water can lead to dehydration and death. Crop failure may also occur and people may die from starvation due to lack of food. People may also be displaced

Warmer and drier conditions can lead to more dead trees & vegetation, making it easier for fires to start and harder to put them out. People face suffocation, injuries and burns as well as destruction to their properties and other buildings, increasing homelessness. Large amounts of $CO_2$ is emitted making people have respiratory illnesses

Warmer temperatures lead to excessive precipitation in some parts of the world as well as snowmelt that increases the sea level and thus higher coastal flood risk. Buildings get destroyed, leading to homelessness and economic losses, food & water shortages are faced and waterborne diseases enter water sources, infecting people

Warmer oceans and more water vapour in the atmosphere lead to more intense cyclones. Strong winds & heavy rain can cause deaths due to flooding and landslides as well as destroy buildings causing economic losses and threatening food security

It increases ocean temperatures and acidity, threatening aquatic life and distribution of aquatic species as they migrate to cooler waters. Hence, the economic livelihoods of those dependant on fisheries are affected and food security becomes worse. Cooler areas may see more fish species though

More severe and frequent weather events make survival for crops difficult, reducing food production. This causes prices to increase, and forces the poor to spend more of their income on food, making them more likely to starve

Warmer temperatures create more conducive environments for vectors like mosquitoes and ticks to survive and breed. Mosquitoes are also able to move to higher altitudes and latitudes where its warmer, putting more people at risk of infection leading to deaths, reduced economic productivity and higher healthcare costs

Higher temperatures causes arctic ice to melt. So, storing food in ice cellars are threatened and the cultural ecosystem services may be disprupted. The numbers of sled dogs have also decreased which are necessary for travel and hunting

Rising sea levels cause low-lying areas like Maldives to be threatened to be uninhabitable which brings high tourist revenue. Corals are affected by coral bleaching and will also lose tourism revenue with no tourists

Poles, parts of Southeast Asia & central Africa

Southwest USA and parts of Sahel region in Africa

Parrotfish & rabbitfish have migrated polewards meaning their population in tropical waters has dropped significantly in the last 50 years

The droughts in California, USA between 2012 to 2016 contributed to the death of 102 million forest trees due to lack of water and spread of diseases.

In Assam, India, unusually excessive rainfall in 2020 resulted in floods which killed more than 200 wild animals, including 8 endangered rhinoceroses

Average coral cover in the Great Barrier Reef has dropped to 30% of what it was in the 1960s, in part due to ocean acidification