Review: Vince G (2009) How to survive the coming century. New Scientist, February 25, 2009 (Issue 2697): 6pp.

Feature Paper: Vince G (2009) How to survive the coming century. New Scientist, February 25, 2009 (Issue 2697): 6pp.

Author Abstract: Alligators basking off the English coast; a vast Brazilian desert; the mythical lost cities of Saigon, New Orleans, Venice and Mumbai; and 90 per cent of humanity vanished. Welcome to the world warmed by 4ºC.

Note to Readers: Follow links above for author email, full article text, or the publishing scientific journal. Author notes in my review are in quotes.

Review: This week I will change tactics a little bit. Usually I either review a scientific journal article or I discuss a topic in science that usually has implications for coral reefs and the marine environment. This week we'll look at a "popular magazine article" (popular not in the sense that the article reviewed this week has been read by many people, but rather in the sense of a journal intended for consumption by lay readers (usually called a magazine). I have avoided such articles until now just as I would avoid reviewing a Wikipedia article: any university student in the hard sciences (hard not in difficulty but to separate from the social sciences) will have been told by their professors that any articles reviewed must be peer reviewed. Scientific journals articles are first submitted and then reviewed by a committee of the authors' peers (selected by the journal of submission) to consider whether the scientific methods and discoveries are worthy not only of publication but that they meet certain scientific standards. Books and popular mass media articles (either in newspapers, magazines, or the internet), while expected to uphold certain ethical standards (not misstating facts and performing due diligence in research) are not often reviewed as intricately as scientific journal articles (often due to either publication guidelines or the anonymous nature of self-publishing as in internet articles). 

However, public perception is often just as important as scientific fact. I would go so far as to say that it doesn't really matter if something is true or not, only whether people believe it is true or not, since people act on their beliefs rather than their knowledge. To put in another way, often we can't know for certain whether something is true so we have to make educated guesses. The same is true of any scientific survey. Since scientists can't possibly know _everything_ about a certain area or a subject, they take samples and assume (with varying degrees of statistical confidence that are blatantly stated) that their subsamples reflect reality on a larger scale. Of course, as discussed last week, the larger a geographic area being extrapolated (often through mathematical models), the greater the chance that patterns at local levels will not be reflected at regional or metacommunity scales.

I remember reading an article published a few years ago (I believe in Science, a preeminent scientific journal) that reviewed more than 600 scientific journal articles about global climate change and couldn't find a _single_ paper where scientists stated that "global warming" didn't exist, yet a similarly extensive review of popular literature found a 50% dissent rate in opinions about global warming. In other words, articles read by "the public" said half of the time that global warming does not exist or is exaggerated (and made claims of dissent among the scientific community) yet such dissent is not actually found among scientists. Rather, scientists argue or discuss differences in models that are aimed to predict the effect of increasing greenhouse gas levels (well-known and accepted as at their highest concentrations in the last 600,000 years through analysis of Arctic and Antarctic ice core samples -- through analyzing gas bubbles trapped in glacial ices that have not been exposed to current atmospheric regimes and thus are uncontaminated). However, while there is a difference of opinion over how global warming will manifest in large-scale weather systems and ocean currents, there is no dissent (at least in the scientific literature) over whether global warming is actually occurring. Scientists agree that _it is_ occurring.

But as scientists, we must accept that "the public" at large isn't reading scientific literature and thus are being exposed to popular media accounts that are interpreted, in most cases, by people who are _not_ scientific experts. 

Therefore, I thought we would look at one such article. I chose this particular article because the author, while a journalist, was the former scientific media editor for the scientific journal Nature (along with Science and the Proceedings of the National Academy of Sciences, it is one of the top three most influential scientific journals -- see my review in Science Corner paper 16). Therefore, the author is a rare breed of journalist so I hope that this article proves acceptable for this week's review.

The article discusses what may happen if the world's global mean temperature rises by 4ºC (in the middle of predicted temperature increases by the end of the 21st century, as reported in a "2007 report of the Intergovernmental Panel on Climate Change"). One point I'd like to make clear (and I've mentioned this a few times in the past) is that when we (as scientists) talk about "global warming" (or global climate change), we are talking about temperature increases for the entire planet as a whole. However, the planet will not (and does not) heat evenly, so some locations will experience higher temperature increases while others may experience less. Also, as the poles of the Earth heat up, ice melts, which causes a mass of cold air to move away from the poles (both through ocean convection and through air masses), which may cause temporary _cooling_ of high latitudes (temperate regions). However, as heating in the poles continues, eventually regulation of the climate will result in overall heating of all areas. 

Note the figure below (from NOAA data; left shows temperature change from 1901 to 2005 on a "per century" basis while the right shows just temperature shifting from 1979 to 2005 on a decadal basis), which shows how temperature has shifted on average in all parts of the world over the last century. Note that not all areas are the same color, meaning that not all areas of the Earth have heated equally. Note on the righthand side of the figure the area north of Antarctica that is blue, showing an overall temperature _decrease_ while most other areas show a temperature increase (and vast areas of the ocean show no temperature change, in white), which I described above.

