Oh Crap.
New research from the University of New South Wales discussed by study author Steven Sherwood, above.
Sherwood’s paper shoots more holes into lingering hopes that climate sensitivity, the amount of warming we expect for a given rise in CO2, might be lower than we thought – that maybe temp rises could be more moderate in the future.
One of the last, lingering, tattered bastions of climate denial has been that, somehow, there might be some kind of moderating feedback in the system, that, as climate warmed and brought more moisture into the atmosphere, more clouds might form, reflecting heat and moderating the changes. This has been the hobby horse for the Richard Lindzens and Roy Spencers of the world.
That hope is being steadily crushed as we learn more.
The research also appears to solve one of the great unknowns of climate sensitivity, the role of cloud formation and whether this will have a positive or negative effect on global warming.
“Our research has shown climate models indicating a low temperature response to a doubling of carbon dioxide from preindustrial times are not reproducing the correct processes that lead to cloud formation,” said lead author from the University of New South Wales’ Centre of Excellence for Climate System Science Prof Steven Sherwood.
“When the processes are correct in the climate models the level of climate sensitivity is far higher. Previously, estimates of the sensitivity of global temperature to a doubling of carbon dioxide ranged from 1.5°C to 5°C. This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3°C to 5°C with a doubling of carbon dioxide.”
The research indicates that fewer clouds form as the planet warms, meaning less sunlight is reflected back into space, driving temperatures up further still. The way clouds affect global warming has been the biggest mystery surrounding future climate change.
Professor Steven Sherwood, at the University of New South Wales, in Australia, who led the new work, said: “This study breaks new ground twice: first by identifying what is controlling the cloud changes and second by strongly discounting the lowest estimates of future global warming in favour of the higher and more damaging estimates.”
“4C would likely be catastrophic rather than simply dangerous,” Sherwood told the Guardian. “For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet“, with sea levels rising by many metres as a result.
The research is a “big advance” that halves the uncertainty about how much warming is caused by rises in carbon emissions, according to scientists commenting on the study, published in the journal Nature. Hideo Shiogama and Tomoo Ogura, at Japan’s National Institute for Environmental Studies, said the explanation of how fewer clouds form as the world warms was “convincing”, and agreed this indicated future climate would be greater than expected. But they said more challenges lay ahead to narrow down further the projections of future temperatures.
Below, Andrew Dessler describes earlier research on the climate sensitivity question.
“This degree of warming would make large swaths of the tropics uninhabitable by humans and cause most forests at low and middle latitudes to change to something else,” says Steven Sherwood of Australia’s University of New South Wales, who led the study.
The changes, Sherwood says, would take Earth “back to the climate of the dinosaurs or worse, and in a geologically minuscule period of time—less than the lifetime of a single tree.”
–“It is an elegant and important paper,” says Penn State climate scientist Michael Mann.
The finding matters, he adds, because a 2013 Intergovernmental Panel on Climate Change (IPCC) report had widened its range of climate sensitivity estimates to embrace the low estimates for how high temperatures will rise by the year 2100. (See also: “Global Warming Report: 5 Big Takeaways.”)
“I argued that the IPCC had erred,” Mann says, based on historical climate patterns. Sherwood and his colleagues, he says, “provide a rigorous physical explanation of just why.”
Climate Sensitivity Settled?
“So can we declare the long-running debate about climate sensitivity to be over?” say climate scientists Hideo Shiogama and Tomoo Oguraof Japan’s National Institute for Environmental Studies, in a commentary accompanying the study.
“Unfortunately not,” they conclude. “Sherwood and colleagues’ study represents a big advance, but questions persist.”
For one thing, better estimates of ocean cloud cover explain only about half of the variation in climate sensitivity estimates. Uncertainty over the cooling effects of ice cover and clouds over the continents remain.
But Mann argues that the paper adds to growing concerns about the “uncertainty” in climate change science being more bad than good for humanity: “We should be taking into account worst-case scenarios when we attempt to gauge the risks posed by climate change.”
