Karin Bojs: When the earth was like a big snowball

”Sometimes it goes the temperature on the earth up, sometimes it goes down.” People who try to wave away the seriousness of the current climate change can throw in this obvious fact as an argument for their case. It happened for example when I spoke in Båstad a few years ago to a collection of high-ranking individuals within the Swedish business community.

And it is quite true that the climate on earth has changed, long before there were any people with coal-fired power plants, cement plants and aircraft. So far had the high näringslivsrepresentanten in Båstad right.

Some of the reasons:

the Earth's orbit and tilt in relation to the sun shifts in some cycles. Milankovic cycles, they usually called, after a Serbian physicist who described the phenomenon.

Volcanoes can emit carbon dioxide, which warms the earth, and even the dust that obscures the sun's rays and thus cool.

ocean Currents may change, which can have a significant regional effect.

the Mountains are crumbling to gravel and glaciers sweeps away the dust, which also affects.

with these issues. Their results are an important piece of the puzzle in models that calculate what is happening with climate today.

a few weeks ago, for example, new findings about the popular is usually called ”snöbollsjorden”. The journal Geology published the new results about what actually happened in the current China to 635 million years ago.

At the time the earth was so cold that glaciers reached all the way down to the equator.

the ice sheet was built up slowly over several million years. But then thawed it up and disappeared on a maximum of a million years, which in geological context, can be considered ”really fast”. Or ”fast and disastrous” Zhou Chuanming from the China academy of sciences and his co-author write in Geology.

the News in the study from China is that scientists have dated zircon in the rock layers with uranium-blymetoden, and able to call in with much more precision than in the past how quickly the glaciers disappeared.

the Reason snöbollsjorden so suddenly thawed up, they can't say for certain. But a qualified hypothesis is that it was about the volcanic eruption which spewed out carbon dioxide in the atmosphere.

, which was published in the Science Advances in a week, looked at the slightly shorter time horizon – only three million years. Matteo Willeit from the Potsdam Institute for Climate Impact Research and his co-authors have compared how the glaciers in the northern hemisphere grew in pace with the levels of carbon dioxide in the air decreased. At the same time, the contrasts between the colder periods of the ice ages and the warmer periods between the ice ages (which essentially is controlled by the above-mentioned Milankovic cycles).

During the whole of the period studied in three million years, temperatures on earth, probably as a maximum of two degrees warmer than in the 1800s.

in about one degree of warming, compared with 1800-century. When this text is written is the concentration of carbon dioxide in the air over 413 parts per million when placed inside the Mauna Loa in Hawaii. Such levels, we have not been in the vicinity of three million years, according to the study in Science Advances.

Both the levels of carbon dioxide in the air and the world's average temperature is increasing at an accelerating speed.

If warming 635 million years ago, the ”fast” and ”disastrous”, as Zhou and his co-authors write in the Geology, then I don't know what words they will take to to describe what's happening right now.