June 2, 2014

In a major effort to curb global warming, the Environmental Protection Agency (EPA) today unveiled proposed rules that would significantly cut carbon pollution from United States electric power plants. The rules would mandate the first nationwide reduction in carbon emissions–30 percent over 2005 levels by 2030. Currently, about 38 percent of yearly U.S. carbon emissions–some 551 million short tons (500 million metric tons)–comes from power plants, particularly those fueled by coal. According to EPA estimates, a 30-percent reduction in carbon pollution from power plants would equal the carbon emitted by two-thirds of all cars and trucks in the United States. However, energy experts noted that more than 38 billion tons (35 billion metric tons) of carbon dioxide was  emitted worldwide in 2012.

EPA Administrator Gina McCarthy said that acting on climate change was a “moral obligation.” Carbon pollution, she said, “supercharges risks not just to our health, but to our communities, our economy, and our way of life. “The administration of President Barack Obama has been under continuing pressure from environmental groups to take significant action to reduce carbon emissions since the administration failed to get a climate change bill through Congress during the president’s first term in office.

Proposed rules from the Obama administration aim to boost the production of electric power from solar farms and other renewable energy plants in order to reduce carbon emissions. (© PhotoDisc/Getty Images)

The rules face a year-long period of public comment as well as fierce legal battles from business and industry groups and political opposition in Congress and some state legislatures. Opponents of the rules have argued that they will boost electric power costs for consumers and increase business costs. The EPA estimates that the rules will cost $7.3 billion to $8.8 billion annually but will lead to economic benefits of $55 billion to $93 billion over the life of the rule. The agency also predicted that the rules will prevent 2,700 to 6,600 premature deaths and 140,000 to 150,000 asthma attacks.

Once the rules are finalized in 2015, states would have until June 2016 to submit rules for ensuring that power plants within their borders meet the emissions cuts. EPA officials stressed that coal-fired plants need not be shut down immediately. Instead, states could install new wind, solar, natural gas, or nuclear units or upgrade pollution and efficiency technology in existing plants. They could also start or join state or regional “cap and trade” programs. Under under such programs, government sets an overall limit on carbon emissions, and then states meet these targets by allowing businesses to buy and sell pollution credits. According to the EPA, even if states meet the pollution-reduction targets, about 30 percent of U.S. electric power would come from coal, compared with 40 percent today.

Additional World Book articles:

• Air pollution
• Fossil fuels
• Greenhouse effect

January 7, 2014

Australia experienced its hottest year on record in 2013, Australia’s Bureau of Meteorology reported at the beginning of the year. Temperatures were 2.16 degrees Fahrenheit (1.2 degrees Celsius) above the long-term average, the warmest year since record keeping was begun in Australia in 1910. The world’s driest continent also had its hottest day, hottest month, hottest winter’s day, and hottest summer in 2013. The record-warm winter culminated in a series of devastating fires in and around Sydney, Australia’s largest city. The hotter-than-normal temperatures, which began late in 2012, were so extreme that the Bureau of Meteorology was forced to change its official weather forecasting map to include two new colors—deep purple and pink—to show areas with temperatures above 122 °F (50 °C).

According to the bureau, all but one of the last 10 years have been warmer than average. “The Australian region warming is very similar to that seen at the global scale, and the past year emphasizes that the warming trend continues,” concluded the authors of the bureau’s annual report. “Most of the warming has occurred since around 1950, and that’s consistent with the global pattern,” bureau meteorologist Neil Plummer stated in an Australian Broadcasting Company interview. He noted that figures from the Australian bureau, and other bureaus around the word, provide a “body of evidence that we’re all seeing a warming over Australia and a warming world.”

Australia is the driest continent. Its vast interior, often called the outback, consists mainly of deserts, such as the Great Victoria Desert (above), and dry grasslands. (© Peter Mead, Tom Stack & Associates)

Concurrently, a study by Australian scientists published in the journal Nature found that increasing levels of carbon dioxide are reducing the thickness of clouds over the oceans, which will, in turn, reduce their cooling impact. The scientists predicted that this effect will cause global temperature to rise by at least 5.6 degrees Fahrenheit (3 degrees Celsius) by the end of this century–shockingly higher than an earlier calculation of 2.7 degrees Fahrenheit (1.5 degrees Celsius).

