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- by Anup Shah
- This Page Last Updated Monday, November 11, 2013
- This page: http://www.globalissues.org/article/233/climate-change-and-global-warming-introduction.
- To print all information e.g. expanded side notes, shows alternative links, use the print version:
What is Global Warming and Climate Change?
Global warming and climate change refer to an increase in average global temperatures. Natural events and human activities are believed to be contributing to an increase in average global temperatures. This is caused primarily by increases in “greenhouse” gases such as Carbon Dioxide (CO2).
A warming planet thus leads to a change in climate which can affect weather in various ways, as discussed further below.
What are the main indicators of Climate Change?
What is the Greenhouse Effect?
The term greenhouse is used in conjunction with the phenomenon known as the greenhouse effect.
- Energy from the sun drives the earth’s weather and climate, and heats the earth’s surface;
- In turn, the earth radiates energy back into space;
- Some atmospheric gases (water vapor, carbon dioxide, and other gases) trap some of the outgoing energy, retaining heat somewhat like the glass panels of a greenhouse;
- These gases are therefore known as greenhouse gases;
- The greenhouse effect is the rise in temperature on Earth as certain gases in the atmosphere trap energy.
Image source: Greenhouse Effect, Wikipedia(Link includes detailed explanation of the above image). Note, image above expresses energy exchanges in watts per square meter (W/m2)
Six main greenhouse gases are carbon dioxide (CO2), methane (CH4) (which is 20 times as potent a greenhouse gas as carbon dioxide) and nitrous oxide (N2O), plus three fluorinated industrial gases: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). Water vapor is also considered a greenhouse gas.
The Greenhouse effect is natural. What do we have to do with it?
Many of these greenhouse gases are actually life-enabling, for without them, heat would escape back into space and the Earth’s average temperature would be a lot colder.
However, if the greenhouse effect becomes stronger, then more heat gets trapped than needed, and the Earth might become less habitable for humans, plants and animals.
Carbon dioxide, though not the most potent of greenhouse gases, is the most significant one. Human activity has caused an imbalance in the natural cycle of the greenhouse effect and related processes. NASA’s Earth Observatory is worth quoting the effect human activity is having on the natural carbon cycle, for example:
In addition to the natural fluxes of carbon through the Earth system, anthropogenic (human) activities, particularly fossil fuel burning and deforestation, are also releasing carbon dioxide into the atmosphere.
When we mine coal and extract oil from the Earth’s crust, and then burn these fossil fuels for transportation, heating, cooking, electricity, and manufacturing, we are effectively moving carbon more rapidly into the atmosphere than is being removed naturally through the sedimentation of carbon, ultimately causing atmospheric carbon dioxide concentrations to increase.
Also, by clearing forests to support agriculture, we are transferring carbon from living biomass into the atmosphere (dry wood is about 50 percent carbon).
The result is that humans are adding ever-increasing amounts of extra carbon dioxide into the atmosphere. Because of this, atmospheric carbon dioxide concentrations are higher today than they have been over the last half-million years or longer.
— The Carbon Cycle; The Human Role, Earth Observatory, NASA
Another way of looking at this is with a simple analogy: consider salt and human health:
- A small amount of salt is essential for human life;
- Slightly more salt in our diet often makes food tastier;
- Too much salt can be harmful to our health.
In a similar way, greenhouse gases are essential for our planet; the planet may be able to deal with slightly increased levels of such gases, but too much will affect the health of the whole planet.
Image source: NASA.(Note, values shown represent Carbon Gigatons being absorbed and released)
The other difference between the natural carbon cycle and human-induced climate change is that the latter is rapid. This means that ecosystems have less chance of adapting to the changes that will result and so the effects felt will be worse and more dramatic it things continue along the current trajectory.
The climate has always varied in the past. How is this any different?
Doesn’t recent record cold weather disprove Global Warming?
Has global warming paused due to recent surface temperature drops?
Most global warming is going into the oceans
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What are the impacts of Global Warming?
For decades, greenhouse gases, such as carbon dioxide have been increasing in the atmosphere. But why does that matter? Won’t warmer weather be nicer for everyone?
