Effects of Climate Change

Climate change is serious and the effects are widespread, felt locally and globally. You can categorise the effects into environmental, social and economic. A good way to frame your answers is to visualise how higher sea levels and erratic weather conditions affect people and communities. For example, how will higher sea levels affect low-lying countries like Bangladesh? Bangladesh is an example of a developing country and so has less financial resources to deal with effects. This would make the consequences of flooding more serious. How would a drought affect farmers in already hot countries like Ethiopia? Less agricultural productivity means less revenue for the economy and less employment. Think about how the effects of climate change affect developing and developed countries differently.

Environmental

1. Agricultural effects:

   a) Crop yields are expected to decrease for all major world crops. For countries such as in West Africa, where food security is already an issue, Cycles of drought and flooding will impact society forcing populations to migrate away from unproductive agricultural land due to a degree rise in average temperatures combined with substantial changes in rainfall and humidity.

   b) Increase in desertification (spread of desert conditions in arid regions) rendering land unusable for farming. Combine this with soil degradation and erosion meaning a lot of the land is virtually useless for agriculture.

   c) Crops will be wiped out in low-lying areas prone to flooding. Bangladesh is located in the low-lying Ganges Delta between India to the west, and Burma to the east, and boasts some of the most fertile agricultural plains in the world. Most of the country is lower than 12 metres above sea level and extremely flood-prone. Less cash crops (crops available on the world market) will mean higher prices making their exports less competitive.

   d) Longer growing seasons in some areas, for example the UK meaning more crops can be grown.

   It helps to mention countries in your answers:

   A good example of a developing countries affected by droughts – Haiti (Half of all Haitians work in agriculture, which is becoming increasingly unstable with changes in climate patterns. Unseasonable droughts have caused widespread crop failure) recent years.

2) Water and Ice

a) When glaciers melt, mass movements occur. This is a large downscale movement of rocks and material.

b) In mountainous regions, melting glaciers are impacting on freshwater ecosystems. Himalayan glaciers feed great Asian rivers such as the Yangtze, Yellow, Ganges, Mekong and Indus. Over a billion people rely on these glaciers for drinking water, sanitation, agriculture and hydroelectric power. This can be a social effect too because it affects humans.

c) Less fresh water will be available in coastal areas as it will mix with sea water, which is salty.

d) Effects on marine wildlife – oceans are excellent carbon storing machines, but higher  carbon dioxide concentrations than normal coupled with an increase in sea temperatures make the oceans acidic. Coral reefs are particularly at risk. Sensitive coral and algae that live on it are starved of oxygen causing the eventual death of coral. Example – Great Barrier Reef in Australia. If global warming remains on its upward path, by 2050 just 5% of Australia’s Great Barrier Reef – the world’s largest coral reef – will remain.

e) Other wildlife – melting glaciers and polar ice caps in the Arctic mean a loss of habitat for polar bears and seals. Climate change has a wide range of negative effects on a series of different animals from rhinos to elephants. You can research how (reasons include changing weather patterns affecting the ecosystem they depend on, wildfires in forests, water and food shortages).

f) Regulation of Earth’s temperatures –  the Antarctic ice sheet is the largest single mass of ice on Earth. It covers almost 14 million sq km and contains 30 million cubic km of ice – accounting for around 90% of all fresh water on the Earth’s surface. This ice plays a vitally important role in influencing the world’s climate, reflecting back the sun’s energy and helping to regulate global temperatures. This reflective capacity  is called the albedo effect.

You must be aware that there are MANY other environmental reasons. You won’t, and indeed can’t be expected to write down EVERY reason in an exam answer. But you will get marks for listing examples and developing points (explaining=why).

 

 

Physical causes of Climate Change

1. Volcanic Eruptions – When sulphur and ash is spurted out the vent during the eruption, they rise high into the atmosphere and reflect heat from the sun, having a cooling effect. Furthermore, the dust from volcanic eruptions creates a layer, shading parts of the earth which could result in a decrease in global temperatures within the next 5 years. Volcanos have a cooling effect on the atmosphere. For example, the eruption of Mount Pinatubo in 1991 caused a dip in global temperatures in the early 1990s
2. Sunspot activity – Cooler periods such as the Ice Age and warmer periods such as the Medieval warm period may have been caused in changes in sunspot activity. Sunspots are black spots on the surface of the sun. Lots of spots mean more solar energy firing out onto the Earth from the sun. Temperatures are greatest when there are plenty of sunspots because it means other areas of the sun are working even harder.
3. Milankovic Cycles – the stretch, wobble and tilt theory. The Milankovich cycles are caused by changes in the shape of the Earth’s orbit around the sun, the tilt of the Earth’s rotation axis, and the wobble of our axis. As the Earth’s orbit changes, so too does the amount of sunlight that falls on different latitudes and in seasons.

There are three general factors that determine the forcing changes in the Milankovitch cycles.

1. Eccentricity (the elliptical changes in the earths orbit around the sun)
2. Obliquity (the tilt of Earth’s axis toward and away from the sun)
3. Precession (the wobble of Earth’s axis toward and away from the sun)

Don’t worry so much about knowing the emboldened words, but it would be helpful to provide some indication of the stretch, tilt and wobble movements of the Earth’s axis.

4. Ocean currents – The world’s ocean is crucial to heating the planet. While land areas and the atmosphere absorb some sunlight, the majority of the sun’s radiation is absorbed by the ocean. Particularly in the tropical waters around the equator, the ocean acts a as massive, heat-retaining solar panel.

