statistics on global warming

Friday, August 3, 2007

GLOBAL WARMING

From the pollens found in layers of mud and from the gas bubbles in ice cores bored through major ice sheets (including an ice core from the Antarctic that gives a record going back well over 200 000 years), we can infer climatic conditions.

Our climate records cover only about 100 years, but these ice cores enable scientists to identify correlations between the composition of the atmosphere and regional climatic conditions in the past.

Recent and predicted increases in concentrations of greenhouse gases in the atmosphere are expected to cause additional warming of average surface air temperatures of the Earth.

It is caused by many external and internal factors.
This occurred in the distant past as the result of natural influences.
However, it is mostly due to human activity now:

For example:
Burning of fossil fuels and the reduction of forests.
Combustion changes the composition of the atmosphere by adding carbon dioxide and other gases. The large-scale destruction of forests releases large amounts of carbon stored in trees and forest soils.

These human-induced changes to the greenhouse effect of the earth's atmosphere are expected to result in global warming and other changes in climate.

Most scientists agree that the threat of climate change is real, but it depends on the extent of change and how it will vary from place to place.

Scientists generally agree that the Earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years. The Intergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the Earth's surface temperature and the models used by climatologists generally agree that the temperature increase, as a global annual average, might be from 1 to 4°C by the year 2100.

They also agree that the effect would be greater in the high latitudes, especially during the winter months and over large land masses. The warmer temperature would trigger other changes, such as a change in global precipitation patterns, a decrease in snow and ice coverage, and a rise in sea levels and that increased concentrations of sulfate aerosols have led to relative cooling in some regions, generally over and downwind of heavily industrialized areas.

GLOBAL WARMING IN SINGAPORE

From this graph we can see that Singapore is going through global warming. from the 26.9degrees celcius in 1989 to as high as 28.3degrees celcius in 1997 and 1998, there is an obvious rise in the mean temperatures in Singapore.

Global warming has affected Singapore in many aspects, and we are doing our best to reduce pollution which may lead to drastic worsening of global warming.

Singapore can continue its effort in making the city full of plants, which can help to greatly reduce the amount of carbon dioxide in the air, and thus to minimise the effect on the atmosphere layer. Also, the government is now promoting the awareness of global warming and the effect it would caused it, and many of the citizens are know what to do as their part.

Some examples like conserving water and energy; repair leaky systems; plan for strength and flexibility in new structures; regulate land use to avoid building on areas vulnerable to flooding; establish water metering and realistic pricing; include water-efficient technology in building codes. The government can also: irrigate less wastefully; design new criteria for adjustable, retrofitable storage structures; consider interbasin transfers and/or recharge of aquifers. In flood-prone areas:continue to improve forecasting and warning systems, and evacuation and relief plans; evaluate and improve present flood-control structures; design new structures to handle more frequent and extreme events. Many of these small actions can make a big difference.

In conclusion, Singapore has the potential to become a non-pollutant city as it is a small country and thus, it is easy for the government to control and promote awareness to every citizens. If all the citizens play their roll as a part of mother nature, the situation of global warming will not worsen as quickly as predicted, even though a gradual rise in temperature over the years is inevitable.

AMOUNT OF CARBON DIOXIDE OVER THE YEARS

Measured amounts of carbon dioxide in the atmosphere.

Ice buried below the surface of the Greenland and Antarctic ice caps contains bubbles of air trapped when the ice originally formed. Measurements from the youngest and most shallow segments of the ice cores, which contain air from only a few decades ago, produce carbon dioxide concentrations nearly identical to those that were measured directly in the atmosphere at the time the ice formed. But the older parts of the cores show that carbon dioxide amounts were about 25% lower than today for the ten thousand years previous to the onset of industrialization, and over that period changed little.

FACTORS AFFECTING GLOBAL CLIMATE

Factors affecting global climate

The Sun gives out radiation, which is the energy that drives our weather and climate. About one third of this solar radiation is reflected back into space. The rest is absorbed by different parts of the climate system: the atmosphere, oceans, ice, land and various forms of life.

Some of this energy is again absorbed and re-emitted through a process known as the Greenhouse Effect. The rest of the energy is lost to space. There is a delicate long term balance between the outgoing radiation and incoming solar energy. Any change in the factors that affect this process of incoming and outgoing energy, or change the energy distribution itself, will change our climate as it determines the amount of heat our Earth surface contains.