Additional World Book articles:

• Bushfires in Australia
• Australia 2009 (a Back in Time article)
• Global warming 2012 (a Back in Time article)
• The Great Meltdown (a special report)
• Meltdown: Climate Change in the Arctic (a special report)

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)

August 29, 2013

Europe is losing one of its main defenses against rising carbon dioxide emissions linked to global warming, a team of researchers from the Netherlands, Finland, Switzerland, and Italy has reported. Their analysis of data from 29 European countries suggests that the ability of the continent’s trees to absorb and sequester (store) carbon dioxide (CO2), an important greenhouse gas, has nearly reached its limit. Forests, much like oceans, are important natural carbon sinks—that is, areas that sequester large amounts of atmospheric carbon. According to the researchers, the amount of carbon dioxide being absorbed by Europe’s forests has been falling since 2005. The scientists also said that the forests may reach a saturation point by 2030, earlier than previously expected.

The researchers, headed by Gert-Jan Nabuurs of Wageningen University and Research Centre in the Netherlands, listed a number of reasons for the trend. Europe’s trees are aging. Green plants absorb CO2 from the atmosphere as they grow and use the carbon for photosynthesis. However, a tree’s ability to sequester CO2 lessens as it ages. Many of Europe’s trees were planted after World War II (1939-1945), which ravaged the landscape.

Forests cover large parts of Europe, such as the sides of this valley in southern Austria. (© Johanna Huber, SIME/4Corners Images)

Aging trees are more susceptible to wildfires, disease, infestation, and other natural disturbances that return the trees’ sequestered CO2 to the atmosphere, the scientists reported. They also noted that Europe has lost forest because of urban sprawl and deforestation. When trees die or shed leaves, they deposit their trapped carbon into the soil. There, certain bacteria may break down some of the plant matter and release carbon back into the atmosphere as CO2. Trees that are cut down release their CO2 back into the atmosphere as they decay, though turning the wood into paper products delays the release for a a short time.

The researchers suggested that European countries should reevaluate their forestry and land-use policies. “I think policymakers at a national level and within the European Union have to be clear that in certain regions, with valuable habitats, that the focus is on old forests and biodiversity,” Nabuurs told the BBC. “But in other regions, maybe it’s time to concentrate more on continuous wood production again and rejuvenate forests again, so then you have growing forests and a continuous flow of wood products.”

Additional World Book articles:

• Carbon cycle
• The Ocean’s Changing Chemistry (a special report)

May 8, 2013

Scientists with the Arctic Monitoring and Assessment Programme held a conference in Bergen, Norway, on May 6-8, at which they discussed their findings on the increasing acidity of the Arctic Ocean. The cause of increasing acid levels in seawater worldwide is higher levels of carbon dioxide (CO2) in the atmosphere. In addition to increasing Earth’s temperature, atmospheric carbon dioxide is also absorbed into the sea water.  This effect slows global warming.  The chemical reaction, however, causes the water to become more acidic. The surface waters of oceans worldwide have become 30 percent more acidic since the Industrial Revolution in the mid-1800′s owing to this phenomenon.

The Arctic Ocean is rapidly becoming much more acidic because of increasing levels of carbon dioxide in the atmosphere. (© Corbis/SuperStock)

The Arctic Ocean is particularly sensitive to this process. That ocean is fed by many rivers and by melting ice. The amount of freshwater, that is, not saltwater, in the Arctic Ocean aids the process of acidification.  The cold temperature of the Arctic Ocean also makes it more vulnerable to increasing acidity.

Scientists believe this growing acidity will have a great effect on Arctic ecosystems, but they are not sure what that effect might be. Studies do indicate that many animals grow more slowly in more acidic water and shell-formation is affected in mollusks.  On the other hand, sea grasses thrive in more acidic water. It is the Arctic’s valuable fish—Arctic cod, for example, which is a food source for humans and marine mammals—that scientists are uncertain about.  More studies need to be undertaken to ascertain how Arctic fish will fare in their changing environment.

This change in the pH level of the Arctic Ocean comes at a time when the area is experiencing other great environmental changes: rising temperatures and diminishing sea ice. It is difficult for scientists to predict what the net effect of these climate-change induced alterations will be.

