in the atmosphere rose from a pre-industrial level of 280 parts per million (ppm) to 379ppm in 2005 [2]. This coincided with an increase in the average global temperature of 0.74circC between 1906 and 2005. In 2013, the U.S. National Oceanic and Atmospheric Administration announced that CO2 levels had reached 400ppm [3]. That same year, the IPCC concluded that “human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes.... it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century” [4]. In 2012, the World Meteorological Organization [5] released analysis showing that the decade spanning 2001-2010 was the warmest ever recorded in all continents of the globe.
The Earth’s climate is changing and the impact of these changes are becoming increasingly more evident. Such visible climate changes include variations in air and ocean temperatures, accelerated melting snow and ice caps, widespread retreat of glaciers, rising global sea level rise and extensive changes in weather patterns. These changes are creating significant global economic, environmental and social impacts.
Climate change refers to a change in climate patterns, in particular a change apparent from the mid to late 20th century onwards, and attributed largely to the increased levels of atmospheric carbon dioxide (CO2) produced by the use of fossil fuels, resulting in numerous climatic shifts and impacts around the globe.
Several gases, such as carbon dioxide and methane (CH4), exist naturally in the atmosphere and contribute to the warming of the Earth's surface by trapping heat from the sun in what is known as the greenhouse effect. When the proportion of such greenhouse gases in the atmosphere is stable, the effect is beneficial, making surface temperatures warmer and alleviating temperature swings. However, human activity is increasing the concentration of greenhouse gases in the atmosphere, which is already causing average temperatures to rise.
Figure 1.1 Greenhouse Gas Effect [1]
Climate scientists from the UK Meteorological Office expect to see one of the largest global rises in atmospheric carbon-dioxide concentration in 2019 with average levels of CO2 expected to reach 411ppm [6]. This forecast is based on a combination of factors including rising anthropogenic emissions and a reduction in the uptake of carbon-dioxide by ecosystems due to tropical climate variability [6]. Most recently, the IPPC reported that human activities are estimated to have already caused approximately 1.0°C of global warming above pre-industrial levels [7]. It concluded that if current rates continue, the world would reach a human-induced global warming of 1.5°C by 2040.
Impacts from this global warming are readily observed and include increases in global average air and ocean temperatures, accelerated melting of snow and sea ice, widespread retreat of glaciers, rising global average sea level, and extensive changes in weather patterns, including changes in precipitation levels and increased storm intensity.
Observations show that Ireland's climate is also changing in line with international climate patterns outlined above. Some of the projected physical climate changes include:
There is broad scientific consensus that human activities, most notably the burning of fossil fuels for energy, have led to the rapid build-up in atmospheric greenhouse gases. The Intergovernmental Panel on Climate Change (IPCC) stated in 2007 that CO2 levels in the atmosphere rose from a pre-industrial level of 280 parts per million (ppm) to 379 ppm in 2005 [2]. This coincided with an increase in the average global temperature of 0.74circC between 1906 and 2005. In 2013, the U.S. National Oceanic and Atmospheric Administration announced that CO2 levels had reached 400 ppm [3]. That same year, the IPCC concluded that “human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes.... it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century” [4]. In 2012, the World Meteorological Organization [5] released analysis showing that the decade spanning 2001-2010 was the warmest ever recorded in all continents of the globe.