Long-term climate change in the world examples

27.06.2018

Send your good work in the knowledge base is simple. Use the form below.

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted at http://www.allbest.ru/

Introduction

Global warming is a process of gradual increase in the average annual temperature of the Earth’s atmosphere and the World Ocean.

It is expected that the warming and rise in the level of the World Ocean will continue for thousands of years, even if the level of greenhouse gases in the atmosphere stabilizes. This effect is due to the high heat capacity of the oceans. In addition to rising sea levels, rising global temperatures will also lead to changes in the amount and distribution of precipitation. As a result, natural disasters, such as floods, droughts, hurricanes and others, may become more frequent, the harvest of agricultural crops will decrease, and many biological species will disappear. Warming should, in all likelihood, increase the frequency and scale of such phenomena. Some researchers believe that global warming is a myth, some scientists reject the possibility of human influence on this process and, finally, there are those who do not deny the fact of warming and admit its anthropogenic character, but do not agree with the fact that the most dangerous on climate are industrial emissions of greenhouse gases. Relevance: The subsequent life of mankind is associated with climate change and therefore it is better to study this phenomenon and be prepared for it, try to prevent it, than live indifferently and expect an inevitable end.

Objective: to show the essence of climate change on Earth and determine its causes. Tasks:

1) To study the phenomenon of climate change.

2) Analyze the causes of this phenomenon.

3) Based on different theories, formulate what is dangerous global warming for humanity.

4) Tell about how to slow down climate change

Causes of climate change on Earth

First, let's talk about the causes of climate change and the factors affecting its change. There are anthropogenic and non-anthropogenic factors, that is, associated with human activity and, on the contrary, independent of us. There are various anthropogenic factors affecting the climate. Among them are such as tectonics lithospheric plates, volcanism, the influence of solar radiation and so on.

According to the plate tectonics theory, the continents of the earth move along the surface at a speed of several centimeters per year. This will continue to occur as a result of which the plates will continue to move and collide. Currently, the continents of North and South America are moving to the west of Africa and Europe. Researchers review several future scenarios. These geodynamic models can be distinguished by subduction of the flow in which the oceanic crust moves beneath the continent. In the introversion model, the younger, inner, Atlantic is subject to subduction and the current movement of North and South America turns in the opposite direction. In the extraversion model, the older, outer, Pacific Ocean is subject to subduction, therefore North and South America are moving towards East Asia.

Introversion

In this scenario, after 50 million years, the Mediterranean Sea may disappear, and the clash between Europe and Africa will create a long mountain range stretching all the way to the Persian Gulf. Australia will merge with Indonesia, and Lower California will slide north along the coast. New subduction zones may appear off the east coast of North and South America, and mountain ranges will form along their shores. In the south of the planet, moving Antarctica to the north will cause melting of the entire ice cap. This, along with the melting of the Greenland ice sheet, will increase the average sea level by 90 meters. Flooding of the continents will lead to climate change.

As this scenario is realized, after 100 million years, the spread of the continents will reach its maximum point and they will begin to merge. After 250 million years, North America will collide with Africa, and South America will be wrapped around the southern tip of Africa. The result will be the formation of a new supercontinent (sometimes called Pangea Ultima) and the ocean, stretching half of the planet. The Antarctic continent will completely change directions and return to the South Pole with the formation of a new ice sheet.

Extraversion

The closure of the Pacific will be completed in 350 million years. This marks the end of the current super continental cycle, in which the continents are divided, and then return to each other approximately every 400--500 million years. After the creation of a supercontinent, the plates may enter into a period of inactivity, since the subduction velocity drops by an order of magnitude. This period of stability can lead to an increase in the mantle temperature of 30--100K every 100 million years, which is the minimum lifetime of past supercontinents. And, as a result, volcanic activity may increase.

Orthoversion

According to this theory, the continents in the future will merge into a single continent in the region of the Arctic Ocean and North America will become the center of the new supercontinent. According to Mitchell and his colleagues, Asia will move toward North America, with which it will later connect. They will also be joined by modern Greenland, which will become part of the supercontinent.

Supercontinent

The formation of a supercontinent can significantly affect the environment. Collision of the plates will lead to the formation of mountains, thereby significantly changing weather conditions. Sea level may fall due to increased glaciation. The rate of surface erosion may increase, resulting in an increased rate at which organic material is absorbed. The formation of a supercontinent can lead to a decrease in global temperature and an increase in the concentration of atmospheric oxygen. These changes may lead to faster biological evolution, as new niches will emerge. This, in turn, can affect the climate and lead to a further decrease in temperature.

