Nowhere is climate change clearer than in the Arctic. Experience a rapid and sometimes unprecedented atmospheric change, the cold of our planet has taken upon itself a greater burden than any other region in the world.
But while arctic is clearly particularly vulnerable to greenhouse gases, the physical factors that drive this unusual change-a phenomenon called arctic amplification-remain elusive and still undecided.
International research has now refuted a popular explanation. While the heat from the tropics can, in fact, vortex to the North Pole and contribute to warming in the region, everything has a negligible effect on Arctic amplification – usually calculated as the ratio of polar warming to tropical warming.
Using complex computer simulations, the researchers suggest instead that the local effects of carbon dioxide within the North Pole itself are driving the phenomenon.
"This study is significant because it explains the hypotheses previously suggested about the cause of increased polar warming, which shows that local concentrations of greenhouse gases, and Arctic climate feedback outweigh the impact of remote processes," said co-author Shane McGregor, a climate scientist at Monash University In Australia.
Arctic sea ice plays a crucial role in balancing the global climate, which means that changes here will have far-reaching effects that will have implications for ecosystems everywhere, not to mention human society.
Getting accurate prediction for polar warming is, therefore, a critical component of climate models. And understanding the factors driving polar warming will only help us in this calculation.
This new study changes our understanding of one important factor, called the vertical atmosphere temperature profile. This sounds complicated, but it is only related to the distribution of carbon dioxide in the atmosphere.
In Arctic, carbon dioxide has a vertically distributed vertical than in the tropics, and the latest research suggests this is what causes the Arctic region such conflicts compared to the rest of the world.
In the tropics, where the temperature and humidity are high, the air can move more easily through the atmosphere and rise to higher and higher altitudes. As carbon dioxide climbs along with it, the upper atmosphere heats up and the resulting energy can easily slide out into space.
But in the Arctic, something else happens. The temperature is colder and the air does not move quickly to the upper atmosphere. Her movement is more stable. This means that carbon dioxide is warming up in the lower parts of the atmosphere so that not quite as energy can escape into space.
Infrared radiation from the sun, thus, becomes more easily trapped in the Earth's atmosphere, increasing the warming of the Arctic.
Even in comparison to other local effects, the vertical atmospheric profile has no effect on Arctic arithmetic.
"Our computer simulations show that these changes in the vertical profile of the vertical atmosphere in the Arctic are superior to other regional feedback factors, such as Albekdo's feedback," Stecker says.
The albo ice feedback is when carbon dioxide warms up the atmosphere, melting snow and sea ice and reducing reflection of the Arctic surface. This allows sunlight to penetrate the upper layers of the soil and the ocean more easily, speeding up the warming process.
But while this feedback system contributes to warming in the Arctic, the new study suggests that it does not exacerbate the problem just as we thought. And it certainly does not affect as a vertical distribution of carbon dioxide in the arctic atmosphere.
The same goes for local changes in the Arctic clouds, warm ocean currents entering the North Pole, and hot winds flowing through the El Niño events.
"Our simulations show that distant physical processes outside the polar regions do not play a major role, as opposed to previous proposals," Stecker concludes.
The debate is expected to continue, but the new findings have given a little more insight into the physical processes contributing to the rapid withdrawal of Arctic ice.
This study was published in Climate change nature.