Other World Book articles:

• Arctic
• The Ocean’s Changing Chemistry: Tipping the Balance? (a special report)

Other websites of interest:

• Arctic Monitoring and Assessment Programme

November 20, 2012

Greenhouse gases have reached unprecedented levels, according to a report by the United Nations (UN) World Meteorological Organization. The report found that the global average of carbon dioxide (CO2) in the atmosphere reached 390.9 parts per million (ppm) in 2011. The concentration of CO2 in the atmosphere has grown by about 40 percent since the year 1750, at the beginning of the Industrial Revolution.

CO2 is released chiefly by burning such fossil fuels as coal and oil. China now produces more CO2 pollution than any other country, followed closely by the United States.

Climate scientists have found that increasing concentrations of CO2 and other greenhouse gases are the chief cause of global warming. Rising concentrations of these gases trap more of the energy in sunlight at Earth’s surface. Thus, the gases act somewhat like the walls of a greenhouse, which allow in light but prevent heat from escaping. As levels of greenhouse gases rise, they cause a gradual increase in Earth’s average surface temperatures known as global warming.

High levels of heat-trapping greenhouse gases are being released into the atmosphere by manufacturing and other human activities. (© age fotostock/SuperStock)

Global warming has already increased Earth’s average surface temperature by about 1.4 Fahrenheit degrees (0.76 Celsius degrees) since the mid-1800′s. Scientists predict that the average surface temperature will rise an additional 2.0 to 11.5 Fahrenheit degrees (1.1 to 6.4 Celsius degrees) by 2100. Climate scientists warn that severe global warming will do great damage to the natural environment and human society.

The UN report also found increases in greenhouse gases apart from CO2. The second most important greenhouse gas is methane, which is produced by natural gas extraction, agriculture, and landfills, among other human-made sources. Methane reached 1,813 parts per billion in 2011, an increase of about 259 percent above its level in 1750. Although the concentration of methane is much lower than that of CO2, methane is a more powerful greenhouse gas.

In May 2012, atmospheric concentrations of CO2 briefly surpassed 400 ppm in the Arctic, according to the National Oceanic and Atmospheric Administration. CO2 concentrations vary by latitude and season, mostly because growing plants take up significant amounts of CO2 through photosynthesis. Scientists expect average global CO2 concentrations to reach 400 ppm no later than 2016. The 400 ppm threshold has mostly symbolic significance, but many climate scientists warn that CO2 concentrations over 400 ppm will cause damaging levels of global warming.

Addtional World Book articles:

• Carbon footprint
• Intergovernmental Panel on Climate Change
• Kyoto Protocol
• Methane: Another Greenhouse Troublemaker (a Special Report)
• The Great Meltdown (a Special Report)

Dec. 6, 2011

The amount of heat-trapping carbon dioxide (CO₂) being pumped into Earth’s atmosphere jumped to record levels in 2010, according to the annual report by the Global Carbon Project (GCP). The GCP is an international collaboration of scientific organizations. The report said that the emissions rose by 5.9 percent, more than one-half billion tons of carbon. It was the largest annual increase since scientists began taking precise measurements of CO₂ emissions in 1959.

The disappearance of sea ice poses a threat to the wildlife of the Arctic Ocean. These satellite photographs show the extent of summer sea ice in 1979 (left) and 2005 (right). The ice covering has decreased as a result of global warming, an increase in the average temperature at Earth's surface. NASA

GCP scientists also calculated that the 2010 rate was almost certainly the largest yearly jump since the beginning of the Industrial Revolution in 1750. Based on these numbers, the scientists calculated that the concentration of CO₂ in the atmosphere has reached its highest level in the past 800,000 years. CO₂ emissions had dropped slightly in 2009 because the worldwide financial crisis had reduced manufacturing. The GCP scientists calculated that about half of the emissions remained in the atmosphere. The rest was absorbed by the ocean and bodies of water on land as part of the carbon cycle.

Other highlights of the report included the following:

• China, India, and the United States led the world in CO₂ emissions in 2010;
• China accounted for 24.6 percent of total emissions, compared with 16.4 percent for the United States;
• A large percentage of the emissions came from the burning of fossil fuels in power plants and factories and the production of cement;
• Annual CO₂ emissions from burning fossil fuels have increased by 49 percent since 1990, the base year used by the Kyoto Protocol for calculating reductions.

Additional World Book articles:

• Global warming
• The Great Meltdown (a Special Report)
• The Ocean’s Changing Chemistry: Tipping the Balance? (a Special Report)