Below, Kevin Trenberth on climate sensitivity.
Happy New Year indeed. Please consider joining our next training with http://www.climatechangeiselementary.org to help slow the inexorable warming. We owe it to our kids and grandkids to do everything we can as rapidly as we can.
Happy new year. We will know things are serious when Nature will stop charging people to read these articles.
@omnologos, Earth’s climate sensitivity to doubling co2 is a function of many variables, but the Springer journals’ paywall is not one of them.
“I won’t listen to them because I don’t like something they do” demonstrates a logical fallacy called ad hominem tu quoque, “you are not pure enough to speak.”
Calm down drd
Nature giving up on their lucrative article selling business will surely be a sign that whatever we know, is more important than Nature’s lucrative article selling business.
In this case Nature’s behavior is an indicator not a cause.
maurizio,
You do know that Nature can be accessed for free at most public libraries?
An indicator? Of what?
That agw is not alarming?
That Sherwood’s study is not important, or accurate, or alarming?
That Nature puts profit before the plight of the human species, because it denies you access to a study for free?
omnologos: “Hey look! There’s a sparrow!”
Where? I haven’t seen any sparrows for years! 🙁
You can access a few decade’s worth of Science if you sign up on their website for free. http://www.sciencemag.org/
You may not be able to see the current issue (or latest issues), but you have access to year’s worth of climate science. Happy New Year…
One thing has been very consistent over the last few years, and that is that the predictions in the published papers have been very conservative. Exaggeration is a sin in science. I’ve learned to estimate that the worst outcome in the published lit is likely the best that we can expect if everything goes well.
Of course, now that 2 deg is a dream, and 3 deg or more is baked in due to a complete lack of effective action, the idea of “everything going well” is ridiculous. Keep an eye on California. Their drought is frying the farm land in the central valley where a lot of America’s food grows. Wells are going dry. When food prices start their inevitable rise, people may finally realize just how serious our situation is.
Of course, the end of agriculture in California’s irrigated Central Valley would also eliminate a lot of corporate farming and forcibly re-localize much of the food economy. I guess that’s a non-cloud with a silver lining.
What irks me is that this proves old DDE right, and that we should have used nuclear energy against OPEC far beyond merely eliminating petroleum from the electric power supply. But for decades, nobody in power gave any heed to those voices, and we now have that 3°C “baked in”… unless we can somehow exploit some force or forces to deliberately and rapidly remove those excess GHGs from the atmosphere.
Can we crush and distribute several cubic kilometers of olivine every year, to “engineer” weathering and uptake of CO2 as carbonate? Humanity extracts and burns more than a cubic mile of petroleum per year, so the scale isn’t unprecedented, but can we recognize the need and muster the will?
Where is it going to “forcibly re-localize” to?
To the regions of the people who buy and eat it. if California’s diminished or gone as a source, pressures for local produce are no longer going to be blocked by the corporates maintaining their markets.
Although I am not much for British royal bestowed titles etc. I am pleased to see that Professor Julia Slingo (the Met Office Chief Scientist) has been awarded title of Dame. She always states climate facts in a clear, precise and no nonsense manner and is finally recognised by the establishment (unlike Lord youknowwho, who is disowned by the house of lords and seems to have inherited any claim to titled fame) . Also the Daily Mail with David Rose has been awarded Climate Change Misinformer Of The Year by mediamatters. Interestingly Prof. Julia is a target of derision on that dreadful denial site ” wattsupwiththat” and David Rose is a champion in the same site. What Up With That ??
http://mediamatters.org/research/2013/12/30/climate-change-misinformer-of-the-year-the-dail/197340
A year of bitter-sweet memories has passed. May this new year bring immense joy and fun to your life. May you reach new heights of success. Happy New Year.
Nit picking I know, but I think that should read the University of New South Wales, which is in Sydney, Australia. Only half a globe away, but the alarming message is still the same.
right you are. thanks