14 DAY TRIAL // The impact of global warming in the far Northern Hemisphere has been noticed for a while now, but a new study published today, says that even though the temperature rise has been smaller in the tropics than in northern temperate areas, the impact of warming could be bigger on life at the tropics.
During the last decades, in the far Northern Hemisphere, global warming has caused major changes, from shifting geographic ranges to species extinctions, and this kind of changes has been predicted, as the warming has been faster in this zone and in the Arctic.
Co-author Raymond Huey, a University of Washington biology professor, said that “just because the temperature change in the tropics is small doesn't mean the biological impacts will be small.
“All of the studies we're doing suggest the opposite is true.”
The new study that the researchers carried on focused on cold-blooded, or ectothermic organisms, whose body temperature is very close to the temperature of their surrounding environment, like reptiles for example.
Scientists used almost 500 million readings of temperatures from over 3,000 stations all around the world, to establish a chart of temperature rises from 1961 to 2009, then looked at the effects of those temperature increases on metabolism.
They expected to find that physiological changes would be greater in the areas with the highest climate warming, but instead they found the complete opposite, according to lead author Michael Dillon, an assistant professor of zoology and physiology at the University of Wyoming.
The researchers focused on metabolic changes as this is the best way of understanding the impact of climate warming.
The explanation is simple: a higher metabolic rate needs more oxygen and more food, according to Huey, and if an organism has to spend more time eating or conserving energy it will have less time and energy for reproducing.
Guided by the idea that metabolic rates for cold-blooded animals rise faster the higher the temperature, the scientists concluded that the effects on metabolism will be higher for animals at the tropics than for those in the northern temperate areas, even though this region has the smallest real warming.
Basically, organisms living in the Arctic will suffer less from global warming – even though temperatures rise more here, and living beings in the tropics will be more affected, because their starting point is at a higher temperature.
For this study, Michael Dillon and co-author George Wang of the Max Planck Institute for Developmental Biology in Tübingen, Germany, analyzed temperature data from the National Oceanic and Atmospheric Administration's National Climatic Data Center.
They gathered readings from 3,186 stations that recorded temperatures at least every six hours during every season from 1961 through 2009.
A previous study from the University of Washington has suggested that a small increase in temperature in the tropics can push organisms beyond their optimal body temperatures and cause them damage, whereas organisms in temperate and polar regions are more resistant to higher warming, as they are already used to huge differences between seasons.
But why these effects of global warming have been ignored at the tropics until now?
The explanation given by the scientists is rather simplistic: temperature increases have been much greater farther north and also, there are very few researchers working in the tropics.
Michael Dillon added that more studies on the impact of warming on organisms in the tropics need to be done.
This research was published in the October 7 edition of Nature.