March 31, 2014

Climate change is seriously affecting every continent and all of the world’s oceans, a major report from the Intergovernmental Panel on Climate Change (IPCC) has concluded. The authors of the massive report, which was compiled by more than 300 scientists from 70 countries, stated 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. For the first time, the IPCC also warned 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. However, the scientists also noted that because of a significant increase in the amount of climate change research, governments have a much better understanding about how they can protect their people and resources.

The IPCC is a United Nations committee that periodically provides reports to world governments regarding the impact of human activities on global warming. The report is the second in a three-part series. The first report in the series, published in September 2013, concluded that scientists are 95 percent certain that humans are the “dominant cause” of global warming. The third report, which will focus on steps governments can take to reduce the effects of climate change, is due in April.

The report identified eight key risks from climate change.

• Rising sea levels, storm surges, and flooding will claim increasing numbers of human victims and cause increasing damage to property and livelihoods in coastal areas and on small islands.
• Inland flooding will cause severe health problems and economic problems in some large cities.
• Extreme weather events will damage roads, bridges, and other infrastructure networks and interfere with governments’ ability to provide electric power, water supplies, and emergency and health services.
• More people living in cities will die in heat waves, especially the elderly and the young and people working outdoors.
• More people will go hungry as warming, drought, flooding, and heavy rains reduce harvests, lead to higher food prices, and interfere with the distribution of food. Poor countries, which generally have contributed the least to global warming, will suffer more than richer high-polluting countries. Also, the poor in richer countries will also bear a heavier burden than their wealthier countrymen.
• People in many rural areas will suffer because they will have less water for drinking and irrigation.
• A loss of ocean species will hurt fishing communities.
• Farmers and livestock producers–and the consumers who depend on them–will suffer as water becomes less plentiful.

Grinnell Glacier in Glacier National Park, Montana, has retreated because of global warming. 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. (Glacier National Park Archives, top, U.S. Geological Survey, photograph by Karen Holtzer, bottom)

The report urged governments to take immediate and ambitious steps to reduce greenhouse gas emissions. “We live in an era of manmade climate change,” said Vicente Barros, a meteorologist from Argentina who chaired the report. “In many cases, we are not prepared for the climate-related risks that we already face. Investments in better preparation can pay dividends both for the present and for the future.” American climate researcher Chris Field, a lead author of the report, noted, “Climate change adaptation is not an exotic agenda that has never been tried. Governments, firms, and communities around the world are building experience with adaptation. This
experience forms a starting point for bolder, more ambitious adaptations that will be important as climate and society continue 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 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)

March 6, 2013

The Australian government’s Climate Commission for the first time has issued a report that directly connects recent extreme weather events to climate change. At least 123 weather records in Australia fell during the period reviewed in the report. A four-month heat wave in late 2012 culminated in January 2013 in massive bushfires that tore through the eastern and southeastern coasts of the country in Australia’s most populous states, New South Wales and Queensland. These record-setting temperatures were followed by torrential rains and flooding that left six people dead and $2.4 billion in damages across the same region. While climate scientists have long been reluctant to link individual weather events directly to climate change, the author of the report–”The Angry Summer”–argued that the extremes of recent weather events suggest an acceleration of change to Earth’s environment.

Wildfires are common throughout Australia due in part to the country’s hot and dry climate. Many wildfires start in the remote countryside known to Australians as the bush. (ACT Emergency Services Agency)

Speaking to the Australian Broadcasting Corporation, the commission’s leader, Tim Flannery, stated, “If you look at the last decade, we’re getting three times as many record hot days as we are record cold days, so the statistics are telling us, too, that there’s an influence on extreme events–they’re shifting. Over the last 50 years,” he noted, “we’ve seen a doubling of the record hot days, we’re getting twice as much record hot weather than we did in the mid-20th century.” The Sydney Morning Herald quotes the author of the report, Will Steffen, as saying, “Statistically, there is a 1-in-500 chance that we are talking about natural variation causing all these new records. Not too many people would want to put their life savings on a 500-to-1 horse.” Professor Steffen is the director of the Climate Change Institute at Australian National University.

Additional World Book article:

• Australia 2008 (a Back in Time article)
• Australia 2009 (a Back in Time article)
• Australia 2010 (a Back in Time article
• Australia 2011 (a Back in Time article)
• The Great Meltdown (a special report)
• Probing the History of Climate Change (a special report)
• What We Know About Global Warming (a special report)