Presently, the preservation of the environment is mandatory, on one hand, pollution and destruction of the natural places where wild animals and plants live (the ecosystems that constitute the habitats of living beings), and on the other hand, the global warming (increase of global medium temperature). The latter, as numerous studies try to demonstrate, since the 70's of the 20th century, results from the accumulation of CO2 (carbon dioxide; 2 oxygen atoms - O2 - and one carbon - C) in the atmosphere, due to burning of fossil fuels. Because this phenomenon is mainly “visible” when taking into account a considerable number of years, there are many people who doubt its existence, and even its real cause. For example, rising sea waters are one of the phenomena most cited as evidence; therefore, it is good to realize that it is already a reality ... the fun, fascinating, for the most curious, is to understand how this fact is proved: it is simple, there are structures, maregraphs, by the sea, like in Cascais (Lisbon - Portugal), which measure the difference between the “height” of the waters at high tide and at low tide, with the midpoint being the “0” (zero) point of altitude on the maps, from which the altitude of the mountains in land are determined... Now, as these structures started operating in 1882, we know that until today, the average sea level has risen about 20 centimeters. The estimate, until 2100, is that it will rise by approximately one meter. Fascinating ... it is also to know that the comparison of the current temperature is made in relation to its average value between 1850 and 1880, since it takes at least 30 years to calculate reliable "atmospheric" values. Additionally, these years were before the Industrial Revolution, a time when the steam engine revolutionized factory production and transport, and with its use the consumption of coal went up a lot, leading to the 1st great release of carbon dioxide (CO2) into the atmosphere, due to human activity! We do not have original photos of the maregraph, but we invite you to a fascinating virtual visit, using the Cascais Town’s Hall page:
In Portugal, for example, there is still another one in Figueira da Foz and, in the rest of the world, these structures also exist in many countries.
We also share this photo at the Garden of the Museum of Natural History in Lisbon: