The numbers of global warming: closer and closer to no-return thresholds
by Roberto Barbiero and Lavinia Laiti (APPA) / translation by Lavinia Laiti
“We are on a highway to climate hell with our foot still on the accelerator”. Thus the Secretary-General of the United Nations Antonio Guterres declared at the opening of Cop27, which officially kicked off yesterday in Sharm El-Sheikh.
To understand the seriousness of the present climate emergency, let’s have a look at some ‘numbers’ from the reports that climate scientists have put on the negotiators’ table as a warning.
The World Meteorological Organisation preliminary Report on the State of the Global Climate 2022 confirms the progressive warming and indicates how, for the current year, the estimated global average temperature could settle 1.15°C above the pre-industrial reference period value (1850-1900). This global warming has been mitigated to some extent by the ‘La Niña’ phenomenon, which causes the cooling of surface temperatures of the Pacific Ocean near the coast of South America. However, at the same time, at the global level, several areas of the Earth have recorded record high-temperature values. Europe, in particular, which has been warming at twice the rate of the global average over the past three decades, experienced the hottest summer on record. This year, Alpine glaciers lost an exceptional amount of ice, with thicknesses reduced by about 3-5 m and exceeding the previous record of the summer of 2003.
The concern of climatologists is related to the progressive approach of the 1.5°C temperature threshold above pre-industrial levels, which could lead us to irreversible changes and points of no return (so-called ‘tipping points’) in terms of the consequences that physical and natural systems could suffer. In particular, under observation are changes in atmospheric circulation, such as monsoons, the slowing of the Atlantic ocean current, the melting of Arctic and Antarctic polar ice, and the loss of the Amazon rainforest. These changes would lead to devastating impacts on ecosystems and, consequently, on human communities. The estimate is that there is a 48% probability that the 1.5°C threshold will be temporarily exceeded in at least one of the next five years.
It is not only ice that is suffering, the waters of the oceans are also changing. The upper layer of the oceans, which is about 2000 m deep, has been warming at an increasing rate in recent decades. Marine heat waves are becoming much more frequent than cold waves: in 2022, more than 55% of the oceans experienced at least one marine heat wave, while only 22% experienced a cold wave. Ice melting is also the main contributor to rising sea levels, whose speed more than doubled between the decade 1993-2002 and 2013-2022, from 2.1 mm/year to about 4.4 mm/year.
Extreme weather events too are increasing in frequency and intensity on a global scale, and 2022 saw a long series of events with dramatic consequences, as listed in the State of the Global Climate report for 2022.
In East Africa, rainfall has been below average in four consecutive rainy seasons with signs that the current season could also be dry. Due to the persistent drought, between 18.4 and 19.3 million people faced a food crisis or worsening food insecurity in June. The situation could worsen further if this drought continues, potentially causing a food crisis in Kenya, Somalia and Ethiopia.
Record rainfall led to extensive flooding in Pakistan in July and August, affecting some 33 million people and forcing as many as 7.9 million to leave their homes. The floods were also preceded by an extreme heat wave in March and April, in both India and Pakistan.
The southern African region was hit by a series of cyclones earlier this year, which hit Madagascar hardest with torrential rains and devastating floods.
In September, Hurricane Ian caused extensive damage and loss of lives in Cuba and southwest Florida.
Many areas of the northern hemisphere were exceptionally hot and dry during 2022. China had the most extensive and long-lasting heat wave since national observations began and the second driest summer on record.
Large parts of Europe experienced repeated episodes of extreme heat. UK recorded a new national record on 19th July, when the temperature exceeded 40°C for the first time in history. This was accompanied by a severe drought, persisting into autumn in Italy, and severe fires. European rivers, including Rhine, Loire and Danube, dropped to extremely low levels.
The increase in the population exposed to the impacts of climate change is considerable all over the world, including in Europe, but it is especially the most vulnerable populations that face and will face increasing socio-economic impacts.
The focus on climate action at COP27 therefore inevitably extends to the necessary policies for adaptation to climate change impacts. Funding and technologies are needed to enable the most vulnerable countries to reduce the risks to which their population is exposed, especially in African countries. An important announcement in this regard was that of António Guterres, who revealed the details of his ‘Executive Action Plan for the Early Warnings for All initiative’, which aims to ensure that all humans are protected by early warning systems within the next five years by providing new initial investments of $3.1 billion between 2023 and 2027. This is an important initiative that, however, cannot replace the need to remove, or at least reduce, the socio-economic obstacles that are at the root of the vulnerabiity in many countries.