Volcanism

Most notably, the climatic effects of eruptions affect the changes in surface air temperature and the formation of meteor precipitation, which most fully characterize climate-forming processes.

Temperature effect. Volcanic ash emitted into the atmosphere during explosive eruptions reflects solar radiation, reducing the temperature of the air on the surface of the Earth. While fine dust in the atmosphere from volcanic eruptions is usually measured in weeks and months, volatile substances, such as SO2, can remain in the upper atmosphere for several years. Small particles of silicate dust and sulfuric aerosol, concentrating in the stratosphere, increase the optical thickness of the aerosol layer, which leads to a decrease in temperature on the Earth's surface.

As a result of the eruptions of Agung volcanoes (Bali Island, 1963) and St. Helens (USA, 1980), the observed maximum decrease in the surface temperature of the Earth in the Northern Hemisphere was less than 0.1 ° C. However, for larger eruptions, such as Tambor volcano (Indonesia, 1815), it is quite possible to lower the temperature by 0.5 ° C or more, since the amount of solar radiation is reduced by about a quarter.

Considering the possible impact on the climate of eruptions, primarily low-latitude volcanoes, or summer eruptions in temperate or high latitudes, it is necessary to take into account the type of volcanic material. Otherwise, this may lead to multiple re-evaluation of the thermal effect. Thus, during explosive eruptions with a dacitic type of magma (for example, a volcano. St. Helens), the specific contribution to the formation of H2SO4 aerosols was almost 6 times less than during the Krakatau eruption, when about 10 km3 of andesite magma was released and about 50 million tons of H2SO4 aerosols. According to the effect of air pollution, this corresponds to an explosion of bombs with a total capacity of 500 Mt and, according to, should have significant consequences for the regional climate.

The role of volcanic activity in the formation of precipitation

Since the most significant change in the amount of aerosols in the atmosphere is determined by volcanic activity, after eruption and rapid leaching of tropospheric volcanic impurities, prolonged precipitation from the lower layers of the stratosphere can be expected with relatively low oxygen and deuterium isotope ratios (heavy hydrogen) and low "primary" carbon content. If this assumption is true, then some “cold” oscillations on the paleotemperature curve are understood, based on experimental studies of polar ice cores that coincide in time with a decrease in the concentration of “atmospheric” CO2.

This partly "explains" the cooling in the Early Dryas, which manifested itself most clearly in the basin of the North Atlantic, approximately 11–10 thousand years ago. The beginning of this cooling could be initiated by a sharp increase in volcanic activity in the period of 14-10.5 thousand years ago, which was reflected in a manifold increase in the concentration of volcanogenic chlorine and sulfates in the ice cores of Greenland.

Based on the above, a preliminary conclusion can be made that volcanic activity, besides the direct impact on the climate, manifests itself in imitation of the “additional” cooling due to the increased amount of snow precipitation.

Anthropogenic impact on climate change

The greenhouse effect is the delay of the planet’s thermal radiation by the Earth’s atmosphere. This phenomenon was observed by any of us: in greenhouses or greenhouses the temperature is always higher than outside. The air we breathe is a necessary condition for our life in many aspects. Without our atmosphere, the average temperature on Earth would be about -18 ° C instead of today's 15 ° C. This change did not just happen, but due to the spread of the following greenhouse gases:

Water vapor

Carbon dioxide

Methane

Nitrous oxide

Halocarbons (hydrofluorocarbons and perfluorocarbons)

Sulfur hexafluoride - All sunlight coming to Earth causes the Earth to emit infrared waves like a giant radiator.

Because of the atmosphere, however, only part of this heat returns directly to space. The rest is trapped in the lower layers of the atmosphere, which contain a number of gases — water vapor, CO2, methane, and others — that collect outgoing infrared radiation. As soon as these gases heat up, some heat accumulated by them re-enters the earth's surface. In general, this process is called the greenhouse effect, the main cause of which is the excessive content of greenhouse gases in the atmosphere. The more greenhouse gases will be contained in the atmosphere, the more heat reflected by the earth’s surface will be retained. Since greenhouse gases do not impede the entry of solar energy, the temperature at the earth’s surface will increase.

With increasing temperature, evaporation of water from oceans, lakes, rivers, etc. will increase. Since heated air may contain a larger volume of water vapor, this creates a powerful feedback effect: the warmer it becomes, the higher the water vapor content in the air, and this, in turn, increases the greenhouse effect.

Human activity has little effect on the amount of water vapor in the atmosphere. But we emit other greenhouse gases, which makes the greenhouse effect more and more intense.

