Climate change

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Climate change fact file

• Overview
• Introduction
• Evidence
• Causes
• Effects
• Prevention
• How to help
• References

Overview

Climate change refers to man-made changes in our climate. It is often also called ‘global warming’, as one of the most well-known effects of climate change is a steady rise in the Earth’s temperature (1).

Other effects include sea levels getting higher, ice melting at the poles, and extreme weather events like hurricanes and droughts becoming more common ⁽²⁾. Many animals are also struggling to survive as their habitats change ⁽³⁾.

Climate change is caused by an increase in the amount of gases in our atmosphere that trap heat. These gases occur naturally and ensure the Earth is maintained at a life-supporting temperature, in a process called ‘the greenhouse effect’. However, human activities that burn fossil fuels like coal and oil are increasing the amount of these gases in our atmosphere, causing the Earth to warm to abnormal levels ^{(2) (4)}.

Scientists are predicting that climate change will cause a mass extinction of many species of plants and animals. As ice melts in the Polar Regions, polar bears and emperor penguins are losing vital habitats, the ocean is also becoming more acidic which is killing many corals. Species that live or breed on low-lying remote islands, like marine turtles, are threatened by rising sea levels and extreme weather, and many plants, which cannot move to find new habitats, are disappearing from parts of their range, due to drought and higher temperatures ⁽³⁾.

It is too late to reverse many of the effects of climate change. But to limit the damage done by climate change many countries have pledged to limit the amount of greenhouse gases in the atmosphere. Renewable energies, such as wind, tidal and solar energy, are being developed so that we do not need to keep burning fossil fuels ^{(1) (5)}.

You can help tackle climate change by:

• reducing, reusing and recycling products that you buy
• walk or take public transport where possible so that you use a car less often
• insulate your home better so that you do not need to use so much energy to heat it
• or simply tell your friends and family about climate change and what they can do to help

Although each action may be small, if many people make small changes it will add up to make a big difference ^{(6) (7)}.

Introduction

What is climate change?

Traditionally, climate change refers to any long-term change in normal weather patterns caused by a process that adjusts the climate, such as a volcanic eruption or a cyclical change in solar activity. ⁽¹⁾

However, the term ‘climate change’ now usually refers to man-made changes in the climate that have occurred since the early 1900s. Climate change is often interchanged with the phrase ‘global warming’, as the principal way in which humans are affecting the climate is through the release of heat-trapping greenhouse gases into the air ⁽⁴⁾.

The Earth’s climate has changed throughout history. In the last 650,000 years there have been seven cycles of glacial advance and retreat. Most of these changes are attributed to very small changes in the Earth’s orbit changing the amount of energy the Earth receives from the sun ⁽⁴⁾.

Changes in the modern climate show a discernable warming trend that can only be partly explained by natural causes ⁽⁵⁾. The overwhelming majority of scientists agree that this is due to rising concentrations of greenhouse gases in the atmosphere caused by human activities. The current human-induced warming trend is of particular significance as it is occurring at an unprecedented rate ⁽¹⁾.

Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. Studying these climate data collected over many years reveal the signs of a changing climate ⁽⁴⁾.

Evidence

There is a wide range of evidence which indicates our climate is warming:

