Global Warming
Facts, Consequences and Solutions
What Is Global Warming? What's Causing It?
Scientists use the term "global warming" to describe the rise in Earth’s average temperature caused by increased atmospheric concentrations of heat-trapping “greenhouse gases,” or global warming pollution.
Burning fossil fuels such as coal, oil, and natural gas; destroying forests; and a range of other activities emit carbon dioxide and other global warming pollutants. These pollutants remain in the atmosphere for more than a century, trapping heat that would otherwise radiate into space, much the same way that glass traps heat in a greenhouse. Scientists predict that as society continues to emit these heat-trapping gases, higher temperatures will be accompanied by an increase in extreme weather events such as torrential rainfalls that can lead to flooding, and droughts that result in drinking water shortages and crop losses, as well as a rise in the global sea level. Even though the first signs already are apparent, a sharp reduction of greenhouse gas pollution could significantly slow and help prevent the worst effects of global warming.
More Warming On the Way
Scientists predict that in the 21st century, Earth could warm by 2.5 to 10.4°F (1.4 to 5.8°C) – more quickly than at any other time in the history of civilization. Such a rise in global temperature would have significant and dangerous effects. Between modern times and the last Ice Age—when much of Canada and the northern U.S. was covered with a thick ice sheet—the difference in global average temperature was only about 9°F (5°C). A rise in temperature of this magnitude could cause a disruption in the stability of the Earth’s climate, causing serious and potentially devastating effects for people, poor and rich alike, as well as the planet's ecosystems.
How Does Global Warming Affect Us?
We are already seeing the effects of global warming. It is affecting life all over the planet as well as our own citizens here in the United States. These effects include more extreme weather events such as killer heat waves, droughts, intense hurricanes, as well as the spread of mosquito-borne diseases.
Impact: Extreme Weather
By some measures, the U.S. has the most varied weather of any nation, with intense heat waves, flash floods, droughts, and hurricanes. The impact of these events on people’s lives and property is enormous. With the intensity of these events predicted to increase due to global warming, the U.S. is quite possibly more vulnerable to climate change than most other nations.
Impact: Killer Heat Waves
In the coming years, global warming is likely to increase the frequency of “killer” heat waves. During the summer of 2003 -- the hottest in at least the past 500 years -- record heat waves scorched Europe. The relentless heat killed at least 27,000 people, breaking all records for heat-induced human fatalities. Scientists have calculated that it is highly likely that human-caused global warming played a role, as detailed in a paper reported by the scientific journal Nature.
Impact: Severe Drought
From 1998 to 2002, below-normal precipitation and high temperatures resulted in droughts covering wide swaths of North America, southern Europe, and South and Central Asia. The drought in the United States during this time was one of the worst in 500 years. During the peak of the drought, about 80 percent of the land area of the western United States was affected, causing drinking water shortages and the loss of forests and crops.
Impact: The Spread of Mosquito-Borne Disease
Around the world, scientists are observing mosquitoes moving into elevations previously too cold for them to survive in. As mosquito populations grow due to warmer climate, they can spread diseases known as vector-borne diseases (such as malaria). In Colombia, mosquitoes that carry dengue fever and yellow fever viruses were previously limited to elevations below 3,300 feet but have recently been found at 7,200 feet. In Mexico, dengue fever has spread above its former limit of 3,300 feet and now can be found at 5,600 feet.
Impact: More Intense Hurricanes
Two recent studies show that global warming may already be making hurricanes stronger and more destructive. Dr. Kerry Emanuel of MIT showed that, on average, hurricanes in the North Atlantic— like the storms that hit the Gulf Coast in 2005—and in the western Pacific are more than twice as powerful today as they were 30 years ago. His data also showed that hurricane strength was very closely related to sea surface temperature: the warmer the ocean, the more powerful the storm. In a second paper, Dr. Peter Webster and colleagues of the Georgia Institute of Technology showed that the number of category 4 and 5 hurricanes – the most intense hurricanes – per year has doubled over the past 35 years. Hurricane Wilma, which slammed Mexico with 150 mph winds in October 2005, was the most intense Atlantic hurricane ever recorded. Given the strong relationship between warm water and destructive hurricanes, scientists expect hurricane intensity to continue to increase as long as the globe continues to warm.
Global Impact: Melting at the North Pole
Satellite data collected from an eight-nation scientific team, including the United States, shows a stunning reduction in Arctic sea ice. Sea ice has declined since measurements began in 1979, and has been disappearing at an accelerated rate over the past four years. The year 2005 set a new record for lowest summertime sea ice cover, and summer sea ice also began melting more than two weeks earlier than normal. The total amount of sea ice lost so far is almost equivalent to the areas of Texas and California combined. At the current rate, summer sea ice could disappear in less than 100 years. The sea ice is one of Earth’s critical “temperature controls,” reflecting some of the sun’s heat back into space. The loss of sea ice, replaced by dark seawater, will cause absorption of more of the sun’s heat, creating more global warming, even less ice, and so forth. The loss of the sea ice will eventually double the amount of warming caused by the heat-trapping pollutants.
Irreversible Consequences
The loss of sea ice is one of the most ominous signs that global warming may be triggering “feedbacks” within the climate system that will speed up the warming process. If the ice sheets surrounding Greenland and Antarctica melt, sea levels would rise by more than 30 feet. It would take more than 1000 years to replace them. Scientists now believe that if global temperatures increase by just a few degrees more, it will be impossible to prevent their disappearance.
The Science Says We Must Act Now
Once global atmospheric temperatures rise above a certain threshold, the melting of the major ice sheets cannot be avoided. Even large reductions in greenhouse gas emissions will not be able to prevent the complete loss of the ice caps and a rise in sea leave of more than 20 feet. While scientists don't yet know the exact point at which this will occur, many believe we must stabilize carbon dioxide concentrations below 450 ppm to avoid the loss of our ice caps. Before the Industrial Revolution the level was 280 ppm. Today it is almost 380 ppm. Under current emission levels, the critical threshold could be reached as early as 2030. But we’ve got to act long before 2030: Carbon dioxide we produce today will stay in the atmosphere for more than a century. So we can’t just wait until we’re near the point of irreversible consequences and suddenly cut our emissions. If we don't implement worldwide action within about 10 years, we would almost certainly shoot well beyond the threshold for irreversible melting of the ice caps.
Comparing Emissions: U.S., Europe and Asia
In 2003, the US emitted 5.8 billion metric tons of carbon dioxide. Western Europe – the EU 15 plus Switzerland, Iceland, Norway, and Turkey – had emissions of 3.9 billion metric tons. Japan emitted 1.2 billion metric tons, China emitted 3.5 billion metric tons, and India emitted just over 1 billion. On a per capita basis, the disparity is apparent: In 2003, the US emitted 20 tons per person per year, compared to 2.7 tons per person in China, and .96 tons per person in India.
How Do We Solve This Problem?
The world will need to reduce its global warming pollution by reducing the use of fossil fuels such as oil and coal, and using cleaner fuels and cleaner technologies, such as those that capture carbon dioxide from the burning of coal. While this is a global problem, individuals can affect it by reducing their own energy use – reducing energy bills and dollars spent at the gas pump in the process – and nations can set the goals for industry and manufacturing.
We Can Start Now
We do not have to wait to save energy and help solve global warming. Changes in our daily lives can help reduce greenhouse gas concentrations. Among the available options for consumers are:
Every one of these solutions has multiple benefits for society, from saving money to reducing our dependence on oil. For more tips, check out our Low Carbon Diet guide [PDF].