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What is climate change

Quick summary

Climate change refers to variations in the Earth’s global climate, or regional climates, over time - changes that have accelerated rapidly over the last century. One of the major effects of modern climate change is the rise in average global air and ocean temperatures commonly referred to as “global warming”.

Did you know that 19 of the 27 years since 1980 were warmest on record?

The Earth has warmed by 1 degree Celsius over the last century. The most authoritative scientific reports to date which is the conclude that this global temperature increase is very likely due to the observed human-induced increases in six major greenhouse gases that trap heat in the atmosphere. Atmospheric carbon dioxide (CO2) levels, for example, have increased to just below 400 parts per million from 300 ppm before industrial times. If we continue business as usual, levels of this major greenhouse gas are expected to rise above 600ppm by 2100, increasing global temperatures by between 2 and 4.5 degrees Celsius.

And these are the predictions for future, slide provided by Harald Winkler Energy research centre www.erc.uct.ac.za

The culprits

Human industry is mostly responsible for climate change, because of the carbon dioxide and other greenhouse gases emitted by factories (particularly cement factories), power plants, airplanes, trucks, cars, and other sources. What few people realize is that burning or clearing tropical forests is also a major source of atmospheric carbon, an estimated 20 percent of the total, which is second only to the power generation sector. Some 35 million acres (close to 11 million ha) of tropical forests (about the size of Italy) are destroyed through slash-and-burn methods each year to make way for livestock farming and crops, releasing millions of tons of carbon dioxide into the atmosphere. In fact, the destruction of tropical forests contributes one quarter of global emissions with agriculture and land use change, more than all of the world's cars and trucks.

Did you know? Predicted deforestation in Central Africa is estimated to release 34 billion tons of CO2 into the atmosphere by 2050. This is roughly equivalent to the United Kingdom’s CO2 emissions over the last 60 years. The Democratic Republic of the Congo risks losing almost half of its forests.

Large scale agriculture is another global warming culprit, as large amounts of the artificial nitrogen fertilizers applied to crops convert into the potent greenhouse gas nitrous oxide. Factory farming is another greenhouse offender. Globally, livestock produce large amounts of methane, a greenhouse gas that is 23 times more potent than CO2. Landfills, where we dump the mountains of waste we produce, are another source of methane, producing 34% of total emissions. In many countries it is law to flare off the methane produced by landfills, but this is not practiced in South Africa. However, in a showcase project at three landfill sites in Durban, methane is captured and used to produce an annual 10 MW of electricity that is fed into the municipal grid. This project by the eThekwini Municipality is a leading example of how to turn climate change to our benefit.

Did you know that the average CO2 emission rate per person in South Africa is about 10 tons of CO2 (or equivalent in other greenhouse gases) per person per year? This is above the global average of 7 tons per person, making South Africa a significant contributor to global greenhouse gas emissions.

Why worry?

The Earth's atmosphere is now warming at the fastest rate in recorded history, posing a threat to sustainable development, especially in developing countries, and could undermine global poverty alleviation efforts and have severe implications for food security, clean water, energy supply, human health, environmental health and human settlements. Human communities are also directly threatened by climate change as seas rise, storms become more intense, and episodes of drought and flooding increase.

Climate change and global warming are also among the greatest threats to biodiversity today and without action will destroy some of the World's most precious ecosystems and result in the extinction of more than a million species. Coral reefs are beaching and many already dying off due to increased sea temperatures and acidification of the oceans to a level not experienced in over 800,000 years. As the Earth's temperature rises and habitats change, wild species that have adapted over millions of years to their specific conditions have to move to more suitable areas. Many species, however, cannot move because they are not suited to their surrounding ecosystems or are hemmed in by human development. Entire populations of species can disappear if they are unable to relocate or adapt to climate changes.

What will happen if the Earth heats up?

The Intergovernmental Panel on Climate Change predicts that temperatures will rise by between 2°C and 4.5°C by 2100, relative to pre-industrial temperatures. Below are estimates of the impacts for each degree of temperature rise based on a major report published by Nicholas Stern, chief British government economist, in October 2006.

The impacts of 1°C rise

  • Small Andean glaciers disappear, threatening water supplies for 50 million people
  • Cereal yields in temperate regions increase slightly
  • At least 30,000 people die every year from climate-related diseases, but winter mortality in Northern Europe and US drops
  • 80% of coral reefs are bleached, including the Great Barrier Reef
  • The Atlantic thermohaline circulation starts to weaken

The impacts of 2°C rise

  • Water availability in some vulnerable regions (Southern Africa and Mediterranean) could drop by 20% - 30%
  • Crop yields in Africa drop by 5% - 10%
  • 40 - 60 million more people are exposed to malaria in Africa
  • Up to 10 million more people are affected by coastal flooding
  • Arctic species, including the polar bear and caribou, run a high risk of extinction
  • The Greenland ice sheet could begin an irreversible melt

The impacts of 3°C rise

  • In southern Europe, serious drought happens occurs every 10 years
  • 1 to 4 billion more people suffer water shortages; up to 5 billion gain water but they could suffer increased floods
  • Another 150 to 500 million people are at risk of hunger (if carbon fertilisation is weak)
  • 1 to 3 million more people die from malnutrition
  • The risk of abrupt changes in monsoons climbs
  • There is a higher risk that the West Antarctic ice sheet, and the Atlantic thermohaline circulation, will collapse

The impacts of 4°C rise

  • Water availability in Southern Africa and Mediterranean could drop by 30% - 50%
  • African agricultural yields drop by 15% - 35%
  • Up to 80 million more Africans are exposed to malaria
  • Another 7 to 300 million people are affected by coastal flooding

The impacts of 5°C rise

  • Some of the large Himalayan glaciers may disappear, affecting one quarter of the Chinese population and millions in India
  • Ocean acidity continues to rise; marine ecosystems are seriously disrupted
  • Sea level rise threatens small islands, low-lying coastal areas such as Florida, (Florida) and major world cities such as New York, London, and Tokyo.

What to do?

There are two key ways of responding to changing climate. One is through mitigation - reducing the intensity of climate change by reducing greenhouse gas emissions, and the second is adaptation - the process of recognizing the effects of climate change and adapting to these changed conditions.

Mitigation recognizes that in the longer term countries and individuals can stem the tide of climate change through activities that reduce the quantities of greenhouse gases we produce. This approach implies radical changes in the use of technology, and employing practices that actively reduce carbon emissions such as innovative industrial processes, the use of cleaner fuels, the implementation of energy efficiency measures and the enforcement of fuel efficient vehicles.

The graph below, sourced from the Stern review, shows the predicted changes in global temperature with various atmospheric CO2 concentrations. A business as usual scenario will produce atmospheric CO2 levels of more than 750 parts per million by 2050, leading to a predicted global temperature increase of between 3 and 5? Celsius. The European Union and the United Nations have set a target of keeping global warming to below 2? Celsius, which means keeping atmospheric CO2 concentrations (or the equivalent in other greenhouse gases) to below 450 parts per million. As current levels are 389 ppm, meeting this target means reducing our current emissions – quite a challenge!

Click here to find out more on how you can mitigate climate change.


Slide provided by Harald Winkler Energy- Research Center www.erc.uct.ac.za

Click here to find out more about how South Africa can adapt to survive climate change.

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