Climate change: Can the world prevent irreversible tipping points?

Climate change: Can the world prevent irreversible tipping points?
Credit: European Space Agency

The dire warnings on global warming in the report released on Monday by the Intergovernmental Panel on Climate Change (IPCC) sent shockwaves around the globe and was described as a code red for humanity by the UN Secretary-General António Guterres.

The report warns that limiting warming to close to 1.5°C or even 2°C will be beyond reach unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions in the coming two decades. Every increase by a fraction of a degree counts and might trigger crucial ecosystems beyond critical thresholds and spell irreversible damage to Earth.

Tipping points at the brink

According to the IPCC report, the concentration of carbon dioxide in the atmosphere is the highest in at least 2 million years. Sea level has risen at a faster rate in at least 3,000 years. Extreme heat, heavy rainfall and wild fires have become more frequent and intense. Droughts are increasing in some regions. Artic ice has decreased by 40 % since 1979.

Scientists are warning about the “tipping points” in climate change, such as the melting of the ice in the Arctic and Antarctica, the thawing of the permafrost and the deforestation and burning of the rain forest in the Amazon, when it will be too late to save the planet. We are not there yet but approaching the abyss if not global warming will be limited to 1,5 – 2 °C by cutting green-house gas emissions.

Some of these climate changes are irreversible but some can be slowed down or even stopped if green-house gas emissions are rapidly reduced globally. Which are the most important tipping points and how close are we irreversible changes?

“Knowledge about previous climate periods show that tipping points are real,” replied Professor Markku Rummukainen at the Centre for Environmental and Climate Science in Lund, the Swedish representative in IPCC. “We cannot put the finger on which temperature increase will trigger the tipping points but the risk that it will happen increases with global warming.”

“Many tipping points, if they do occur, will of course result in large consequences on a global or regional scale. Examples of tipping points are the ocean current system in the North Atlantic Sea, large eco systems such as the rain forest in the Amazon, the melting of the ice shelves in the Western Antartic and the Greenland ice.”

On the positive side, global warming responds quickly to net zero emissions and by net negative emissions warming can even start to decrease, he says.

“Mountain glaciers, permafrost and Artic ice can also recover if the temperature is retrieving. However, sea level rise, diminishing ice in Greenland and Antarctica and the warming of the deep sea will be irreversible in the long-term spanning hundreds to thousands of years.”

Professor Emeritus Pinhas Alpert at the Department of Geophysics, Tel-Aviv University, is convinced that the figures in the IPCC report on the increase of global warming are reliable. The author of more than 400 papers on climate change since 1979, he also represented Israel at the IPCC meeting in Shanghai in 2001.

He has himself contributed to the estimations by running the first climate estimation of doubling CO2 as early as 1985. The model he developed at the Hebrew University has been adopted by e.g. Belgium. He was an invited lecturer at the university at Louvain-La-Neuve and cooperated with Belgian climate researcher Professor Guy Schayes.

“In the past IPCC worked with two scenarios, business as usual, which will lead to an increase in global warming by 5 – 6°C by 2100, or a more optimistic scenario that mankind will realise by 2040 that the situation is really bad.”

“In fact, climate change is accelerating more than IPCC first thought,” he says. One of the things that worry him most are the tipping points. He wrote a personal opinion about it just before the publication of the IPCC report. “Unfortunately, the occurrence of extreme weather events, particularly in the last decade or two, points to an acceleration which would not have happened without human influence."

“The question we ask in these days is if we have reached an irreversible situation in the global climate,” he summarised the paper.

Another recent article published in Nature Climate Change draws attention to the Atlantic Meridional Overturning Circulation (AMOC), the key circulation system of the Atlantic Ocean. It moves heat from the Tropical region to the Northern hemisphere by transporting warm water masses northward at the ocean surface (Gulf Stream), and returning as a cool current southward at the bottom of the ocean.

According to the paper, empirical evidence reveals that, in the course of the last century, the AMOC may have evolved from relatively stable conditions to a point close to a critical transition following the melting of the Greenland ice sheet and Arctic sea ice. If it would collapse, it would have severe impacts on the global climate system and further multi-stable Earth system components.

“This tipping point is irreversible,” says Professor Alpert. “If AMOC would collapse, it will change our climate irreversibly, not only in Northern Europe and North America but also impact the rest of the world.”

European Commission position

In mid-July, the European Commission adopted a package of proposals (“Fit for 55”) to make the EU’s climate, energy, land use, transport and taxation policies fit for reducing net greenhouse gas emissions by at least 55% by 2030, compared to 1990 levels.

The fit for 55 package was described by the Commission as a “comprehensive and interconnected set of proposals that will enable the necessary acceleration of greenhouse gas emission reductions” in the next decade.

The Brussels Times asked the Commission about its first reaction to the IPCC report and whether it could already now identify elements and policies in the fit for 55 package which might have to be adjusted or changed.

“The Commission concurs with the sense of urgency communicated by the IPCC report on the physical science of climate change, which is the most authoritative and up-to-date scientific assessment of how and why our climate is changing,” a Commission spokesperson replied and referred to a tweet by President Ursula von der Leyen on 9 August:

The spokesperson added that the report’s findings “clearly reinforce the rationale underpinning the EU’s determination to become climate-neutral by 2050, which is now a legally binding objective under the European Climate Law and responds to the urgency of acting now to tackle the climate emergency”.

“The report confirms that the world is warming rapidly due to human influence. It sets out the need to reduce CO2 emissions to net zero, significantly cut emissions of other greenhouse gases (such as methane), and scale up action to protect our natural carbon sinks such as forests and oceans,” the spokesperson summarised but declined to address the impact of the report on its policy package.

“Needless to say, the action of the G20 economies, whose emissions collectively account for some 80% of the global total, will be critical to determining our success.” This is also what the UN Secretary-General underlined when he called on all nations, especially the G20, to join the net zero emissions coalition.

How likely is that to happen considering the global divide among the big green-house gas emitters in the G20: Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Republic of Korea, Mexico, Russia, Saudi Arabia, South Africa, Turkey, the United Kingdom, the United States, and the EU.

The still developing countries among the G20 think that the industrialised countries, which have been the biggest emitters in the past, are more responsible for climate change and therefore should compensate the other countries. The historical role of the US as the biggest emitter of accumulated carbon dioxide in the atmoshphere has been replaced by China, the current biggest producer of greenhouse gases.

“They have a point and I can understand their argument,” admits Professor Alpert. “However, emissions must be cut by all big emitters. If we don’t do a global effort, things will only become worse.” He has noticed policy changes in China and India. “Today I hear different voices, both because of climate change concerns and economic reasons.”

“I’m a bit optimistic that the recent extreme weather events – wild fires, heat waves, flooding – have brought China and the rest of the world to the recognition that climate change originates in human activity (anthropogenic).”

He is not so optimistic about his own country, Israel, which only belately committed to reduce carbon dioxide emissions to 27 % by 2030 and 85 % by 2050 but has not yet enacted any climate law as the EU.

The emission of carbon dioxide per capita in India is only half a tonne compared to 10 tonnes per capita in Europe. If the goal according to IPCC is to drastically reduce the emission per capita worldwide, then the main burden falls on Europe and other rich countries but developing countries must limit their emissions to their current levels.

M. Apelblat

The Brussels Times

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