Earth‘s Legacy Blog

What major climate anomalies and episodic events occurred in 1998?  

In terms of significant and extreme climate events the year 1998 is remarkable as the Climate Prediction Center of the National Oceanic and Atmospheric Administration (NOAA) states. The quantity and vehemence of extreme weather events rise. Europe deals with flooding and heat waves over the year. South America records the highest global temperature in yearly average. In North and Middle America four hurricanes hit the east coast during August (Charley, Bonnie), September (George) and October (Mitch). Overall there were heavy tropical rains and atypical humidity over the year. At the same time the weather in summer was so dry it caused fires in this area.

Also the coastal region of Mexico and Jamaica was exposed to Hurricane Gilbert. China suffered from floods. At the beginning of 1998 Indonesia experienced high deficits of precipitation leading to a dry environment and fires. The weather in East Africa was humid in the beginning and developed to dry in the end of the year. South Africa faced droughts first then storms. 

In conclusion it can be said that no continent was unharmed.

What environmental hazards are associated with climate change and who is most affected?

As can be seen there are several environmental hazards. A latitude of regularly occurring changes in weather seems normal. But what people do notice are extreme weather events such as hurricanes, floods, storms, droughts or longer periods of heat and sea level rise. Especially lowland regions for example Bangladesh are at risk to suffer from storm tides. As commonly known extreme weather events can result in unmanageable damages leaving many dead or homeless. Africa is one of the most endangered regions worldwide dealing with the consequences of climate change. It is recorded that droughts lead to most dead people than any other disaster recorded. Developing countries in general are at high risk with impacts on their environment and inhabitants particularly because of quick change rates in temperature. 

How do volcanic eruptions affect temperature extremes?  

If a volcano erupts it emits fine particles called aerosols into the atmosphere and lower stratosphere (larger eruption). They contain of gases and minerals which are able to reflect incoming shortwave radiation. This happens when they form to clouds and lead to a temporary cooling of the atmosphere. Often this change in temperature has effects on many different countries and continents over a shorter or longer period of time depending on the extent of the eruption because of atmospheric circulation that transports aerosols through the atmosphere and stratosphere. Larger particles have lower effects on temperature because they don‘t stay as long in the atmosphere as smaller particles. 

In contrast it is also possible that the temperature rises after a volcanic eruption. Different greenhouse gases (H₂O, CO₂) and Sulfur Dioxide (SO₂) are emitted into the atmosphere and cause global warming. This effect is rather rare. 

What are adaptation and mitigation?  

The most effective way to face climate change is to combine climate change adaption and mitigation. 

Adaption is a process where the environment adapts to already existing and still changing circumstances. For example plants are growing in a region where they were not able to grow but due to changes in temperature they adapt and find new areas to grow. 

Mitigation is a process where actions take place to limit and counteract further changes in the environment. Climate damaging greenhouse gases are reduced or removed from the atmosphere. 

What is the greenhouse effect?  

The earth sees itself exposed to direct sunlight. To create a balance between incoming and outgoing radiation the earth has to radiate energy back into space. One half of incoming shortwave radiation is absorbed and warms the surface of the earth while the other half is reflected back into the atmosphere. While reflecting back into the atmosphere greenhouse gases re-emit the radiation in all directions while remaining near the earth‘s surface and causing an increasing temperature. The barrier that is created by greenhouse gases can be understood as a warming blanket. 

The increasing amount of greenhouse gases (e.g. H₂O, CO₂) humans emit into the atmosphere is a driver to the greenhouse effect. More gases re-emit higher amounts of radiation which cause the earth to increase its temperature. 

What is the ‘runaway’ greenhouse effect? 

The planet Venus is the most similar planet to the earth regarding size. Venus‘s atmosphere contains high amounts of CO₂  and clouds that are made of sulphuric acid (H₂SO₄) which cover the whole Planet. Almost no sunlight reaches the surface. Nevertheless it has a temperature of approximately 525°C. One explanation for this is the closeness to the sun, the other reason is the greenhouse effect. The thick layer of clouds prevent the radiation from leaving the atmosphere. As a result of the high temperatures water evaporates and saturates the atmosphere which creates the so called ‚blanket‘.   

References

Houghton, J. (2015). Global warming: The complete briefing. 5th edition. Cambridge: Cambridge University Press.

Deutscher Wetterdienst (n.d.), Volcanic Ash [online] Available from: https://www.dwd.de/EN/research/observing_atmosphere/composition_atmosphere/aerosol/cont_nav/volcanic_ash.html. [18 October 2023]

Center for Science Education, UCAR (n.d.), How volcanoes influence climate [online] Available from: https://scied.ucar.edu/learning-zone/how-climate-works/how-volcanoes-influence-climate#:~:text=The gases and dust particles,the characteristics of the eruption. [18 October 2023]