An overall warming of the planet, based on average temperature over the entire surface.
Changes in regional climate characteristics, including temperature, humidity, rainfall, wind, and severe weather events.
Let's explore the differences between these two concepts in more detail
Global Warming — The Heat is On
Planet Earth's current warming trend is based largely on natural warming and cooling cycles that have been happening for eons; as well as human-caused additions to greenhouse gases, which are boosting the atmosphere's ability to trap heat in the biosphere. Minor factors like an overall increase in the sun's solar intensity play a smaller role.
While greenhouse gases are an essential component of a livable planet—they're what keep Earth from being a lifeless ball of ice—humans are causing greenhouse gas levels to increase so quickly that it's causing the average global temperature to rise much faster than it would naturally.
This warming is predicted to lead to a variety of negative effects, including:
- Melting (and possible disappearance) of glaciers and mountain snow caps that feed the world's rivers and supply a large portion of the fresh water used for drinking and irrigation.
- A rise in sea levels due to the melting of the land-based ice sheets in Greenland and Antarctica, with many islands and coastal areas ending up more exposed to storm damage or even underwater.
- Increasingly costly "bad weather" events such as heat waves, droughts, floods, and severe storms.
- Lowered agricultural productivity due to less favorable weather conditions, less available irrigation water, increased heat stress to plants, and an increase in pest activity due to warmer temperatures.
- Increases in vector-borne infectious diseases like malaria and Lyme Disease.
- Large numbers of extinctions of higher-level species due to their inability to adapt to rapidly changing climate and habitat conditions.
The first two of these effects are mostly related to increasing average temperatures. Items 3-6 are related to heat too, but also playing a role are non-temperature factors—i.e. "climate-change factors."
Climate Change—Beyond Withering Weather
Climate change is about much more than how warm or cool our temperatures are. Whereas "global warming" refers to increasing global temperatures, "climate change" refers to regional conditions. Climate is defined by a number of factors, including:
- Average regional temperature as well as day/night temperature patterns and seasonal temperature patterns.
- Precipitation (average amounts and seasonal patterns).
- Average amount of sunshine and level of cloudiness.
- Air pressure and winds.
- Storm events (type, average number per year, and seasonal patterns).
To a great extent, this is what we think of as "weather." Indeed, weather patterns are predicted to change in response to global warming:
- some areas will become drier, some will become wetter;
- many areas will experience an increase in severe weather events like killer heat waves, hurricanes, flood-level rains, and hail storms.
It's tempting to think that all of these changes to the world's climate regions will average out over time and geography and things will be fine. In fact, colder climates like Canada may even see improved agricultural yields as their seasonal temperatures rise. But overall, humanity has made a huge investment in "things as they are now, where they are now." Gone are the days of millennia ago when an unfavorable change in climate might cause a village to pack up their relatively few belongings and move to a better area. We have massive societal and industrial infrastructure in place, and it cannot be easily moved. Climate-change effects will generally not be geographically escapable in the timeframe over which they happen, at least not for the majority of humans and species.
What is the greenhouse effect?
There are two meanings of the term "greenhouse effect". There is a "natural" greenhouse effect that keeps the Earth's climate warm and habitable. There is also the "man-made" greenhouse effect, which is the enhancement of Earth's natural greenhouse effect by the addition of greenhouse gases from the burning of fossil fuels (mainly petroleum, coal, and natural gas).
In order to understand how the greenhouse effect operates, we need to first understand infrared radiation. Greenhouse gases trap some of the infrared radiation that escapes from the Earth, making the Earth warmer that it would otherwise be. You can think of greenhouse gases as sort of a "blanket" for infrared radiation-- it keeps the lower layers of the atmosphere warmer, and the upper layers colder, than if the greenhouse gases were not there.
About 80-90% of the Earth's natural greenhouse effect is due to water vapor, a strong greenhouse gas. The remainder is due to carbon dioxide, methane, and a few other minor gases.
