Prof. WILL STEFFEN
“It is clear from observations of climate change-related impacts in Australia alone—the massive bushfires of the 2019-2020 Black Summer, the third mass bleaching of the Great Barrier Reef in only five years, and long-term cool-season drying of the country’s southeast agricultural zone—that even a 1.1°C temperature rise has put us into a dangerous level of climate change.”
The Earth System, the Great Acceleration and the Anthropocene
link.springer.com/chapter/10.1007/978-3-030-78795-0_2
Prof. HANS JOACHIM SCHELLNHUBER
"Our survival would very much depend on how well we were able to draw down CO2 to 280 parts per million.”
How to survive the coming century
newscientist.com/article/mg20126971-700-how-to-survive-the-coming-century/
Prof. NERILIE ABRAM
"People and ecosystems are already suffering from the impacts of climate change across the world, and these impacts will worsen unless we move quickly to radically reduce global greenhouse gas emissions. But we've also let this problem get to the point where rapid emission reductions alone won't be enough—we also need to develop ways to remove large amounts of carbon dioxide from the atmosphere and to preserve critical parts of the Earth system while we still can."
Reducing carbon emissions not enough, expert warns
phys.org/news/2021-06-carbon-emissions-expert.html
Sir DAVID KING
“Today the level of greenhouse gases (GHGs) in the atmosphere is already so high that rapid emissions reduction is no longer sufficient to avoid an unmanageable future for mankind. We also must have the capability to remove GHGs at scale from the atmosphere, and to repair those parts of the climate system, such as the Arctic Circle, which are passing or have passed their tipping point.”
Foreword to Degrees or risk
breakthroughonline.org.au/dor
Prof. JAMES HANSEN
“We will need to return to a global climate no warmer than the middle of the 20th century, and likely somewhat cooler, for the sake of maintaining global shorelines. “
November temperature update and the big climate short
columbia.edu/~jeh1/mailings/2021/NovemberTUpdate+BigClimateShort.23December2021.pdf
Warming past 2°C
Prof. WILL STEFFEN,
Steffen said the dominant linear, deterministic framework for assessing climate change is flawed, especially at higher levels of temperature rise. Model projections that don’t include these feedback and cascading processes “become less useful at higher temperature levels… or, as my co-author John Schellnhuber says, we are making a big mistake when we think we can ‘park’ the Earth System at any given temperature rise – say 2°C – and expect it to stay there.”
Earth's climate monsters could be unleashed as temperatures rise
theguardian.com/environment/planet-oz/2018/oct/06/earths-climate-monsters-could-be-unleashed-as-temperatures-rise
Prof. HANS JOACHIM SCHELLNHUBER
“If the [climate system] tipping elements interact and cascades develop, then the heating could become independent [i.e. self sustaining] at 2°C. Whether that is the case is perhaps the most important question of science right now because it would mean the end of our civilisation.”
twitter.com/Jumpsteady/status/1194667496625836032
Prof. JOHAN ROCKSTRÖM
“I barely even want to talk about 2.7 degrees… If we go beyond 2°C it’s very likely that we have caused so many tipping points that you have probably added another degree just through self-reinforcing changes… The moment that the Earth system flips over from being self-cooling — which it still is — to self-warming, that is the moment that we lose control.”
COP26: Why the UN climate conference matters like never before
forbes.com/sites/davidrvetter/2021/10/22/with-one-week-till-cop26-climate-talks-experts-set-out-whats-at-stake/
Have we avoided worst-case warming?
Prof. MICHAEL E MANN, February 2022
And as Mann explains, “When one accounts for so-called carbon cycle feedbacks that are still not well captured in most models, it is still very plausible that CO2 concentrations could rise to levels of 700 parts per million (ppm) or higher, enough to yield 4ºC to 5ºC of warming.” As an example of carbon-cycle feedback, the professor of atmospheric science at Penn State points to the escape of methane from thawing permafrost into the atmosphere, which in turn causes further warming.
Fact check: Have we really avoided the ‘worst case’ climate change scenarios?
euronews.com/green/2022/02/16/fact-check-have-we-really-avoided-the-worst-case-climate-change-scenarios
KIRA VINKE and colleagues
“Ultimately, the damages of 4°C or 5°C warming would entail a complete loss of human civilization as we know it. The probability for such extreme impacts occurring as a result of higher global warming levels is close to 1 (certainty), given the wealth of evidence.”
Corona and the climate: a comparison of two emergencies
doi.org/10.1017/sus.2020.20
