Friday, November 29, 2019

Scientists warn climate tipping points may be close, endorse need for climate emergency action

Two peer reviewed statements by scientists just prior to the UN climate conference COP25 to be held in Madrid, Spain from December 2 to 13, have made clear the existential crsis humanity now faces with climate change and the dire need to ramp up climate action at the climate conference.

The first statement, authored by 5 eminent scientists, but signed by some 11,000 climate scientists, warns "clearly and unequivocally that planet Earth is facing a climate emergency."

The second statement highlights that we may be very close, or perhaps have even initiated, climate tipping points that could push earth into a hothouse state. Our time for action to have some control over future climate may be limited, action now is of the essence, we have a climate emergency. Australian scientist Will Steffen was one of the eminent scientists who authored this statement.

The first statement, signed by 11,000 scientists, articulated that scientists have been ringing the alarm bells for some 40 years, with little political response:

Exactly 40 years ago, scientists from 50 nations met at the First World Climate Conference (in Geneva 1979) and agreed that alarming trends for climate change made it urgently necessary to act. Since then, similar alarms have been made through the 1992 Rio Summit, the 1997 Kyoto Protocol, and the 2015 Paris Agreement, as well as scores of other global assemblies and scientists’ explicit warnings of insufficient progress (Ripple et al. 2017). Yet greenhouse gas (GHG) emissions are still rapidly rising, with increasingly damaging effects on the Earth's climate. An immense increase of scale in endeavors to conserve our biosphere is needed to avoid untold suffering due to the climate crisis (IPCC 2018).

The scientists identify that "The climate crisis is closely linked to excessive consumption of the wealthy lifestyle. The most affluent countries are mainly responsible for the historical GHG emissions and generally have the greatest per capita emissions".

That means most of us in the developed world.

"The climate crisis has arrived and is accelerating faster than most scientists expected (figure 2, IPCC 2018). It is more severe than anticipated, threatening natural ecosystems and the fate of humanity (IPCC 2019). Especially worrisome are potential irreversible climate tipping points and nature's reinforcing feedbacks (atmospheric, marine, and terrestrial) that could lead to a catastrophic “hothouse Earth,” well beyond the control of humans (Steffen et al. 2018). These climate chain reactions could cause significant disruptions to ecosystems, society, and economies, potentially making large areas of Earth uninhabitable." warn the scientists.

"We need bold and drastic transformations regarding economic and population policies." say the scientists. They suggest six critical and interrelated steps that can be undertaken:

  • Energy - "The world must quickly implement massive energy efficiency and conservation practices and must replace fossil fuels with low-carbon renewables (figure 1h) and other cleaner sources of energy if safe for people and the environment (figure S2). We should leave remaining stocks of fossil fuels in the ground (see the timelines in IPCC 2018) and should carefully pursue effective negative emissions using technology such as carbon extraction from the source and capture from the air and especially by enhancing natural systems (see “Nature” section). Wealthier countries need to support poorer nations in transitioning away from fossil fuels. We must swiftly eliminate subsidies for fossil fuels (figure 1o) and use effective and fair policies for steadily escalating carbon prices to restrain their use."
  • Short-lived pollutants - "We need to promptly reduce the emissions of short-lived climate pollutants, including methane (figure 2b), black carbon (soot), and hydrofluorocarbons (HFCs). Doing this could slow climate feedback loops and potentially reduce the short-term warming trend by more than 50% over the next few decades while saving millions of lives and increasing crop yields due to reduced air pollution (Shindell et al. 2017). The 2016 Kigali amendment to phase down HFCs is welcomed."
  • Nature - "We must protect and restore Earth's ecosystems. Phytoplankton, coral reefs, forests, savannas, grasslands, wetlands, peatlands, soils, mangroves, and sea grasses contribute greatly to sequestration of atmospheric CO2. Marine and terrestrial plants, animals, and microorganisms play significant roles in carbon and nutrient cycling and storage. We need to quickly curtail habitat and biodiversity loss (figure 1f–1g), protecting the remaining primary and intact forests, especially those with high carbon stores and other forests with the capacity to rapidly sequester carbon (proforestation), while increasing reforestation and afforestation where appropriate at enormous scales. Although available land may be limiting in places, up to a third of emissions reductions needed by 2030 for the Paris agreement (less than 2°C) could be obtained with these natural climate solutions (Griscom et al. 2017)."
  • Food - "Eating mostly plant-based foods while reducing the global consumption of animal products (figure 1c–d), especially ruminant livestock (Ripple et al. 2014), can improve human health and significantly lower GHG emissions (including methane in the “Short-lived pollutants” step). Moreover, this will free up croplands for growing much-needed human plant food instead of livestock feed, while releasing some grazing land to support natural climate solutions (see “Nature” section). Cropping practices such as minimum tillage that increase soil carbon are vitally important. We need to drastically reduce the enormous amount of food waste around the world."
  • Economy - "Excessive extraction of materials and overexploitation of ecosystems, driven by economic growth, must be quickly curtailed to maintain long-term sustainability of the biosphere. We need a carbon-free economy that explicitly addresses human dependence on the biosphere and policies that guide economic decisions accordingly. Our goals need to shift from GDP growth and the pursuit of affluence toward sustaining ecosystems and improving human well-being by prioritizing basic needs and reducing inequality."
  • Population - "Still increasing by roughly 80 million people per year, or more than 200,000 per day (figure 1a–b), the world population must be stabilized—and, ideally, gradually reduced—within a framework that ensures social integrity. There are proven and effective policies that strengthen human rights while lowering fertility rates and lessening the impacts of population growth on GHG emissions and biodiversity loss. These policies make family-planning services available to all people, remove barriers to their access and achieve full gender equity, including primary and secondary education as a global norm for all, especially girls and young women (Bongaarts and O’Neill 2018)."

