The National Statistics Office yesterday published a range of statistics on the environment on the occasion of World Environment Day, an annual event observed on 5 June.

This seeks to enhance environmental awareness on a particular theme worldwide. For 2006, the theme chosen by the United Nations is ‘Deserts and Desertification’ embodied in the slogan ‘Don’t Desert the Drylands’.

Desertification is a complex process that results from a combination of natural forces and human actions. These interact with the local environment to produce a set of conditions which degrade the land to the extent of diminishing or even forfeiting its biological and economic productivity. Since areas which are threatened by desertification are those characterised by arid, semi-arid and dry, sub-humid climatic regimes, Malta is also at risk of being affected by this process.

Climate

Temperature and rainfall are the two main climatic parameters that define climatic regimes. Climate is defined as the average weather conditions over a long-term period which usually spans a minimum of 30 years.

Data covering the period 1975-2005 shows the seasonal nature of the Maltese climate, with predominantly high temperatures and low rainfall during the summer months (from May to October) contrasting with lower temperatures and higher rainfall in the winter months (from November to April). Although not overly evident, the linear trend exhibited by both sets of data is significant since it suggests that the Maltese climate has become warmer and drier during this 30-year period.

The linear trend for temperature is positive and thus, from 1975 to 2005, has annually increased by 0.0415°C on average. On the other hand, the data shows a negative linear trend in rainfall; on average this has decreased by an annual 1.0226 mm.

It must be kept in mind that there is a degree of variability in the Maltese climate. The data marked fluctuations from one year to another. In the period under review, annual mean temperature ranged from 17.9°C to 20°C while annual rainfall ranged from a high 907.7mm to a low 233.2mm. These variations in weather data are bound to have a marked effect on any averages or trends that can be discerned from the data. For example, with regard to rainfall, were the value for 2003 – the highest in the 30-year range – to be removed, on average, rainfall would have decreased by 3.748 mm per annum during the period under review.