Tuesday, December 15, 2015

On Saturday evening in Paris, France, world leaders finalized a deal to try to stem Earth’s surging temperature. The 2015 Paris Climate Conference, also called COP21, reached an agreement on climate in order to keep global temperatures from rising more than 3.6 °F (2 °C) from levels in the mid-1800’s. COP21 is an acronym for the 21st annual session of the Conference of the Parties. The Paris agreement is a landmark measure in the way that it sets a long-term goal for slowing global warming and provides methods for countries to achieve that goal.

Sunset in Sahara Desert. Credit: © Anna Gibiskys, Shutterstock

Global warming is an increase in the average temperature at Earth’s surface, referring specifically to the warming observed since the mid-1800’s. If it continues unchecked, it may melt ice on land near Earth’s poles, raising sea levels; lead to widespread droughts; and cause certain plant and animal species to become extinct. Natural processes have caused Earth’s climate to change in the distant past. But scientists have found strong evidence that human activities have caused most of the warming since the mid-1900’s. Such activities include the release of greenhouse gases like carbon dioxide into the atmosphere, where they trap heat like a blanket around Earth. Researchers have also found that most of the temperature increase occurred from the mid-1900′s to the 2000′s.

Climate change leaders succeeded in forming the Paris agreement through much skillful compromise. For example, many coastal and island nations—which will be the most affected by climate change—wanted any resolution coming from the Paris talks to be legally binding. Larger, heavier-polluting countries preferred a nonbinding agreement. COP21 reached a compromise where countries are legally required to set and review emissions reduction targets, but the enforcement of those targets by the countries is voluntary. The climate agreement also contains measures for more developed countries to assist less-developed ones in environmentally responsible economic development. Though developing nations were not part of the problem of high greenhouse gas emissions in the past, they must be part of the solution through limited emissions in the future. Economic assistance for these countries will help them improve life for their citizens without negatively impacting the climate.

As in any compromise, no one side got exactly what it wanted. Some environmental groups say that the agreement does not go far enough and will not stop the planet from exceeding the 3.6 °F (2 °C) threshold as it promises, for example. But the Paris agreement represents a turning point in how humanity tackles climate change. Based on the deal outlined over the last two weeks, all countries will do their part to limit their emissions with the hope of slowing the march of climate change.

Additional World Book articles:

• Greenhouse effect
• Holding the Line at 2° (a Behind the Headlines article)
• The Great Meltdown (a special report)
• Probing the History of Climate Change  (a special report)
• What We Know About Climate Change (a special report)

Monday, November 30, 2015

For the next two weeks, officials from 195 countries will meet in Paris to discuss what world governments can do about the problem of climate change. The 2015 Paris Climate Conference, also called COP21, aims to reach an agreement on climate in order to keep global temperatures from rising more than 3.6 °F (2 °C) from levels in the mid-1800’s. COP21 is an acronym for the 21st annual session of the Conference of the Parties.

Sunset in Sahara Desert. Credit: © Anna Gibiskys, Shutterstock

Global warming is an increase in the average temperature at Earth’s surface, referring specifically to the warming observed since the mid-1800’s. If it continues unchecked, it may melt ice on land near Earth’s poles, raising sea levels; lead to widespread droughts; and cause certain plant and animal species to become extinct. Natural processes have caused Earth’s climate to change in the distant past. But scientists have found strong evidence that human activities have caused most of the warming since the mid-1900’s. Such activities include the release of greenhouse gases like carbon dioxide into the atmosphere, where they trap heat like a blanket around Earth.

World governments face many challenges in creating a viable agreement and averting global climate disaster. For instance, countries are divided over whether or not the agreement should be a legally binding treaty. Because of the difficulty of getting such a treaty approved in his home country, U.S. Secretary of State John Kerry said on Wednesday that he did not expect the agreement to be legally binding. Other leaders, however, such as French President François Hollande, have insisted that the agreement must be legally binding so that the international community can ensure that countries meet their targets.

COP21 is focused on preventing temperatures from rising more than 3.6 °F (2 °C) from pre-industrial levels. However, scientists estimate that Earth’s average surface temperature has already risen by about 1.4 °F (0.76 °C). Also, greenhouse gases continue to heat Earth for many years, so global temperatures will continue to rise for decades, even if humans stop producing greenhouse gases today. Furthermore, some scientists and the governments of coastal countries—which would bear the brunt of the impact of climate change—argue that such a temperature increase will still have dire global consequences. Whatever the case, the Paris conference is the best chance humanity has today to avoid further environmental and humanitarian disaster.

Additional World Book articles:

• Greenhouse effect
• The Great Meltdown (a special report)
• Probing the History of Climate Change  (a special report)
• What We Know About Climate Change (a special report)

November 4, 2014

Earth faces “severe, pervasive and irreversible impacts for people and ecosystems” if climate change continues at its current rate, according to a summary assessment of some 30,000 studies on climate change by the Intergovernmental Panel on Climate Change (IPCC). A committee of the United Nations, the IPCC provides scientific information to world governments about the impact of human activities on global warming.

According to the new report, cutting the emissions of greenhouse gases, particularly carbon dioxide, is essential to prevent global warming from rising more than 3.6 °F (2 °C) above levels at the start of the Industrial Revolution. This increase in average surface temperatures is widely accepted by scientists as the “tipping point” for devastating climate change. To meet this goal, the IPCC reported, the amount of power obtained from renewable forms of energy must increase from 30 percent to 80 percent of all power by 2050. And unless efficient forms of carbon capture and storage (CCS) are developed, people should quit burning fossil fuels altogether by 2100. Also known as carbon sequestration, CSS involves capturing the carbon dioxide released by burning fossil fuels and storing it in deep underground rock formations.

