climatic change: climate and greenhouse effect

D. the waited consequences: The climatic changes and the inertia of the systems

The climatic changes led by this increase of the concentration of gases to greenhouse effect will have multiple and difficult consequences to surround. However, they should cause some modifications, to the scales regional and global, of the temperature, the precipitations and other variables of the climate, what could result in world changes in the humidity of soil, by an elevation of the middle level of the sea and by the perspective of episodes more serious of strong heats, of floodings, of droughts...

What changes in relation to the natural climatic variations that the man could know, it is that the middle speed of the warming up will be superior to everything that could occur, with an elevation of temperature ever attack since more of two millions of years. This climatic disturbance spread on about hundred years will be comparable to the variations of temperatures that separate us of a glacial age (5 to 6°C) and therefore of an unequaled size since at least 10 000 years. Let's recall that the last age glacial date of about 18 000 years and that several thousands of years were necessary so that the temperature lowers from 5 to 6°C, it is indeed, here question of about hundred years...
Let's note that the Cretaceous superior (has about 80 millions years) was the hottest period of the history of the Earth with about 6°C more than today (A. Nicolas, 06/2004)

The answers of the different systems (climatic, ecological, socioeconomic) affected by these climatic changes are characterized by an inherent inertia that makes some consequences will be irreversible or will persist of millennia.
Moreover, the consequences will pass the capacity of answer of the natural and human systems that could be altered destroyed definitely either.
The stabilization, or even the reduction of the broadcasts to a level little elevated won't permit to warn the climatic changes in progress anymore. Of as much more that in general, several years are necessary to the implementation of plans of actions on behalf of our societies facing important problems, a precious time that can increase the length of some effects considerably.
Finally note that some regional changes come from natural climatic variations and localized that can appear then in contradiction or in exaggeration of the consequences waited globally like an exaggerated cooling.
> The main consequences of the climatic changes

It is again very difficult to plan with accurateness the climatic consequences for every region of the globe. What seems acquirement, it is then the repetitive character of events exceptional.
The two waited main consequences are a displacement toward the poles of the tropical climatic zones (of about 100 km by degree of elevation of temperature)
"Broadly speaking, the thermal gaps between the seasons and the continents will be less marked, the elevation of temperature will be stronger to the poles that to the equator, on the continents that on the oceans, the night that the day and more elevated in winter that in summer. The régime hydrologique will be modified by the acceleration of the evaporation-precipitation cycle.
The melting of the Arctic floe will affect the circulation thermohaline while introducing the soft water that could attenuate the forcing of the salty and dense waters that participates then in the warming up of the northern hemisphere.
"The elevation of the level of the seas could reach close to one meter! And that, in a medium-term irreversible way henceforth. Indeed, the warming up of the atmosphere puts the score of years before reaching the bottom of the oceans. He/it creates himself/itself therefore a thermal phenomenon capable to maintain the rise of the level of the oceans during several hundreds years.
The three main consequences are the accentuation of the erosion of the coastlines, the increase of the vulnerability to the storms that generate the floodings and the salinisation of the coastlines then unfit to the cultures.

"A supplementary warming up of 4 to 7 degrees is waited in Arctic in the next hundred years with repercussions planètaires: floodings of the inshore zones, rise of the level of the oceans, modification of the migration journeys, slowing of the oceanic exchanges...
"The pergélisol of the polar regions, subpolaires and mountainous, an inheritance descended of the last glaciation 120 000 years ago, should continue to melt, with landslides that will affect the infrastructures, the rivers and the ecosystems of the humid zones.
"The frequency, the intensity and the length of the extreme phenomena (heatwaves, floodings, droughts, cyclones...) will be accentuated, although it is not even possible to affirm it for example for the storms, the tornados or the spindly.
"The quality of the soft water could be altered, although it can be compensated by more important debits in some regions.
"Already, the living is affected by the climatic change since movements of thousands of species are recorded on all continents. Thus, thirty nine species of European and North American butterflies progressed until 200 northbound km in 23 years. Modification of the life cycles, growth of the risk of extinction of some vulnerable species, displacement of the areas of répartion and reorganization of the interactions between the species (fragmentation, competition) are the main consequences of it.
According to the biologists, a warming up of 1°C results in a northbound displacement of 180 km (and of 150 m in altitude), on average, of the areas of distribution of the species.
"The global warming up could weaken the Gulf Stream, running hot that eases the climate of the western Europe dragging for the stroke an important cooling on Northern Europe and the coast is United States of -5°C (plausible valued hypothesis to 5%).
"All socioeconomic sectors would undergo the consequences of supplementary stress imposed to the physical and social infrastructure, active of a modification of the construction practices to an adaptation of the systems of health care and to changes of the life styles of subsistence based on the traditional knowledge.
"The rates of harvest in the sectors of agriculture, the foresterie and fishings are sensitive to the climate. Thus, the enrichment of air in CO2 encourages the development of the biomass (+30% according to the INRA in 2004) and the elevation of the temperature would increase the season of pasture in France.
On the other hand, the adaptation of these sectors to the natural disasters should be important as testify the decline economic of the French market of wood of it after the storms of 1999.
"On the human health: the consequences will be a lot of extensively negative certainements. These impacts will be able to be direct (as the exhibition to new thermal stress and to new types of extreme phenomena) or indirect (growth of the presence of some pollens, mildews or polluting atmospheric, malnutrition, risk increased of illnesses transmitted by vectors or due to the contamination of water, overcharge of the system of health care).
Indeed, the geographical extension of several major illnesses as the malaria (1 billion of infected people), the dengue, the leishmaniose... Depends of the rise of the temperatures.
"The constructions and the urban centers must adapt to the multiplication of the natural disasters, what is not obviously again the case (as testifies the flooding of The New Orleans of it in August 2005) due to a lack of reliable data on the periods back from the storms for example.
"More of about hundred millions of people living in deltas, on islands and on the coastlines should move probably. Let's note that like New York (19 millions of inhabitant), 16 of the 20 world megapolis are situated in side of sea where the elevation of the level of waters could reach close to one meter!
In general, these are the populations of the developing countries who will be the more exposed to the consequences of the climatic changes notably because of their lack of means.
"The greenhouse effect encourages the destruction of the ozone layer. Indeed, gases to greenhouse effect cool the superior layers of the atmosphere (the stratosphere) what stirs the destructive action of the ozone of the molecules of CFC chlorine. Thus, the populations who live today in Arctic will receive a dose of UV 30% superior
"The acidity of the oceans increases meaningfully. The level of the oceans decreased (the acidity increases therefore) of 0,1 since the industrial revolution. The decrease should be of 0,3 of here to 2100, menacing seriously the marine organisms: the growth of the coral and the plankton would slow down and the shells of the ptéropodes (minuscule marine snails) would be dissolved.