The World Meteorological Organization (WMO), a United Nations agency in charge of climate issues, has confirmed that due to increasing greenhouse gas concentrations and accumulated heat, the three warmest years ever observed so far were 2015, 2016 and 2017. This ranking is part of a long-term trend, as the eight warmest years cover the period from 2015 to 2022.
In this ranking, 2016 was the warmest year and, excluding the El Niño phenomenon that is pushing temperatures higher, 2017 ranks first. The WMO found that in 2017, the average global surface temperature was 1.1˚C higher than the pre-industrial period between 1850 and 1900 and in 2016 that difference was 1.2˚C. The organization’s secretary general, Petteri Taalas, says the important thing is to look at the long-term trend in temperature, which is showing an upward trend.
Seventeen of the eighteen warmest years are in the 21st century, and the warming has been particularly pronounced in the Arctic, which will have long-lasting and far-reaching impacts on sea levels and weather patterns in other parts of the world. In order to determine the mean and variability of key climate elements that affect the most climate-dependent sectors such as water management, agriculture, energy, or health, the national weather services use a 30-year interval as a reference.
The interval between 1981 and 2010 thus provides an average for comparison with the temperatures observed in 2017, for example. In addition to the upward trend in temperatures caused by the increase in the concentration of greenhouse gases, there are episodic climatic phenomena such as El Niño, which tends to warm the climate, and El Niña, which tends to cool the climate.
For example, El Niño contributed to the record warmth of 2016, and weak El Niña contributed to the high temperatures measured in 2017. Petteri Taalas reminds us that the warmth of 2017 was also accompanied by extreme weather conditions that made it the costliest year for climate disasters for the United States and resulted for other countries in economic slowdown or even regression due to tropical cyclones, droughts and floods.
With average temperatures in 2022 about 1.15˚C above the pre-industrial period, the even temporary possibility of exceeding the 1.5˚C limit set by the Paris Agreement increases over time. The El Niña phenomenon, because of the cooling it causes, thus explains why the year 2022 ranks only the fifth or sixth-warmest year.
This phenomenon, which is expected to last from January to March 2023, cannot reverse the long-term trend of global warming caused by the record levels of greenhouse gases measured in the atmosphere. The upward trend in average temperature, which for the period 2013 to 2022 is 1.14˚C above the pre-industrial period, had been confirmed by the IPCC’s sixth report, which estimated the higher average temperature for the period 2011 to 2020 to be 1.09˚C.
The WMO secretary-general says 2022 was characterized by record floods in Pakistan resulting in human and economic losses, record heat in China, Europe, and North and South America, and persistent drought in the Horn of Africa that could cause a humanitarian disaster. At the end of the year, severe storms affected large areas of North America, causing heavy snowfall and low temperatures in the east and heavy rain, flooding in the lowlands and heavy snowfall in the mountains in the west.
Petteri Taalas believes it is necessary to improve preparedness for such extreme events and to achieve the United Nations’ goal of providing early warning systems to all the world’s inhabitants within five years. He points out that today only half of the 193 Member States have early warning services worthy of the name, which worsens the economic and human toll, as well as the great deficiencies in basic weather observations in Africa and island states, which seriously affect the quality of weather forecasts.
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