It is the carbon dioxide concentration that is increasing, due to the burning of fossil fuels (as well as from some rainforest burning). This is the man-made portion of the greenhouse effect, and it is believed by many scientists to be responsible for the global warming of the last 150 years.
Also, the concentration of methane, although small, has also increased in recent decades. The reasons for this increase, though, are uncertain.
1. WHAT IS THE GREENHOUSE EFFECT ?
The greenhouse effect can be visualized as follows: Imagine that Earth has been encircled by a giant glass sphere. The heat of the sun penetrates through the glass. Some of the heat is absorbed by the Earth, and some of it is radiated back towards space. The radiated heat reaches the glass sphere and is prevented from dispersing any further.
Similarly, the earth is surrounded by a blanket of gases. This blanket traps energy in the atmosphere, much the same way as glass traps heat inside a greenhouse. This results in an accumulation of energy, and the overall warming of the atmosphere. The 'greenhouse effect' is the popular expression for the above process.
Global warming and climate change result from the greenhouse effect. The consequences of global warming and climate change could well include:
- the eradication of entire ecosystems
- increased frequency and intensity of storms, hurricanes, floods and droughts
- melting glaciers and polar ice
- rising sea levels resulting in the permanent flooding of vast areas of heavily
- increased frequency of forest fires
- spread of tropical diseases due to insect proliferation
Climate models show that atmospheric temperatures will increase by between 1.5 and 4.5°C by the year 2100 if a "wait and see and do nothing" approach is adopted. The global temperature increase since the last ice age (10,000 years ago) has been about 5°C.
This may not sound like much, but such drastic temperature rise would be unprecedented for modern civilization, both in terms of its intensity and its rate of increase. It is projected to have drastic social, economic and ecological implications:
- Because of thermal expansion of the water and melting of continental glaciers sea levels would rise, possibly as much as two feet, by the end of next century.
- Rising temperatures could lead to changes in regional wind systems which would influence global rainfall distribution and lead to the redistribution and frequency of floods, droughts and forest fires. Windstorms and hurricanes could become more frequent and more intense.
- Increased sea temperatures would cause coral bleaching and the destruction of coral reefs around the world.
- Climate change would create favorable conditions for growth in insect populations. This would likely have a negative effect on agriculture and human health, and result in a spread of malaria and other tropical diseases.
- Water supplies would become disrupted in some regions, particularly in already vulnerable, arid areas.
3. DOES THE GREENHOUSE EFFECT OCCUR NATURALLY?
Yes, it does. The greenhouse effect is a natural process which made life on Earth possible. Without naturally occurring greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide, the Earth's surface temperature would be 33°C cooler - a chilly -18°C rather than the tolerable 15°C.
However, since the beginning of industrialization, 200 years ago, concentrations of these gases have increased substantially . It is estimated that the Earth's average temperature has risen by 0.5 to 0.6°C since 1880 because of emissions of greenhouse gases from human activity.
The main sources of these emissions, particularly carbon dioxide, methane and nitrous oxide, are the combustion of large amounts of fossil fuels in the energy and transport sectors, deforestation and the use of intensive farming methods.
These terms are often used to describe the same problem, but actually relate to cause and effect, or problem and consequence. The greenhouse effect is the cause and global warming and climate change are the consequences.
The greenhouse effect causes an accumulation of heat (or energy) in the Earth's atmosphere. The global climate must then adjust to deal with that extra accumulation of energy, and these adjustments result in global warming and climate changes.
Global warming results from an increase in the temperature of the Earth's lower atmosphere. Climate changes result from alterations to regional climatic events such as rainfall patterns, evaporation and cloud formation.
The greenhouse effect is caused by gases in the atmosphere which have the ability to absorb the sun's energy that is usually radiated back into space from Earth. Energy from the sun comes into the earth as short-wave radiation; some is absorbed and some is radiated back as long-wave radiation. The 'greenhouse gases' allow the short-wave radiation to pass through to Earth but absorb the long-wave radiation that is reflected back to space. These gases include naturally occurring gases - primarily water vapour, carbon dioxide, methane, nitrous oxides - as well as industrial chemicals such as chlorofluorocarbons (CFCs).
