"Weather changes at dangerous levels will occur within several decades," scientists warn

ByJussi Ollila

Although the progress of global warming has long been said, a theory that reverses the conventional common sense has been newly announced. According to that theory, the speed of progress of weather change at dangerous level is so fast that it can not be comparable with the conventional level, tracing the worst scenario will cause the sea level to rise significantly within the next 50 years and even in major cities adjacent to the ocean It is supposed to happen when people can not live.

Scientists Warn of Perilous Climate Shift Within Decades, Not Centuries - The New York Times
http://www.nytimes.com/2016/03/23/science/global-warming-sea-level-carbon-dioxide-emissions.html?_r=0

This theory was announced by Dr. James Hansen and his research team, who was the forerunner of climate science and also the climate scientist of NASA. The research team(PDF)Published paperAlready had a draft version announced in 2015 to raise the debate, but it is also predicted that the discussion will recur when this official version is announced.

In the paper, the research team will study the results of climate simulation and past climate changePaleoclimatology, And estimates of future climate change by using data such as mass loss of ice sheets in the ongoing Antarctic and Arctic Greenland. If we continue to use fossil fuels at the current pace and continue to emit greenhouse gases, we point out that humankind will face severe climate change in the future. Dr. Hansen talks about the interview of the New York Times that "We are now trying to give young people the uncontrollable circumstances" that is creating a future crisis situation I will.

In the paper, the occurrence of feedback that the land ice flows into the sea and the "fresh water" mixes in the seawater, the rate at which the ice sheets of Antarctica and Greenland collapse increases will greatly affect the mechanism of climate change It is stated. This is not the melting of the icebergs floating on the sea,Climate change occurs due to melting of ice on the landIt is totally different from the theory that "the iceberg is floating in the ocean so it melts, but the sea level does not rise". Thanks to the fact that fresh water flows out into the sea, the feedback of the collapse of the ice sheets accelerates and the seawater quantity increases literally, and the temperature difference between the polar region and the equator is increasing, It is stated that there is a danger of generating a powerful typhoon at no level.

ByOregon State University

According to the paper, firstly melting of the ice sheet creates a layer of fresh water on the seawater surface of Antarctica and Greenland. Next, this layer will influence the ocean current, the seawater will slow down the flow that circles the earth a lot, and in some cases you may stop part of the flow. This ocean current has a role of largely moving the heat of the earth and releasing a part of it to outer space, but when the ocean current is weakened (or stopped), the management of heat is imbalanced, Rise. Furthermore, this seawater temperature rise will further promote dissolution of the ice sheet, which is said to cause positive feedback that thermal energy continues to stay on the earth.


Furthermore, it is pointed out that the speed of climate change caused by this can progress faster than conventionally assumed. It was held in 200915th Conference of the Parties to the Framework Convention on Climate Change(COP 15) mentioned the goal of "keeping the temperature rise within 2 degrees C less than before the Industrial Revolution" and agreed, but as of 2015 the temperature has already risen by 1 degree. In my thesis, when I investigated the era of the peak of the warm season which was thought to be slightly higher than the present temperature 120,000 years ago, it was found that the sea level was higher than the current level by 6 to 9 meters It turns out that the earth is approaching that level though it is known. In addition, the time to reach that situation is not the "one century level" conventionally thought, but if it follows the worst scenario it is said that there is a danger of progressing by half of 50 years scale.

While there are voices saying that the theory discussed in this paper clarifies the puzzle of climate change mechanism that occurred in the past earth, scientists who would not agree with this theory It exists. Professor Michael Mann, climate scientist at the University of Pennsylvania said, "Some of the arguments in this paper are truly extraordinary, they conflict with the understanding of the current climate change," I talk about contents.

Although opinion from both agreeing and opposing sides is present like this, it is believed that virtually all scientists agree that "the emission of greenhouse gases that would cause serious danger We are not implementing the effort to reduce it quickly enough ". Man professor who shows a cautious view on the article also said that, "We will pretend not to look at the idea of ​​Professor Hansen knowing the danger."

ByNASA Goddard Space Flight Center