If the current rates continue, the carbon dioxide content in the atmosphere will double by 2060 compared with the pre-industrial level, and by the end of the century - four times. This is very disturbing, since the life cycle of CO2 in the atmosphere is more than one hundred years, compared with the eight-day cycle of water vapor.

Cement industry

Cement production is inextricably linked to the increase in environmental pollution due to the resulting emissions of carbon dioxide. Cement enterprises account for 5% of global carbon dioxide emissions, which is the main reason global warming. Cement does not have the potential for cost-effective disposal, and for each new road and for the construction of each new building, cement is needed.

In addition, the benefits provided by green production can increase pollution. The European Union provides subsidies to Western companies that buy obsolete cement plants in poor countries and modernize them using green technology. But even the greenest technology can reduce carbon emissions by only 20 percent. Therefore, when Western companies acquire Eastern enterprises, the amount of emissions per ton of cement produced decreases. But, as a rule, the volume of cement production increases many times, and, accordingly, the overall degree of pollution increases. The European Union effectively restricts production for European cement producers in their own countries, limiting the maximum permissible annual emissions. But even a sharp decline may not be enough to halt the growth of total emissions from cement production.

Aerosols

Ozone is a gas that naturally occurs in the Earth’s atmosphere and is concentrated mainly in the ozone layer, which is located 10-40 km above the Earth’s surface in the stratosphere. In the atmosphere, aerosol pollution is perceived in the form of smoke, fog. By their origin aerosols are divided into natural and artificial. The first occur in natural conditions without human intervention. They enter the troposphere (less often the stratosphere) during volcanic eruptions, meteorite combustion, dust storms that raise soil and rock particles from the earth’s surfaces, and forest and steppe fires. During the eruption of volcanoes, black storms or fires, huge dust clouds are formed, which often spread over thousands of kilometers. Storm winds dropping from the crests of waves droplets of seawater saturated with salts of chlorides and sulphates, which precipitate both on the water surface and on land. The main sources of artificial aerosol air pollution are thermal power plants that consume high ash, coal, metallurgical, cement, magnesite and carbon black plants.

Land use

In natural areas of the globe, soil, vegetation and climate are closely interrelated. Heat and moisture determine the nature and pace of chemical, physical and biological processes, as a result of which the rocks change on the slopes of different steepness and create a huge variety of soils. It is possible that the construction of new roads and cities in the place of fields and forests plays no less a role in global warming than carbon dioxide emissions into the atmosphere and the resulting greenhouse effect.

The fact that the unsustainable land use is responsible for the cataclysms that shook the countries of Western and Central Europe in the summer of 2002 began almost immediately after the water level in European rivers began to decline.

According to the calculations of researchers, over the past three hundred years, it was agricultural activity of man that had the greatest influence on climate processes. Even more than the greenhouse effect.

In particular, it has been proved that if a rain forest is cut down in this area and cereals are planted in the “liberated” place, then we can expect a decrease in the level of water evaporation and, as a result, an increase in the average daily temperature. On the other hand, irrigation of arable land leads to an increase in humidity, a drop in average temperature and an increase in the norm of precipitation in this region.

Trees planted in regions famous for their snowfall reduce the reflectance of sunlight and, naturally, increase the average daily temperature even though the concentration of CO2 is reduced by photosynthesis. Again, new forests increase the relative humidity in the region and increase the greenhouse effect. Anthropogenic impact is most pronounced in the tropics.

Possible scenarios of global climate change

Scenario 1 - global warming will occur gradually.

Earth is a very large and complex system consisting of a large number of interconnected structural components. There is a moving atmosphere on the planet, the movement of air masses distributes thermal energy over the latitudes of the planet, there is a huge accumulator of heat and gases on Earth - the World Ocean (the ocean accumulates 1000 times more heat than the atmosphere) Changes in such a complex system cannot happen quickly. Centuries and millennia will pass before any tangible climate change can be judged.

Scenario 2 - Global warming will occur relatively quickly.

The most "popular" scenario at the moment. According to various estimates, over the past hundred years, the average temperature on our planet has increased by 0.5–1 ° C, the concentration — CO2 has increased by 20–24%, and methane by 100%. In the future, these processes will receive further continuation and by the end of the XXI century, the average temperature of the Earth's surface may increase from 1.1 to 6.4 ° C, compared with 1990 (according to IPCC forecasts, from 1.4 to 5.8 ° C). Further melting Arctic and Antarctic ice can accelerate global warming processes due to changes in the planet’s albedo. According to some scientists, only the ice caps of the planet due to the reflection of solar radiation cool our Earth by 2 ° C, and the ice covering the ocean surface significantly slows down the heat exchange processes between relatively warm oceanic waters and the colder surface layer of the atmosphere. In addition, above the ice caps there is practically no main greenhouse gas - water vapor, since it is frozen.

