Third rock from the sun: Our changing planet

October Skychart. (Barry Malpas)

October Skychart. (Barry Malpas)

Earth's climate has changed. During the last 650,000 years there have been seven ice ages. The last one ended around seven centuries ago, marking the modern climate era in which human civilization advanced.

Most of these climate changes are attributed to small variations in the Earth’s orbit that varies the amount of solar energy our planet receives. With data obtained from Earth-orbiting satellites and other scientific advances, the big picture of current changes in climate shows it is primarily the result of human technological activities made predominately over the past one and a half centuries. These activites are increasing the climate effects on a global scale at a rate that is previously unprecedented.

One of the most egregious culprits is the generation of carbon dioxide, which has the ability to trap heat energy in the atmosphere, acting like a greenhouse, causing the Earth’s atmosphere to warm in response.

Ice cores drawn from Greenland, Antarctica, and mountain glaciers show that Earth’s climate reacts to changes in CO2. Paleo-climate evidence is also observed in ancient tree rings, ocean sediments, coral reefs and layers of sedimentary rocks, which reveal that current warming is occurring 10 times faster than the average rate of any previous ice-age-recovery.

Listed are some examples of the major effects that have been observed that indicating rapid climate change

Global temperature rise

Earth’s average surface temperature has risen about 2.0 degrees Fahrenheit since the late 19th century, most of which has occurred in the past 35 years. This change has been shown to be driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. The five warmest years on record have taken place since 2010.

Warming oceans

Earth’s oceans have absorbed much of this increased heat, with the top 2,300 feet of ocean warming more than 0.4 degrees in the past 50 years. One of the results is the increase of number and size of hurricanes and other major storms around the globe.

Shrinking ice sheets, glacial retreat and decreased snow cover

Greenland and Antarctic ice has decreased in mass with Greenland losing an average of 280 billion tons of ice per year between 1993 and 2016, and with Antarctica having lost about 120 billion tons during the same time period. The rate at which the Antarctic ice has lost mass has tripled in the last decade. Glaciers are retreating everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa. Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past 50 years and that the snow is melting earlier. Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades the polar sea will be navigable by the end of this century. The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing since 1950.

Rising sea levels

Average sea level has risen about eight inches during the 20th century, while the rate during the last two decades is nearly double that, and is accelerating every year. The increase of heat to the North American climate is having the effect of melting the permafrost, which is expected to release an estimated amount of twice the carbon dioxide into the atmosphere that already exists which will speed up the effects of the climate changes listed above during this century. If the generation of CO2 levels continues to rise unabated, the oceans could rise 10-30 feet by the end of the century.

Before we start thinking about terra-forming places like Mars, the moon and other planets in the solar system it might be wise to take measures that we do not un-terra-form Earth first.

Williams Monthly Star Party

Members of the Coconino Astronomical Society, in conjunction with the city of Williams, will host its monthly Star Party from 7:30 to 9:30 p.m. at Glassburn Park, in the natural area west of Rod’s Steakhouse parking lot. Several large telescopes will be on hand to view the moon, planets and other celestial objects.


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