Levels of atmospheric carbon dioxide (CO2) are higher today than at any time in the past 400,000 years. Although CO2 levels fluctuate naturally, the levels are much higher than they would have been if people were not burning such huge amounts of fossil fuels, including coal, oil, and gas. About 60 percent of fossil-fuel emissions remain in the atmosphere, causing global warming. (National Oceanic and Atmospheric Administration)

The new report, called the Synthesis Report, combines the findings of three assessments released over the past 14 months. Those reports were compiled by more than 800 scientists from 100 countries. One assessment, released in March 2014, concluded that rising global temperatures are threatening the world’s food supplies, intensifying violent storms and droughts, pushing sea levels dangerously higher, and causing serious disruptions in land and ocean ecosystems. In that report, the IPCC also warned for the first time that climate change poses a threat to human security by increasing the risk of violent conflict over natural resources and because of large-scale migrations by people fleeing difficult environmental conditions. In another assessment, released in September 2013, IPCC scientists reported being 95 percent certain that humans are the “dominant cause” of global warming.

The Synthesis Report also offered hope. It noted that the cost of even the most aggressive actions to reduce emissions would have only a small effect on world economic growth in this century. In addition, governments and industry are spending some $200 billion a year less on combating climate change than they are on developing new sources of fossil fuels. “We have the means to limit climate change.” said R. K. Pachauri, chair of the IPCC. “The solutions are many and allow for continued economic and human development. All we need is the will to change. …”

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)
• What We Know About Climate Change (a special report)

September 27, 2013

Scientists are 95 percent certain that humans are the “dominant cause” of global warming, the authors of a landmark report from the Intergovernmental Panel on Climate Change (IPCC) announced today. The authors of the report stated emphatically that global warming is “unequivocal” on the ground, in the air, and in the oceans; and that since the 1950′s, many of the observed changes in the climate system are “unprecedented over decades to millennia.”

The glacier Qori Kalis in the Andes Mountains in Peru melted substantially between 1983 and 2000. According to scientists at the Byrd Polar Research Center of Ohio State University, this melting provides a clear sign of global warming (© Lonnie G. Thompson, Byrd Polar Research Center, Ohio State University).

IPCC Co-chair Qin Dahe wrote, “Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and that concentrations of greenhouse gases have increased.” Speaking today at a news conference in Stockholm, Co-chair Thomas Stocker declared that climate change “challenges the two primary resources of humans and ecosystems, land and water. In short, it threatens our planet, our only home.” Both scientists contend that since 1950, humans are clearly responsible for more than half of the observed increase in temperatures through the burning of fossil fuels.

The IPCC report downplayed a so-called pause in the increase in temperatures in the period since 1998. The authors pointed out that this period began with a very hot El Nino year: “Trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends.”

The authors of the report warned that continued emissions of greenhouse gases at current levels would trigger further warming and changes to all aspects of the world’s climate system. They predict that continued emissions of greenhouse gases at current levels could result in sea levels rising by the end of this century by 10 inches (26 centimeters) at the low end and 32 inches (82 centimeters) at the high end. They conclude that to halt or even forestall these changes will require “substantial and sustained reductions of greenhouse gas emissions.”

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)
• What We Know About Climate Change (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)

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)

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)

April 19, 2012

New rules that would require oil and natural gas companies to capture and contain gas emissions from drilling operations and pipelines were announced on April 18 by the Environmental Protection Agency (EPA). The rules would chiefly affect hydraulic fracturing operations–called “fracking” for short–which have become a widespread source of natural gas in the past decade. Fracking involves drilling deep wells and forcing a chemical-laced fluid through rocks to tease out natural gas trapped within. Although most of the natural gas is captured for sale, some natural gas and other emissions escape into the atmosphere, creating air pollution. The EPA rules would force operators to burn or capture all gas emissions by 2015. After 2015, operators must capture all emissions. The new rules also apply to pipelines that transport natural gas.

Emissions from fracking operations include volatile organic compounds (VOC’s), which contribute to smog and may have both short- and long-term health effects. VOC’s include such carcinogens (cancer-causing compounds) as benzene and hexane. Fracking also releases methane, a potent greenhouse gas that traps heat in Earth’s atmosphere, causing global warming. The EPA estimated that the rules will cut 95 percent of VOC emissions after 2015. The agency also predicted that the rules will reduce greenhouse gas emissions by around 28 million to 44 million tons (25.4 million to 40 million metric tons) per year–equivalent to the amount produced by generating electric power for a few million homes.

Ages ago, the remains of tiny marine organisms sank to the sea floors and were buried by sediments, left. The decaying matter became gas and oil trapped in porous rock under nonporous rock, center. Later, Earth's crust shifted, and dry land appeared over many deposits, right. (World Book diagram by George Suyeoka)

The American Petroleum Institute said that many fracking operations have already complied with the rules. The industry welcomed the delay in enforcing emission capture. The EPA predicted that the new rules will save the oil and gas industry $11 million to $19 million per year above the cost of new equipment because the captured gas can be sold for additional profit.

Addtional World Book articles:

• Natural gas liquids
• Environmental pollution 2011 (Back in Time article)
• Geology 2011 (Back in Time article)