The change in temperatures is likely to change our planet forever. Here's what's happening and why it's our fault. In its 4.5 billion years of history, the "Earth” has undergone continuous changes in its surface temperature. Today's average is, globally, about 15 ° C, but on several occasions, it has risen or fallen a lot due to natural or celestial phenomena such as volcanic eruptions, meteorite impacts, variations in solar activity or earth orbit.
Life on Earth has reacted to all this "stress" as best it could, in some cases adapting and sometimes disappearing in the so-called mass extinctions, which have even wiped out 90% of the planet's species.
However, the geological period we are going through is seeing a rise in temperatures much faster than in the past.
From the Industrial Revolution onwards, and especially in the last 60 years, the rise in global temperatures has been closely linked to human occupations: productive activities, transport, even house heating are largely based on fossil fuels (like coal and oil), which alter the composition of the atmosphere by releasing the greenhouse gases into the air.
The greenhouse effect is the phenomenon by which the earth's atmosphere traps part of the solar radiation that comes back into space, after having warmed the earth's surface. Some gases present in the air we breathe absorb some of the "return" thermal energy and diffuse it in all directions (a bit like in greenhouses used to grow plants even in winter).
Without this "capture," the Earth would be about 30 ° C colder.
But human activities, releasing gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) into the atmosphere - which are powerful greenhouse gases - have amplified the phenomenon, making the amount of solar heat retained excessively and increasing the "fever" of the planet: the last four years (2015-2018) have been, as far as average temperatures are concerned, the hottest ever since we are able to measure these parameters.
These polluting emissions capable of retaining solar heat remain in the atmosphere for a long time: it would take several hundred years to bring them back to the levels they were 250 years ago. And certainly, deforestation, that is the felling of trees to use timber or make way for roads or crops does not help!
The forests, our "green lungs," absorb CO2 and release oxygen to breathe. Between emissions produced and cut trees, the concentration of carbon dioxide in the air is today higher than any level it has ever touched in the last 800 thousand years.
For this effect, over the last 100 years, average temperatures on Earth have risen by 0.8 ° C. It may seem little, but it is very much if we consider that 0.6 degrees we have "bought" them only in the last 30 years, and that this is enough to accelerate the fusion of the mountain glaciers and ice caps that cover western Antarctica and Greenland.
Pollution and climate are closely linked, for several reasons. A very trivial one is that the same sources, such as industries and traffic, which produce the main polluting air compounds (for example, fine particles or nitrogen oxides) are also responsible for carbon dioxide emissions, which is one of the main anthropogenic greenhouse gases responsible for global warming. In addition to this, there is an even more subtle bond: some pollutants, or substances that dirty the air and make it unbreathable and harmful to health, can also act as "climate-altering" substances that can change the climate.
An example is a cloud of fine dust already mentioned above and, in particular, the famous "black carbon," the soot. When the soot is transported by the winds, it can reach even the high altitudes and settle on the snow and on the glaciers, making these white surfaces darker and more subject to heat, and therefore melt. Another example is ozone. While in the stratosphere ozone protects us from the ultraviolet rays of the sun, in the troposphere (the part closest to the surface) this gas is both a pollutant that can harm health, and a greenhouse gas, and is, therefore, able to overheat the planet if its concentrations increase, for example during episodes of photochemical smog.
The dissolved waters, in fact, end up in the oceans, while the water that is already there in the sea, with rising temperatures, the sea level rises; threatening the most exposed coastal areas, increasingly at risk of flooding. Some islands such as those in the Kiribati archipelago, in the Pacific Ocean, emerge only a few meters from the water: if the seas continue to grow at the rate of 3 millimeters per year, as it is today, these lands are likely to end up submerged.
The sea ice around the North Pole is shrinking, putting at risk the survival of the animals that fish on these ice, like polar bears; many animal species are disappearing because they cannot adapt to temperature changes, others have changed habitats, moving upwards in search of freshness; and the same is true for plants, which are put to the test by the altered rhythms of the seasons, which make them flower too soon, before pollinating insects become active, or surprise them with frosts or sudden downpours.
Due to rising temperatures, hurricanes and storms could become more violent, floods, and droughts more frequent. This is already making it harder to count on agricultural crops, which need regular seasons and fear rains that are too scarce or too abundant.
As you can see, climate change is not an abstract or distant entity, but something that already concerns us very close today. To slow down these transformations and try to live in peace with the elements of our Planet, we need political decisions. We need to invest in clean energy such as the Sun, wind, and waves, cut greenhouse gas emissions and absorb, for example through forests, those that you just can't avoid producing.
In recent days, the European Commission has presented a long-term strategy that aims to reduce net emissions to zero (and ensure, therefore, that the quantity of pollutants emitted is equal to the amount absorbed). For everyone, it is clear that we will have to try to stay in the lower of the two scenarios established by the Paris Climate Agreements (COP21), the last world conference to decide how to act against global warming.
Jan 15, 2020