 |
Fig. 2 The greenhouse effect
|
|
|
|
The Earth has a natural temperature control system. Certain atmospheric gases are critical to this system and are known as greenhouse gases. On average, about one third of the solar radiation that hits the earth is reflected back to space. Of the remainder, some is absorbed by the atmosphere but most is absorbed by the land and oceans. The Earth's surface becomes warm and as a result emits infrared radiation. The greenhouse gases trap the infrared radiation, thus warming the atmosphere. Naturally occurring greenhouse gases include water vapour, carbon dioxide, ozone, methane and nitrous oxide, and together create a natural greenhouse effect. However, human activities are causing greenhouse gas levels in the atmosphere to increase. Greenhouse gases are mixed throughout in the atmosphere.
Vocabulary
Predominant – преобладающий, доминирующий
Baseline – основание, базисная линия
fossil fuel combustion – сгорание твердого топлива
forestry sector – лесной массив, сектор лесного хозяйства
deforestation – вырубка леса
decomposition – разложение, распад, гниение
manure – удобрение, навоз
livestock – домашний скот
digestion process – процесс пищеварения
afforestation – засаживание лесом
Read the text and answer the following questions:
1. Comment on the diagram.
2. What are greenhouse gases caused by?
3. Talk about the main sources of emissions.
4. What is the role of human activity in producing emissions.
5. What do industry and agriculture emissions include?
6. Describe the processes presented at figure 2.
Climate changes
Since 1901, the Earth has warmed over 0.7°C. Warming in our future is heavily dependent on our actions in the short and mid-term. Even if emissions are capped at 2000 levels, an average temperature increase of 0.1°C per decade is already underway due to the time lag between the initial emitting of greenhouse gases, the subsequent changes in the atmosphere, and the continued self-amplifying processes which feed into other processes, called positive feedbacks.
Anthropogenic emissions are destabilizing the Earth's climate system. This is directly affecting air and ocean temperature, precipitation and extreme weather events, and creating positive feedbacks in the climate. For example, with more heat trapped in the atmosphere, global average air and ocean temperatures will rise, leading to a positive feedback in which one change results in another process altering the climate in a similar direction - further melting ice and snow both on land and at sea, raising the sea level, and causing other ecosystem changes. The complexity of the climate system also includes dampening, negative feedbacks. Another example, with warmer air temperatures, more water will evaporate and enter the atmosphere, resulting in more clouds. This in turn increases the atmospheric reflectivity, of the Earth and reduces the amount of solar radioactive energy absorbed.
|
|
|
This 0.1°C warming will thus occur regardless of our actions. A recent study found that the effects of climate change are largely irreversible, with impacts from carbon dioxide lasting more than 1,000 years. While current and future actions to reduce emissions will not deter the 0.1°C warming, they can prevent further warming. The threshold, or tipping point, of no return, in which the world is catapulted into catastrophic climate change, is generally understood based on science to occur at a 2°C increase over pre-industrial temperatures; however, as emissions continue rising, the world will pass other thresholds, triggering a domino effect of significant and adverse changes in the climate. Avoiding catastrophic climate change is an imperative, but changes even close to catastrophic do not bode well for the world either.
The number of cold days and cold nights in most of the world has a 90 per cent likelihood of decreasing while the number of hot days and hot nights are on the rise. Heat waves will make more regular appearances, as will heavy rainfall which can contribute to flooding. These changes will have asymmetric impacts on regions of the world based on each unique location and ecosystem. Countries further from the equator are expected to experience heavier precipitation, whereas tropical and sub-tropical regions are expected to receive less precipitation.
According to the Intergovernmental Panel on Climate Change (IPCC), an international scientific body established by the World Meterological Organization and UN Environment Programme and responsible for assessing climate change science through consensus, the world could warm by 1.8-4.0°C by 2100. As scientific understanding of the interaction between warming air temperatures and ice sheet melting improve, the possibility of sea level rise reaching one meter is increasing as well.
