Global Atmosphere – Greenhouse Gases

There is compelling evidence that warming of the climate system due to human influence is taking place. The mechanisms for these processes include increasing levels of greenhouse gases (GHGs) in the atmosphere. In May 2013, carbon dioxide levels in the atmosphere exceeded 400 ppm for the first time in several hundred millennia. Levels of carbon dioxide in the remote atmosphere have increased by 0.28 and 2.93 parts per million (ppm) per year since 1960. Ongoing increases in levels of GHGs can be expected to result in a rise in global temperatures, which could trigger a wide range of risk scenarios. A level of 450 ppm is considered to be the atmospheric concentration of carbon dioxide at which temperature change can still be limited to 2 °C. This is a benchmark of climate change specified so as to limit the dangerous effects of climate change. The international community has initiated a series of programmes to address GHG emissions, underpinned by a significant effort to develop robust emission inventories: however, these initiatives have had limited success in limiting the rising trends in GHG emissions. The key issues encountered during these programmes include: population and economic growth; scientific credibility; political priorities; outsourcing of emissions; and difficulties in implementing renewable energy technologies. In this context, the scientific community has an ongoing role to produce data and analysis to link individual, corporate and state actions and policies to evaluations of GHG emissions, and analysis of evidence for changes in the global climate. The scientific and policy communities should continue to engage with the public, to provide reliable information about the vitally important issues associated with global climate change. Public support for positive action and investment to mitigate climate change is essential to support the decisions which will need to be taken in the coming decades.