August 19, 2015

On Tuesday, August 18, U. S. President Barack Obama outlined a plan to cut methane gas emissions from oil and natural gas drilling. The plan calls on petroleum companies to  capture much of the methane produced when they drill new wells. Currently, some of this methane gets released into the atmosphere. There, it contributes to the greenhouse effect, which drives global warming.

Oil pumps and other types of petroleum-industry equipment may soon be regulated to reduce methane emissions. Credit: © PhotoStock10/Shutterstock

The greenhouse effect is caused by certain gases in the atmosphere that let sunlight pass into the atmosphere but trap heat close to the planet’s surface. Although the greenhouse effective existed long before people evolved, human activity, especially since the Industrial Revolution, has likely added to it. One such activity is the burning of fossil fuels, such as coal, oil, and natural gas. This burning releases large amounts of the greenhouse gas carbon dioxide. But human activities, including drilling for fuel, have also produced emissions of another greenhouse gas—methane.

Methane is a powerful greenhouse gas. A molecule of methane lasts for an average of 12 years in the atmosphere before being broken down by sunlight. This is much shorter than carbon dioxide, which can linger in the atmosphere for thousands of years. The molecular structure of methane, however, makes it much more efficient at trapping heat than carbon dioxide. In fact, methane is 25 times more powerful than is carbon dioxide when it comes to contributing to the greenhouse effect, even with its relatively short lifespan.

The Obama administration and its allies want to cut methane emissions as part of a broader strategy to reduce the amount of greenhouse gases the United States produces. Oil and gas companies and some members of the U. S. Congress oppose the plan, saying it will increase the cost of energy. Some environmental groups also criticized the proposal. They argue that it does not go far enough because it will not hold existing wells to the same high standards.

Other World Book articles:

• Carbon Offsets: Reducing Your Footprint (Special report)
• Methane: Another Greenhouse Troublemaker (Special report)

May 7, 2014

Climate change, once considered a distant threat, is currently affecting every region of the United States and every area of the U.S. economy, according to the 2014 National Climate Assessment. The report, released by the administration of President Barack Obama, was prepared by some 250 climate scientists working over several years. The report also emphasized that human activities–not the sun, volcanoes, or other natural factors–are the chief cause of the rise in average global temperatures during the past 50 years.  President Obama used the publication of the report as the launching point for a media campaign to arouse public support for government action to reduce emissions of greenhouse gases, linked by nearly all scientists to climate change.

The assessment, which is the third such review, is the first to is the first to comprehensively track the effect of climate change on every part of the United States. According to the report:

• In the Northeast, heat waves, heavy downpours, and sea-level rise pose growing challenges to many aspects of life. Infrastructure, agriculture, fisheries, and ecosystems will be increasingly affected. Since 1958, the amount of precipitation falling on this region during the heaviest rainstorms and snow storms has jumped 71 percent, with extremely wet weather expected to increase by an additional 70 percent by 2100.
• In the Southeast, sea-level rise poses widespread and continuing threats to the region’s economy and environment. Extreme heat will affect health, energy, agriculture, and more.
• In the Midwest, the increase in heavy downpours and flooding is expected to continue, causing erosion, declining water quality, and damage to transportation, agriculture, human health, and infrastructure. Heat waves are expected to become more frequent.
• In the Southwest, increased heat, drought, and insect outbreaks have increased wildfires. In 2011, New Mexico, Arizona, and Texas had the largest wildfires in their recorded histories. The current drought in the Western States represents the driest conditions in 800 years. Declining water supplies, reduced agricultural yields, health impacts in cities due to heat, and flooding and erosion in coastal areas are additional concerns.
• In the Northwest, sea-level rise, erosion, flooding risks to infrastructure, and increasing ocean acidification post major threats. Increasing wildfires, insect outbreaks, and tree diseases are currently causing widespread tree die-off.

Many scientists believe that climate change is resulting in ever-more extreme storms, such Hurricane Sandy in October 2012. In this NASA satellite image overlaid with a World Book map, the center of the storm is shown approaching the New Jersey coast. (World Book map; image provided by National Aeronautics and Space Administration)

The report notes that there is still time to act to limit the amount of change and the extent of damaging impacts. Many states and cities as well as some corporations, it said, are beginning to incorporate climate change into their planning.

Additional World Book articles:

• Intergovernmental Panel on Climate Change
• Kyoto Protocol
• The Great Meltdown (a Special Report)

See also:

• The National Climate Assessment

September 9, 2013

Human activities influenced at least some of the extreme weather events that occurred across the world in 2012, according to new research on the causes of 12 events that occurred on 5 continents and in the Arctic. The research, Explaining Extreme Events of 2012 from a Climate Perspective, included 19 studies conducted by 78 scientists working in 11 countries. All of the events would have occurred even without rising global temperatures, with “natural weather and climate fluctuations” playing “a key role in the intensity and evolution” of the events, the scientists concluded. However, they also reported compelling evidence that human activity—particularly the release of large amounts of carbon dioxide and other heat-trapping greenhouse gases from the burning of fossil fuels—contributed to about half of the events.