Global warming will be accompanied by a rise in world ocean level. From 1995 to 2005, the level of the World Ocean has already risen by 4 cm, instead of the predicted 2 cm. If the level of the World Ocean will continue to rise at the same rate, then by the end of the XXI century the total rise of its level will be 30 - 50 cm, which will cause partial flooding of many coastal areas, especially the populous coast of Asia. It should be remembered that about 100 million people on Earth live at a height of less than 88 centimeters above sea level. In addition to rising sea levels, global warming affects the force of the winds and the distribution of precipitation on the planet. As a result, the frequency and scale of various natural disasters (storms, hurricanes, droughts, floods) will increase on the planet.

Currently, 2% of all land is suffering from drought, according to some scientists, by 2050, drought will cover up to 10% of all continent lands. In addition, the seasonal distribution of precipitation will change.

Scenario 3 - Global warming in some parts of the Earth will be replaced by a short-term cooling

It is known that one of the factors for the occurrence of ocean currents is the temperature difference between the Arctic and tropical waters. Melting of polar ice increases the temperature of the Arctic waters, and therefore causes a decrease in the temperature difference between tropical and Arctic waters, which is not passable, in the future will lead to a slowdown of the currents.

One of the most famous warm currents is the Gulf Stream, thanks to which in many countries of Northern Europe the average annual temperature is 10 degrees higher than in other similar climatic zones of the Earth. It is clear that stopping this oceanic heat conveyor will greatly affect the Earth’s climate. Already, during the Gulf Stream, it has become weaker by 30% compared with 1957. Mathematical modeling has shown that to completely stop the Gulf Stream it will be enough to raise the temperature by 2-2.5 degrees. Currently, the temperature of the North Atlantic is already warmed by 0.2 degrees compared to the 70s. If the Gulf Stream stops, the average annual temperature in Europe will drop by 1 degree by 2010, and after 2010 a further increase in the average annual temperature will continue. Other mathematical models "promise" a stronger cooling of Europe.

According to these mathematical calculations, a complete stop of the Gulf Stream will occur in 20 years, as a result of which the climate of Northern Europe, Ireland, Iceland and Great Britain can become colder than the present by 4-6 degrees, rains will increase and storms will become frequent. Cooling will also affect the Netherlands, Belgium, Scandinavia and the north of the European part of Russia. After 2020–2030, warming in Europe will resume under scenario No. 2.

Scenario 4 - Global Warming Replaced by Global Cooling

The halt of the Gulf Stream and other oceanic causes global warming on the Earth and the onset of the next ice age.

Scenario 5 - Greenhouse Disaster

The greenhouse catastrophe is the most "unpleasant" scenario of the development of global warming processes. The author of the theory is our scientist A.V. Karnaukhov, its essence is as follows. The increase in average annual temperature on Earth, due to an increase in anthropogenic CO2 content in the Earth’s atmosphere, will cause a transition into the atmosphere of CO2 dissolved in the ocean, and also provoke decomposition of sedimentary carbonate rocks with additional carbon dioxide emission, which, in turn, will raise the temperature on Earth even higher. which would entail a further decomposition of carbonates lying in the deeper layers of the earth’s crust (the ocean contains carbon dioxide 60 times more than in the atmosphere and almost 50,000 times more in the earth’s crust ). Glaciers will melt intensively, reducing the albedo of the Earth. Such a rapid increase in temperature will contribute to an intensive influx of methane from thawing permafrost, and an increase in temperature to 1.4–5.8 ° C by the end of the century will contribute to the decomposition of methane hydrates (icy compounds of water and methane) concentrated mainly in the cold places of the Earth.

To better imagine what will happen to Earth, it is best to pay attention to our solar system neighbor, the planet Venus. With the same parameters of the atmosphere as on Earth, the temperature on Venus should be above Earth on all by 60 ° C (Venus is closer to Earth than the Sun) i.e. to be around 75 ° C, but in reality the temperature on Venus is almost 500 ° C. Most of the carbonate and methane-containing compounds on Venus long ago were destroyed with the release of carbon dioxide and methane. At present, the atmosphere of Venus consists of 98% of CO2, which leads to an increase in the planet's temperature by almost 400 ° C.

If global warming follows the same scenario as on Venus, then the temperature of the surface layers of the atmosphere on Earth can reach 150 degrees. Increasing the temperature of the Earth even at 50 ° C will put an end to human civilization, and an increase in temperature by 150 ° C will cause the death of almost all living organisms on the planet.

