On Melting Glaciersand Rising Sea Levels

Though Lomborg never demonstrated in chapter 2 of Cool It that global warming would lead to a net reduction in human mortality, he began chapter 3 by claiming to have settled that issue, and by pledging to expose "many other" environmentalists' "exaggerations" concerning the impacts of global warming: "In chapter 2, we looked at what happens just when temperatures increase and saw that it was no catastrophe. But, of course, there are many other concerns about global warming, each often presented as a disaster-in-waiting, urging us to drop everything else and focus on cutting CO 2. As it turns out, these statements are often grossly exaggerated and divert us from making sound policy judgments. Let's take a realistic look at some of them." 1

The global warming "exaggerations" that Lomborg supposedly uncovered in chapter 3, which he titled "Global Warming: Our Many Worries," were listed in the chapter as follows: "Melting Glaciers," "Rising Sea Levels," "Penguins in Danger?" "Extreme Weather, Extreme Hype," "Flooding Rivers," "A New Ice Age over Europe," "Malaria in Vermont," "More Heat Means More Starvation," and "Water Shortages." The first two of these issues — melting glaciers and rising sea levels—will be examined in this chapter. Most others will be examined in subsequent chapters. Melting Glaciers

Before examining what Lomborg wrote about melting glaciers, it would first be informative to review what the 2007 IPCC assessment report said about the issue. The IPCC's glossary defines a glacier as "a mass of land ice that flows downhill under gravity," which is maintained by an "accumulation of snow at high altitudes" and "balanced by melting at low altitudes or discharge into the sea." Beyond defining what a glacier is, it's also important to note that glaciers are part of the Earth's cryosphere, defined by the IPCC as

"the component of the climate system consisting of all snow, ice and frozen ground (including permafrost) on and beneath the surface of the Earth and ocean." The 2007 IPCC assessment also described the general features of the Earth's cryosphere as follows:

Currently, ice permanently covers 10% of the land surface, with only a tiny fraction occurring outside Antarctica and Greenland. Ice also covers approximately 7% of the oceans in the annual mean. In midwinter, snow covers approximately 49% of the land surface in the NH [Northern Hemisphere]. An important property of snow and ice is its high surface albedo [the fraction of solar radiation reflected by the Earth's surface, expressed as a percentage4]. Because up to 90% of the incident solar radiation is reflected by snow and ice surfaces, while only about 10% is reflected by the open ocean or forested lands, changes in snow and ice cover are important feedback mechanisms in climate change.. The cryosphere stores about 75% of the world's freshwater. At a regional scale, variations in mountain snowpack, glaciers and small ice caps play a crucial role in freshwater availability. 5

Upon describing the cryosphere, which includes glaciers (land ice), the 2007 IPCC assessment described the effects of global warming on the Earth's snow, ice, and frozen ground: "Since the change from ice to liquid water occurs at specific temperatures, ice is a component of the climate system that could be subject to abrupt change following sufficient warming. Observations and analyses of changes in ice have expanded and improved since the TAR [the 2001 IPCC assessment report], including shrinkage of mountain glacier volume, decreases in snow cover, changes in permafrost and frozen ground, reductions in Arctic sea ice extent, coastal thinning of the Greenland Ice Sheet exceeding inland thickening from increased snowfall, and reductions in seasonally frozen ground and river and lake ice cover."6

The 2007 IPCC assessment then itemized its findings in a more specific fashion with respect to the impact of global warming on the Earth's cryosphere.

These included:

Snow cover has decreased in most regions [of the world], especially in spring;

The maximum area covered by seasonally frozen ground decreased by about 7% in the NH [Northern Hemisphere] over the later half of the 20th century, with a decrease in spring up to 15%;

Annual average Arctic sea ice extent has shrunk by about 2.7 percent per decade since 1978 based upon satellite observations;

During the 20th century, glaciers and ice caps have experienced widespread mass losses and have contributed to sea level rise.

Given that glaciers are part of the Earth's cryosphere, and that most of the Earth's cryosphere is melting or thawing due to global warming, it would have made sense for Lomborg to situate the issue of melting glaciers within the context of the cryosphere, as the 2007 IPCC assessment report did. However, while arguing that the issue of "melting glaciers" is exaggerated, Lomborg never mentioned that ice and snow generally are melting and breaking up on a global scale. Nor does the word "cryosphere" appear in Cool It. This permitted Lomborg to focus on the issue of melting glaciers without situating that phenomenon within the larger context of the melting and thawing cryosphere, which is a powerful indicator of the effects of global warming.

In addition to the 2007 IPCC report's conclusions about global warming and the Earth's cryosphere, the 2001 IPCC assessment report—published six years before Cool It—also linked the melting of the Earth's cryosphere (including glaciers) to global warming:

Changes in sea level, snow cover, ice extent, and precipitation are consistent with a warming climate near the Earth's surface. Examples of these include... widespread retreat of non-polar glaciers... and decreases in snow cover and sea-ice extent and thickness;8

Decreasing snow cover and land-ice extent continue to be positively correlated with increasing land-surface temperatures There is now ample evidence to support a major retreat of alpine and continental glaciers in response to 20th century warming;9

Glaciers and ice caps will continue their widespread retreat during the 21st century and Northern Hemisphere snow cover and sea ice are projected to decrease further Modeling studies suggest that the evolution of glacial mass is controlled principally by temperature changes, rather than precipitation changes, on the global average.10

Given the 2007 and 2001 IPCC assessments on the impact of global warming on the cryosphere, including glaciers, it is clear that Lomborg had to attempt to overcome overwhelming evidence to show that scientists and environmentalists had exaggerated the effects of global warming on glaciers.

Furthermore, upon updating its assessment of the impact of global warming on the cryosphere, the 2007 IPCC assessment included a new chapter titled, "Observations: Changes in Snow, Ice and Frozen Ground."11 Lomborg completely ignored this chapter in his assessment of "Melting Glaciers" in Cool It. With respect to global warming and glaciers, the new IPCC chapter reported: "Glaciers and ice caps provide among the most visible indications of the effects of climate change." 12

In addition—and this point is highly relevant to Lomborg's analysis — the 2007 IPCC assessment report noted that the atmospheric warming responsible for these changes in the Earth's cryosphere, including a significant melting of glaciers, was not due to natural causes, that is, increased solar insolation (the amount of solar radiation reaching the Earth): "The present day near-global retreat of mountain glaciers cannot be attributed to the same natural causes [as the retreat of glaciers thousands of years ago], because the decrease of summer insolation during the past few millennia in the Northern

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