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UNOG Bi-weekly press briefing: Update on Weather - February WMO 09 February 2021

“Relatively cold February does not negate the long-term warming trend from climate change, says World Meteorological Organization (WMO

Data for February shows a very mixed patterns for the end of the northern hemisphere winter and southern hemisphere summer.

“The month of February was much colder than the 1991 to 2020 average over much of Russia and Northern America, much warmer than average over the parts of the Arctic and in other parts of the world,” said Clare Nullis, a spokesperson for the World Meteorological Organisation (WMO).

The contiguous USA had its coldest February since 1989, according to a report issued by the US National Oceanic and Atmospheric Administration.

“It saw 62 all-time daily cold minimum temperature records in a space of February 11-16,” Nullis told journalists in Geneva on Tuesday.

Following this, 69 all-time daily cold maximum temperature records were broken on February 15-16.

February’s weather was influenced by a large scale and interconnected atmospheric circulation patterns and a recent meteorological event called a Sudden Stratospheric Warming Event about 30 km over the North Pole.

This led to a weakening of the polar vortex; an area of low pressure and cold air surrounding the Earth’s North and South poles, with swirling westerly jet stream winds circulating around them.

Those winds are normally strong enough to keep the coldest air in the Arctic during the winter. But the weakening allowed the cold air to spill out into the mid-latitudes, including the USA, and for the warmer air to enter the Arctic.

However, according to Nullis, “Cold records, cold waves are becoming rarer, we can see this from statistics, heat waves, heat records are becoming much more frequent,” a trend which the WMO expect to continue.

“The fact that we’ve got COVID which temporarily put a break on emissions last year does not mean that the need for climate action is diminishing.”

Mauna Loa station in Hawaii, which is used as a benchmark reference station, reported that average carbon dioxide concentrations in February were up from 413.4 parts per million in February 2020, to 416.75 parts per million this year.

“The temperature increased, climate change, greenhouse gas concentrations continued to rise,” warned Nullis.

With the start of the 2020s, Copernicus C3S, and other national meteorological and hydrological services in Europe switched to a new 1991-2020 baseline to calculate climatological averages.

Before this, the most current and widely used standard reference period for calculating climate normals was the 30-year period 1981-2010.

The WMO have recommended that the new 30-year baseline, 1991-2020, should be adopted globally, to update the climate normals and support decision-makers in climate sensitive sectors such as agriculture, health, energy, infrastructure and transportation.

But for the purposes of historical comparison and climate change monitoring, WMO still recommends the continuation of the 1961-1990 period.

For the purpose of Paris Agreement on climate change and its temperature targets, its annual state of the climate reports, WMO also uses the pre-industrial era as the baseline for tracking global temperature increase, because this is what is used in the Paris Agreement on Climate Change.

Thus, the average global temperature in 2020 is set to be about 1.2 °C above the pre-industrial (1850-1900) level.

UNOG Bi-weekly press briefing: Update on Weather - February WMO 09 February 2021

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