Two degrees is too much

Two degrees is too much

By James Hansen and collaborators

The bad news about the weather is just being repeated and, paradoxically, equally ignored. The last case of the many that there are, and that in general we cannot cover on this website, deals with the possible rise in sea level well above that predicted so far by the current models.

The corresponding article is published openly and is endorsed by 17 scientists in the discipline, but has not been peer-reviewed. It is signed, among others, by James Hansen, the most respected and famous climatologist in the world, among other things for not being wrong so far.

Until the present study, it was assumed that by the end of the century there could be a rise in temperatures of 2 degrees Celsius compared to the pre-industrial level with more or less bearable consequences. All this with certain control in our greenhouse gas emissions that would not exceed certain limits (and that we do not respect yet).

However, according to this new study, those 2 degrees would have higher consequences than assumed. This warming will produce a greater melting of the ice and an inevitable sharp rise in sea level that will cause the coastal areas to suffer serious consequences by the end of the century.

The study authors reach this conclusion based on what happened on Earth during the Eemian period, just before the last ice age. At that time the atmospheric temperature was one degree warmer than now. They have been able to verify that the sea level was higher than what current models would predict for those conditions.

They have found a feedback loop that can explain the discrepancy. A small increase in warming produces a small melting of the polar ice, but this generates changes in the marine currents that tend to melt more ice: the more ice melts, the faster the rest that remains begins to melt due to the heat trapped in the water that there below.

Fresh water is less dense than salty water and the former, the product of the melting of the ice sheet, according to this study will accumulate around Greenland and Antarctica. This layer will act as a blanket around Antarctica, floating on top of the rest of the salty water and preventing the accumulated heat from radiating into the atmosphere. The result will be a rapid melting of the ice.

Above, this layer of water would disrupt the ocean currents that carry heat from the tropics to the poles, so the tropics would heat up even faster, while at high latitudes the surface of the water would cool. This difference in temperature would generate super storms of a size and fury never seen by modern humans. However, there is evidence, found in the Bahamas, that these storms did occur 120,000 years ago. Debris left by the waves of these storms was deposited 40 meters above current sea level, including rocks weighing thousands of tons (header photo).

According to the authors of the study, a rise of 2 degrees will lead to a dangerous situation in which coastal areas and countries made up of islands will face disastrous consequences due to the rise in at least 5 meters of sea level and the scourge of super storms. This means, for example, the disappearance of the map of entire countries made up of small islands in the Pacific.

It is easy to imagine that this phenomenon will have serious consequences in the form of conflicts and massive emigration flows due to the economic collapse that it will entail in certain countries. As stated in the article, this "could make the planet ungovernable, threatening the warp of civilization."

However, there is still no consensus among climatologists on this result and it has been criticized for shape defects (it is not peer-reviewed) by some of them, so we will have to wait for the results of more studies to confirm the results. At the moment it cannot be guaranteed that the study is wrong.

The IPCC predictions seem increasingly conservative regarding what is happening, which is worse than predicted. At the opposite pole is this study. In essence, many of the consequences of human-caused climate change are difficult to assess and predict. How will plants and food production respond to this?

But there are no positive or optimistic predictions, only some are less bad than others and the only solution is to reduce our emissions as soon as possible. Gambling must be done wisely or the mistake of being too optimistic can have dire consequences.

Hansen hopes that this report increases the urgency with which the world takes action against emissions. He believes that the concentration of carbon dioxide should be lowered to 350 ppm, down from the 400 ppm already achieved today if disastrous consequences are to be avoided.

The "end of the century" thing may sound very vague and distant to readers, but this means that those born now, children and grandchildren of the current inhabitants of this world, are likely to see it for the most part.


Video: James Hansen: 2 Degrees is a Recipe for Disaster (May 2021).