Anup Shah, Climate Change and Global Warming Introduction, GlobalIssues.org, Last updated: Thursday, February 08, 2007
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).
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.
Six main gases considered to be contributing to global climate change 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.
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.
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
A documentary aired on the National Geographic Channel in Britain on August 9, 2003 titled What’s up with the weather. It noted that the levels of carbon dioxide for example, were currently at their highest levels in the past 450,000 years.
Increased greenhouse gases and the greenhouse effect is feared to contribute 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:
* The five warmest years on record, in order (warmest first) are:
1. 2005
2. 1998
3. 2002
4. 2003
5. 2004
* According to the World Meteorological Organization (WMO), the 1990s was the warmest decade;
* The 1900s was the warmest century during the last 1,000 years.
However, 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!
Super-storms
Mentioned further above was the concern that more hurricanes could result. The link used was from the environmental organization WWF, written back in 1999. In August/September 2004 a wave of severe hurricanes left many Caribbean islands and parts of South Eastern United States devastated. In the Caribbean many lives were lost and there was immense damage to entire cities. In the U.S. many lives were lost as well, some of the most expensive damage resulted from the successive hurricanes.
In its wake, scientists have reiterated that such super-storms may be a sign of things to come. “Global warming may spawn more super-storms”, Inter Press Service (IPS) notes.
Interviewing a biological oceanography professor at Harvard University, IPS notes that the world’s oceans are approaching 27 degrees C or warmer during the summer. This increases the odds of major storms.
* When water reaches such temperatures, more of it evaporates, priming hurricane or cyclone formation.
* Once born, a hurricane needs only warm water to build and maintain its strength and intensity.
Furthermore, “as emissions of greenhouse gases continue to trap more and more of the sun’s energy, that energy has to be dissipated, resulting in stronger storms, more intense precipitation and higher winds.”
There is abundant evidence of an unprecedented number of severe weather events in the past decade, [professor of biological oceanography at Harvard University, James] McCarthy says. In 1998, Hurricane Mitch killed nearly 20,000 people in Central America, and more than 4,000 people died during disastrous flooding in China. Bangladesh suffered some of its worst floods ever the following year, as did Venezuela. Europe was hit with record floods in 2002, and then a record heat wave in 2003.
More recently, Brazil was struck by the first-ever recorded hurricane in the South Atlantic last March.
“Weather records are being set all the time now. We’re in an era of unprecedented extreme weather events,” McCarthy said.
Historical weather patterns are becoming less useful for predicting the future conditions because global warming is changing ocean and atmospheric conditions.
“In 30 to 50 years’ time, the Earth’s weather generating system will be entirely different,” he predicted.
— Stephen Leahy, Global Warming May Spawn More Super-Storms, Inter Press Service, September 20, 2004
