Global health. The current scenario and future perspectives

85 f) Global warmin g 14 Global warming, also known as climate change, involves the worldwide increase in the Earth’s temperature caused by the emission of greenhouse gases (GHGs) released by human activity. This temperature increase leads to a series of environmental problems, such as a rise in sea levels worldwide due to glacier melting, higher levels of precipitation and more frequent severe weather. According to the Intergovernmental Panel on Climate Change (IPCC) in its sixth report of 2021, GHG emissions from human activities are responsible for about 1.1°C of warming since 1850-1900, and they predict that the global average temperature over the next 20 years will reach or exceed a warming of 1.5°C. According to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA), global surface temperatures in 2019 were the second warmest since modern record- keeping began in 1880. These were surpassed only by those in 2016, which leads to recognizing the past five years as the hottest of the past 140 years. The cause of global warming is human emissions of GHGs, including the burning of fossil fuels associated with industrial development and energy production, agricultural/livestock activities and other land uses, transportation (land, air and sea) and construction. These activities emit GHGs, such as CO 2 , methane, nitrous oxide, chlorine, fluorine and bromide. To address these problems, in 1992, the United Nations Framework Convention on Climate Change (UNFCCC) established the commitment to “achieve stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.”. The Convention provides a general framework for intergovernmental efforts to address the challenges posed by climate change. Currently, 197 countries have joined the UNFCCC (including Chile in 1994). Subsequently, in 1997, governments agreed to incorporate an addition to the Convention known as the Kyoto Protocol, which had more stringent and legally binding measures. The Kyoto Protocol, which came into effect in 2005, was a stricter and more detailed procedure for implementing the objectives of the UNFCCC. This protocol committed signatory developed nations to achieving a 5-7% reduction in GHG emissions between 2008 and 2012 with respect to 1990 emissions. Developing nations do not have these specific targets but are 14 Editor’s note: More on Climate Change and Global Health in the corresponding chapter.