Nathan Scandella (personal)

Climate Change Mythbusting

One of the arguments that's become popular amongst conservatives (I mean "climate change skeptics") is that "global warming" isn't happening, and we only need to look at Antarctica for evidence of that.

The argument says that there is both evidence of cooling in Antarctica, and increased ice area; climate change isn't really a global phenomenon, but only the result of self-important scientists choosing to examine evidence only where it supports their beliefs (sort of how Religion operates ... which, I suppose makes religious conservatives uniquely qualified to identify this kind of tactic).

There are a few problems with this rationale. First, it ignores the reason for cooling in Antarctica. Secondly, it fails to separate land ice from sea ice, in the discussion. Thirdly, it ignores the fact that climate change affects different parts of the world in different ways.

There have been studies that show cooling trends in parts of Antarctica. However, we also know that air flows around the globe have caused the man-made hole in the ozone layer to locate partly over Antarctica, despite the fact that no industry exists there. This is actually an affirmation of the greenhouse affect. Ozone, like CO2 or methane, is a greenhouse gas, and a significant reduction in its presence in the upper atmosphere will reduce that layer's ability to retain the earth's heat, leading to cooling. Now, you might say, "Great. We've figured out a way to counteract global warming. Let's forge ahead. CFCs for everyone!". But, that doesn't work. As much as we might gain some benefit from the cooling associated with destroying our ozone layer, we'd then be unleashing a massive skin-cancer problem. Trading one large problem for another doesn't seem like good policy. Furthermore, we've already started making progress in letting the ozone "hole" repair itself. While that's good for our skin, that also means that in coming generations, places like Antarctica aren't likely to remain "protected" from warming by the counter-balancing effect of an ozone hole. So, that's more bad news. This is similar to the problem associated with us learning to reduce the smog and particulate emissions from many industrial processes recently. While that's necessary for our overall health, the airborne particulate has actually been reducing the recent warming effect. When smog and contrails and airborne particles are reduced, we have an even larger problem with climate change.

Next, Antarctica is made up of land ice, and sea ice. This is a very different landscape than the Arctic. In Antarctica, the land ice essentially represents mountains of ice, on the order of a mile thick. The sea ice is located around the (warmer) perimeter of the continent, and floats on ocean water. The temperatures inland in Antarctica are always well below freezing. Therefore, a few degrees of climate change will have no direct melting effect on land ice. So, skeptics cannot in fact point to this ice and say, "see it's not melting". Antarctica's inland ice doesn't melt. What it does do is flow and calve, like all glaciers, as a result of gravity's pull. In general, there actually has been a reduction in Antarctic land ice recently. Sea ice, on the other hand, has grown. Unfortunately, the growth rate of Antarctic sea ice is not as rapid as the rate of contraction of sea ice in the Arctic.

In order to understand the growth in sea ice, you need to consider what makes snow and ice. They must come from water. That can either come from water vapor in the air, rainfall, or liquid water in the sea. Most people probably don't know what the snowiest mountain in the world is. It's not in the Himalayas, nor is it in Antarctica. It's actually Mt. Baker, near Seattle, Washington. The second-snowiest is another local mountain, Mt. Rainier, just a couple hours due south of Mt. Baker. Although western Washington state is not a particularly cold place (compared with Antarctica, or the Himalayas), it is well-suited to produce mountain snowfall. The reason is because the air contains so much moisture. Air can hold water vapor in proportion to its temperature. Warmer air, not cooler, can hold more water vapor. When that warm air, saturated with water vapor from the Pacific Ocean, gets cooled in the mountains east of Seattle, huge amounts of snow are produced. This is key to understanding snow and ice formation in other locations.

The sea ice in Antarctica is generated in the part of the continent that's always the warmest: the coast. Some of Antarctica actually extends north of the antarctic circle. In these areas, if nearby ocean air has been warmed, it can then hold more water, and dump more snow on the sea ice's perimeter. The interior of Antarctica may be getting colder (and drier), but the perimeter can still be adding sea ice. If this were happening at a rate greater than the rate of ice/snow loss around the world, then there would be a net cooling effect, due to the snow's ability to reflect incident sunlight. Unfortunately, as shown in a previous graph, Antarctic sea ice is not growing fast enough. In addition, the snow being lost in areas closer to the equator is actually more important (per square mile) in reflecting sunlight, because the sunlight near the equator hits the earth directly, and not at an angle, as it does near the poles. When considering these important subtleties, one realizes that the South Pole is not a beacon of hope after all.

There's one more important distinction between land and sea ice. When Antarctica loses land ice (as it has), that ice (melted, or dumped into the ocean) raises sea levels. If see ice melts, or breaks off, it does not (for the most part) raise sea levels, because that ice was floating already. Remember that ice and water have different densities, and that 90% of the iceberg is under water? So, in other words, from a sea-level perspective, we should be concerned if we're losing land ice, and adding sea ice. That's not a great tradeoff.

Finally, we need to realize that even if things were looking better in Antarctica, that's not of much help to us, the humans. We don't live in Antarctica. We live in places, like Seattle, that get drinking water from nearby mountains, whose snowpack has been deteriorating significantly. The majority of scientists describe this issue as one of "Climate Change", not necessarily "Global Warming". The distinction is key. The nature of weather on Planet Earth suggests that changes in one area may be offset by changes in another area. However, the pace of change (for better or worse), is what makes humans scramble to adapt. We have proven our ability to grow our species in the conditions as we now know them. Will we be able to do the same, under different conditions? Nobody knows exactly. The safest bet is certainly to avoid changing the conditions on earth any more rapidly than necessary. While mass migration of human beings has happened before, over the course of our history, that doesn't mean such an event is desirable. I'm inclined to believe that most modern humans would be unenthusiastic about enduring the conditions that our migratory ancestors did thousands of years ago. Do we really want to bring that hardship upon ourselves again, just to keep driving bigger SUVs, leave our lights on all the time, and buy so much junk that we can't even keep up with the pace of throwing it all out?

It's a pretty simple tradeoff, really.

Posted at 05:59PM Jun 27, 2009 by Nathan in Environment  |  Comments[0]