The problem is that human activities have increased the atmospheric concentration of these gases well beyond their natural levels, and have introduced new greenhouse gases, such as CFCs. This in turn is throwing the natural climatic systems off balance.
One of the major greenhouse gases from human sources is carbon dioxide (CO2). While CO2 is naturally occurring, its concentration in the atmosphere is rapidly increasing because of the burning of the fossil fuels- oil, coal and gas.
Human activity is not only producing more CO2, but is also severely damaging the ability of the earth to absorb carbon, via its carbon sinks, the forests and oceanic plankton. Growing forests absorb CO2. Massive worldwide forest destruction results in much fewer trees to soak up CO2, and releases the stored CO2 from the trees into the atmosphere.
Similarly, the destruction of the ozone layer by human-made chemicals, such as CFCs, is allowing increased levels of harmful UV-B radiation to reach the surface of the earth. Increased levels of UV-B radiation could reduce the density of plankton in the oceans. Since plankton are the primary carbon sink of the planet, reduction in their density could result in less CO2 being absorbed from the atmosphere.
Damage to the planet's carbon sinks, through deforestation and ozone layer depletion, thus makes a direct contribution to the enhanced greenhouse effect.
6. HOWCANRELATIVELY LITTLE CO2 EMITTED BY HUMANS MAKE A DIFFERENCE ?
There is an important difference between the CO2 produced by nature and that emitted by human activities. While nature produces about 30 times more CO2 than human activity, the carbon emitted by nature is part of a finely balanced cycle. The emissions by humans are over and above the natural balance, and consequently result in a net increase in the concentrations of atmospheric CO2.
Since the industrial revolution about 850 billion tonnes of CO2 have been emitted due to combustion of fossil fuels, oil, coal and natural gas. An additional 370 billion tonnes have been added through changes in land use and deforestation.
Every year humans emit around 25 billion tonnes of CO2 into the atmosphere, which equals approximately 48,000 tonnes every minute.
Some estimates show that a reservoir of 37, 000 billion tonnes of CO2 is buried in the ground as oil, coal and gas. The largest portion of this CO2 reservoir is in coal, and the second largest is in natural gas. This is a chilling reminder of what is in store for the planet, should we decide to continue to burn fossil fuels without any restrictions. Experts estimate that emission of 2,500 billion tonnes of CO2 - a mere 7% of the existing stock of fossil fuels - will result in a doubling of pre-industrial concentrations of CO2.
We know that the greenhouse effect is really happening through a number of sources:
- First, the fact that some gases have the ability of trapping heat is based on simple physics. No credible scientist questions this fact.
- Second, measurements since the mid-fifties have shown that the levels of greenhouse gases in the atmosphere are steadily increasing , and that these increases correspond to industrial emissions of greenhouse gases.
- Third, measurements of air trapped in 250, 000 year old ice cores show that: (a) the concentration of greenhouse gases in the atmosphere have varied in the past and these variations have occurred concurrently with temperature changes; and (b) greenhouse gases have been increasing since pre-industrial times.
Concentrations of CO2 - the most important greenhouse gas emitted by human activities - is now almost 30% higher than before the industrial revolution, when the wide scale burning of fossil fuels started. It is estimated that during this time global temperatures have increased between 0.3 and 0.6°C . Most experts hold the enhanced greenhouse effect as the most plausible explanation for this temperature increase.
In 1988, the United Nations Environment Programme (UNEP) and the World Meteorological Organization WMO established the Intergovernmental Panel on Climate Change (IPCC), consisting of more than 300 of the world's leading experts, to investigate climate change.
The IPCC concluded, both in 1990 and in 1992, that a doubling of greenhouse gases in the atmosphere will lead to "serious consequences for the world's social, economic and natural systems".
