Global Warming: Get the Facts
According to a recent report from the Intergovernmental Panel on Climate Change (IPCC) the Earth's average surface temperature has increased 1.3 degrees F over the past 100 years. Most scientists agree that this increase is caused by human activity - primarily the burning of fossil fuels. What may seem like a small temperature change has devastating consequences - rising sea levels, loss of Arctic habitat, extinctions, increasingly intense hurricanes, and drought and famine.
Fortunately, we can make a difference. By taking individual action at home and promoting sound energy policy and legislation in our communities, states and nation, we can help protect our global habitat — for birds, wildlife and our own future.
Click on any question below to jump to the answer.
What is global warming?
Global warming is the increase in Earth's surface temperatures. Scientists say that Earth's surface temperatures rose by an estimated 1.3 degrees F in the last hundred years. In fact, eleven of the last twelve years rank among the warmest since temperatures were first recorded in the late 19th century. The chart below plots the global average temperature from the late 19th century to the year 2000.
Why is global warming a critical problem for all of us?
Even small increases in average global temperatures can have devastating effects on people, wildlife, and the places we live. Rising temperatures in the Arctic have already reduced average ice cover, disrupting the feeding habits of polar bears and the way of life of Inuit communities. Reduced rainfall in parts of the tropics and subtropics is wreaking havoc on food production and wildlife habitat alike. Like many other organizations around the world, Audubon believes that the actions we take today can slow and eventually reverse these and other damaging patterns, protecting the quality and diversity of life on Earth for present and future generations.
Couldn't global warming just be a natural occurrence?
It's true that Earth's climate has always been in flux. Periods of warming have followed ice ages. A decade of warmer temperatures can be followed by a decade of cooler temperatures. But the current warming trend has been documented over a period of more than one hundred years. And it's occurring much faster than previous episodes of global warming.
What causes global warming?
In its February 2007 report, the Intergovernmental Panel on Climate Change, established by the World Meteorological Organization and the United Nations Environment Programme, expressed more than 90 percent confidence that global warming is caused by human activity — namely, an increase in the amount of carbon dioxide, methane, and other heat-trapping "greenhouse" gases in the atmosphere.
Like glass in a greenhouse, these gases allow the sun's heat through the atmosphere, but then trap much of it near the Earth's surface. For billions of years they have played an important role in maintaining the proper temperatures for life to thrive. But since the Industrial Revolution, human activity has led to a dramatic increase in the amount of these heat-trapping gases. Carbon dioxide levels have risen from pre-Industrial levels of 280 parts per million to 379 parts per million. The amount of methane, another greenhouse gas, has more than doubled. The result has been a measurable warming trend called global climate change or, more specifically, global warming.
How do we know global warming is really happening?
Over the last several decades, scientists have carefully studied patterns of climate change around the world. In its most recent assessment, the IPCC reviewed hundreds of these studies on such topics as past climate changes, observations of retreating ice, warming and rising seas, and other changes, as well as a wide array of supercomputer simulations to model how the planet has and will be affected by increasing amounts of greenhouse gases. Together these studies offer a stark portrait of a rapidly changing world:
- Temperatures have risen about 1.3 degrees F since the late 19th century. Greenhouse gas levels in the atmosphere have increased by 18% (nitrous oxide), 35% (carbon dioxide), and 148% (methane).
- Mountain glaciers and snow cover are declining in most parts of the world.
- The Greenland and Antarctic ice sheets are melting and breaking up.
- The area covered by Arctic sea ice in winter has shrunk about 2.7% each decade since 1978, with even greater summertime reductions.
- Global sea levels rose between 5 and 9 inches during the 20th century.
- The North Atlantic has shown increased hurricane intensity since 1970.
- Precipitation amounts have increased in northern Europe, the eastern Americas, and parts of Asia. Elsewhere, droughts have become longer and more severe.
What are the likely impacts of global warming if it continues at current rates?
Most experts agree that at current rates of greenhouse gas build-up, the climate could warm by about 3.5 to 8 degrees Fahrenheit sometime after 2050, and the average global temperature might rise even higher. The expected consequences of such warming include major disruptions to agriculture, water supplies, and the diversity of life on Earth. The Greenland ice sheet could disappear in several thousand years. Hurricanes and typhoons are expected to become more intense. Precipitation is expected to increase at high latitudes and decrease in subtropical areas. Moreover, if greenhouse gases continue to build at even a moderate rate, experts predict that sea levels will be 7 to 24 inches higher by 2100, causing devastating erosion and flooding of the coastal cities and villages where millions of Earth's inhabitants live.
Can anything be done to stop global warming?
No matter what we do now, global warming will continue and will cause serious changes in our climate. However, prompt and dramatic action is likely to slow its rate of increase and to avoid some of the worst potential consequences. Experts say the most important action is to move away from burning massive amounts of fossil fuels, especially coal and oil, and to aggressively pursue nonpolluting energy options.
Every time we burn fossil fuels to drive our cars, heat our homes, run our factories, light our cities, and more, we release carbon dioxide and other greenhouse gases into the atmosphere. Our greenhouse gas emissions have increased in recent decades because of both human population growth and the rising rates of affluence and consumption. Larger houses, bigger and faster cars and SUVs and more airplane travel all mean more energy consumption. In fact, the United States, with only about 5% of the global population, contributes about 25 percent of greenhouse gas emissions because our fuel consumption is so high.
Some scientists are also studying another strategy called carbon sequestration. Earth's plants, soils, and oceans absorb huge amounts of carbon dioxide. Some scientists believe that we can augment these so-called "ecosystem services". We can protect and improve natural resources such as tropical forests that absorb large amounts of carbon. We may even be able to inject excess carbon dioxide deep into the Earth.
I'm not an energy expert, though; so what can I do?
As individuals, each of us makes countless choices each day that contribute to the amount of fossil fuels we use. We also drive the actions of corporations in our choices of consumer goods and our investment decisions. Learn how your choices can make a difference.
We can also influence policymakers with our letters, phone calls, and votes -Learn how you can get involved.
For a list of resources click here.