Archives par mot-clé : Tipping point

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Claim: The World is On the Brink of Five Climate Tipping Points

by E. Worrall, Sep 12, 2022 in WUWT

Is anyone else fed up with us approaching but never actually crossing all those dangerous tipping points?

World on brink of five ‘disastrous’ climate tipping points, study finds

Giant ice sheets, ocean currents and permafrost regions may already have passed point of irreversible change

Damian CarringtonEnvironment editor
@dpcarringtonFri 9 Sep 2022 04.00 AEST

The climate crisis has driven the world to the brink of multiple “disastrous” tipping points, according to a major study.

It shows five dangerous tipping points may already have been passed due to the 1.1C of global heating caused by humanity to date.

These include the collapse of Greenland’s ice cap, eventually producing a huge sea level rise, the collapse of a key current in the north Atlantic, disrupting rain upon which billions of people depend for food, and an abrupt melting of carbon-rich permafrost.

At 1.5C of heating, the minimum rise now expected, four of the five tipping points move from being possible to likely, the analysis said. Also at 1.5C, an additional five tipping points become possible, including changes to vast northern forests and the loss of almost all mountain glaciers.

In total, the researchers found evidence for 16 tipping points, with the final six requiring global heating of at least 2C to be triggered, according to the scientists’ estimations. The tipping points would take effect on timescales varying from a few years to centuries.

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Read more: https://www.theguardian.com/environment/2022/sep/08/world-on-brink-five-climate-tipping-points-study-finds

The abstract of the study;

Exceeding 1.5°C global warming could trigger multiple climate tipping points

David I. Armstrong McKay* https://orcid.org/0000-0002-0020-7461 d.mckay@exeter.ac.uk
Arie Staal https://orcid.org/0000-0001-5409-1436
Jesse F. Abrams https://orcid.org/0000-0003-0411-8519
Ricarda Winkelmann https://orcid.org/0000-0003-1248-3217
Boris Sakschewski https://orcid.org/0000-0002-7230-9723
Sina Loriani https://orcid.org/0000-0001-6660-960X
Ingo Fetzer https://orcid.org/0000-0001-7335-5679
Sarah E. Cornell https://orcid.org/0000-0003-4367-1296
Johan Rockström
Timothy M. Lenton* https://orcid.org/0000-0002-6725-7498 d.mckay@exeter.ac.uk

9 Sep 2022

Vol 377, Issue 6611

DOI: 10.1126/science.abn7950

Climate tipping points occur when change in a part of the climate system becomes self-perpetuating beyond a warming threshold, leading to substantial Earth system impacts. Synthesizing paleoclimate, observational, and model-based studies, we provide a revised shortlist of global “core” tipping elements and regional “impact” tipping elements and their temperature thresholds. Current global warming of ~1.1°C above preindustrial temperatures already lies within the lower end of some tipping point uncertainty ranges. Several tipping points may be triggered in the Paris Agreement range of 1.5 to <2°C global warming, with many more likely at the 2 to 3°C of warming expected on current policy trajectories. This strengthens the evidence base for urgent action to mitigate climate change and to develop improved tipping point risk assessment, early warning capability, and adaptation strategies.

Read more (paywalled): https://www.science.org/doi/10.1126/science.abn7950

Unfortunately the study is paywalled, so I can’t tell you the timeframe of these alleged tipping points. Not that the predicted dates matter that much – in my experience, tipping point predictions are usually quietly ignored or deleted when the deadline expires.

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NEW STUDY: “Part Of North Atlantic Is Cooling”…”Natural Fluctuations Have Been Primary Reason”

by P. Gosselin, Apr 30, 2022 in NoTricksZone

New studies on the Atlantic current system assess the threshold between natural fluctuations and a climate change-driven evolution

25 April, 2022/Kiel, Germany. With a new publication in the scientific journal Nature Climate Change, researchers from Kiel once again contribute to the understanding of changes in the Atlantic Meridional Overturning Circulation (AMOC) – also known as the “Gulf Stream System”. It is important both for the global climate as well as for climate events in Europe. The authors focus on the question whether human-induced climate change is already slowing down this oceanic circulation. According to the new study, natural variations are still dominant. Improved observation systems could help detect human influences on the current system at an early stage.

Is the Atlantic Meridional Overturning Circulation (AMOC) slowing down? Is this system of ocean currents, which is so important for our climate, likely to come to a halt in the future? Are the observed variations a natural phenomenon or are they already caused by human-induced climate change? Researchers from various scientific disciplines use a wide range of methods to better understand the gigantic oceanic circulation.

“The AMOC provides Europe with a mild climate and determines seasonal rainfall patterns in many countries around the Atlantic. If it weakens over the long term, this will also affect our weather and climate. Other consequences could be a faster rise in sea levels at some coasts or a reduction in the ocean’s ability to take up carbon dioxide and mitigate climate change”, Professor Dr. Mojib Latif, Head of the Research Unit: Marine Meteorology at GEOMAR Helmholtz Centre for Ocean Research Kiel, explains. “We depend on the AMOC in many ways – but so far, we can only guess how it will develop, and whether and how strongly we humans ourselves will push it towards a tipping point where an unstoppable collapse will take its course.”

Using observational data, statistical analyses and model calculations, a team led by Professor Latif has therefore examined changes in the current system over the past one hundred years in greater detail. The results have now been published in the scientific journal Nature Climate Change. According to the researchers, part of the North Atlantic is cooling – a striking contrast to the majority of ocean regions. All evaluations indicate that since the beginning of the 20th century, natural fluctuations have been the primary reason for this cooling. Nonetheless, the studies indicate that the AMOC has started to slow down in recent decades.

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