Confirmation that 2019 concludes warmest decade on record
The annual global temperature figures for 2019 confirm that the past decade was the warmest on record.
Multiple data sets suggests that 2019, a year without a strong classical El Niño, is the second warmest year for annual global temperatures in records that begin in 1850. Only 2016 has been warmer, a year when temperatures were boosted by a significant El Niño.
Scientists at the Met Office Hadley Centre, the University of East Anglia's Climatic Research Unit and the National Centre for Atmospheric Science produce the HadCRUT4 dataset, which is used to estimate global temperature.
The HadCRUT4 global temperature series shows that the average for 2019 as a whole was 1.05±0.1 °C above pre-industrial levels, taken as the average over the period 1850-1900.
NASA and NOAA have also published their global mean temperature estimates for 2019. All three datasets (NASA, NOAA and HadCRUT4) agree that the last five years were the warmest five years since each global record began. NASA and NOAA have positioned 2019 as the second warmest year in their records.
Dr Colin Morice of the Met Office Hadley Centre said: “Our collective global temperature figures agree that 2019 joins the other years from 2015 as the five warmest years on record.
“Each decade from the 1980s has been successively warmer than all the decades that came before. 2019 concludes the warmest ‘cardinal’ decade (those spanning years ending 0-9) in records that stretch back to the mid-19th century.”
Dr Morice concluded: “While we expect global mean temperatures to continue to rise in general, we don’t expect to see year-on-year increases because of the influence of natural variability in the climate system.”
On a more regional level, this confirmation follows close on the heels of the recent Met Office announcement that the 2010s have been the second warmest of the cardinal decades over the last 100 years of UK weather records.
The Bureau of Meteorology in Australia have also recently confirmed that 2019 was the warmest and driest year on record in Australia. 2019 was also one of the warmest years on record for Europe, including a record-breaking summer heatwave.
The HadCRUT4 global temperature dataset is compiled from many millions of air and sea surface temperature measurements taken across the globe. Regional variations in temperature help us to understand the mechanisms that cause warming in response to the continuing build-up of greenhouse gases in the atmosphere.
The land-air temperature component of this global temperature dataset is undertaken as part of NCAS’ research into Long-Term Global Change at the University of East Anglia’s Climatic Research Unit.
Prof Tim Osborn, Director of Research at UEA’s Climatic Research Unit, said: "While we know that human activities are causing the globe to warm, it is important to measure this warming as accurately as possible. We are confident that the world has warmed by about 1 °C since the late nineteenth century because different methods of working out the global temperature give very similar results."
The Met Office recently released its forecast for global average temperature for 2020. This estimates the global average temperature for 2020 to be 1.11 °C above the pre-industrial average period (from 1850–1900). Unless an unpredictable event such as a large volcanic eruption occurs, this will likely extend the recent run of hottest years.
The main contributor to global warming over the last 170 years is the rapid increase in greenhouse gas emissions due to human activities, primarily burning of fossil fuels and changes in land use. The effects of man-made climate change are not limited to the temperature of the earth’s surface, but can be seen across the land, oceans and ice.