For reference, all countries with coasts will see changing coastlines of varying levels. Low-lying coastal countries, on the other hand, could witness flooding of large portions of their land. These areas are likely to be heavily populated. For example, one metre of sea level rise in Bangladesh translates into flooding of 14,000-30,000 km2, or 10-20 per cent of its total area, which would displace a fifth of the country's population. For many small island nations, one metre translates to near to total inundation, requiring complete population migration.
Vocabulary
to be capped – оставаться на предельном уровне
destabilizing – дестабилизация, выход из состояния равновесия
feedback – обратная связь, ответная реакция
to alter – менять
to trigger - вызывать
dampening – становиться влажным
irreversible – окончательный, необратимый
imperative – настоятельный, повелительный, обязывающий
precipitation – осадки
subsequent – последующий
to bode – предвещать
domino effect - цепная реакция
inundation – затопление, наводнение
|
|
|
Read the text and answer the following questions:
1. What destabilizes the Earth’s climate system?
2. What are the consequences of rising ocean temperatures?
3. Does human activity contribute to 0.1°C warming of climate?
4. What is the threshold for a catastrophic climate change?
5. What are the predictions about further climate change on the planet?
6. What does IPCC stand for and does this organization do?
7. What are the scientific predictions concerning sea level and coastal line?
Current impacts
Glaciers and sea ice are already melting at increasing rates. The ice loss of about half a meter during the decade from 1996-2005 is about twice the ice loss during the previous decade and four times the ice loss during the decade before. Coral reefs, an indicator of ocean health and stability due to their sensitivity to warming sea surface temperatures and ocean acidification, are dying off at an alarming rate. The latest review of coral reefs in 2008 found that 20 per cent of the world's coral reefs had been destroyed or severely damaged. Taking into consideration climate change, all coral reefs are at risk of extinction.
Recent climate-related impacts on land are quite diverse. Three examples are expanding ranges of pests, severe heat waves, and more frequent flooding events. Pine beetles have been moving up in latitude and altitude as regions experience warmer winters and, in taking advantage of already stressed higher temperatures and drought conditions, have had devastating effects on forests. And these forests are important carbon sinks which take up greenhouse gas emissions. In the western United States, nearly 4 million acres of forest were killed in 2007 alone. In Central America, Belize experienced its first ever major pine beetle outbreak in 2000, a natural disaster which had a higher tree mortality rate than any other natural disaster in the country since 1944 when such monitoring began.
In the last century, some regions of the world (eastern North and South America, northern Europe, and northern and central Asia) saw an increase in precipitation while other regions (the Sahel belt south of the Sahara desert, the Mediterranean region, southern Africa, and parts of southern Asia) saw less. Europe bore the brunt of extreme weather events in the form of unusually intense flooding in 2002, followed by the heat wave in 2003 which resulted in the deaths of an estimated 30,000 people. In France, the average summer temperature in 2003 was 3.6°C above the long-term norm.
The IPCC agrees that climate change would increase the intensity and severity of extreme weather events, altering what is considered normal for these events. Natural variability has and will continue to play a leading role in these events, but climate changes are expected to exacerbate them. Evidence of this is accumulating globally, as anthropogenic emissions rise, along with the number of weather-related disasters.
Natural hazards like earthquakes are far less susceptible to human influence than weather-related natural hazards like hurricanes, winter storms, flooding, and wildfires. The 1980s saw on average 300 disasters a year of weather-related disasters, and that number grew to 480 in the 1990s, and in the last decade has increased to 620. Meanwhile, worldwide economic losses associated with these disasters topped $214 billion (USD) in 2005 as a result of an intense hurricane season. While climate change does not directly cause these events, destabilizing the climate system will affect “primarily increase “ the likelihood and severity of extreme weather events.
Future impacts of climate change on the Earth and human vulnerabilities to those impacts could be numerous. While some regions of the world could experience more annual rainfall, water resources both above and below ground in many regions of the world will also be strained, as precipitation patterns shift. Where glaciers and annual snowmelt are the primary source for surface waters, regions can expect declining water availability over the next 100 years. For example, glaciers in Tibet are the start of six major rivers located in the some of the most heavily populated regions of the world.
|
|
|