Among other things, the IPCC concluded that emissions of greenhouse gases from human activities contributes to the natural greenhouse effect and will lead to an additional warming of the atmosphere. The IPCC estimated that a doubling of CO2 would lead to a global warming of 1.5 to 4.5°C.
In most scientific circles the issue is no longer whether or not climate change is a potentially serious problem, but rather, how the problem will develop, what its effects will be, how these can be best detected, and what measures can be taken to reduce the damage.
The media, at times, leaves the impression that scientists are still discussing whether or not the climate is really changing as a result of emissions of greenhouse gases. This is not the case. In actuality there is a broad agreement on this issue among scientists and experts, as represented by the Intergovernmental Panel on Climate Change (IPCC).
No scientific material has ever been presented in scientific fora which challenges the main conclusions of the IPCC, in spite of the fact that the IPCC has an open process that invites critical views.
The Intergovernmental Panel on Climate Change (IPCC) stated in its 1990 report that "the unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more". However, recent events are leading to an reassessment of that statement by many scientists. Increasing number of scientists are declaring that the recently observed global warming trend is not natural and is likely to be linked to the greenhouse effect.
- The nine hottest years on record have all occurred since 1980, despite the 2-3 year cooling effect of the Mount Pinatubo volcanic eruption in 1991. 1994 was the third or fourth hottest year on record.
- Since the mid-19th. Century global temperatures have increased by around 0.5°C. Temperatures have increased in all seasons in the Southern Hemisphere, and in spring, winter and autumn in the Northern Hemisphere.
- The European summer of 1994 brought temperatures up to 6°C above average, which induced massive fires in Southern Europe, chronic air pollution problems across the continent, and severe water shortages in many cities.
- Scientists at the Max-Planck Institute For Meteorology in Hamburg concluded from a recent examination of recent temperature records that they are 90 - 97.5 percent certain that the observed warming of the last 20-30 years is not due to natural variability.
- A study of global mean temperatures over 1000 years prompted Princeton University researchers to recently state, "...these results suggest that the observed trend is not a natural feature of the interaction between the atmosphere and oceans. Instead, it may have been induced by a sustained change in the thermal forcing, such as that resulting from changes in atmospheric greenhouse gas concentrations and aerosol loading."
- According to scientists, the retreat of glaciers and the warming of the tundra permafrost is clear evidence of climatic change. Currently, there is a pronounced loss of ice mass and mountain glacier retreat occurring all over the world.
- Alpine plants are migrating upwards in the Austrian and Swiss Alps in response to warming temperatures, migratory birds are confused, trees and small animals are migrating Northward in Canada, marine organisms are migrating northward in California, all in response to warming air or sea temperatures.
- In May 1994, the British Antarctic Survey reported the fastest sustained atmospheric warming on the Antarctic Peninsula, since reliable worldwide temperature observations began 130 years ago. A startling 2.5°C warming in Antarctica has been reported since 1940. Linked with that warming has been the disintegration of Antarctic ice-sheets; the recent unforeseen calving of a giant iceberg, the size of Cyprus (78km long and 37km wide); the decline of adelie penguin populations; and the blooming of plants.
- The medical journal the Lancet reported in January 1994 that increased temperatures in Pakistan since 1878 have extended the period suitable for the development of the malarial parasite. Paul Epstein, of the Harvard School of Public Health, considers that climate change may be liberating pests and pathogens from ecological controls and predation. He cites as an example that mosquitoes which transmit yellow and dengue fever were formerly restricted to less than 1000 metres in altitude by temperature, but are now reported at 2, 200 metres in India and Colombia.
While the details of weather, in a particular region, are hard to predict from week to week, weather patterns over years, that is the climate, are easier to identify, understand and predict. The overall system, the climate, is predictable, even though the details, the day to day weather, are much less certain.
For example, while it may be nearly impossible to predict, two months in advance, what the weather will be like on a given Saturday in Paris, if the month in question is July, most climate models can correctly predict that it won't snow.
