Not-so-happy World Meteorological Day

Today (23 March) marks World Meteorological Day, which every year celebrates the establishment of the World Meteorological Organization (WMO) and the contribution of national meteorological and hydrological services to the safety and wellbeing of society. But this year’s event has a somewhat sombre tone, with the WMO revealing that numerous climate records were broken in 2016.

According to the WMO Statement on the State of the Global Climate in 2016, last year was the warmest on record — 1.1°C above the pre-industrial period and 0.06°C above the previous record set in 2015. As noted by WMO Secretary-General Petteri Taalas, “This increase in global temperature is consistent with other changes occurring in the climate system.

“Globally averaged sea surface temperatures were also the warmest on record, global sea levels continued to rise and Arctic sea-ice extent was well below average for most of the year,” continued Taalas.

“With levels of carbon dioxide in the atmosphere consistently breaking new records, the influence of human activities on the climate system has become more and more evident.”

Each of the 16 years since 2001 has been at least 0.4°C above the long-term average for the 1961–1990 base period, according to the report. Global temperatures continue to be consistent, with a warming trend of 0.1 to 0.2°C per decade.

The 2015–2016 El Niño event was found to boost warming in 2016, on top of long-term climate change caused by greenhouse gas emissions. Global sea levels also rose very strongly during the El Niño event, with the early 2016 values reaching new record highs, while global sea ice extent dropped more than 4 million km² below average in November — an unprecedented anomaly for that month.

Carbon dioxide levels in the atmosphere reached 400 ppm in 2015 — the latest year for which WMO global figures are available — and will not fall below that level for many generations to come because of the long-lasting nature of CO₂. Meanwhile, the very warm ocean temperatures contributed to significant coral bleaching and mortalities in many tropical waters, with important impacts on marine food chains, ecosystems and fisheries.

Extreme weather events in 2016 included severe droughts in southern and eastern Africa and Central America; Hurricane Matthew causing widespread suffering in Haiti as the first category 4 storm to make landfall since 1963; and heavy rains and floods affected eastern and southern Asia.

Newly released studies for 2017, which are not included in the report, indicate that ocean heat content may have increased even more than previously reported. Provisional data also indicates that there has been no easing in the rate of increase in atmospheric carbon dioxide concentrations.

At least three times so far this year, the Arctic has witnessed the polar equivalent of a heatwave, with powerful Atlantic storms driving an influx of warm, moist air. This meant that at the height of the Arctic winter and the sea ice refreezing period, there were days which were actually close to melting point. Antarctic sea ice has also been at a record low.

Research indicates that changes in the Arctic and melting sea ice are leading to a shift in wider oceanic and atmospheric circulation patterns. This is affecting weather in other parts of the world because of waves in the jet stream — the fast moving band of air which helps regulate temperatures. Areas including Canada and much of the US were unusually balmy, while others, including parts of the Arabian peninsula and North Africa, were unusually cold in early 2017.

“Even without a strong El Niño in 2017, we are seeing other remarkable changes across the planet that are challenging the limits of our understanding of the climate system,” said World Climate Research Programme Director David Carlson. “We are now in truly uncharted territory.”