The problem that scientists face is in predicting how such simple facts (heating of the poles) manifest in reality to change very complex (and not completely understood) weather patterns on a global scale. Everything in nature is seeking an equilibrium (often through the effects of entropy). However, when we look at weather systems that have been established over thousands of years (the global ocean "conveyor belt" that transports water from the poles to the equator and back takes about 1000 years to complete a single cycle), it has proven very difficult to accurately predict _how_ changes will manifest. For example, while scientists know that more tropical storms and hurricanes are occurring in the Atlantic Ocean than ever before, they cannot yet predict how many storms will occur each season or exactly where because there aren't enough data available for the global climate system.

Given this uncertainty, the author of this week's review article discusses what various scientists and governmental groups think about the survival of the "world as we know it." The author points out that "the good news is that the survival of humankind itself is not at stake: the species could continue if only a couple of hundred individuals remained. But maintaining the current global population of nearly 7 billion, or more, is going to require serious planning."

The author is also correct to point out the difference between a localized difference in 4ºC versus "an average warming of the entire globe." In the figure above, just in the 25 years from 1979 to 2005, the highest noted temperature increase was only about 1ºC. Imagine the _entire_ globe, therefore, increasing by 4ºC and it becomes clear that the unpredictable and "extreme" weather we've seen in the last few decades is _nothing_ compared to what is in store.

Often, to predict the future, we look to the past. Scientists are the same. I've already noted how global carbon dioxide levels can be measured accurately until about 600,000 years ago, but the fossil record can also help infer certain levels. The author notes that "the last time the world experienced temperature rises of this magnitude [4ºC over the entire globe] was 55 million years ago, after the so-called Palaeocene-Eocene Thermal Maximum event." During that time in the Earth's history (shortly after, in a geologic sense, the reign of the dinosaurs) there were no polar ice caps. Sea levels were 100 meters higher than today (the highest they can go given a complete melting of all ice on Earth, unlike the predictions of some movies like 2012 or Waterworld), over 90% of ocean life died off through the release of vast methane stores at the bottom of the ocean, and the atmosphere of the Earth was "filled with around 5 gigatonnes of carbon." 

Should just all the ice on Greenland melt, for instance, sea levels would rise by about 10 meters, not to mention the 100 meters (333 feet) higher sea levels should all ice melt. While 33 feet doesn't sound like a lot for most places, the reality is that many coastal regions would be submerged (including nearly all of Florida, Bangladesh, the Maldives, many Pacific Islands, and a vast sea would bisect the United States through flooding huge parts of Texas and extending north). Something like 90% of the people on the planet live within 150km of a coastline, meaning that most coastal cities would also be affected and many agricultural regions (often in low-lying basins adjacent to rivers, which tend to deposit fertile soils) would be destroyed through saltwater inundation.

The author points out that fully "half of the world's surface lies in the tropics, between 30º and -30º latitude, and these areas are particularly vulnerable to climate change." Also, since the equator is warmer, sea levels would rise faster there than in higher latitudes through expansion of already hot water masses.

The author discusses various dissenting views of predictions on how humanity will survive in a "doomsday" scenario as the Earth's global climate system adjusts to regulate itself. While such predictions are purely guesswork (based on expectations from large-scale changes), the reality is that change IS coming and that since the atmosphere is nearly the same over the entire world in terms of carbon dioxide levels (though localized pollution levels certainly occur and there are differences in moisture levels and pressure levels, which help to drive the global ocean conveyor belt mentioned earlier), we can expect at the very least that as global atmospheric carbon dioxide levels increase, environmental changes will also be on a global level.

Turning to the sociological, the author notes that "in order to survive, humans may need to do something radical: rethink our society not along geopolitical lines but in terms of resource distribution. [However] taking politics out of the equation may seem unrealistic: conflict over resources will likely increase significantly as the climate changes, and political leaders are not going to give up their power just like that. Nevertheless, overcoming political hurdles may be our only chance [since] we will need to abandon huge areas and move people to where the water is."

All of the above may seem more like science _fiction_ than science but the unfortunate reality is that science only goes so far. Science can work to explain current events and patterns and try to predict (with varying degrees of statistical confidence) environmental regimes in the future, but it is up to politicians to decide how to use such knowledge. Unfortunately, with some of the most powerful (politically and militarily) nations of the world (United States of America, Australia, China) continuing to pollute and contributing greatly to atmospheric climate change on a global level, and with increasing cattle production (cows alone account for nearly 25% of all greenhouse gas emissions globally compared to only 2% for all airline traffic and 4% for all shipping traffic) and deforestation and increasing ocean acidification (discussed in several past Science Corner articles), it remains unclear whether humanity will act in time to stave off a "doomsday" and rise to meet the challenge facing future generations.

Only time will tell...