Rapid changes in global temperature
Increased greenhouse gases and the greenhouse effect has contributed to an overall warming of the Earth’s climate, leading to a global warming (even though some regions may experience cooling, or wetter weather, while the temperature of the planet on average would rise).
Consider also the following:
At the end of the 1990s, the World Meteorological Organization (WMO) had noted that not only was the 1990s the warmest decade but at the time, the 1900s was the warmest century during the last 1,000 years.
It is the rapid pace at which the temperature will rise that will result in many negative impacts to humans and the environment and this why there is such a world-wide concern.
Extreme Weather Patterns
Most scientists believe that the warming of the climate will lead to more extreme weather patterns such as:
- More hurricanes and drought;
- Longer spells of dry heat or intense rain (depending on where you are in the world);
- Scientists have pointed out that Northern Europe could be severely affected with colder weather if climate change continues, as the arctic begins to melt and send fresher waters further south. It would effectively cut off the Gulf Stream that brings warmth from the Gulf of Mexico, keeping countries such as Britain warmer than expected;
- In South Asia, the Himalayan glaciers could retreat causing water scarcity in the long run.
While many environmental groups have been warning about extreme weather conditions for a few years, the World Meteorological Organization announced in July 2003 that “Recent scientific assessments indicate that, as the global temperatures continue to warm due to climate change, the number and intensity of extreme events might increase.”
The WMO also notes that “New record extreme events occur every year somewhere in the globe, but in recent years the number of such extremes have been increasing.” (The WMO limits the definition of extreme events to high temperatures, low temperatures and high rainfall amounts and droughts.) The U.K’s Independent newspaper described the WMO’s announcement as “unprecedented” and “astonishing” because it came from a respected United Nations organization not an environmental group!
Extreme weather events on the increase
With global warming on the increase and species’ habitats on the decrease, the chances for various ecosystems to adapt naturally are diminishing.
Many studies have pointed out that the rates of extinction of animal and plant species, and the temperature changes around the world since the industrial revolution, have been significantly different to normal expectations.
An analysis of population trends, climate change, increasing pollution and emerging diseases found that 40 percent of deaths in the world could be attributed to environmental factors.
Rising Sea Levels
Water expands when heated, and sea levels are expected to rise due to climate change. Rising sea levels will also result as the polar caps begin to melt.
Rising sea levels is already affecting many small islands.
The WorldWatch Institute reports that “[t]he Earth’s ice cover is melting in more places and at higher rates than at any time since record keeping began”. (March 6, 2000).
Rising sea levels will impact many coastlines, and a large mass of humanity lives near the coasts or by major rivers.
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Greenhouse gases and emissions resulting from human activity
Every few years, leading climate scientists at the UN’s Intergovernmental Panel on Climate Change (IPCC) have released major, definitive reports detailing the progress in understanding climate change. From the outset they have recommended that there be emission reductions. This body is comprised of hundreds of climate scientists around the world.
Differences in Greenhouse Gas Emission Around the World
As the World Resources Institute highlights there is a huge contrast between developed/industrialized nations and poorer developing countries in greenhouse emissions, as well as the reasons for those emissions. For example:
- In terms of historical emissions, industrialized countries account for roughly 80% of the carbon dioxide buildup in the atmosphere to date. Since 1950, the U.S. has emitted a cumulative total of roughly 50.7 billion tons of carbon, while China (4.6 times more populous) and India (3.5 times more populous) have emitted only 15.7 and 4.2 billion tons respectively (although their numbers will rise).
- Annually, more than 60 percent of global industrial carbon dioxide emissions originate in industrialized countries, where only about 20 percent of the world’s population resides.
- Much of the growth in emissions in developing countries results from the provision of basic human needs for growing populations, while emissions in industrialized countries contribute to growth in a standard of living that is already far above that of the average person worldwide. This is exemplified by the large contrasts in per capita carbons emissions between industrialized and developing countries. Per capita emissions of carbon in the U.S. are over 20 times higher than India, 12 times higher than Brazil and seven times higher than China.
