Sunday, September 5, 2010

The Complexities of Climate Change: ongoing studies to determine mankind's impact

The complexity of global warming and its effects are highlighted in journal articles cited by SeaWeb in its latest Marine Science Review (issue #359). The challenge to scientists in determining the long-term effects is how best to correlate a myriad of artificially introduced components that can either increase or even decrease atmospheric and ocean temperatures.

A study in Nature Geoscience examines the complexities behind the El Nino-Southern Oscillation (ENSO) which begins in the tropical Pacific but whose effects extend worldwide. Predicting the frequency and extant of this oscillation has been a challenge even in the best (aka "al naturale") of circumstances. By interjecting man-made factors, the predictability becomes even more difficult. But it is clear that a strong ENSO raises temperatures along the equator, changing wind patterns that impact temperature gradients between surface and deep water layers both at the equator and beyond.

Another study in Nature Geoscience examined issues related to atmospheric aerosols - particles and gases in the atmosphere that have the ability to actually lower temperatures (an extreme example of this would be the extended "winter" that doomed the dinosaurs brought on by ejecta from a meteorite impact). With man-made pollutants, like smog, sometimes both effects - heating and cooling - are at work due to the nature of what is being thrown into the air. This can make it challenging for scientists to determine the end net result and for those who have proposed the use of man-made atmospheric aerosols to moderate temperature, called radiation management, the results are questionable. One fact is known: atmospheric aerosols ultimately weaken the ozone layer, as we had over the Arctic, which increases temperatures.

There were two studies in Toxicon that examined the increase of Ciguatera, a fish poisoning that occurs with the ingestion of algal toxins. As it works its way up the food chain, the effect accumulates and becomes magnified. Human consumption of infected fish can produce some nasty gastrointestinal and even neurological effects. One study, focused on the Caribbean, and showed that the incidence of ciguatera was highest where high and relatively consistent sea surface temperatures (SST) occurred. In contrast, another study in the South Pacific showed that there is a temperature threshold over which ciguatera prevalence is dampened, but determining where and when this dampening effect occurs is challenging due to the oscillation of ocean currents in the area.

And lastly, a study in Climate Policy reminded us all of where the impacts of climate change will fall on human populations. Equatorial, developing countries - in Africa, the Indian subcontinent, Latin America, and small island states - will feel the greatest effects, affecting subsistence-level economies. And this will have to be taken into consideration when establishing international policies. The industrial world, existing in colder latitudes, has produced over 66% of the global greenhouse gases, but its equatorial neighbors will experience over 75% of the effects within this century.

Climate ecology, like many of the natural forces from evolution to the birth of the universe, is an incredibly complex system unto itself. This makes the study and outcomes of man-made intrusions a very difficult one to forecast. But there is no doubt that mankind is having an impact. I receive 20 to 30 summaries on climate change studies each month from SeaWeb - the data is there, the research is ongoing, and the reality of climate change should be a worldwide concern.

No comments: