Global weather body updates ‘normal’ baseline for a rapidly warming world
Keeping pace with the rise in global average temperatures due to climate crisis, the World Meteorological Organisation has updated its climatological normal, replacing the 1981 to 2010 baseline with the 1991 to 2020 period, which will now be used as a benchmark.
Despite an overlap of 20 years in the two baselines, global mean temperature increased by 0.22 degrees Celsius (°C) between the two periods, said a new report — WMO State of the Global Climate report 2022 — released on Friday.
The report also flagged that global mean temperature in 2022 was 1.15°C above pre-industrial levels, inching very close to the 1.5°C threshold, flagged by climate scientists as a critical point beyond which several impacts of the climate crisis will become irreversible. The years 2015 to 2022 were the eight warmest in the 173-year instrumental record, and the long-term rate of temperature change is around 0.2°C per decade, the report said. 2022, WMO said, was either the fifth or sixth warmest year on record.
Climatological normals are used as a benchmark against which current conditions can be compared. They are typically based on a mean of 30 years of data.
Breaching the 1.5°C warming barrier would lead to irreversible impacts and risks for human and natural systems, all growing with the magnitude and duration of overshoot, the Intergovernmental Panel on Climate Change’s Synthesis Report warned last month. Acknowledging that the 1.5°C goal will be breached within the next few years even in the lowest emissions scenario, IPCC’s Synthesis Report said the rise in average global temperature could be gradually reduced again by achieving and sustaining net negative global CO2 emissions.
The WMO report used the new baseline for the first time for a better understanding of natural variability as opposed to warming associated with climate change. The recent baseline, for instance, factors in the impact of immediate and shortterm natural climate drivers such as La Nina and the negative phase of the Indian Ocean Dipole which were both present through much of 2022.
India, too, may start doing the same soon. “India Meteorological Department will also follow the new climatological normal soon. This is done to take care of long term climate trends as well as natural variability,” said M Rajeevan, secretary, ministry of earth sciences.
According to the report, in 2022, record annual temperatures were reported in Western Europe (where a number of countries had their warmest year on record, including the UK, France, Ireland, Portugal, Spain, Belgium, Luxembourg, Italy, Germany and Switzerland), the western Mediterranean, parts of Central and Eastern Asia, and New Zealand, WMO said.
Over the ocean, record warmth extended across wide areas of the North and South Pacific as well as areas of the Southern Ocean. No areas experienced record-low annual temperatures in 2022. However, conditions were colder than the 1991-2020 average in Canada, parts of southern and northern Africa, parts of Australia (New South Wales had its coolest year since 1996), and parts of South America.
La Nina is associated with a “cold tongue” of cooler-than-average surface waters in the central and eastern equatorial Pacific, which is typically surrounded by areas of warmer-than-average waters running from the North Pacific, WMO said. But in 2022, record warmth was measured over large areas of the North and Southwest Pacific. Such severe temperatures in 2022 showed that impact of climate change is obscuring the impact of other transient natural weather phenomenon.
Concentrations of the three main greenhouse gases — carbon dioxide (CO2), methane and nitrous oxide (NO) — reached record highs in 2021, the latest year for which consolidated global values are available. Despite continuing La Nina conditions, 58% of the ocean surface experienced at least one marine heatwave during 2022. Global mean sea level continued to rise in 2022, reaching a new record high for the satellite altimeter record (1993-2022). The rate of global mean sea level rise has doubled between the first decade of the satellite record (1993-2002, 2.27mm per year) and the last (2013-2022, -4.62mm per year), the report highlighted .
The pre-monsoon period last year was exceptionally hot in India and Pakistan, said WMO. In India, grain yields were reduced by the extreme heat and there were a number of forest fires, particularly in Uttarakhand. Drought intensified in the Greater Horn of Africa region, focused on Kenya, Somalia and southern Ethiopia.
“Heatwaves in the 2022 premonsoon season in India and Pakistan caused a decline in crop yields. This, combined with the banning of wheat exports and restrictions on rice exports in India after the start of the conflict in Ukraine, has threatened the availability, access to and stability of staple foods within international food markets and posed high risks to countries already affected by shortages of staple foods. Heavy monsoon rains caused severe flooding and landslides in Pakistan, leading to the spread of water-borne diseases, with the greatest impacts in the most vulnerable and food-insecure regions of southern and central Pakistan,” the report said.
There was also significant flooding in India at various stages during the monsoon season, particularly in the north-east in June, with over 700 deaths due to flooding and landslides, and a further 900 from lightning, WMO added.
“There is a 50% chance of hitting the lower goal (1.5°C) of Paris Agreement during this El Nino. More records will be broken during this period (El Nino)... the G20, especially India and China, should act on climate because of their dependence on Himalayan glaciers, exposure to cyclones, inequality and poverty which could be motivating these countries to join the climate friendly club,” said WMO Secretary-General Petteri Taalas during a press conference to launch the report on Friday.