Global warming refers to a worldwide phenomenon of rising air and ocean temperatures. Observed since the 20th century, this change is mainly due to the amount of heat trapped on the earth’s surface as a result of greenhouse gas emissions (CO2, etc.).
CO2 emissions
CO2 (carbon dioxide) emissions are either natural or anthropogenic (caused by human activity). Natural emissions are linked to natural fires, the respiration of animals, plants, aquatic micro-organisms, soil or even volcanic origin. Anthropogenic emissions come from heating, vehicles, arson, fossil fuel power plants.
What is the growth of CO2 emissions?
2018, an unprecedented year. While global agreements to fight global warming are increasing, carbon emissions broke a record last year: 33.1 gigatonnes of carbon emissions (an increase of 1.7%, the highest since 2013). The countries mainly responsible are China, the United States and India.
What explains this increase is the demand for energy, which continues to rise year after year. In order to meet this demand, fossil fuels such as gas and coal are used. And although renewable energies are developing, it is still not enough.
So what are the figures to remember?
- India: +4.8
- United States: +3.1
- Europe: -1.3
- Germany: -4.5
What are the consequences of CO2 emissions on our environment?
Since CO2 is naturally present in the air, it is not harmful to living organisms. However, this CO2 is also accompanied by emissions of soot, heavy metals and various pollutants that have harmful effects on living organisms. The latter are therefore sensitive to variations in the concentration of CO2 in the atmosphere. This has increased from 280 ppm (parts per million) at the beginning of the industrial revolution to 400 ppm in 2013.
This can have a number of consequences for flora and fauna.
- In birds and mammals: CO2 can kill by asphyxiation from a certain threshold and duration of exposure. Its chemical properties, which are superior to those of oxygen, make it capable of rapidly crossing many types of biological membranes (including the central nervous system).
- In the oceans: ocean circulation is also affected by CO2 emissions, as is the migration of many fish species. Water temperatures are rising with global warming (as the oceans absorb a third of human CO2 emissions, which also makes the oceans more acidic), so many fish are moving towards the poles where water temperatures change less rapidly. As for ocean currents, they could slow down or even stop. The absorbed CO2 could be released and worsen climate change.
- On the flora: at low doses, CO2 allows the growth of many plant species. After experiments, this fact proves to be true up to a certain threshold, beyond which plant growth stabilises or even decreases. It is currently difficult to determine the level of this threshold because it varies according to the species. This is known as environmental acidification.
Plant and animal migrations
Chorology (the study of the geographical distribution of living species and its causes) shows a change in the distribution area of different animal and plant species. This rather complex and heterogeneous change has been observed since the middle of the 20th century. It shows a migration of certain plant species to places where they have a better chance of survival.
As for animal species, their migrations, which are better known, continue or even increase. “Thus, previously absent from France in winter, the greylag goose is now taking up residence in France, (…) the st. pierre, formerly confined to the Mediterranean, is now fished in Brittany. (ScienceEtAvenir).
And if these species do not migrate, they disappear.
An American study by Professor Thomas Veblen of the University of Colorado demonstrates the ravages of global warming. After a study of forest plots in the western United States over a period of thirty years, Thomas Veblen has claimed that the mortality rate of trees has doubled over this period. The main cause (although other factors may influence this result) is linked to a 0.5°C warming of the climate, which aggravates drought.
And this disappearance affects both terrestrial and marine species. The marine concern currently lies with the Great Barrier Reef, which has been halved in just two years.
The natural phenomenon of desertification refers to “the degradation of land in arid, semi-arid and dry sub-humid areas as a result of various factors, including climatic variations and human activities” (definition adopted in Chapter 12 of Agenda 21).
What about our resources?
Agriculture is also affected by the current rapid increase in CO2 concentration, and forecasts for the next century are not optimistic. Various universities (Harvard, UC Davis, the USDA, etc.) have conducted a study on the nutritional quality of food available in the United States. Some cereals and legumes will be less and less nutritious than they are today. This is of great concern to international organisations regarding iron and zinc deficiencies. This is already a major public health problem with almost 2 billion people worldwide.
So what should we learn from all this information?
Although natural CO2 is beneficial for plant growth and proliferation, anthropogenic emissions are more dangerous and harmful than we might think.
As we have explained, CO2 emissions from human activity are causing an increase in ocean and land temperatures. This change is causing droughts, with deserts advancing more rapidly in some areas (such as China); increasing acidity in the oceans (which is contributing to a decline in biodiversity); and even the disappearance of plant and animal species.
Our human activity is having a cascading impact on the wildlife and ecosystems we know today.
So the question that arises if we do nothing is more than obvious: what will tomorrow’s world look like?
