What are the consequences when glaciers melt?

Glaciers that have melted in the Himalayas, home to the world's largest mountains, have filled up and burst the banks of nearby glacial lakes, filling rivers and causing widespread flooding and death to nearby populations downstream. Similar consequences will likely befall those now living near other glaciers around the world.

How did abrupt climate changes in the past come to be called Dansgaard-Oeschger events?

Danish geophysicist Willi Dansgaard (1922-) discovered that by measuring the levels of oxygen isotopes and deuterium (a hydrogen isotope) in glaciers, as well as dust content and the acidity of ice, it was possible to reconstruct what the Earth's climate was in the past. He came about his conclusion by studying ice cores drilled out of glaciers in Greenland in the 1960s with Swiss physicist Hans Oeschger (1927-1998), the inventor of the Oeschger counter, a radiation measuring device. Oeschger and Dansgaard drilled ice corps samples dating back some 150,000 years in Earth's history. Layers in the ice showed that there had, in that time, been 24 abrupt changes in the world's climate. These are now called Dansgaard-Oeschger events.

Does global warming increase the incidence of diseases?

Warmer temperatures tend to encourage pests to flourish. This includes everything from insects and rodents to viruses and germs. Mosquitoes, which are responsible

A worker drills for ice core samples in the Arctic Ocean. Such samples reveal important historical details about changes in the Earth's atmosphere. (photo by Mike Dunn, North Carolina State Museum of Natural Sciences, courtesy NOAA).

A worker drills for ice core samples in the Arctic Ocean. Such samples reveal important historical details about changes in the Earth's atmosphere. (photo by Mike Dunn, North Carolina State Museum of Natural Sciences, courtesy NOAA).

for killing more human beings than any other animal on the planet because they spread disease through exposure to blood, thrive nicely in hot to temperate climates. Their breeding cycles become shorter, which allows them to reproduce more frequently each year. Mosquitoes spread diseases such as malaria and dengue fever. Rodents, carrying disease-spreading parasites like fleas and ticks, also spread their ranges as climates warm. The problem is multiplied by the fact that along with global warming comes drought, flooding, and famine, which lead to poverty, homelessness, and unsanitary water supplies. All of these encourage unsanitary living conditions that help spread diseases, such as cholera. According to a 2008 statement by the World Health Organization, about 150,000 people are dying every year from malnutrition, diarrhea, and malaria, much of it provoked by climate change. Hardest hit are poorer countries in Africa and Southeast Asia.

What is the effect of global warming and climate change on average temperatures?

By the year 2100, relative to 1990, world temperatures could rise from 2 to 11.5°F (1.1 to 6.4°C) and sea levels may rise about three to five feet (one or two meters).

Do we have any evidence of global warming in the past?

Yes, there is a great deal of evidence for global warming events in the past. The following lists two of the more well-known ones:

Mid-Cretaceous Period—During this period (between about 120 and 90 million years ago), new ocean crust was produced at about twice the normal rate. Large volcanic plateaus were forming in the ocean basins, ocean temperatures were very high, and there was a peak in worldwide petroleum formation. Just as startling was the sea level, which was about 330 to 660 feet (100 to 200 meters) higher than at present. The reasons for the high temperatures were probably numerous, including the release of carbon dioxide (a greenhouse gas) by volcanic eruptions, creating a "super greenhouse" effect. This led to temperatures about 20 to 22°F (10 to 12°C) above our current

How high would the oceans rise if all the ice sheets melted?

It is estimated that if all the ice sheets melted, including the polar ice caps, ice on Greenland and Iceland, and all the glaciers on the planet, the average worldwide sea level would rise by about 250 feet (76 meters). Such a rise would decimate almost all coastal cities, shrink the living space on all the continents, cause massive climate fluctuations, and change our lives forever.

average global temperatures. Interestingly enough, it is thought that the large volume of basalts that erupted on the ocean floor displaced a great deal of ocean water, causing sea levels to rise. And with the rise in sea level and temperatures, organisms flourished, eventually providing material necessary for petroleum formation.

Eocene Period—During this time (between about 55 to 38 million years ago), temperatures also increased, with tropical vegetation reaching about 45 to 55 degrees north and south of the equator, or about 15 degrees higher than today. Based on rock samples, it appears that the Earth had between 2 and 6 times the amount of carbon dioxide we have today. Scientists believe this global warming was caused by continental collisions, events that released large amounts of this greenhouse gas into the atmosphere. (This also shows how the rock cycle and tectonic processes can affect atmospheric conditions.)

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