2.9 Climate Changes

Climate changes and their consequences on the environment, flora, fauna and human health have been recently reviewed in a EEA Report (EEA, 2008).

Recent observations confirm that the global mean temperature has increased by 0.8 °C compared with pre-industrial times for land and oceans, and by 1.0 °C for land alone. Europe has warmed more than the global average (1.0 and 1.2 °C, respectively), especially in the south-west, the north-east and mountain areas. Projections suggest further temperature increases in Europe between 1.0–5.5 °C by the end of the century, which is also higher than projected global warming (1.8–4.0 °C).

European glaciers are melting rapidly: those in the Alps have lost two thirds of their volume since 1850, with loss accelerating since the 1980s. Snow cover has decreased by 1.3 % per decade during the past 40 years, with the greatest losses in spring and summer, and decreases are projected to continue. These various changes will cause natural hazards and damage to infrastructure and changes in river flows and seasonality, thus substantially affecting the hydrological cycle in river catchment areas.

According to satellite observations, the rate of global mean sea-level rise has increased to 3.1 mm/year in the past 15 years (compared with a global average of 1.7 mm/year in the 20th century). Because of ocean circulation and gravity effects, sea-level rise is not uniform but varies across European seas. Projections suggest that sea level and sea surface temperature of some European seas could rise more than the global average.

Warming of surface water can have several effects on water quality and hence on human use and aquatic ecosystems. Changes include movement of freshwater species northwards and to higher altitudes, changes in life-cycle events (phenology), for example spring phytoplankton and zooplankton blooms up to one month earlier than 30–40 years ago. Climate change may thus favour and stabilise the dominance of harmful cyanobacteria in phytoplankton communities, resulting in increased threats to the ecological status of lakes and enhanced health risks, particularly in water bodies used for public water supply and bathing.

Climate change, in particular milder winters, is responsible for the observed northward and uphill distribution shifts of many European plant species and of birds, insects, mammals and other animal groups. Climate change has caused advancement in the life cycles of many animal groups (phenology), including frog spawning, bird nesting and the arrival of migrant birds and butterflies, and these trends are projected to continue. Projected climate change will favour certain species in some forest locations, while making conditions worse or others, leading to substantial shifts in vegetation distribution. Changes in distribution and the timing of seasonal events of both pests and pollinators will further change forests, although the types of change are difficult to project.

Projected increased variations in rainfall pattern and intensity will make soils more susceptible to erosion. Projections show significant reductions in summer soil moisture in the Mediterranean region, and increases in the north‑eastern part of Europe. Climate change alters the habitat of soil biota, which affects the diversity and structure of species and their abundance. Ecosystem functioning is modified consequently, but quantified knowledge of these impacts is limited. Soil degradation is already intense in parts of the Mediterranean and central-eastern Europe and, together with prolonged drought periods and increased numbers of fires, is already contributing to an increased risk of desertification. In many cases, desertification is irreversible, leading to adverse social, economic and environmental effects.

Since the beginning of the 21st century, the variability of crop yields has increased as a consequence of extreme climatic events, e.g. the summer heat of 2003 and the spring drought of 2007. Since extreme events are projected to increase in frequency and magnitude, crop yields will become more variable. Increases in water demand for agriculture (by 50–70 %) has occurred mainly in Mediterranean areas and this is projected to continue, thus increasing competition for water between sectors and uses.

Increased temperatures can have various effects on human health. Heat waves are projected to become much more common later in the century as the climate continues to change, with mortality risk increases by between 0.2 and 5.5 % for every 1 °C increase in temperature above a location‑specific threshold. There is some evidence that winter mortality in Europe has decreased, but this could have other causes, particularly improved housing and the prevention of winter infections. A number of vector-borne diseases are expected to increase in the near future. The tiger mosquito, a transmitter of a number of viruses, has extended its range in Europe substantially over the past 15 years and is projected to extend even further. Ticks and the associated Lyme disease and tick-borne encephalitis are moving into higher altitudes and latitudes. There is a risk of additional outbreaks of Chikungunya (a virus that is highly infective and disabling but not transmissible between people) and a potential for localised dengue to re-appear. Changes in the geographic distribution of the sandfly vector are occurring in several European countries and there is a risk of human Leishmania cases further north. The possible spread of these diseases is very dependent on early detection and the preventive measures in place. Some water- and food-borne disease outbreaks are expected to become more frequent with rising temperatures and more frequent extreme events. The risk is very dependent on human behaviour and the quality of health care services and their ability to detect early and act.

The impact on health of extreme weather events (floods, storms, droughts, heat waves, forest fires) are dealt with in Chapter 10.