Drought is a complex concept that has different aspects. Generally it means a deficit of moisture or precipitation with respect to the average of the certain area. Accordingly, the meteorological drought is distinguished, which means that there are less rainfall compared with the long-term average falls. This makes hydrological drought conditional because there is less water in the watercourses; and then there is a drought of groundwater in which their supplies are more difficult to replenish.
Not a Drought like a Drought
Another category is agricultural drought, which is reflected in agricultural crops, and then also the socio-economic drought, where the lack of moisture has serious economic or socio-political implications.
The lack of precipitation is the primary cause of drought, but it is not the only one. The situation is also affected by the vapor, which depends on the time and intensity of sunlight and temperature, but also on the wind speed, the higher the higher the evaporation of moisture.
The effect of drought increases food prices, reduces drinking water resources, causes forest fires and affects human health.
Greenhouse gases emitted by agriculture, transport, power plants and human activities have increased the risk of drought, according to the journal Nature.
Human activity has impact on the world’s risk of drought, according to a study from 20th century study. Study about hydroclimate changes is associated with human activity. Increasing risk grew between 1900 and 1949. The risk decreased between 1950 and 1975, but since 1975 the risk has been increasing.
However, previous records are not so detailed, so scientists have so far hardly estimated how much human activity has affected drought.
Paul Durack, co-author and research scientist at the Lawrence Livermore National Laboratory at the Australian Science Media Center, who: “The study is the first to highlight that global change and global rainfall, global-scale droughts have now also been found to be impacted by human activities. This is a bad news for Australia, and similar climate regions such as California in the US. These regions have experienced devastating recent droughts, and if the model projected changes continue, they will become more commonplace into the future.”
What Trees Can Tell Us about Drought
Concentrated circles tell us the age of the tree. Scientists are able to determine how much moisture the tree has taken in a certain year at a particular location. If the line is narrower between the concentrated circles, it means that the year was warm and dry. Trees do not grow so fast during cold or dry periods, so circles are thinner.
The authors of the study predict more droughts in the years to come. The study concludes that “the human consequences of this, especially the large parts of North America and Eurasia, are likely to be north,” especially because of the increase of greenhouse gas emissions and climate change.
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