New Study: Earth Warmest in 12,000 Years

By David L. Brown

According to a report released yesterday by the Goddard Institute for Space Studies, the Earth has now become warmer than at any time since the end of the last Ice Age. Goddard, a part of NASA, based the conclusion on study of temperature records over the past 100 years, finding that the rate of increase has been climbing rapidly during the past three decades. The work was done by a scientific team headed by NASA’s James Hansen, long an advocate for steps to help mitigate climate change due to human action. Here is a quote from the news release, which can be read in full here:

The study … concludes that, because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels in the current interglacial period, which has lasted nearly 12,000 years. An “interglacial period” is a time in the Earth’s history when the area of Earth covered by glaciers was similar or smaller than at the present time. Recent warming is forcing species of plants and animals to move toward the north and south poles.

Hansen lays the blame for global warming squarely on human activity. According to the release:

“This evidence implies that we are getting close to dangerous levels of human-made pollution,” said Hansen. In recent decades, human-made greenhouse gases have become the largest climate change factor. Greenhouse gases trap heat in the Earth’s atmosphere and warm the surface. Some greenhouse gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities.

The study notes that the world’s warming is greatest at high latitudes of the Northern Hemisphere, and it is larger over land than over ocean areas. The enhanced warming at high latitudes is attributed to effects of ice and snow. As the Earth warms, snow and ice melt, uncovering darker surfaces that absorb more sunlight and increase warming, a process called a positive feedback. Warming is less over ocean than over land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there.

This new data confirms what climate scientists have been saying with ever-growing conviction, and makes it clear that humanity must act soon if we are to avoid the possibility of a catastrophic runaway heating event that could disrupt weather patterns so severely that it could make at least some parts of the globe uninhabitable. A recent study by the National Research Council came to a similar conclusion but did not have enough data to state the present average temperature had reached its highest in 12,000 years as the present report does (search the archives for my article “NRC Committee: Global Warming Is Real,” June 22).

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This graph from the Goddard report clearly illustrates the steady upward trend of global temperatures since about 30 years ago, revealing an overall warming of 0.6 degree C. This may not seem like a lot, but because the effect is not spread evenly around the Earth some places are becoming much hotter while others actually are becoming cooler. This is placing many plant and animal species under stress as their habitats change. A notable example is the polar bear, faced with the rapid thawing of the sea ice and frozen tundra upon which it relies for its very existence.

The impact of warming on the oceans is of particular concern. According to the Goddard report:

One of the findings from this collaboration is that the Western Equatorial Pacific and Indian Oceans are now as warm as, or warmer than, at any prior time in the Holocene. The Holocene is the relatively warm period that has existed for almost 12,000 years, since the end of the last major ice age. The Western Pacific and Indian Oceans are important because, as these researchers show, temperature change there is indicative of global temperature change. Therefore, by inference, the world as a whole is now as warm as, or warmer than, at any time in the Holocene.

According to [David] Lea [of the University of California-Santa Barbara, one of the study participants], “The Western Pacific is important for another reason, too: it is a major source of heat for the world’s oceans and for the global atmosphere.”

The report points out that the planet’s temperature is now just 1 degree C. (1.8 degrees F) from being at the highest point in the past million years. From the news release:

According to Hansen, “That means that further global warming of 1 degree Celsius defines a critical level. If warming is kept less than that, effects of global warming may be relatively manageable. During the warmest interglacial periods the Earth was reasonably similar to today. But if further global warming reaches 2 or 3 degrees Celsius, we will likely see changes that make Earth a different planet than the one we know. The last time it was that warm was in the middle Pliocene, about three million years ago, when sea level was estimated to have been about 25 meters (80 feet) higher than today.”

The authors of Star Phoenix Base have been following this subject for years, and they are struck with how the subject is rushing to the forefront. Hardly a week can go by without the appearance of new findings concerning the threat of climate change. Until recently many nay-sayers were able to cast doubt on the potential problem, but the reality of global warming now seems impossible to deny.

When will our world leaders wake up to the fact that what we are doing to our planet threatens our very civilization, and that we are facing two choices: Either continue to burn fossil fuels like there is no tomorrow (in which case there well may not be), or make heroic efforts to reform our energy and transportation infrastructures and reduce emissions of greenhouse gas before we are faced with a runaway heating event that could put all of humanity in the same boat with the polar bear.

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