According to the optimistic scenario of Karnaukhov, if the amount of CO2 entering the atmosphere remains at the same level, then the temperature will be 50 ° C, it will be established on Earth in 300 years, and 150 ° C in 6000 years. Unfortunately, progress is unstoppable, with each year, CO2 emissions are only increasing. According to a realistic scenario, according to which CO2 emissions will grow at the same rate, doubling every 50 years, the temperature of 50 ° C on Earth will already be established in 100 years, and 150 ° C in 300 years.

Implications of global climate change

global warming climatic atmospheric

Extreme natural phenomena beat all records in almost all regions of the world. And natural disasters entail economic consequences. Every year the damage from natural disasters increases. What consequences may global warming entail?

Change in the frequency and intensity of precipitation. In general, the climate on the planet will become more humid. But precipitation will not spread evenly across the earth. In regions that already receive enough rainfall today, their precipitation will become more intense. And in regions with insufficient moisture, dry periods will become more frequent.

Sea level rise. During the twentieth century, the average sea level rose by 0.1-0.2m. According to scientists, over the 21st century, sea level rise will be up to 1 m. In this case, coastal areas and small islands will be the most vulnerable. Such states as the Netherlands, the United Kingdom, as well as the small island states of Oceania and the Caribbean will be the first to be in danger of flooding. In addition, high tides will increase, erosion of the coastline will intensify.

Threat to ecosystems and biodiversity. Species and ecosystems have already begun to respond to climate change. Migratory species of birds began to fly earlier in the spring and later fly away in the fall. There are predictions of extinction of up to 30–40% of plant and animal species, since their habitat will change faster than they can adapt to these changes. When the temperature rises by 1 ° C, a change in the species composition of the forest is predicted. Forests are a natural carbon reservoir (80% of the total carbon in the earth’s vegetation and about 40% of carbon in the soil). The transition from one type of forest to another will be accompanied by the release of large amounts of carbon.

Melting glaciers The present-day glaciation of the Earth can be considered one of the most sensitive indicators of global changes taking place. Satellite data show that, since the 1960s, there has been a decrease in snow cover by about 10%. Since the 1950s. In the Northern Hemisphere, sea-ice area has decreased by almost 10-15%, and the thickness has decreased by 40%. Experts predict the Arctic and Antarctic Research Institute (St. Petersburg), after 30 years, the Arctic Ocean during the warm period of the year will be completely opened from under the ice. The thickness of the Himalayan ice melts at a speed of 10-15 m per year. With the current speed of these processes, two-thirds of China’s glaciers will disappear by 2060, and by 2100 all glaciers will melt completely. Accelerated melting of glaciers creates a series of immediate threats to human development. For densely populated mountainous and foothill areas, avalanches, flooding or, conversely, a decrease in the flow of rivers, and, as a result, a reduction in fresh water, are particularly dangerous.

Agriculture. The impact of warming on agricultural productivity is ambiguous. In some areas with a temperate climate, yields may increase in the case of a slight increase in temperature, but decrease in the case of significant temperature changes. In tropical and subtropical regions, overall yields are projected to decline. The worst blows can be dealt to the poorest countries, the least prepared to adapt to climate change. According to the IPCC, by 2080, the number of people facing the threat of famine could increase by 600 million, which is twice the number of people who now live in poverty in sub-Saharan Africa. However, according to A. Kapitsa, “An excess of carbon dioxide contributes to an increase in crop yields”.

Water consumption and water supply. One of the consequences of climate change may be a shortage of drinking water. In regions with arid climate (Central Asia, the Mediterranean, South Africa, Australia, etc.), the situation is further aggravated by a decrease in precipitation. Due to the melting of glaciers, the runoff of the largest water arteries of Asia - Brahmaputra, Ganga, Yellow River, Indus, Mekong, Saluen and Yangtze, is significantly reduced. The lack of fresh water will not only affect people's health and agricultural development, but also increase the risk of political disagreements and conflicts over access to water resources.

Human health. Climate change, according to scientists, will lead to increased risks to human health, especially of the less well-off segments of the population. So, reducing food production will inevitably lead to malnutrition and hunger. Abnormally high temperatures may lead to exacerbation of cardiovascular, respiratory and other diseases. According to the World Health Organization (WHO), additional mortality in European countries from heat waves in August 2003 in the UK was 2045, in France - 14802, in Italy - 3134, in Portugal - 2099.

