Scientists have been warning us of global warming for some time, and pointing to evidence of melting Arctic ice and unexpected weather patterns around the world.
They suggest that increased carbon dioxide levels in the atmosphere is to blame -- that human activity, and the burning of fossil fuels for energy, transportation and industry is the reason. Many people have been skeptical about the connection.
Finally, scientists have found the undeniable link, buried deep in Antarctic ice!
Ice: The Secrets They Preserve
The history of earth’s climate comes from ice cores. When snow falls, it brings with it chemicals and particles of dust, ash and radioactive isotopes that are in the air. In places like Antarctica, the snow never melts – so layers of snowfall over millions of years of history get compressed into ice. Scientists (Paleoclimatologists) dig several hundred meters deep into Antarctic ice and bring up cylinders of ice called “ice cores.”
Ice cores also hold gas bubbles containing oxygen and carbon dioxide from back in time. Pollen and dust in the cores can tell researches the direction of the wind in a year. When all of these details are pieced together the climate and weather patterns in any given year can be recreated back in time! Researchers date the core by physically counting back layers like they do with tree rings.
The Missing Connection
The biggest global warming event in our Earth's history was the end of the last Ice Age around 10,000 years ago. However, when the gas bubbles in Antarctica's ice cores were dated, it did not match with the period of global warming. The bubbles were sometimes off by as much as 1400 years, and sitting much deeper in the ice.
This led many to question - Does CO2 levels have any relation to rising temperatures? Researchers now have the answers and it has to do with the way air gets trapped in layers of ice! You may have noticed how snow falls and it tends to be light with lots of spaces. Now imagine the snow did not melt and fresh snow fell on top of this layer next year. The atmospheric air from this year can easily move into the space of last year's snow until the snow freezes into ice.
When testing the isotopes of nitrogen-15 on a section of the ice core, scientists noticed that the air did not belong to the period the ice was formed but belonged to more recent times. As they looked deeper into the cores, researchers were able to identify the gas molecules that belonged to the period of the end of the last ice age. These molecules showed high levels of carbon dioxide.
Now that our Earth has yielded the clue, perhaps time for people and countries to come together and take action?