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Climate: “It is time to act” warns the IPCC


Accelerating warming, intensifying impacts causing unprecedented suffering to humanity responsible for this devastation, and only one way to avoid the worst, drastically reduce greenhouse gas emissions.

Here are the main conclusions of the sixth round of assessment by UN climate experts (IPCC) broken down into some 10,000 pages and three reports – climate physics, impacts and adaptation, emission reduction solution – published in August 2021, February 2022 and this Monday. Like the previous evaluation cycles which have taken place approximately every six or seven years since 1990, this trilogy will serve as a reference for the coming years.

Accelerating warming, intensifying impacts causing unprecedented suffering to humanity responsible for this devastation, and only one way to avoid the worst, drastically reduce greenhouse gas emissions.

Here are the main conclusions of the sixth round of assessment by UN climate experts (IPCC) broken down into some 10,000 pages and three reports – climate physics, impacts and adaptation, emission reduction solution – published in August 2021, February 2022 and Monday. Like the previous evaluation cycles, which have taken place approximately every six or seven years since 1990, this trilogy will serve as a reference for the coming years.

No more doubt

No offense to climate skeptics, scientific evidence has removed the slightest doubts that could remain: humans are “unquestionably” responsible for global warming which has gained around +1.1°C since the pre-industrial era. .

The rate of increase in the concentration of CO2 in the atmosphere between 1900 and 2019, largely linked to fossil fuels, is at least ten times higher than during any other period of the last 800,000 years and the concentration of CO2 in the atmosphere has never been so high for more than 2 million years.

Bye bye 1.5°C

The 2015 Paris Agreement aims to limit global warming to “well below” +2°C, if possible +1.5°C. But in all the scenarios considered by the IPCC – from the most optimistic to the most pessimistic – the global temperature should reach +1.5°C or +1.6°C compared to the pre-industrial era around 2030. That is ten years earlier than previously estimated.

Even if there is a possibility of then returning below the +1.5°C threshold by the end of the century, even a temporary overshoot would cause “irreversible” damage to certain fragile ecosystems (poles, mountains, coasts) , with cascading effects on populations.

Even if the States’ current commitments to reduce emissions by 2030 were respected, not exceeding +1.5°C at least temporarily would be “out of reach” and reaching +2°C would be difficult. Without strengthening current policies, warming could even reach 3.2°C by 2100, twice as much as the ideal goal of the Paris agreement.

Avalanche of suffering

The devastating consequences of climate change, long seen as a dash on the horizon, have become a reality in every corner of the planet, with 3.3 to 3.6 billion people already living there”very vulnerable“, that’s almost half of humanity. And that’s just the beginning.

Drought, heat waves with literally unbearable temperature extremes in places, storms, floods, water shortages, loss of agricultural crops… The secondary effects of the warming of the atmosphere and the oceans are set to intensify, with a disproportionate impact on the most vulnerable, such as the poor and indigenous peoples.

Without forgetting the possible exodus of hundreds of millions of people faced with the inexorable rise in sea level mainly linked to the melting of the ice caps of Greenland and Antarctica.

Even if warming is limited to +2°C, the oceans could gain around 50 cm in the 21st century and this increase could reach almost 2 meters by 2300 – twice as much as estimated by the IPCC in 2019.

No choice

The IPCC keeps repeating that its role is not to make recommendations, but the scenarios it has drawn up leave no choice if humanity wants to ensure a “liveable future” on the planet: even for limit to °2C, we need “a rapid, radical and most often immediate reduction in greenhouse gas emissions in all sectors”, insists the IPCC, emphasizing energy, transport, industry, the agriculture and cities.

To limit global warming to +1.5°C, a major transformation of the energy system would be needed, with the reduction in the use (without carbon capture technique) of coal, oil and gas respectively by around 100 %, 60% and 70% by 2050 compared to 2019.

Breakpoints

These three IPCC reports have never made so much room for the possibility of tipping points, abrupt changes in the climate system at “low probability” corn “significant impactswhich “cannot be excluded”.

Among them, the point of no return leading to the total collapse of the ice caps, capable of raising the sea by tens of meters; the thawing of permafrost which contains immense volumes of carbon; or even the transformation into savannah of the Amazon which absorbs a vital part of the CO2 emitted by human activities.

If scientists are currently uncertain about the warming threshold that would trigger these “singular events on a planetary scale”, they know that the risk is greater at +2°C than at +1.5. °C. And that we go into a “very high risk” by +2.5°C.

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