An increase in temperature can lead to a change in the geographical distribution of various species that are carriers of diseases. With an increase in temperature, the ranges of heat-loving animals and insects (for example, encephalitic ticks and anopheles mosquitoes) will spread to the north, while the people inhabiting these territories will not be immune to new diseases.

To this, it should be added that global warming threatens to create or is already creating such additional socio-economic threats as subsidence due to the melting of permafrost (such changes can be dangerous for buildings, engineering and transport facilities); the increased load on the underwater pipelines and the likelihood of their accidental damage and ruptures, as well as obstacles to navigation due to increased river channel processes; the expansion of the range of infectious diseases (eg, encephalitis, malaria) and others.

Ways to prevent climate change

The international community, recognizing the danger associated with the continuous increase in greenhouse gas emissions in 1992 in Rio de Janeiro at the United Nations Conference on Environment and Development agreed to sign the United Nations Framework Convention on Climate Change (FCCC).

International agreements. In December 1997, the Kyoto Protocol was adopted in Kyoto (Japan), which obliges industrialized countries to reduce greenhouse gas emissions by 5% from the 1990 level by 2008–2012, including the European Union should reduce greenhouse gas emissions by 8% , USA - by 7%, Japan - by 6%. It is enough for Russia and Ukraine that their emissions do not exceed the level of 1990, and 3 countries (Australia, Iceland and Norway) may even increase their emissions because they have forests that absorb CO 2.

For the Kyoto Protocol to enter into force, it is necessary that it be ratified by the states, which account for at least 55% of greenhouse gas emissions. Today, the protocol has been ratified by 161 countries of the world (more than 61% of global emissions). In Russia, the Kyoto Protocol was ratified in 2004. The United States and Australia, which made a significant contribution to the greenhouse effect, but refused to ratify the protocol, were a notable exception.

In 2007, a new protocol was signed in Bali, expanding the list of measures to be taken to reduce the anthropogenic impact on climate change. Here are some of them:

1. Reduce the burning of fossil fuels

2. Increase the use of renewable energy.

3. Stop the destruction of ecosystems.

4. Reduce energy losses during energy production and transportation.

5. Use new energy efficient technologies in industry.

6. Reduce energy consumption in the residential and construction sector.

7. New laws and incentives.

8. New ways to move

9. Promote and stimulate energy saving and careful use of natural resources by the inhabitants of all countries.

Conclusion

Climate change is considered one of the most serious global environmental issuesfacing humanity today. In the worst case scenario, climate change will lead to catastrophic damage to the environment, human health, and the global economy. The people of the Earth are united not only by political, economic, cultural ties, but also by a single air and water oceans, a single earth surface. The air masses do not know state borders, and man has not yet learned how to manage them. The creation of good weather in limited territories is a matter for the not-so-distant future. Therefore, the Earth, Air, and Water are universal human values; all humanity must protect and save them from a catastrophe.

Established in the 40s, international organizations - the UN, UNESCO, set out to create a world without wars. In many ways, it was possible. Now these organizations must set a goal - to protect the world from environmental disasters. If an environmental disaster occurs, there will be no winners or losers. Man must not contradict the laws of nature, in order to conquer nature, one must obey it. And I think that you should not passively relate to the problem I described, but you need to look for ways out of this difficult situation and the future of our planet depends on each of us.

Posted on Allbest.ru

Main\u003e Abstract\u003e Ecology

1. Earth's climate system

2. Causes of climate change

3. Main observed changes

4. Future climate

Bibliography

1. Earth's climate system

The parameters of the climate system.The Earth’s climate system covers the atmosphere, ocean, land, the cryosphere (ice and snow) and the biosphere. This complex system is described by a number of parameters, some of which are obvious: temperature, precipitation, humidity of the air and soil, condition of the snow and ice cover, sea level. The climate system is also described by more complex characteristics: the dynamics of large-scale circulation of the atmosphere and the ocean, the frequency and strength of extreme meteorological phenomena, and the limits of the habitats of plants and animals. Often, with small variability of “simple” parameters, significant changes of “complex” occur, which basically means climate change.

Links between components of the climate system.Global climatic, biological, geological and chemical processes and natural ecosystems are closely related. Changes in one of the processes may affect others, and the secondary effects may exceed the primary effects. Positive for human life changes in one of the areas may overlap caused by their secondary changes, detrimental to the lives of people, animals and plants. Gases and aerosol particles, which humanity has emitted into the atmosphere since the beginning of the industrial revolution, change not only the composition of the atmosphere, but also the energy balance. This, in turn, affects the interaction between the atmosphere and the ocean - the main generator of extreme weather events. The ocean occupies a large part of the planet, and it is the currents and the circulation of waters that determine the climate of many densely populated regions of the world. Potentially very dangerous change in the circulation of ocean waters, such as the Gulf Stream, under the influence of global climate change.

