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 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)