The 2020 is confirmed as one of the hottest years since at least the mid-nineteenth century: temperatures continued to rise across the world, both at the surface and in the oceans; carbon dioxide levels reached new records and the ice continues, inexorably, to melt. This is what is reported in the new study released on 25 August by the American Meteorological Society (Ams) and overseen by the National Oceanic and Atmospheric Administration (Noaa).

The report, entitled State of the climate 2020, is based on data and information gathered through a network of 530 scientists spread across 60 countries, and considers tens of thousands of measurements drawn from independent datasets. The result is a comprehensive and extremely detailed analysis that reflects the current climate situation, the changes under way and future prospects.

From temperatures to hurricanes: the worrying factors

The study identified a series of unequivocal indicators showing how our planet is becoming increasingly warmer. The main parameters highlighted concern the concentration of greenhouse gases, temperatures in constant rise and the warming of the seas.

New record for greenhouse gas emissions

In 2020, despite the closure or slowdown of many productive activities caused by the coronavirus pandemic, harmful emissions reached a new record: the annual average for CO2 concentration in the atmosphere was 412.5 parts per million, up from the 410 recorded in 2019. This is the highest level both since this particular type of measurement began and over the past 800,000 years, according to analyses of ice cores.

The consequences also affect the oceans which, in 2020, absorbed 3 billion tonnes more carbon dioxide than they produced: the highest value since 1982 and 30 per cent higher than the average of the past two decades.

Temperatures rising both at the surface and in the seas

Last year the average temperature of the Earth's surface was between 0.54 and 0.62 degrees Celsius – the value varies slightly depending on the datasets used – above the average levels recorded between 1981 and 2010. 2020 therefore ranks among the three hottest years since at least the mid-1800s, when modern measurements began. The news, though concerning, did not surprise experts: the last seven years, since 2014, have consistently been the worst in centuries.

In the troposphere, the region of the atmosphere immediately above the Earth's surface, the average temperature was equal to the record already set in 2016. The next layer, known as the stratosphere, instead continued to cool — a phenomenon considered natural and expected by experts.

At the same time, the situation in the oceans continues to worsen: last year was the third hottest on record for sea surface temperatures – surpassed only by 2016 and 2019 – while temperatures in the upper layer of the seas, from the surface down to a depth of 2,000 metres, were the highest ever recorded. Sea levels rose by approximately 91 millimetres compared with 1993 values, when these measurements began, and are increasing at a rate of 3 centimetres every ten years.

The rise in water temperatures, especially in areas closest to the surface, can contribute to increasing the intensity of hurricanes and accelerating the melting of ice. In 2020, indeed, 102 tropical storms were recorded, a figure considerably higher than the 1981–2010 average of 85. Three of these storms reached category 5, the highest on the Saffir-Simpson scale, which measures the intensity of winds and hurricanes.

From the Arctic to the Antarctic, the ice continues to melt

In 2020 the average temperature of the Arctic region was the highest in the past 121 years, up approximately 2.1 degrees from the 1981–2010 period. The record was reached on 20 June when in Verkhoyansk, in Siberia, temperatures hit 38 degrees Celsius.

Rising temperatures bring with them a phenomenon unusual for the Arctic: wildfires, which in 2020 released 34 per cent more carbon dioxide than in 2019. The main events took place in north-eastern Siberia, compromising the health of the ice.

Nor can Antarctica escape the consequences of climate change: during the southern summer – which runs from December to March (the equivalent of our winter) – particularly high temperatures for the region were recorded, culminating in 18.3 degrees Celsius measured last February at the Esperanza research station in Argentina.

Europe: the hottest year

2020 was the hottest year ever recorded in Europe, with overall temperatures above the average by 1.9 degrees Celsius. A long list of countries – including France, the Netherlands, Switzerland, Belgium and Latvia – reached new climate records.

At the same time, in many regions – including the Baltic states and Greece, but also France and Germany – precipitation was considerably below normal, while the opposite trend occurred in the north of the continent, on the Iberian Peninsula and in some Italian regions as well.

Both winter and spring were generally warmer than usual, and the overall rise in temperatures continued through the summer months, which were also marked by sudden and uneven rainfall.

Overall, the report highlighted a series of trends demonstrating how the climate is changing, painting an increasingly unsustainable picture for the planet.