The effects of global warming and climate change will not impact the same way upon every region in the world, or upon all species of life. For example, a slight temperature increase in some of the colder parts of the world may create less hostile conditions for human habitation and improve conditions for agriculture. Similarly, changing rainfall patterns may favour some species over others.
However, favourable consequences of the greenhouse effect for some regions or species does not mitigate its overall negative global impacts. The social, economic and ecological disruptions brought about by climatic changes worldwide are projected to greatly outweigh regional benefits.
The impacts of global warming and climate change could become a source of increased tension between nations and regions .
While the developed, industrialized world is responsible for 75% of all CO2 emissions, these impacts will most likely hit hardest upon the poorer, underdeveloped parts of the world.
For example, as sea levels rise countries like Bangladesh will suffer much more from the loss of valuable arable and populated lands, then European or North American countries, even though in comparison, they will have emitted only a tiny fraction of the greenhouse gases.
The effect of drowning coastlines could lead to hundreds of millions of climate refugees. Where will these refugees go? How will they be cared for? Undoubtedly, such a catastrophe will seriously exacerbate the already critical refugee problem in the world.
A severe disruption of the world's food supplies through floods, droughts, crop failures and diseases brought about by climate change would trigger famines, wars and civil disorder in many countries.
Most human societies - especially subsistence agricultural societies - have evolved over many centuries by adapting to their present climatic conditions. Their agriculture, technologies, economies and culture are based on familiar circumstances. These societies are likely to find climate change, on the scale and speed predicted for the coming decades, to be very traumatic.
Similarly, many natural ecosystems will not be able to adjust fast enough to a rapidly warming world. This could lead to sharp increases in the already alarming rate of species extinction on the planet.
The bottom line is that the emissions of greenhouse gases must be reduced. We must develop industrial practices and means of transportation which are less dependent on fossil fuels, and ultimately, manage completely without them.
Since the problem is global, the solutions must be international. The international community took a first step in 1992 when the Framework Convention on Climate Change was signed by 167 countries in Rio. The Framework Convention morally committed industrialized countries to stabilizing their emissions of CO2 by the year 2000 at 1990 levels. However, since the 1990 levels of global CO2 emissions enhanced the greenhouse effect, the 1992 agreement is obviously inadequate.
Unfortunately, few, if any, of the industrialized countries will even meet this weak target. Consequently, the next step must be to make this commitment legally binding, and to strengthen it through a CO2 Reduction Protocol aimed at meeting the objectives of the Convention. The minimum goal must be a 20% reduction in CO2 emissions by 2005, based on 1990 levels.
The industrialized countries have the lion's share of the responsibility for creating the problem and for finding the solutions. They have developed their industrial base, and consequently, their higher standards of living, through the use of vast amounts of fossil fuels. This has resulted in high concentrations of CO2 in the atmosphere.
Furthermore, their per capita emissions of CO2 continues to be tens of times larger than all of the developing countries.
For example, the United States, the largest single emitter, annually pumps into the atmosphere approximately 20 tonnes of CO2 per person. With less then 5% of the world's population, the United States is responsible for 25% of global CO2 emissions. In a comparison, the entire developing world, consisting of more than 100 countries and representing almost 80% of the world's population, is responsible for approximately the same amount of CO2 emissions.
It is becoming apparent that the world may not be able to survive with fossil fuels. This means that we must develop renewable sources of energy which are environmentally sustainable. Fortunately, we already posses the technology at hand to provide clean and reliable sources of energy for meeting human needs.
Renewable systems include solar photo voltaic power systems, solar hot water systems, wind turbines, bio-fuel plantations, hydroelectric systems and so on. These energy sources are sustainable because they never 'run out'.
Most importantly, many renewable energy sources, such as wind power and solar thermal, are already cheaper than conventional fuels-- even though the price of fossil fuels and nuclear power does not reflect their full environmental and economic costs.