• Global temperature rise: The Earth has been warming since 1880. It has already increased by about 0.75°C globally, and by almost 1°C in Europe alone ⁽⁵⁾. The 1990s were the warmest decade in the past 1,000 years ⁽⁵⁾, with the 20 warmest years having occurred since 1981 ⁽⁴⁾. Current climate models predict an increase in average temperature in the region of 3 to 5°C over the next 100 years, with an increase in frequency of extremely hot periods and generally warm years ⁽²⁾.
• Warming oceans: Oceans have been absorbing more than 80 percent of the heat added to the atmosphere, with the top 700 metres of the ocean showing the greatest warming ⁽⁴⁾.
• Sea level rise: Since 1900, sea-levels have risen by about 17 centimetres globally. Evidence shows the rate of sea-level rise is increasing ⁽⁴⁾.
• Shrinking ice sheets: The Greenland and Antarctic ice-sheets, which between them store the majority of the world’s fresh water, have both started to shrink ⁽¹⁾.
• Declining Arctic sea-ice: Arctic sea-ice has been declining since the late 1970s, reducing by about 0.6 million square kilometres per decade - an area around the size of Madagascar. Average Arctic temperatures have also increased at almost twice the global average rate in the past 100 years ⁽²⁾.
• Glacial retreat: Glaciers are retreating almost everywhere around the world - including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa ⁽¹⁾. It is likely that 75 percent of the glaciers in the Swiss Alps will disappear by 2050 ⁽⁵⁾.
• Extreme events: In the last decade, there were three times more weather-related natural catastrophes in the world than in the 1960s, including heat waves, floods, droughts and forest fires ⁽⁵⁾. More intense and longer droughts have also been observed over wider areas since the 1970s, particularly in the tropics and subtropics ⁽²⁾.
• Ocean acidification: The carbon dioxide content of the Earth’s oceans is increasing by about 2 billion tonnes per year. This has increased ocean acidity by about 30 percent ⁽⁴⁾.
• Wildlife behaviour: Many species are changing their behaviour, from butterflies appearing earlier in the year to birds starting to change their migration patterns ⁽¹⁾.

Causes

What causes climate change?

Just as the world’s most respected scientific bodies have confirmed that the Earth is getting hotter, they have also stated that there is strong evidence that humans are driving the warming ⁽²⁾.

Scientists agree the main cause of climate change is human activities which magnify the ‘greenhouse effect’ – a natural process in which gases in the atmosphere warm the Earth by trapping heat that is radiating towards space ^{(2) (4)}.

A layer of greenhouse gases, including water vapour and smaller amounts of carbon dioxide, methane and nitrous oxide, act as a thermal blanket surrounding the Earth. This absorbs heat and warms the surface to a life-supporting average of 15°C. As energy slowly escapes out of our atmosphere, some of it is absorbed by the greenhouses gases, which warms the Earth further. Although these gases are present naturally, human activity is increasing their concentrations, thereby exacerbating the greenhouse effect ⁽⁴⁾.

Carbon dioxide (CO2) is the main greenhouse gas of concern. A finite amount of carbon is stored in fossil fuels, the sea, living matter and the atmosphere. Without human influence there is a fine balance in the amount of carbon in these stores, but when humans cut down trees or burn fossil fuels, they release extra carbon into the atmosphere ⁽⁴⁾.

Warming caused by man-made emissions of greenhouse gases also increases the amount of water vapour in the air by boosting the rate of evaporation from the oceans and elsewhere. This amplifies the warming effect, as well as the amount of rain and snow falling to Earth which can lead to extreme weather patterns ⁽⁴⁾.

Fossil fuels

The greatest source of man-made emissions is the burning of fossil fuels ⁽²⁾. As the world’s population grows, more people are burning fossil fuels for energy. By driving cars, heating our homes with oil, gas, or electricity from coal-fired power stations, we release greenhouse gases into our atmosphere. In 2005, burning fossil fuels sent about 27 billion tonnes of carbon dioxide into the atmosphere ⁽⁸⁾.

Food production also leads to the burning of fossil fuels. Land must be cleared for farming, which often contributes to deforestation. Food is also often transported across the world to reach distant markets, meaning fossil fuels are burnt in the process. Fertiliser production for crops and methane gas emitted by livestock also contributes to emissions.

Scientists estimate that forest loss and other changes to the use of land account for around 23 percent of current man-made carbon dioxide emissions ⁽⁹⁾. This is because forests are a natural ‘sink’ of carbon dioxide. By harnessing the sun’s energy, plants absorb carbon dioxide from the air as they grow, turning the carbon molecules into the building blocks of their trunks, branches and leaves. But when forests are cleared or burned, their stored carbon is released back into the air, contributing to global warming ⁽⁹⁾.

Effects

What species does climate change affect?