However, as the greenhouse effect is being overly enhanced by human factors or even some natural factors, the Earth suffers from global warming, and the examples below are just some factors which would have cause global warming to wrosen drastically throughout the next 10 years.

1. Natural Factors

Over the history of the Earth, the climate has changed. The ice ages and intervening warm periods are examples. Some changes are global in scale, while others have been regional or hemispheric. There are a number of natural factors that contribute to changes in the Earth's climate over various time scales. It is important to understand these factors when attempting to detect a human influence on climate:

Changes in Solar Output. The amount of energy radiating from the sun is not constant. There is evidence of an 11-year solar cycle (variation in energy output) in the temperature record of the Earth. Longer period changes may occur as well.

Changes in the Earth's Orbit. Slow variations in the Earth's orbit around the Sun change where and when solar energy is received on Earth. This affects the amount of energy that is reflected and absorbed. These orbital variations are believed to be a factor in initiating the ice ages.

The Greenhouse Effect. When energy from the sun enters the Earth's atmosphere, about a third of it is reflected back to space. Of the rest, the atmosphere absorbs some, but most of it is absorbed by the surface of the Earth. The Earth emits energy at longer wavelengths. Some of this energy escapes to space but some of it is absorbed again and re-emitted by clouds and greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide. This helps to warm the surface and the troposphere (lowest layer of the atmosphere), keeping it 33 °C warmer than it would otherwise be. This is the natural Greenhouse Effect, and vital to life as we know it.
Solar energy enters the atmosphere: some is reflected. This energy is absorbed by the Earth and reradiated back to space at longer wavelengths. Greenhouse gases absorb this energy and reradiate much of it back to the surface, much like an insulating blanket.

Aerosols. These are very fine particles and droplets that are small enough to remain suspended in the atmosphere for considerable periods of time. They both reflect and absorb incoming solar radiation. Changing the type and quantity of aerosols in the atmosphere affects the amount of solar energy reflected or absorbed.

2. Human Factors

Enhancing the Greenhouse Effect. Naturally occurring greenhouse gases (e.g. water vapour, carbon dioxide, methane, nitrous oxide) keep the Earth warm enough to support life. Scientific studies show that a variety of human activities release greenhouse gases. These include the burning of fossil fuels for producing electrical energy, heating and transportation. By increasing their concentrations and by adding new greenhouse gases like CFCs, humankind is capable of raising the average global temperature.

Land Use Change. As humans replace forests with agricultural lands, or natural vegetation with asphalt or concrete, they substantially alter the way the Earth's surface reflects sunlight and releases heat. All these changes also affect regional evaporation, runoff and rainfall patterns.

Atmospheric aerosols. Humans are adding large quantities of fine particles (aerosols) to the atmosphere, both from agriculture and industrial activities. Although most of these aerosols are soon removed by gravity and rainfall, they still affect the radiation balance in the atmosphere. Whether this effect adds to or offsets any warming trend depends on the quantity and nature of the particles as well as the nature of the land or ocean surface below. The regional effects, however, can be significant.

THE FEW MAIN GREENHOUSE GASES-

The main greenhouse gases

Carbon dioxide (CO2)Human source: Comes mostly from burning fossil fuels (oil, gas, and coal) for electricity and in cars and factories. Also from forest burning.Annual increase: 0.5%Life span: 50-200 years

Methane (CH2)Human source: Bacterial decomposition of organic matter (without oxygen) in rice paddies, swamps, garbage dumps, and intestines of ruminants like cows and sheep. Also from buning wood, mining coal.Annual increase: 1%Life span: 10-12 years

Chlorofluorocarbons (CFCs)Human Source: Chemically synthesized for use as coolants in refrigerators and air conditioners. Also in foam insulation, aerosol sprays.Annual increase: 4%Life span: up to 10 000 years

Nitrous oxide (N2O)Human source: Bacterial reactions in soil and water and from the breakdown of nitrogen-based chemical fertilizers. Also from burning fossil fuels and wood (deforestation).Annual increase: 0.4%Life span: 150 years

Note: Man-made greenhouse gases include those manufactured and those released due to processes controlled through human activity (e.g., the burning of fossil fuels). Some greenhouse gases, such as chlorofluorocarbons (CFCs), are entirely man-made, while only a small percentage of others, such as carbon dioxide, are man-made. Although man-made greenhouse gases are a small percentage of the overall total, they are changing the balance.