Global Warming & Climate Change
Author: Rehana Dada ~ Producer & presenter: SAfm and 50/50 Environmental TV Programme
( Article Type: Overview )
What is Global Warming and Climate Change?
"Global warming", or "climate change", refers to the rise in the planet's overall temperature due to anthropogenic (human-related) increase of greenhouse gasses in the atmosphere. "Greenhouse gases" (GHGs) are a range of natural atmospheric gases that are responsible for trapping the sun's heat on the planet - which enables life as we know it to exist on Earth.
But, because of land-use change and the burning of fossil fuels, GHGs have increased since industrialisation. Water vapour and carbon dioxide are the main GHGs but it is the release of carbon dioxide from burning fossil fuels that is considered to have had the greatest recent impact on the earth's climate. While they occur in relatively small concentrations, methane and nitrous oxides are two of the most potent greenhouse gasses. Since the beginning of industrialisation, methane has more than doubled in concentration and nitrous oxides have risen by 8%.
How real is Climate Change?
The phenomenon of climate change is now accepted by most credible scientists as a reality. While the temperature rise we are currently experiencing is by no means the highest in the planet's history, the changes we are currently experiencing are too sudden and dramatic for many species to be able to adapt. In the past, such dramatic and sudden changes have led to massive extinction events, such as the disappearance of the dinosaurs.
So far, 2016 is the hottest year on record. The average temperature in the first six months of 2016 was 1.3C warmer than the pre-industrial era in the late 19th century, according to Nasa.
In addition, proof of climate change is evident in such disasters as the melting of mountain glaciers and the polar ice caps, coral-reef bleaching because of higher sea temperatures, as well as more severe and more frequent Pacific Ocean storm events.
Warning signs of climate change include periods of unusually warmer weather, melting glaciers, polar warming, coral-reef bleaching, heavy precipitation events, longer droughts and dry periods, a rise in sea level, changes in plant and animal distribution and population, and increased environmental degradation and natural disasters.
What are the potential effects on the planet?
By 2100, it is currently anticipated that average global temperatures will rise by between 1°C and 6°C, with greater warming at the poles than at the equator. The possible impacts of global warming range from changes in rainfall, which affects agriculture, river courses and wetlands, as well as changes in the distribution of biodiversity, including disease-causing organisms.
Who will suffer the most?
In the short term, if no measures are taken to help communities adapt, people's vulnerability to poverty will be increased partly because of ecosystem degradation. The rural poor, subsistence farmers and fisherfolk who depend on natural ecosystems will be particularly vulnerable.
How will Global Warming and Climate change affect biodiversty?
A rapid extinction of species is probable because many (plants in particular) will not be able to change their distribution range fast enough. The destruction of wetlands, especially peatlands, adds significantly to the increased release of greenhouse gasses because these habitats are effective carbon stores. In addition, if the oceans and the Arctic tundra warm significantly, millions of tons of frozen methane may be released into the atmosphere.
The oceans are important climate regulators, but their ability to mitigate the impacts of the anthropogenic release of carbon dioxide will be reduced because as they warm their ability to absorb heat and carbon dioxide will decrease. Already stressed because of habitat destruction, increased pollution, wetlands degradation and increased sediment load in rivers, the oceans' resilience to climate change will become lower and already severe coral bleaching has been experienced in the Indian and Pacific oceans. The resultant stress on human communities who depend on fisheries and coastal areas for survival could be enormous. Rising sea levels would result in the flooding of coastal areas and many island states could be lost entirely, resulting in a large number of environmental refugees flocking to other countries. Low-lying countries such as Bangladesh and Denmark would therefore come under severe population pressures, as would countries, such as Australia, that may become a harbour for environmental refugees.
While most changes are expected to occur slowly and over decades, scientists also expect sudden dramatic change events at times. Most parts of the world are expected to warm significantly and already it is seen that average polar temperatures are higher, but because of changes in wind and ocean currents, some parts of the world will experience cooling. Scientific knowledge is not currently accurate enough to predict exactly what changes will occur and all climate processes are not yet fully understood. For example, in areas where rainfall is expected to increase, there is no way to judge whether there will be an even increase throughout the year or rapid flood events for a short part of the year. Part of the knowledge gap relates to the effect of clouds, pollution particles in the air, and how the oceans will respond. There is also a lack of understanding around micro-climatic processes. What many scientists are now saying, however, is that the effects are likely to be worse than previously predicted.
