Some scientists believe that the global climate warming can have positive effects. For instance, agricultural crops and livestock yield can increase. That means the local climate change. However, despite these assumptions, it is as yet unknown how microorganisms will behave that can impact the quality of water, soils and air. We all are witnesses of hurricane winds, dust storms, and soil salinization and flooding even in quite safe areas.
Fig. 3 Rise of atmospheric CO2 concentration according to the data of Mauna Loa station, Hawaii [Source: C.D. Keeling and T.P. Worf, Scripps Institute of Oceanography, and P. Tans, NOAA CMDL]
Modeling of climatic processes shows that this concentration of greenhouse gases will entail an average warming of the Earth's surface by 1.5-4.5 °C. Warming will probably be stronger in polar areas (up to 10 °C) and less - near the equator (1-2 °C). Significant differences arise relating to how this warming will influence cloudiness and how it will affect the distribution of solar radiation. However no one repudiates the probability of warming.
At first sight warming seems moderate. However, air temperature increases by 4.5-5.5 °C above the peaks of 38 °C can be catastrophic. Moreover such warming will entail melting of mountain glaciers and polar ices sufficient to raise the world ocean level by 1.5 m. This will cause flooding and more exposure of vast littoral areas to storms, i.e. it will force people to leave settled coastal areas and migrate deep inland. In this connection many countries of the world face a number of vital questions. To what extent are we ready to rearrange and re-equip all seaports with regard to rising sea levels? Are the inland cities and towns ready to receive millions of resettled people? These and other acute questions require answers.
Figure 4. Three possible scenarios of global temperature change by the year 2100. [source: J. Jaeger, Developing Policies for Responding to Climate Change: s summary of the discussions and recommendations for the workshop held in Villach. 28 September to 2 October 1987. Stephen Schneider. Science of climate modeling and discussion of prospects of global warming. 1993]
This Figure presents the trend of global warming in the 21st century according to the data obtained by an international group of scientists. It shows warming from a very moderate temperature increase of 0.5 °C to a catastrophic warming of 5 °C and more, as early as before the end of the next century. The latter can definitely be called catastrophic because it corresponds in magnitude to the warming that took place between 5 and 15 thousand years ago, and that marked the transition from the last drift period to the present-day inter-glacial epoch. The full transition of the warming epoch took 5-10 thousand years and was accompanied by a sea level rise of 100 m, migration of various kinds of vegetation of thousands of kilometers, radical changes in the living environment of animals and plants, extinction of some living organisms and evolution of others, as well as by other significant changes in the environment.
The effect of global warming on precipitation and agriculture seems to be even stronger. Different temperature at the poles and equator is the main driving force of atmospheric circulation. Stronger warming at the poles will weaken the circulation. This will change the picture of atmospheric circulation and therefore - the precipitation distribution.
For North Africa, as it is currently a desert, increase in precipitation will probably have a positive effect. However the USA and Canada will lose under these conditions. The central part of North America is one of the most important agricultural regions in the world, producing huge amounts of maize and wheat. Precipitation in the region, already a minimum for its current crops, is expected to reduce significantly. Irrigation will hardly remedy the situation because the level of ground water is already going down in most of this territory because of agricultural consumption. Agriculture will probably manage to adapt to another climate, e.g. by shifting areas under crops to the north. However the main difficulty is in the lack of knowledge - what to expect. Farmers now lose on average every fifth yield because of unfavorable weather. In climate shifts the weather inconstancy will be even more tangible and crop losses may increase catastrophically
Climatologists and biologists are able to assess the effects of Earth's temperature changes of 1-2 °C. However more significant temperature fluctuations can entail such climate changes that are beyond scientific experiment and anticipation. No one can surely predict what changes will take place in ocean currents, or how climate will change in that or another place of the Earth with the disappearance of Arctic ices. Likewise we cannot forecast how it will affect the fauna of ocean and inland, fisheries, the redistribution of plowing lands in the continents, the forests and the health of people. To predict possible consequences is more difficult if the changes occur permanently and with acceleration rather than being suspended by human interference. Thus, if anthropogenic emissions of greenhouse gases are not controlled strictly, there will be no "winners" under global warming as has been recently suggested by some scientists and politicians.
"… The speed of changes in the carbon dioxide concentration observed in the atmosphere within the last century is absolutely unprecedented, nothing similar has been on the Earth over the last 200 million years. The causes of these changes are the anthropogenic emissions of carbon dioxide and at the same time of other gases including greenhouse gases, technological products of civilization and human activities…
Rather simple calculations already presented in a number of scientific publications can show that during the last century radical deviation from the balance of equilibrium has occurred in the atmosphere and climate system of the Earth. If earlier carbon dioxide uptake was performed by the biota of both ocean and inland, now, according to recent data, this function is being fulfilled only by ocean. Inland ecosystems emit more CO2 than they absorb. Moreover, the ecosystems disturbed by a man finally emit CO2 instead of absorbing it.
This change in the equilibrium regime is an extremely formidable factor. And irrespective of possible scenarios according to which further events will develop, the mankind will face catastrophic consequences if it doesn't stop the process of the climate system's deviation from equilibrium…"