Many of these renewable energy options can be designed, built, and exploited locally and at less costs than conventional systems. They contribute significantly to national economies because they exploit indigenous labour and materials.
In rural areas, the most sophisticated solar arrays can provide sufficient high-quality energy, at a cost lower than power from electricity grids. Solar power could radically improve the living conditions of the world's poorest people. Fortunately, the technology is spreading:
- 200,000 solar photo voltaic systems have been installed around the world, including 37,000 in Mexico, 20,000 in Kenya, 16,000 in Indonesia, 15,000 in China, 4,500 in Sri Lanka, 4,000 in the Dominican Republic and 1,000 in Brazil.
- In Kenya more rural households obtain their electricity from solar energy than from the official policy of grid extension.
- In the Dominican Republic, Enersol, a US-based non-governmental organization, has successfully trained local entrepreneurs to assemble, market, install and service photo voltaic systems. The program began in 1985 with 6 systems, grew to a 100 in 1987, more than 1,000 in 1989 and 4,500 in 1994. Since 1992, Enersol has replicated their successful Dominican program in Honduras and Guatemala and contributed to projects in Bolivia and Costa Rica. The Solar Electric Light Fund (SELF) has taken the Enersol model and has established a number of successful 'solar seed' projects around the world.
The European Commission's 'Power for the World Program' (a global photo voltaic action plan) estimates that providing solar electricity to a billion people in the developing world would cost $60 billion ($3 billion a year for 20 years). This is only 3% of annual energy investments in developing countries and less than 0.5% of current military expenditure.
Similar solar solutions are also available for industrial applications to supply reliable grid connected electricity. In the United States, as part of a plan to develop a 1,000 MW Solar Enterprise Zone in the Nevada desert, ENRON has announced plans to build a 100 MW solar power station. Such a power station would be the largest solar operation in the United States, producing enough power for a city of 100,000 people.
Here are some of practical steps that you can take to reduce human contributions to the greenhouse effect.
- LEARN about the greenhouse effect, global warming and climate change. Learn about alternate, non-fossil fuel based energy sources. Inform your family, friends and colleagues.
- WRITE to your local newspapers and other media outlets and demand they regularly feature stories regarding global warming, climate change and the greenhouse effect. The media has the responsibility to inform the public about this urgent subject.
- DEMAND your government fulfills your country's commitments to stabilizing emissions of CO2 by the year 2000 at 1990 levels, and makes further commitments to a 20% reduction in CO2 emissions by 2005, based on 1990 levels.
- TAKE responsibility for making simple changes in your energy consumption. The main greenhouse gas, CO2, comes from the burning of fossil fuels. Two key areas where individuals can help reduce the emissions of CO2 are in electricity consumption and transportation. Coal and gas-fired power plants burn huge amounts of fossil fuels and consequently emit vast amounts of CO2. A car produces more than its own weight in carbon dioxide each year, roughly 2 tonnes per year.
- Turn off that light. Switch to energy efficient light bulbs. Encourage others to do the same.
- Buy energy efficient appliances. Use your consumer power to support industries and products that strive for high energy efficiency.
- Demand that your electricity utility reward energy saving consumers with lower rates, instead of offering the cheaper rates to the largest users of electricity.
- Reduce Private Transport:
- If you must drive a car, make sure it is fuel efficient. Try to cut down the amount of car journeys you make each week. Join a car pool to go to work or school.
- Bike or walk if you are going somewhere local.
- Support Public Transport:
- Public transport is the best way to cut CO2 emissions from cars. Effective public transport reduces the need for building new roads - another key source of CO2. In turn, the money saved on road building can go into improving the public transport sector. These measures will also improve urban air-quality.
- Use public transport.
- Demand your municipality provide fast, convenient and economical public transport.
- SUPPORT the development of renewable energy technologies.
- DEMAND your government aims to achieve a minimum 3% per year penetration of your country's energy supply system with renewable technologies.