Oceans help distribute energy and heat throughout the planet. When water molecules are heated, they exchange freely with the air in a process called evaporation. Ocean water is constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and storms that are then carried by trade winds, often vast distances.

Oceanic currents move around energy by surface winds and tides (gravitational effects of the sun and moon). Major current systems typically flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere, in circular patterns that often trace the coastlines.

Human causes of Climate Change

There are human and physical causes of climate change.

1. Enhanced Greenhouse Effect

This refers to the human influence on the greenhouse effect.

Since the Industrial Revolution began around 1750, humans have contributed to the warming of the planet by adding Co2 and other heat-trapping gases into the atmosphere. Human activities, such as the burning of fossil fuels and changes in land use, release large amounts of CO₂, causing concentrations in the atmosphere to rise. Human activities currently release over 30 billion tons of CO₂ into the atmosphere every year.

2. CFCs – Another group of greenhouse gases includes the chlorofluorocarbons (CFCs). CFCs have been responsible for depleting the ozone layer as they attack and destroy ozone molecules. The ozone layer helps keep out harmful ultraviolet rays that cause sunburn to skin and damage to plants. Holes in the ozone layer caused by CFCs, which can be found in aerosols, fridges and making foam plastics, let harmful ultraviolet radiation in and contribute to the greenhouse effect. Remember – CFCs do not occur naturally in the atmosphere – they are synthetic compounds that only originate from human sources.

3. Nitrous oxide from fertilizers– they are used in agriculture but also the burning of fossil fuels and organic matter. Remember nitrous oxide is a harmful greenhouse gas which traps heat in the atmosphere.

4. Methane – methane is much more potent than Co2 despite having a shorter lifespan. Human causes of methane release include decomposing organic matter (landfills, sewage) and from natural gas extraction (methane escapes during oil and gas extraction (e.g. fracking) operations and is released into the atmosphere).

5. Deforestation – trees  are the lungs of the planet and store carbon.Forests in areas such as the Congo and the Amazon represent some of the world’s largest carbon stores on land. But when forests are logged or burnt, that carbon is released into the atmosphere, increasing the amount of carbon dioxide and other greenhouse gases and accelerating the rate of climate change. So much carbon is released that they contribute up to one-fifth of global man-made emissions, more than the world’s entire transport sector.

Evidence of Climate Change

Before we explain the different kinds of evidence demonstrating climate change is happening, we have to define what climate change is. Climate change is a large-scale, long-term shift in the planet’s weather patterns (temperature, precipitation, winds and other factors) or average temperatures. Earth has had tropical climates and ice ages many times in its 4.5 billion years. Since the last ice age, which ended about 11,000 years ago, Earth’s climate has been relatively stable at about 14 °C. However, in recent years, the average temperature has been increasing. The climate has always been changing, but overall average global temperature have been increasing.

Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization.

The graph above shows that average temperatures have been increasing. For your Higher exam, you maybe asked to interpret climatic trends on a graph. It is important you are able to provide as much detail about what is happening. What is the line showing? Can I back my answer up with statistics? Are there any obvious trends?

Evidence of Climate Change

Scientific evidence for warming of the climate system is unequivocal.

– Intergovernmental Panel on Climate Change

We always hear about climate change on the news, but how do we know it is happening? Let’s first look at clues coming from our changing landscapes. These vital signs refer particularly to evidence of global warming.

1. Sea level rises – the most commonly referred to vital sign. Satellite measurements and samples tell us that the Global Mean Sea Level (GMSL) has risen by 4 to 8 inches (10 to 20 centimeters). This is attributed to rising global temperatures which have caused melting of the polar ice caps and melting ice caps. The oceans absorb 80% of the additional heat trapped by the greenhouse gases. To help you visualise this, think of the oceans as large, vast sponges soaking up the heat. Water expands when it is heated up, so warmer waters need more space.
2. Look at the graphs and data! The planet’s average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century (a good statistic for your answers!). The year 2016 was the warmest year on record.
3. Ice sheets are shrinking in size – The thickness of the Arctic sea ice is rapidly declining and the the Greenland and Antarctic ice sheets have decreased in mass.
4. Glaciers are retreating (moving back) – Almost everywhere in the world including the Himalayas, Andes and Alaska.
5. Extreme weather patterns – Not only are there more heat waves, but a strong characteristic of climate change occurring is the number of extreme weather patterns. Global warming causes droughts, for example. The length of the UK growing season is increasing, winters are getting wetter and summers drier.

 

Collecting the Evidence

There are various ways you can collect the evidence.

1. Ice cores – scientists can take samples from ice caps (like a slushie drink). These samples are called ice cores. Looked inside the ice cores are trapped air and little bubbles of carbon dioxide which are preserved year after year with more snowfall. These samples can tell us about subtle changes in temperatures from decades back.
2. Rocks and Fossils – these can tell us about the climate from thousands of years ago. Limestone found in Yorkshire would have been formed on the bottom of a warm seabed millions of years ago.
3. Weather recordings – instruments like thermometers can accurately record temperatures in remote settings.
4. Tree rings – their growth layers, appearing as rings in the cross section of the tree trunk, record evidence of floods, droughts, insect attacks, lightning strikes, and even earthquakes that occurred during the lifespan of the tree. Each year a new tree ring is added. Thick rings are a sign of favorable climate, abundant rainfall, and good growing conditions. Thin rings indicate poor growing conditions and lack of rain, as well as natural disasters such as droughts, floods, and volcanoes.