Animals and plants unable to adapt to a rapidly changing climate are seriously threatened by climate change. Scientists predict that man-made climate change could contribute to a mass extinction of wildlife in the near future.

Climate change will leave many species without any suitable habitat. Others may be forced to migrate long distances to find hospitable surrounds. Climate change is also causing some migratory species, including many birds, to leave their wintering grounds for breeding areas earlier in the year, leading to competition with resident species for food and nesting areas ⁽³⁾.

Island inhabitants

Species on remote islands occupy a particularly precarious position in the face of climate change. With an already restricted range, these species are unable to travel to find new suitable habitat, making them extremely vulnerable to extreme weather events such as hurricanes and drought. For example, the hawksbill turtle is at risk of rising sea levels and increases in storm activity, which will destroy its nesting habitat. Rising air temperatures may also result in turtle populations developing a skewed sex ratio, as sex is determined by the temperature at which the eggs are incubated ⁽³⁾.

Polar Regions

The loss of sea-ice and ice-sheets is adversely affecting species from both poles. In the Antarctic, the decline in the extent of the pack-ice will result in the loss of emperor penguin breeding habitat, while reduced ice cover means less krill, a vital source of food for many Antarctic species. In the Arctic, the polar bear uses sea-ice as a platform from which to hunt its seal prey. But warming temperatures are reducing the availability of this vital habitat, causing many bears to forage on the mainland where food is more difficult to find ⁽³⁾.

Corals

The impacts of climate change are certainly not restricted to the Polar Regions, however, with species from tropical regions also struggling in the heat. Even slight rises in ocean temperatures can lead to coral bleaching, which leaves coral weak and vulnerable to harmful diseases. The environmentally sensitive staghorn corals, which comprise around 160 species, are already exhibiting signs of significant declines ⁽³⁾.

Plants

The sedentary nature of plants makes them particularly vulnerable to climate change. A prime example is the quiver tree from the Namib Desert in southern Africa, which is disappearing from northern parts of its range due to drought stress ⁽³⁾.

Invasive species

While climate change is the most serious threat to the survival of many species, some are benefiting from a changing climate. Warmer climates and changes in rainfall levels are opening up previously inhospitable habitats to many species, including those described as ‘generalists’.

But while most of these invasive species do no harm in their new environments, a small number do disproportionate harm and are thriving at the expense of those species adapted to a narrow range of environmental conditions, unable to quickly adapt to the changing climate. Combined with global trade and transport networks, which are often blamed for the introduction of non-native animals, the threat of invasive species is likely to result in a huge environmental and economic cost.

Prevention

Mitigating climate change

Climate change is already having many discernible effects on our natural environment, meaning some of the impacts of climate change are irreversible. Even if greenhouse gas emissions are substantially reduced, the long lifespan of carbon dioxide in the atmosphere means that we cannot avoid further climate change ⁽²⁾.

Current scientific evidence indicates that the effects of climate change will only remain manageable if global temperatures rise by no more than 2ºC above pre-industrial levels. For this to happen, worldwide emissions must peak by 2020 and be cut to 50 percent of 1990 levels by 2050 ^{(2) (5)}.

If we do not soon take drastic action to reduce our emissions, climate change will cause more and more costly damage and disrupt the functioning of our natural environment, which supplies us with food, raw materials and other vital resources. This will negatively affect our economies and could destabilise societies around the globe, as well as cause permanent damage to our planet’s biodiversity.

Most countries have responded to climate change by becoming parties to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty that aims to stabilise greenhouse gas concentrations in the atmosphere at a level that prevents dangerous human-interference of the climate. Many countries are also heavily investing in clean energies, such as wind, tidal and solar energy, to reduce their dependency on fossil fuels ⁽⁵⁾.

