Warming of the climate system is unequivocal and it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. Observations show that global average temperatures have increased by 0.85˚C since 1850 (IPCC, 2013). The atmosphere and ocean have warmed, the amount of snow and ice have diminished and sea level has risen, as the concentrations of GHGs have increased. Since the 1950s, many of the observed changes are unprecedented over decades to millennia. The impacts are observed on natural and human systems on all continents and across the oceans. Evidence of climate-change impacts is clearest in natural systems. (IPCC, 2014).
The largest unknown in the analysis of future climate change is the amount of additional GHG’s we will put into the atmosphere over the next few decades. To address this uncertainty, the IPCC has recommended analysis based on a set of scenarios called Representative Concentration Pathways (RCPs), which chart a number of possible futures depending on the effectiveness of global measures to reduce emissions However, even in the most optimistic scenarios, additional changes to climate are projected and these will result in impacts, which will require adaptation.
Research at national level has shown that changes in Ireland’s climate are in line with global trends. Temperatures have increased by about 0.8°C over the period 1900-2012 - an average of about 0.07°C per decade. Due to the slow response time of the climate system, changes are projected to continue and increase over the coming decades. Even if GHG emissions came to an end, some changes, such as sea-level rise, are projected to continue up to and beyond the end of this century.
For Ireland, climate change impacts are projected to increase in the coming decades and could include the following:
- Sea level rise;
- More intense storms and rainfall events;
- Increased likelihood and magnitude of river and coastal flooding;
- Water shortages in summer ;
- Increased risk of new pests and diseases
- Adverse impacts on water quality; and
- Changes in distribution and phenology (the timing of lifecycle events) of plant and animal species on land and in the oceans.