Earth’s average surface temperature rose by about 1.4 Fahrenheit degrees (0.76 Celsius degree) from the mid-1800′s to the early 2000′s. Researchers have also found that most of the temperature increase occurred from the mid-1900′s to the 2000′s. Natural processes have caused Earth’s climate to change in the distant past. But scientists have found strong, clear evidence that human activities have caused most of the warming since the mid-1900′s.

A new reports suggests that coastal flooding from ocean storms will increase because of global warming. (AP/Wide World)

The difficulty in determining whether and to what degree human activities are influencing storms, heat waves, and other extreme weather events has made scientists cautious about linking global warming to any particular event. Recent advances in computer modeling and a greater understanding of climate data, however, have greatly improved scientists’ ability to distinguish natural weather factors from human-related factors. The new report has added to scientists’ understanding of the impact that climate change “adds, or doesn’t add, to any extreme event,” said Thomas R. Karl, director of the National Climatic Data Center in Asheville, North Carolina.

The scientists concluded that natural weather patterns were responsible for heavy rains that caused devastating floods in India, China, and Japan and for high summer rainfall in the United Kingdom in summer 2012. In addition, climate change only slightly influenced extreme rains in New Zealand in December 2011 and in Australia from October 2011 to March 2012.

In the United States, climate change had little effect on the drought that struck the midwestern United States in the summer, the scientists reported. However, human activities played a role in the accompanying heat waves that struck that region as well as the eastern United States. Temperatures during these hot spells are higher now than in the past and occur four times as often. The authors of the study also suggested that global warming will increasingly lead to more coastal flooding like that which occurred during Hurricane Sandy.

Some of the strongest evidence involved the record loss of sea ice in the Arctic. The scientists concluded that this loss resulted “primarily from the melting of younger, thin ice from a warmed atmosphere and ocean. This cannot be explained by natural variability alone.”

Additional World Book articles:

• The Great Meltdown (a special report)
• Methane (a special report)
• Meltdown: Climate Change in the Arctic (a special report)
• Probing the History of Climate Change (a special report)
• Twisted–More Terrible Storms (a special report)
• What We Know About Global Warming (a special report)

November 30, 2012

Greenland’s ice sheets are melting at a rate five times faster than they were in the 1990’s, according to a new study of polar ice sheets reported in the journal Science. The study, which involved 47 climate scientists from 26 labs around the world, also found that the melting in West Antarctica has accelerated by about 50 percent. The only ice sheet that shows no signs of melting is in East Antarctica, the highest and coldest area on the planet. That ice sheet is actually growing, because rising temperatures have increased snowfall. Warmer air holds more water, so higher temperatures typically increase snowfall in cold areas. However, the small increase in ice there is not enough to offset the loss of ice from West Antarctica. The melting is being caused by global warming—the gradual increase in average temperatures at Earth’s surface. Most climate scientists have concluded that global warming is caused mainly by greenhouse gases released by burning such fossil fuels as coal and oil.

The study found that the melting ice sheets have caused nearly ½ inch (11 millimeters) of the rise in sea level since 1992, or about 20 percent of the overall rise. The scientists cautioned that it is difficult to determine how quickly sea level may rise in the future, largely because of uncertainties about how quickly glaciers will flow into the sea. But there is no question that the rise in sea level has also accelerated. Most climate scientists expect sea level to rise by 3 to 6 feet (1 to 2 meters) by 2100.

The retreat of a mountain glacier can provide visible evidence of global warming. These photographs show two late-summer views of Grinnell Glacier in Glacier National Park, Montana. In the photo taken around 1940, top, Upper Grinnell Lake had only begun to form at the glacier’s end. By 2006, bottom, melting ice had caused the lake to swell in size. Researchers predict that warming will melt all of the park’s glaciers by 2030. (Glacier National Park Archives, top; U.S. Geological Survey, photograph by Karen Holtzer, bottom.)

The new research provides more evidence that the Arctic is warming more quickly than any other area of the planet. In September, scientists at the National Snow and Ice Data Center reported the greatest melt of Arctic sea ice ever recorded. In fact, all six of the record-setting years for melting sea ice have occurred in the last six years. Melting sea ice does not add to rising sea level, because sea ice already floats on ocean water. But warming polar waters eat away at the edges of ice sheets on land, causing glaciers to flow into the ocean more quickly. Ice that melts from land does cause rising sea level.

The research helps to resolve scientific uncertainty about the rate of melting in the polar ice sheets. Different methods of measurement have found somewhat different rates of melting. The new research combined three different sources of data. The first was altimetry, which involves aircraft using lasers to measure the elevation of the ice sheet. Another source was satellites that measure ice using radar. The third source was satellites that measure tiny changes in Earth’s gravitational field. This field varies slightly depending on the mass of ice in a given location. Together, the three methods of measurement show the accelerating loss of polar ice.

Additional World Book articles:

• Kyoto Protocol
• Ice formation
• Intergovernmental Panel on Climate Change
• The Great Meltdown (a Special Report)
• Global warming (2011) (a Back in Time article)
• Global warming (2010) (a Back in Time article)