How to help

Climate change is a huge challenge for the planet, and requires action by all levels of government, but there are many things that you can do to reduce your own energy consumption:

• Make your home more energy efficient: There are many ways that you can reduce your household emissions, including replacing your traditional light bulbs with energy efficient ones, turning off appliances when they are not in use, invest in double glazing, replace domestic and electrical equipment with energy saving models, and sealing and insulating the building ⁽⁶⁾.
• Make your lifestyle greener: Everything we do in our day to day lives emits carbon dioxide into the atmosphere. That means that even making small changes in what we do, or how we do it, can have a positive impact in preventing the onset of climate change. Shop less and try to reduce your consumption, or try walking or taking public transport rather than using a car ⁽⁶⁾.
• Buy sustainably sourced products: As forest loss is a significant contributor to climate change, ensure you buy sustainably sourced timber products. There are various labelling schemes, such as those run by the Forest Stewardship Council (FSC) and the Programme for the Endorsement of Forest Certification (PEFC), which show that a product has come from a sustainably managed source ⁽¹⁰⁾.
• Reduce, reuse and recycle: Huge amounts of waste end up in landfill sites every day. Biodegradable waste breaks down into methane, thereby contributing to climate change. Recycling more, composting and reusing helps reduce these emissions and also helps conserve energy in the manufacturing process. If there is a recycling program in your community, recycle your newspapers, beverage containers, paper and other goods. Also try to use products in containers that can be recycled and items that can be repaired or reused ^{(6) (7)}.
• Eat less meat: Foods such as beef and dairy make a deep impression on a consumer’s carbon footprint. Even eating one less meat meal each week would help tackle climate change ⁽⁸⁾.
• Use green power: There are two ways to use green power: you can buy green power or you can modify your house to generate your own green power by installing energy generating innovations such as wind turbines or solar panels ^{(6) (7)}.
• Use water efficiently: Municipal water systems require a lot of energy to purify and distribute water to households. Saving water, especially hot water, can substantially lower household greenhouse gas emissions ⁽⁶⁾.
• Spread the word: Why not get involved in fundraising and awareness-raising events that promote greener lifestyles. Tell family and friends that energy efficiency is good for their homes and good for the environment because it lowers greenhouse gas emissions ⁽⁶⁾.

Find out more about climate change and how you can help:

• Intergovernmental Panel on Climate Change (IPCC): www.ipcc.ch
• IPCC Fourth Assessment Report, Summary for Policy Makers. Available at:
  www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
• NASA - Global Climate Change: climate.nasa.gov/
• Met Office - Climate Change: www.metoffice.gov.uk/climate-change/
• The Guardian - Ultimate Climate Change FAQ:
  www.guardian.co.uk/environment/series/the-ultimate-climate-change-faq
• U.S. Environmental Protection Agency - Climate Change: What you can do:
  www.epa.gov/climatechange/wycd/index.html
• The Nature Conservancy – Climate Change: What you can do:
  www.nature.org/initiatives/climatechange/activities/art19630.html

References

1. Met Office - Climate Change:
   http://www.metoffice.gov.uk/climate-change/
2. IPCC (2007) Summary for policymakers. In: Solomon, S. et al. (Eds.) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K. and New York, USA.
3. IUCN (2009) Species and Climate Change: More than Just the Polar Bear. IUCN/Species Survival Commission. Cambridge, UK. Available at:
   http://www.iucn.org/what/tpas/biodiversity/resources/publications/?4562/Species-and-Climate-Change
4. NASA - Global Climate Change:
   http://climate.nasa.gov/
5. European Commission - Climate Change:
   http://ec.europa.eu/clima/sites/campaign/index_en.htm
6. U.S. Environmental Protection Agency - Climate Change: What you can do:
   http://www.epa.gov/climatechange/wycd/index.html
7. The Nature Conservancy - Climate Change: Climate Saving Tips
   http://www.nature.org/initiatives/climatechange/activities/art19630.html
8. Directgov - Causes of climate change:
   http://www.direct.gov.uk/en/Environmentandgreenerliving/Thewiderenvironment/Climatechange/DG_072920
9. Guardian - How do trees and forests relate to climate change?
   http://www.guardian.co.uk/environment/2011/feb/11/forests-trees-climate
10. Forestry Commission:
    http://www.forestry.gov.uk/website/forestry.nsf/byunique/infd-7m8fz7