6 causes and 10 consequences of climate change

Climate change is the variation in the conditions that define the climate of a region between two periods of time. During its evolution, the Earth has experienced several climatic changes, for example in the glaciations.

The causes of the current climate change are mainly due to the activities of human beings and its consequences can be devastating for life on the planet.

Causes of climate change

1. Global surface temperature rise

There are records of temperature measurement with thermometers since 1760. Other strategies have been used to estimate it before this time, such as tree growth rings.

However, it is known that in the last 50 years the temperature increased with respect to the previous 200 years. We now know this as global warming.

2. Greenhouse gas emission

Gases such as water vapor, carbon dioxide (CO₂), methane and nitrous oxide can absorb infrared radiation. This causes the greenhouse effect on Earth, a phenomenon that causes the atmosphere to warm up.

This phenomenon has existed for millions of years and without it, the Earth's temperature would be below zero Celsius, preventing life.

However, as a result of the industrial revolution and the excessive consumption of fuels such as oil, coal and gas Naturally, the concentration of greenhouse gases in the atmosphere has increased, and with it, global warming. atmosphere.

3. Solar radiation

The most important source of energy for Earth is the Sun, the star of the solar system. The Sun's activity undergoes cycles and although this has increased since 1900, its impact on current climate change is not considerable.

4. Volcanic activity

Volcanic eruptions can cause alterations in the climate of certain regions. In general, the eruptions of volcanoes induce a cooling of the atmosphere and the surface of the oceans.

5. atmospheric aerosols

Atmospheric aerosols are small particles that float in the air. For example, volcanic ash and desert sand can affect visibility and solar radiation reaching the Earth's surface.

Tropospheric aerosols act mainly by cooling the climate system, since they reflect solar radiation. That is, they act as a kind of sunscreen, preventing the sun's rays from reaching the earth's surface.

6. Land use and deforestation

The transformation of forests and jungles into arable land and urban areas has contributed greatly to regional climate change.

It is known that urban areas hold more heat, due to construction and the lower density of plants. On the other hand, lower forest density means less fixation of carbon dioxide that is released into the atmosphere.

Consequences of climate change

1. ocean warming

The ocean has been warming since 1971 and the trend will continue until the end of the 21st century, even with reduced CO₂ levels.

This brings with it alterations in the pattern of life of marine species, which seek move towards deeper areas or towards higher latitudes, or favoring species of waters warm.

2. sea ​​level rise

The global average sea level rose 20 cm between 1901 and 2018, at a faster rate in the period 2006-2018. This is due to the thermal expansion of the ocean and the contribution of melting ice from the land.

3. heavy rainfall

There has been an increase in rainfall, both in frequency, intensity and quantity. This is most notable on a regional scale.

For example, in June 2022, Pakistan received three times more rain than in the previous 30 years, resulting in large and severe floods, with many human and material losses.

4. More common and intense droughts

In some regions, the lack of water has intensified due to high temperatures. This also brings with it the danger of forest fires.

5. Declining Arctic ice cap

Since the late 1970s, the area and thickness of the Arctic sea ice has been steadily declining. By December 2022, the extent of the polar cap was almost 12 million square kilometers, which represents a reduction of 12% since 1978 (data from the National Snow & Ice Data Center).

6. Alteration of the carbon cycle

The carbon cycle is the passage of carbon through different states and compounds between organic matter, the atmosphere, the oceans and the earth's crust. Carbon in the form of carbon dioxide is used by plants for photosynthesis, while forming carbonates it is deposited in rocks and soil.

The continuous increase in carbon dioxide concentrations in the atmosphere stimulates its uptake by the oceans and vegetation. This is reflected in more greenery on satellite maps.

7. ocean acidification

With the increase of CO₂ in the atmosphere, part of it dissolves in the water and reacts producing an increase in the acidity of the ocean. This is a consequence of the alteration of the carbon cycle that we mentioned earlier.

With more acidic waters, many marine ecosystems are affected. For example, the oyster industry on the west coast of the United States suffered damage due to acidification of the waters.

8. Reduced Northern Hemisphere Snow Cover in Spring

In Europe, North America and Russia, a decrease in snow cover has been recorded during the spring months since 1978. This brings with it a reduction in the water storage capacity for the summer months, which affects the vegetation and fauna of these regions.

9. Duration of the longer planting season in the Northern Hemisphere

In agricultural areas of Europe, farmers have reported a longer period in which they can sow and harvest. Warmer temperatures encourage seed and plant growth.

In addition, there has been an increase in the vegetation of the terrestrial surface since 1980 and an advance in the flowering of trees in spring.

10. Displacement of terrestrial and marine species

Certain species, such as mosquitoes and other insects, develop better in high temperatures, so it is estimated that they will move to temperate regions. For example, mosquitoes that transmit dengue fever and other tropical viral diseases have been detected in Europe.

In the oceans, the movement of fish towards polar zones where the waters remain colder has been recorded.

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References

Arias, P.A. et al. (2021) Technical Summary. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, p. 33−144. doi: 10.1017/9781009157896.002.

Barton A. et al. (2015) Impacts of coastal acidification on the Pacific Northwest shellfish industry and adaptation strategies implemented in response. Oceanography. 28:146–159. doi: 10.5670/oceanog.2015.38

Cheung, W.W.L., Watson, R., Pauly, D. (2013) Signature of ocean warming in global fisheries catch. Nature 497:365-368

Dessler, A. (2016) Introduction to modern climate change. 2nd ed. Cambridge University Press. NY

Sigl, M. et al. (2015) Timing and climate forcing of volcanic eruptions for the past 2,500 years. Nature 523>543-549