2023-12-05 17:37:00
It was two years ago, in August 2021. On the occasion of the release of a flagship report of the Intergovernmental Panel on Climate Change (IPCC)Swiss climatologist Sonia Seneviratne, coordinator of the chapter on extreme events, warned The Tribune :
“The possibility of limiting global warming to +1.5°C is becoming increasingly remote. […] If we continue like this, it will really be too late within one or two years. »
Once the deadline has passed, the results are bitter: as the 28th UN climate conference (COP28) opened on Thursday in Dubai, not only have greenhouse gas emissions not decreased, but these even continue to grow. To the point that the primary objective of the Paris Agreement, this international treaty signed in 2015 at the end of COP21, seems definitively buried. Because it was then a question of “ continue action to limit temperature rise to 1.5°C compared to pre-industrial levels ”, and, failing that, “ significantly below 2°C “. Today, the increase is 1.1°C.
Towards a warming of 2.9°C if commitments are respected
If the target officially remains the same, few people still believe it is possible to achieve it. In recent days, studies have multiplied in this direction, like so many alarm signals. That of the International Energy Agency, first, which pointed out at the end of November that oil and gas companies play a more than marginal role in the energy transition, with 1% of their total investments dedicated to this subject. Added to it the report of Net Zero Trackerposted online this Monday, which recalls that only 13% of the 150 countries aiming for carbon neutrality have made at least one commitment to gradually eliminate the use, production or exploration of coal, oil and gas.
The 120 scientists of Global Carbon Budget delivered the final blow on Tuesday, affirming in a new publication that there is a 50% chance that global warming will exceed 1.5°C consistently in “ about seven years “. And for good reason, emissions linked to the use of fossil fuels in 2023 increased by 1.1% compared to the previous year, “ exceeding the rebound effect linked to the end of Covid-19 », According to Philippe Ciais, research director at the Climate and Environmental Sciences Laboratory and co-author of the study. To have a chance of limiting the rise in temperatures to 1.5°C, we would therefore have to reduce global CO2 emissions by 42% by 2030. A challenge.
Result: according to the research group’s study Climate Action Tracker, also presented this Tuesday, Climate commitments made by countries around the world will lead to warming of 2.5˚C by the end of the century. This is in line with the conclusions of the UN, which affirmed in November that warming would reach 2.9°C for unconditional promises and 2.5°C when including conditional commitments.
Enough to portend the worst, at the very moment when the Guardian revealed that COP28 President Sultan Al-Jaber stressed that ending fossil fuels could “ return humanity to the cave age » during a tense exchange with former Irish president Mary Robinson.
Cascading consequences
However, the dramatic effects of rising temperatures are well known: each additional 0.5°C will cause increases ” clearly perceptible ” of the’ ” intensity and frequency » extreme events – heat waves, precipitation and droughts – for “ all regions of the world », Repeats the IPCC regularly.
Regarding torrential rains, for example, “ for each degree higher, the amount of additional rain will increase by approximately 7% “, we can read in its summary report published in August 2021. The same goes for droughts: while their average duration around the Mediterranean is around 40 days per year (i.e. 50% more compared to the 20th century), this figure will be increased to 60 days in a world at +1.5°C, and to 70 days if +2°C were reached.
Beyond extreme events, the degree of temperature rise will determine the evolution of slow components, such as sea level rise, which has progressed ” faster since 1900 than in any previous century in at least the last 3,000 years » – notably because of the melting of the ice. Over the next 2,000 years, the global average sea level is expected to rise by around 2 to 3 meters if warming is limited to +1.5°C, and by 2 to 6 meters if it is limited to +2 °C and from 19 to 22 meters with a warming of +5°C.
These changes will also have consequences on biodiversity, on human health, but also on agriculture, by affecting global production. Above all, combined extreme events will multiply:
« For coastal flooding, for example, there will be a combination of increased extreme rainfall and rising sea levels, which will further increase the perils. “, explained Sonia Seneviratne in August 2021.
An increase in emissions driven by India and China
Faced with these bleak prospects, however, States are not remaining idle. Moreover, CO2 emissions linked to fossil fuels are decreasing in certain regions, notably in Europe (-7.4%) and the United States (-3%), due in particular to the gradual elimination of coal (at the origin of 41% of global emissions), the Global Carbon Budget said on Tuesday. In the OECD, these experienced a decline of 1.2% per year during the decade 2013-2022, compared to -0.7% between 2003 and 2012.
« This shows that climate policies can be effective! », comments Philippe Ciais.
But overall, they remain driven by India (+8.2%) and China (+4%). For the latter country, which concentrates 31% of total emissions, a sharp increase is expected for emissions from oil (+9.9%), natural gas (+6.5%) and coal (+3. 3%). In India, which this year became the most populous country in the world, coal is expected to account for most of the increase (+9.5%), followed by oil (+5.3%), natural gas (+5.6%) and cement (+8.8%). Since 2022, India’s emissions have been ” higher than those of the European Union ”, according to the report. Be careful, however: per capita, Indian emissions remain seven times lower than those of the Americans, and three times lower than those of Europeans.
In this context, the exit from fossil fuels promises to agitate States during COP28. While waiting to know if it will be part of the measures cited in the final official text, a provisional version was made public this Tuesday. It summarizes in 24 pages the different options put forward by the approximately 200 leaders who are feverishly negotiating in Dubai. From a “orderly and fair exit from fossil fuels” to nothing at all on the subject, all options are on the table, suggesting fierce battles to come.
The detonating effect of methane
The Global Carbon Budget study, already worrying, does not take into account another greenhouse gas, which is the second largest contributor to climate change: methane. Less concentrated than CO2, this gas has a warming power 25 times more powerful on a scale of one hundred years, and 80 times more on a scale of twenty years.
“Since 2015, the emissions it releases are increasing more rapidly than previously observed. If we included it in our study, its results would worsen,” says Philippe Ciais, specifying that the Global Carbon Budget is preparing a dedicated article in May.
To date, methane has contributed to around 30% of global warming since the pre-industrial era, according to the United Nations. Reduce all emissions by 30% by the end of the decade would have Besides “the same effect on global warming by 2050 as moving the entire transport sector to net zero CO2 emissions “, according to the director of the International Energy Agency (IEA), Fatih Birol. It remains to take action, while the rejections of of methane remain “ stubbornly raised ”, according to this organization.
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