Whilst 2017 has been a cooler year than the record-setting 2016, it is very likely to be one of the three warmest years on record, and the warmest not influenced by an El Niño event. The five-year average 2013-2017 global average temperature is currently close to 1°C above the average for 1880-1900 and is likely to be the highest five-year average on record. The world also continues to see rising sea levels, with some level of acceleration and increasing concentrations of greenhouse gases. The cryosphere continued its contraction, in particular in the Arctic where sea ice extent continued shrinking, and Antarctic sea ice extent started shrinking since last year after a multi-year period of stable or even slight expansion The overall risk of heat-related illness or death has climbed steadily since 1980, with around 30% of the world’s population now living in climatic conditions with extreme hot temperatures persisting several days a year. Between 2000 and 2016, the number of vulnerable people exposed to heatwave events has increased by approximately 125 million.
According to the international Monetary Fund (IMF), for the median low-income developing country, with annual average temperature conditions around 25°C, a 1°C increase in temperature could lower per capita economic output by about 1.2 percent.
There were many significant weather and climate events in 2017, including a very active North Atlantic hurricane season, major monsoon floods in the Indian subcontinent, and continuing severe drought in parts of east Africa.
In September 2017, the three major and devastating hurricanes that made landfall in the southern United States and in several Caribbean islands in rapid succession broke modern records for such weather extremes and for associated loss and damage.
Massive internal displacement in context of drought and food insecurity continues across Somalia.
From November 2016 to mid-June 2017, nearly 761 000 drought-related internal displacements were recorded by the United Nations High Commissioner for Refugees (UNHCR).
Information used in this report is sourced from a large number of National Meteorological and Hydrological Services (NMHSs) and associated institutions, as well as the World Climate Research Programme (WCRP) and the Global Atmosphere Watch (GAW). Information has also been supplied by a number of other United Nations and other international agencies, including the Food and Agriculture Organization (FAO), the World Food Program (WFP), the World Health Organization (WHO), UNHCR, the International Organization for Migration (IOM), the International Monetary Fund (IMF), the UN International Strategy for Disaster Reduction (UNISDR) and the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO).