Climatic Changes

Climatic changes are defined as alterations in global climate and particularly variations of climatological conditions that span over long temporal scales. These have to be statistically significant changes in mean state of the climate or in modes of climate variability and should be valid for a period of some decades (at least 30 years) or even longer.

Usually they are driven by natural processes such as variations of solar activity, changes in the orbit of the Earth around the Sun or large volcanic eruptions. Besides such natural causes, that are mostly occurring on very long time-scales (several thousands of years), anthropogenic activities can also cause large-scale changes in the climate system of our planet.

Modern Climate Change

Global warming and human-induced climate change are according to the scientific community by far the most challenging environmental threats of the last decades. Observed increase of mean global temperature and sea level rise, record-breaking declines in ice-covered oceans and continents, increased frequency and severity of extreme events are only few expressions modern-time climate change. There is very high confidence that this is mainly attributed to anthropogenic activities such as intensification of the greenhouse gas effect through industrialization, fossil fuel use and land use changes (e.g. deforestation).

 As a result of such human interventions, the mean global temperature of the planet has increased about 1°C since the pre-industrial era (1850-1900). Last year (2019) was the second warmest year since the beginning of reliable and systematic temperature observations. So far, 2016 was the warmest year ever recorded. Each of the last three decades is warmer than any preceding decade on record, while there are indications that this 30-year period is the warmest of the last 1400 years, at least for the northern hemisphere.

Mean global levels of carbon dioxide (CO2), the most widespread greenhouse gas, have exceed 410 ppm and according to geological evidence are on the highest levels of the last 800.000 years. Natural CO2 sinks (e.g. oceans, lithosphere, vegetation) cannot fully absorb the emissions from human activities. As a result, these long-lived pollutants are accumulated in the atmosphere. Besides CO2, concentrations of other greenhouse gases in the atmosphere such as methane (CH4), nitrous oxide (Ν20) and tropospheric ozone (Ο3) have also increased dramatically during the last 150 years as a result of human activities.

What are the impacts?

The scientific community highlights the importance for aggressive measures for climate change mitigation through the reduction of greenhouse gas emissions and concentrations. Otherwise, the impacts of global warming will be dramatic and irreversible for the coming decades or even centuries. If “business-as-usual” climate change projections become a reality, every sector in our lives will be severely affected by the further increases in temperature, mean sea level rise, changes in the hydrological cycle and most frequent occurrence of severe extreme events. Human health, agriculture and food security, water resources and energy management, transportation, tourism are only few of the socio-economic sectors that are expected to be significantly impacted. Besides human activities, climate change is also affecting the natural environment. Unfortunately, some ecosystems might not have the necessary time or space to adapt to the much warmer conditions, while this might give the opportunity for invasive species to expand against the native flora and fauna species.

What is expected for the Mediterranean?

The Mediterranean Basin has already been affected and it is believed to be one of the most prominent climate change hot spots. It is considered a high-impact region since the accelerating temperature increase is combined with an observed drying trend. Particularly after the 1980s, the Mediterranean is warming faster than the global mean rates.

Future climate projections suggest a further increase in air temperature that in the high-emission scenarios could exceed 4-5 °C by the end of the current century. In such pathways, the mean precipitation is expected to further decrease. This decline will likely be most pronounced in the wet part of the year which is more important in replenishing the water resources in the drier parts of the Mediterranean. At the same time, individual rainfall events of high-impact are expected to become more intense. For the summer season, extreme phenomena such as prolonged droughts and unprecedented heat waves are modelled to become more frequent and intense in the following decades introducing new challenges in the region.

Observed global (green curves) and Mediterranean (blue curves) mean annual temperature anomalies from 1880 and onwards (source: Cramer et al. 2018)

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Projected changes of mean annual precipitation for the end of the 21st century under a “business-as-usual” future pathway (RCP8.5). Data represent the ensemble mean of high-resolution EURO-CORDEX climate models.

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Projected change of mean annual temperature for Cyprus under a “business-as-usual” future pathway (RCP8.5). Data represent the ensemble mean of high-resolution EURO-CORDEX climate models:

Change of mean annual temperature for Cyprus under a “business-as-usual” future pathway (RCP8.5). Data represent the ensemble mean of high-resolution EURO-CORDEX climate models:

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