Feedback mechanisms.Between the components of the climate system there is often a feedback, - strengthening the secondary effect causes and strengthening the primary, etc. In this case, the changes are increasing with increasing speed. For example, a reduction in snow cover due to an increase in temperature reduces albedo — a reflection of solar radiation back into the atmosphere — and increases the amount of energy absorbed by the Earth, which, in turn, raises the temperature and leads to more active melting of snow and ice. This is an example of positive feedback. There are also negative feedbacks in the climate system. For example, increased cloudiness caused by more intense evaporation at high temperatures reduces the intensity of solar radiation, and, ultimately, reduces the temperature at the earth's surface.

Greenhouse effect.The greenhouse effect is not a new question. As early as 1827, the French scientist Fourier gave his theoretical substantiation: the atmosphere transmits short-wave solar radiation, but delays the long-wave thermal radiation reflected by the Earth. At the end of the XIX century, the Swedish scientist Arrhenius came to the conclusion that due to the burning of coal, the concentration of CO2 in the atmosphere changes, and this should lead to climate warming. In 1957 - the International Geophysical Year - observations have already shown that there is a significant increase in the concentration of CO2 in the atmosphere. Russian scientist Mikhail Budyko made the first numerical calculations and predicted strong climate change.

The greenhouse effect is caused by water vapor, carbon dioxide, methane, nitrous oxide and a number of other gases whose concentration in the atmosphere is insignificant. Of course, the greenhouse effect has existed since the Earth had an atmosphere. Another thing is the enhancement of the greenhouse effect due to the fact that humankind began to burn fossil hydrocarbon fuel and emit CO2, which has been removed from the atmosphere by plants for millions of years and “stored” in the form of coal, oil and gas. But the matter is not so much actually in warming, as in the imbalance of the climate system. The sharp CO2 emissions are a kind of chemical push to the climate system. The average temperature on the planet does not change much, but its vibrations become much stronger. What we see in practice is a sharp increase in the frequency and intensity of extreme weather events: floods, droughts, extreme heat, sudden changes in weather, typhoons, etc.

Fig.1. Greenhouse effect

The evolution of the global climate.Earth's climate has never been the same. It is subject to fluctuations in all time scales - from decades to millions of years. The most noticeable fluctuations include a cycle of about one hundred thousand years — glacial periods, when the Earth’s climate was mostly colder compared to the present, and interglacial periods, when the climate was warmer. These cycles were caused by natural causes. According to a number of scientists, even now we are in a “movement” from one ice age to another, but the rate of change is very small - about 0.020С over 100 years. Another thing is that since the beginning of the industrial revolution, climate change has been accelerating (in order of magnitude 100 times faster than moving to the ice age) and largely as a result of human activity, which releases greenhouse gases into the atmosphere when burning fossil fuels and also destroys large part of the forests of the planet.

The climate of the past.Numerous studies have shown that in many places, for example, in the Sahara, there was a humid climate and rich vegetation. Paleoclimatic data based on ice cores, tree rings, lake bottom sediments, coral reefs, allow us to reconstruct the climate of the past. Many millions of years ago, during the time of the dinosaurs, the climate was much warmer, an average of 70C on the planet as a whole. Then the climate gradually became colder, and in the history of the Earth was a lot drastic changes (mostly cold spells) when a mass extinction of living organisms was observed. There is one more important conclusion: a change in the temperature of the Earth by 20C is a lot, it already leads to a mass extinction of species. At the same time, in the paleoclimatic scale “sharply” means tens and hundreds of thousands of years, and when “sharply” means hundreds of years, the consequences can be catastrophic.

Climate change of the last millennia.Since the last retreat of the glaciers from Central Europe, there have been two stages of astonishingly rapid natural warming. The first occurred about 15 thousand years ago at the end of the last glacial period, the second about 3000 years ago. In general, over the past 10 thousand years, the average global temperature has slightly decreased due to active volcanic activity and other natural causes, after which it sharply increased in the twentieth century.

Warming or cooling of 20C over the past few thousand years has never been. Natural variability did not exceed 1,50С. In the medieval warm period (about 1000 years ago, one can remember that it was then that Greenland was discovered, called the Green Land by the Vikings) was significantly warmer than it is now, but then there were no prerequisites for further enhancing the effect of climate change. For several thousand years until the 1850s. the volume of greenhouse gases in the atmosphere was relatively stable, after which a sharp increase in the concentration of CO2 began. If this trend continues, further climate change is predicted, and uneven over the globe.