The statement concludes with some positive news, that human well being can be improved if we make the transformational changes that are being called for: "The good news is that such transformative change, with social and economic justice for all, promises far greater human well-being than does business as usual. We believe that the prospects will be greatest if decision-makers and all of humanity promptly respond to this warning and declaration of a climate emergency and act to sustain life on planet Earth, our only home."

Climate tippings points may be close warn scientists

The second article was published in Nature as a comment on 27 November, 2019, and warns of the risk of climate tipping points being relatively close, the existencial risk they pose, and the need to take strong climate action to avoid the risk.

Scientific research has clearly been moving the bar lower over time for what may be considered dangerous for our climate and passing points where climate tipping points kick in. We now find that at 1.5C of warming we may be dangerously close to initiating several climate tipping points.

There are several ocean and atmosphere tipping points that have interconnections. In other words, they can feed off and affect other tipping points.

We argue that cascading effects might be common. Research last year14 analysed 30 types of regime shift spanning physical climate and ecological systems, from collapse of the West Antarctic ice sheet to a switch from rainforest to savanna. This indicated that exceeding tipping points in one system can increase the risk of crossing them in others. Such links were found for 45% of possible interactions14.

More concerning is that there appears to be observational data of these interconnections already kicking in:

For example, Arctic sea-ice loss is amplifying regional warming, and Arctic warming and Greenland melting are driving an influx of fresh water into the North Atlantic. This could have contributed to a 15% slowdown15 since the mid-twentieth century of the Atlantic Meridional Overturning Circulation (AMOC) , a key part of global heat and salt transport by the ocean3. Rapid melting of the Greenland ice sheet and further slowdown of the AMOC could destabilize the West African monsoon, triggering drought in Africa’s Sahel region. A slowdown in the AMOC could also dry the Amazon, disrupt the East Asian monsoon and cause heat to build up in the Southern Ocean, which could accelerate Antarctic ice loss.

Being scientists, they have even probvided a maths formula to demonstrate we have a planetary climate emergency and state: "In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute (see ‘Emergency: do the maths’)".

We define emergency (E) as the product of risk and urgency. Risk (R) is defined by insurers as probability (p) multiplied by damage (D). Urgency (U) is defined in emergency situations as reaction time to an alert (τ) divided by the intervention time left to avoid a bad outcome (T). Thus:

E = R × U = p × D × τ / T

The situation is an emergency if both risk and urgency are high. If reaction time is longer than the intervention time left (τ / T > 1), we have lost control.

The scientists end with a stark call for strong action from the diplomats and ministers who will be attending COP25.

"We argue that the intervention time left to prevent tipping could already have shrunk towards zero, whereas the reaction time to achieve net zero emissions is 30 years at best. Hence we might already have lost control of whether tipping happens. A saving grace is that the rate at which damage accumulates from tipping — and hence the risk posed — could still be under our control to some extent."

"The stability and resilience of our planet is in peril. International action — not just words — must reflect this."

The scientific method tends to be conservative. There have been calls for a climate emergency approach by Australian climate analysts David Spratt and Phillip Sutton going back to 2007.

"The term “climate emergency” was popularised by David Spratt and Philip Sutton in a 2007 report and subsequently in their June 2008 book Climate Code Red: The case for emergency action. The book argued that we must “devote as much of the world’s economic capacity as is necessary, as quickly as possible, to this climate emergency." writes David Spratt in a May 2019 blogpost on “Climate emergency”: Evolution of a global campaign.

Now we need everyone on board with the social and economic transformations needed irrespective of ideology or political leanings. Time now is of the essence for the very survival of human civilisation and planetary biodiversity.


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