Essay on Global warming

Greenhouse gas emissions. The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively Svante Arrhenius in 1896. This is the process by which absorption and emission of infrared radiation by atmospheric gases cause heating of the atmosphere and surface. On Earth, the main greenhouse gases are water vapor (responsible for approximately 36-70% of the greenhouse effect, without clouds), carbon dioxide (CO2) (9-26%), methane (CH4) (4-9%) and ozone (3-7%). Atmospheric concentrations of CO2 and CH4 have increased by 31% and 149% respectively compared with the industrial revolution in the middle of the XVIII century. According to some studies, such levels are met for the first time in the last 650 000 years – the period for which reliable data were obtained from samples of polar ice, as described in Global warming will bring killer heat, floods and storms to Britain.

About half of all greenhouse gases produced in the economic activities of mankind, remain in the atmosphere. About three-quarters of all anthropogenic emissions of greenhouse gases over the past 20 years were the result of mining and burning of oil, natural gas and coal. Most of the remaining emissions were caused by changes in the landscape, especially deforestation. In favor of the theory of anthropogenic contribution to present climate change as a result of greenhouse gas emissions and can testify to the facts that the observed warming leads primarily to an increase in average temperatures in the high (polar) latitudes, an increase in average temperatures in winter at mid-latitudes and a decrease in nocturnal cooling. And also the fact that rapid heating of the troposphere occurs on a background is not very rapid cooling of the stratosphere, as stated in Global warming meltdown in the UK.

Human activity. Recent findings reinforce the theory that the cause of global warming is human activity. A study with the participation of scientists from Scotland, Canada and Australia showed that the probability of natural and not man-made causes of climate change on the planet is not more than 5%. According to the same survey in 1980 the average temperature on earth has risen by 0.5 degrees Celsius, and the Earth continues to heat up by about 0.16 degrees per decade.

Changes in solar activity. There have been proposed various hypotheses to explain changes in Earth’s temperature corresponding changes in solar activity. The third IPCC report states that solar and volcanic activity can explain half of the temperature changes before 1950, but their overall effect was then approximately equal to zero. In particular, the impact of the greenhouse effect since 1750, according to the IPCC, is 8 times higher than the effect of changes in solar activity. Later work refined assessment of the impact of solar activity to warming after 1950. Nevertheless, the findings were roughly the same: “The best assessment of the contribution of solar activity in the warming ranges from 16% to 36% contribution to the greenhouse effect” (“Does the model underestimated the contribution of solar activity in recent climate change,” Peter A. Scott et al, “Journal of Climate”, December 15, 2003). However, there are several papers suggesting the existence of mechanisms that enhance the effect of solar activity, are not considered in current models, or that the importance of solar activity in comparison with other factors underestimated. Such statements are disputed, but in an active area of research. The findings, which will result from this discussion, can play a key role in the issue of the extent to which mankind is responsible for climate change, and how – the natural factors. There are many other possible explanations for this increase in average global surface temperature, without involving the role of industrial greenhouse gas emissions, including: the observed warming in the range of natural climate variability and does not need a separate explanation; warming is the result out of the cold Little Ice Age; observed warming is too short time, so it can not be said for sure whether it occurs at all.

It should be noted that in addition to the influence of anthropogenic factors, the climate on our planet, certainly depends on many processes in the Earth – Sun – Space. In addition to random, but repeated in the history of the Earth and catastrophic in its consequences of collisions with large asteroids and comets, the Earth’s atmosphere feels and recurrent effects of planetary and cosmic origin.

There can be distinguished four groups of cycles:

“Extra long” – by 150-300 million years – characterized as the greatest climate changes on Earth. They are likely to be associated with an orbital period of the Sun around the center of mass of our galaxy and solar system passages through the region of the Milky Way with different densities of the gas-dust matter, which, depending on its composition, how can escape the Sun’s radiation and increase the intensity of it thermonuclear reactions.

“Long” cycles associated with plate tectonics and the intensity of volcanic activity. They are firmly installed in paleogeology record, but not regular over the period, lasting from a few to tens of millions of years.

“Short” periods, so called. “Milankovitch cycles” lasting 93 000 41 000 and 25 750 years, caused by periodic oscillations of the perihelion of the Earth’s orbit and the orientation of Earth’s rotation axis defined by the phenomena of nutation and precession. From these two astronomical phenomena on the overall surface insolation is primarily influenced by periodic changes in the angle of inclination of the axis of rotation of the Earth to the plane of its orbit, then there is nutation.

And finally, the last category, conventionally called the “ultra” periods. They are connected with the rhythms of solar activity, among which assumes the existence of periods of 6000, 2300, 210 and 87 years, except of course the existing 22-bit and 11-year cycles of solar activity.

Superposition of different nature and duration of periods of change in the intensity of solar radiation reaching the planet, coupled with the thermal inertia of the oceans, the movement of continents, volcanic activity, and possibly the influence of reverse reaction of the Earth’s biosphere as a whole – and determines the average temperature Earth’s surface and the distribution of climatic zones in different geological epochs. This complex set of alternating geophysical and cosmic impacts on the Earth’s climate, may, according to some, cause the observed warming in our time. People are currently unable to influence the processes of such magnitude, as stated in What is Global warming?