While climate change is a major contributing factor to many of the negative effects mentioned earlier, the situation is made considerably worse by the further negative impacts of inappropriate or bad development, overuse of resources and environmental degradation. The accumulated result of these negative impacts plus the effect of climate change put together is a scenario that some scientists now refer to as the threat of "global change".
What is the affect of Climate Change in South Africa?
Climate change is already a measurable reality and along with other developing countries, South Africa is especially vulnerable to its impacts {source - WSouth Africa is expected to become hotter and drier, leading to changes in agricultural production and biodiversity distribution. Even in the eastern part of the country where rainfall is expected to increase, the impact will not necessarily be positive because increased rainfall at inappropriate times could cause exceptionally destructive floods and impacts to natural river courses and human infrastructure. Changes in rainfall will affect food production and may cause increases in diseases.
The impact of drought is most severe in arid regions. In the Suid Bokkeveld region of the Northern Cape, where annual rainfall is about 150–400mm, rooibos production declined by 40% in 2004/ 2005 because of prolonged drought. Seedlings struggle to survive and one garden no longer exists. Community adaptation measures include management of aliens to reduce unnecessary water loss, organic farming practices, continued monitoring and data collection, and improved communication between the affected farmers, communities, government, NGOs and research institutes as well as the introduction of sustainable harvesting techniques for wild rooibos, medicinal plants and fuel wood.
Across South Africa, changes have also been noted in tree cover. Forests are expanding at the expense of grasslands. On a global scale, records show that trees have increased in savannas since the 1950s. It is possible that higher CO2 levels in the atmosphere are responsible for making trees grow faster than they used to. In the Kruger National Park, declines have been noted in roan, sable, eland and tsessebe since the mid-1980s and these populations are expected to decline further over the next 4-6 years. Several factors are considered to be responsible for this. In the mid-1980s, the mean temperature increased by 0.4°C, then during the 1990s the rainfall during the dry period was exceptionally low. This was made worse by the fact that the dry period was particularly prolonged. The resultant change in vegetation created stronger competition with other herbivores and increased exposure to predation. These species are at the edge of their distribution range and it is now being questioned whether their range is shifting to outside park boundaries. In Masai Mara in Kenya, a similar decline was noted in large herbivores.
Perhaps the most striking sign of climate change in South Africa is seen in the change in distribution of the kokerboom, Aloe dichotoma. It is found in the western parts of South Africa, Namibia and Angola in the succulent karroo, the world's only arid biodiversity hotspot with over 5 000 species. The kokerboom is a long-lived drought-resistant species, but over the past 45 years or so, significant declines have been noted in many old populations, particularly in the warmer parts of its range - mostly at lower altitudes and closer to the equator. There is higher mortality with extreme water stress. At the same time, in the southern part of its range, the plant is increasing in population. The conclusion reached by researchers at the South African Biodiversity Institute is that the kokerboom is shifting its range southwards and that this shift is related to climate change. Other succulent karroo species might be able to ward off extinction by shifting their range as well but in general desert ecosystems are not resilient to climate change, and species that disperse slowly are not likely to survive. This is particularly worrying in the succulent karroo where 40% of its species are range-restricted endemics.
What action is South Africa taking to mitigate Climate Change?
South Africa’s response to climate change has two objectives: • Effectively manage inevitable climate change impacts through interventions that build and sustain South Africa’s social, economic and environmental resilience and emergency response capacity. • Make a fair contribution to the global effort to stabilise greenhouse gas (GHG) concentrations in the atmosphere at a level that avoids dangerous anthropogenic interference with the climate system within a timeframe that enables economic, social and environmental development to proceed in a sustainable manner. This response is guided by principles set out in the Constitution, the Bill of Rights, the National Environmental Management Act, the Millennium Declaration and the United Nations Framework Convention on Climate Change. These principles are detailed in section 3. The overall strategic approach for South Africa’s climate change response is needs driven and customised; developmental; transformational, empowering and participatory; dynamic and evidence-based; balanced and cost effective; and integrated and aligned. [Source: National Climate Change Response White Paper]
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