Climate Change Impacts Can Be Seen Today

Posted: 22-Nov-2005; Updated: 16-Aug-2007

Killer heat waves

Models show that human-caused global warming has already doubled the chance of "killer" heat waves like the one that hit Europe in July-August of 2003. That summer was the continent’s hottest in 500 years, killing at least 27,000 people and costing European economies more than $14.7 billion (13 billion euros).

Torrential rains and flooding

According to the available data, global warming has increased the intensity of precipitation events over recent decades. In December 1999, for instance, Venezuela saw its highest monthly rainfall in 100 years, with massive landslides and flooding that killed approximately 30,000 people.

Hurricanes and tropical storms

The destructive potential of tropical storms in the North Atlantic and Pacific has risen over the past 30 years. Furthermore, an increasing number of tropical storms across the globe are reaching the highest Category 4 or 5 intensity, an increase from 20% in the 1970s to 35% in the past decade. This increase in storm intensity correlates significantly with increasing sea surface temperatures.

Drought, forest pests and wildfires

From 1998 to 2002, droughts covered wide swaths of North America, southern Europe, and southern and central Asia. The western U.S. endured one of its most severe droughts in 500 years. The worldwide drought has been linked to unusually warm ocean waters, caused in part by global warming. In 2004, Alaska had its warmest and third driest summer, resulting in its worst forest fire year on record.

Rising sea level

During the 20th century, sea levels around the world increased by an average of 4 to 8 inches (10 to 20 cm), ten times the average rate over the last 3,000 years. If sea level continues to rise, thousands of square miles of land in densely populated areas such as the eastern U.S. and Bangladesh may be lost, and flooding during storm surges will worsen.

Shrinking snowpack and vanishing glaciers

Mountain snowpack and glaciers constitute critical reservoirs of fresh water. In almost every mountainous region across the world, glaciers are retreating in response to the warming climate. In the European Alps, ice that had hidden and preserved the remains of a Stone Age man melted for the first time in 5,000 years. In the Peruvian Andes, glacial retreat has accelerated sevenfold over the past four decades. In Africa, 82 percent of the ice on Mt. Kilimanjaro has disappeared since 1912, with about one-third melting in just the last dozen years. In Asia, glaciers are retreating at a record pace in the Indian Himalaya, and two glaciers in New Guinea will be gone in a decade.

Disintegrating polar ice and melting permafrost

Since 1950, the Antarctic Peninsula has warmed by 4?F (2?C), four times the global average increase. In 2002, a Rhode Island-sized section of the Larsen B ice shelf, which sits offshore of the Peninsula, disintegrated in only 35 days. The ice shelf acts as a dam for glaciers on land; its break-up is causing a worrisome speed-up of glacier flow into the ocean, which could raise global sea level. The surface area of the Arctic's sea ice has shrunk by 10 to 15% in spring and summer, and the ice has thinned by about 40% in late summer and early autumn. A shortened season for hunting ice-dwelling seals is seriously damaging the health of the Hudson Bay's polar bears and causing them to have 15% fewer cubs. At present rates of shrinkage, Arctic sea ice could disappear completely each summer by the end of this century, pushing polar bears to the brink of extinction. Continued warming could not only destroy traditional societies that hunt seals and other food sources, but also create a worsening cycle in which disappearing ice allows the ocean to absorb more heat from the sun, which in turn leads to even warmer temperatures and more melting. Because the permafrost on which they are built is melting, buildings and roads in Alaska and Siberia have been sinking and breaking up. The 4,000 year-old Eskimo village of Shishmaref has been so severely eroded by ocean waves that the entire community was forced to relocate.

Damage to coral reefs

The past 25 years have witnessed a higher incidence around the world of large-scale coral "bleaching" events caused by excessively high ocean temperatures. In 1997-98 alone, the largest bleaching event on record seriously damaged 16% of the reefs in the world and killed 1,000-year-old corals. Within the next few decades, continued warming could cause mass bleachings to become an annual event, wiping out some reef species and ecosystems along with the food, tourism income, and coastline protection they provide.

Disease outbreaks

Higher temperatures accelerate the maturation of disease-causing agents and the organisms that transmit them, especially mosquitoes and rodents. Higher temperatures can also lengthen the season during which mosquitoes are active, as has already been observed in Canada. Warming has also been linked to the recent spread of tropical diseases, including malaria, dengue fever and yellow fever, into high-altitude areas in Colombia, Mexico, and Rwanda that had never seen the diseases before.