World Meteorological Day – Climate Change on Andros Island
27 Mar 2019
23 March was the World Meteorological Day and its theme the sun, which delivers the energy that powers all life on Earth. Energy which
Energy that, if it continues to be trapped in the atmosphere due to an increase in the carbon dioxide, will lead to significant changes at a global level. Climate change is expected to also affect the island of Andros, according to a study by the National Observatory of Athens carried out in the framework of the project.
The National Observatory of Athens team recorded the climatic state on Andros Island, and simulated its future climate, according to the moderate and unfavorable scenarios for climate change.
To estimate the current situation with respect to the past, climatic models were used which resulted in an increase in average annual maximum - Tmax and minimum - Tmin temperatures for the period 1971-2000 with average temperatures of about 20.5 °C and 15.2 °C, respectively.
Also, the analysis of the climatic indicators showed that the average number of hot days (Tmax> 30oC) is about 10 days/year and of tropical nights (Tmin> 20oC) about 85 days/year. As for seasonal results over the same period, hot days in the summer are about 10 days/year, while tropical nights are 70 days in the summer and about 15 in the autumn.
The total average annual rainfall over the period 1971-2000 was about 450mm/year and is highly variable with decreasing trend. The drought period was about 59 days/year, while on a seasonal basis it is 20-80 days in the summer and 5-30 days in all other seasons.
For the future simulations, two new IPCC emissions scenarios were implemented, the weak climate change mitigation scenario (RCP4.5) and the non-mitigation business as usual scenario with high emissions (RCP8.5).
The analysis results indicated that for the island of Andros, for the near future (2031-2060), the mean maximum temperature increases (compared to the period 1971-2000) to 22.3°C and 22.8°C, while for the distant future (2071-2100) to 23.3°C and 25oC for the RCP4.5 and RCP8.5 scenarios, respectively. The mean minimum temperature for the near future is expected to be 17.3°C (RCP4.5) and 18.3°C (RCP8.5), while for the distant future the Tmin will increase only for the RCP8.5 climatic scenario to 20.4°C. The amount of tropical nights will increase in the near future to about 120 (RCP4.5) or 130 (RCP8.5) days/year and to 140 (RCP4.5) or 160 (RCP8.5) days/year in the distant future.
The amount of hot days (Tmax>30°C) will also increase in the near future to about 25 (RCP4.5) or 35 (RCP8.5) days/year and to 55-82 days/year in the distant future. The total rainfall (PR) is expected to reduce to 350mm/year in the near and distant future for both climatic scenarios. It is noted that the drought period (PR<1mm) will be in the near future 130 (RCP 4.5) or 110 (RCP 8.5) days and 135 (RCP 4.5) - 140 (RCP 8.5) days in the distant future, while in a seasonal basis it will last 90 days (for almost the whole summer), during spring it ranges between 20 (near future) and 90 (distant future) days and from 10 (near future) to 50 (distant future) days during winter and autumn.
Consequently, based on the forecasts an increase of temperature is expected on the island, as well as a significant increase in warm nights and days and periods of drought, while rainfall is expected to decrease.
NOTE: The scenarios that have been defined by IPCC for the estimation of the climate change are based on the greenhouse gases concentration pathways and are four, describing the different future climatic conditions, all of them are considered possible. The pathways are labelled after a possible range of radiative forcing values in the year 2100 compared to the values during the pre-industrial period (+2.6, +4.5, +6.0, +8.5 W/m2). Thus, a moderate rate of predicted radiation change is considered in the RCP4.5 scenario and a high rate in RCP8.5.