At the 1997 Kyoto Conference, industrialized countries were committed to an overall reduction of emissions of greenhouse gases to 5.2% below 1990 levels for the period 2008—2012. (The Intergovernmental Panel on Climate Change (IPCC) said in its 1990 report that a 60% reduction in emissions was needed…)
The United States is the World’s Largest Emitter of Greenhouse Gases Per Capita
Around 2007, China surpassed the US as the world’s largest emitter of greenhouse gases in terms of total output. Per person (“per capita”), however, China’s emissions are much smaller.
Until recently, the United States was the world’s largest emitter of greenhouse gases. However, it remains the largest emitter when measured in terms of emissions per person.
Due to its much longer period of industrialization, the US has emitted far more into the atmosphere than China (greenhouse gases such as CO2 linger on in the atmosphere for decades).
In addition, the US:
- Accounts for roughly four percent of the world’s population;
- Accounts for approximately 20% of global emissions and some 40% of industrialized country emissions;
The previously 15-member European Union is also large Emitter
The previously 15 member-nations European Union (E.U.), if considered as a whole (for it is more comparable to the U.S.):
- Accounts for roughly 3 percent of the world’s population;
- Accounts for around 10% of global emissions and 24% of industrialized countries’ man-made emissions of the six main gases;
- Recent years have seen a reduction in emissions from those initial 15-member states. However,
Rich Nations Have “Outsourced” Their Carbon Emissions
Developing Countries Affected Most
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Skepticism on Global Warming or That it can be human-induced
For a very long time, something of contention and debate in the U.S. had been whether or not a lot of climate change has in fact been induced by human activities, while many scientists around the world, Europe especially, have been more convinced that this is the case.
In May 2002, the Bush Administration in the U.S. did admit a link between human activities and climate change. However, at the same time the administration has continued its controversial stance of maintaining that it will not participate in the international treaty to limit global warming, the Kyoto Protocol, due to economic priorities and concerns. (More about the Kyoto Protocol, U.S. and others’ actions/inactions is discussed in subsequent pages on this section.)
Throughout the 1990s, especially in the United States, but in other countries as well, those who would try and raise the importance of this issue, and suggest that we are perhaps over-consuming, or unsustainably using our resources etc, were faced with a lot of criticism and ridicule.
Bush Administration Accused of Silencing its own Climate Scientists
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Many Sources Of Greenhouse Gases Being Discovered
Pollution from various industries, the burning of fossil fuels, methane from farm animals, forest destruction, rotting/dead vegetation etc have led to an increased number of greenhouse gases in the atmosphere. And, as international trade in its current form continues to expand with little regard for the environment, the transportation alone, of goods is thought to considerably contribute to global warming via emissions from planes, ships and other transportation vehicles. (For more about trade and globalization in its current form and how it affects the environment, as well as other consequences, visit this web site’s section on Trade, Economy, & Related Issues.)
Even sulphur emitted from ships are thought to contribute a fair bit to climate change. (If you have registered at the journal, Nature, then you can see the report here.) In fact, sulphur based gas, originating from industry, discovered in 2000 is thought to be the most potent greenhouse gas measured to date. It is called trifluoromethyl sulphur pentafluoride (SF5CF3).
NewScientist.com reports (December 22, 2003) on a study that suggests soot particles may be worse than carbon dioxide in contributing to global warming. The soot particles also originate from industry, and during the industrial revolution, was quite common. While on the positive side there is less soot these days and perhaps easier to control if needed, alone, as one of the scientists of the study commented, “It does not change the need to slow down the growth rate of carbon dioxide and eventually stabilize the atmospheric amount.”
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Warming happening more quickly than predicted
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For decades, scientists and environmentalists have warned that the way we are using Earth’s resources is not sustainable. Alternative technologies have been called for repeatedly, seemingly upon deaf ears (or, cynically, upon those who don’t want to make substantial changes as it challenges their bottom line and takes away from their current profits).
In the past, some companies and industries have pushed back on environmental programs in order to increase profits or to survive in a tough business world.
The subsequent pages on this site look at the political issues around tackling climate change.
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Author and Page Information
- by Anup Shah
- Created: Monday, July 20, 1998
- Last Updated: Monday, November 11, 2013