Updated: Sep 25, 2020
This article is the third in a series focusing on explaining the causes and effects of climate change.
Beyond theoretical knowledge and climate studies, the worrying component of climate change is first and foremost the one we feel, i.e. the impacts on climatic events. However, the climate has not waited for us to study it before beginning its transformations.
According to the World Meteorological Organization (WMO) report, the observed global average temperature from 2015 to 2019 has increased by 1.1°C compared to the pre-industrial period, and by 0.2°C compared to the period from 2011 to 2015. Each of the last three decades has been warmer than any previous decade since climate records began in 1850. This warming has been accompanied by several effects around the globe.
The amount of ice lost annually from the Antarctic ice sheet has increased at least six-fold. The global average sea level rose by 5 mm per year, confirming an accelerating trend compared to the previous decade. The oceans, which play an important role in absorbing and storing excess heat caused, are getting warmer. The carbon dioxide part absorbed by the oceans reacts with seawater and changes the acidity, which has increased by 26% since the beginning of the industrial revolution. These changes in temperature and acidity are accompanied by a decrease in the amount of dissolved oxygen (called deoxygenation), on which marine life depends for its survival. The frequency and intensity of temperature anomalies, particularly heat waves, continue to increase. Droughts and fires frequency and intensity also follow this trend.
The major transformations observed above are not without consequences for living things. Animals, insects, plants, bacteria, we are all dependent on our environment. As the temperature rises, living beings have to adapt. For many animals, insects and plants, this means migrating to follow the climate that suits them best, moving away from the equator to get closer to the poles. Marine species move towards the poles at an average rate of six kilometres per year, while land animals move at a slower rate. These marine migrations can benefit some at the expense of others. The fact is that the effects of climate change on wildlife are already significant.
Finally, we are also seeing an increase in disease around the world, carried directly by climate change, or through a host such as the tiger mosquito that is spreading in Europe. In some cases, as with the tiger mosquito, climate does not directly play a role in the conquest of new territories by the carrier, but rather affects the incubation period and thus the likelihood of spreading the disease in question.
Chances are that warming and its observed consequences will continue to evolve during this century. This evolution will depend on our ability to reduce or at least contain our global greenhouse gas emissions. At the current rate or beyond, we are exposed to further warming and many induced changes in the global climate system, even greater than those observed during the 20th century.
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