Especially strong changes are now taking place in the continental areas of high and temperate latitudes, while there are areas where the temperature has dropped. In general, on the globe, warming has reached 0.6 ° C, which is already a lot, because this is about 1/3 of the way to very serious environmental losses.

2. Causes of climate change

Natural causes.Natural factors of climate change include the displacement of the orbit and the angle of the Earth (relative to the position of its axis), changes in solar activity, volcanic eruptions and changes in the amount of atmospheric aerosols (solid suspended particles) of natural origin. An assessment of the contribution of various factors to radiative forcing (warming of the atmosphere) shows that compared to 1750 by 2000, the change in solar radiation increased the warming by 0.1-0.5 W / m2, the change in the amount of tropospheric ozone - by 0.2 -0.5 W / m2. But, on the other hand, the change in the concentration of sulphate compounds reduced the heating by 0.2-0.5 W / m2, and the stratospheric ozone - by 0.05-0.2 W / m2. That is, there is a combination of multidirectional factors, each of which is much weaker than the increase in the concentration of greenhouse gases in the atmosphere, the result of which is estimated as heating by 2.2-2.7 W / m2.

Volcanic eruptions.As a result of the eruptions, significant volumes of suspended particles, aerosols, are emitted into the atmosphere, they are carried by tropospheric and stratospheric winds and do not allow some of the incoming solar radiation. However, these changes are not long-term, the particles settle relatively quickly. So a large eruption of the Santorini volcano in the Mediterranean around 1600 BC. er which probably led to the fall of the Minoan Empire, significantly cooled the atmosphere, as can be seen from the rings of the annual growth of trees.

The eruption of Tambor volcano in Indonesia in 1815 reduced the average global temperature by 30C. In the following year, there was “no summer” in Europe and North America, but over the course of several years, everything improved. As a result of the eruption of the volcano Penatubo in 1991 in the Philippines, so much ash was thrown to an altitude of 35 km, that the average level of solar radiation decreased by 2.5 W / m2, which corresponds to global cooling of at least 0.5-0.7 ° С. However, despite this, the last decade of the twentieth century was the warmest over the entire observation period. It should be noted that it is not the force of the eruption that is important, and not the amount of ejected ash, but how much of it was thrown to a greater height, 10 km or more, since this is what determines the radiation effect of the eruption.

Solar cycle and Earth orbit.The intensity of solar radiation varies, albeit within relatively small limits. Direct measurements of the intensity of solar radiation are available only for the last 25 years, but there are indirect parameters, in particular, the activity of sunspots, which has long been used to estimate the intensity of solar radiation. In addition to changing the flow from the Sun, the Earth receives a different amount of energy depending on the position of its elliptical orbit, which is oscillating. Over the past million years, the glacial and interglacial periods have changed depending on the position of the orbit of our planet. Smaller fluctuations in the orbit have been observed in the last 10 thousand years and the climate has become relatively stable. However, in any case, fluctuations in the orbit are a rather inertial phenomenon, it is of fundamental importance on a thousand-year time scale, while the anthropogenic impact on climate has a much shorter time scale.

Anthropogenic causes.The anthropogenic causes include, first of all, an increase in the concentration in the atmosphere of greenhouse gases, mainly CO2, resulting from the burning of fossil fuels. Other causes are the release of aerosol particles, deforestation, urbanization, etc.

The balance of solar and longwave radiation.In general, the incoming solar radiation (342 W / m2) is equal to the reflected radiation (107 W / m2) plus the long-wave radiation coming from the Earth (235 W / m2). In order of magnitude, the disturbance caused by human activity is less than 3 W / m2 or less than 1% of the total balance. Radiation fluxes can be greatly influenced by anthropogenic changes in the underlying surface, albedo changes due to deforestation, melting of snow cover, etc.

Increasing atmospheric concentrations of greenhouse gases.The concentration of greenhouse gases (carbon dioxide, methane, nitrous oxide) increased during the twentieth century and now this growth continues with increasing speed. CO2 concentration increased from 280 ppm (parts per million) in 1750 to 370 ppm in 2000. It is believed that in 2100 the concentration of CO2 will be in the range from 540 to 970 ppm, mainly depending on how the world energy industry develops. Greenhouse gases are characterized by a long term in the atmosphere. Half of all CO2 emissions remain in the atmosphere for 50–200 years, while the second half is absorbed by the ocean, land, and vegetation. In this case, the main role belongs to the ocean, according to some estimates, approximately 80% of the absorption of CO2 and the “production” of oxygen fall on phytoplankton.