The alarmist media are promoting a new scare this week: "OMG, the warmer it gets, the fewer clouds blocking the sunshine, still warmer it gets, ad infinitum." That is the narrative beneath headlines like these from the usual suspects (in alphabetical order for Monday, Feb. 25, 2019)
A World Without Clouds Quanta Magazine11:08 Mon, 25 Feb
'A World Without Clouds. Think About That a Minute': New Study Details Possibility of Devastating Climate Feedback Loop Common Dreams17:11 Mon, 25 Feb
At High Enough CO2 Levels, Clouds Will Start to Physically Break Apart ScienceAlert01:40
Atmospheric Carbon Dioxide Could Make Clouds Vanish Newsweek11:28 Mon, 25 Feb
Low-level clouds that cover the oceans could disappear as a result of rising CO2 Daily Mail18:17 Mon,
Carbon dioxide 'could destroy clouds' and turn our planet into a 'Hothouse Earth' Yahoo! UK & Ireland07:15
Climate change kills off clouds over the ocean in new simulation TechCrunch18:16 Mon, 25 Feb
Climate Change Could Make These Super-Common Clouds Extinct, Which Would Scorch the Planet Live Science17:32 Mon, 25 Feb
Climate Change Is Eliminating Clouds. Without Them, Earth Burns Futurism16:32 Mon, 25 Feb
Cloud break-up linked to high CO2 levels (Nature Geoscience) Nature Asia04:53
Cloud Loss Due To High Carbon Dioxide Levels Could Make Earth 14 Degrees Hotter, Climate Change … Tech Times09:42
Cloudy, with a chance of fewer clouds Cosmos11:08 Mon, 25 Feb
Clouds' cooling effect could vanish in a warmer world Nature.com15:32 Mon, 25 Feb
Extreme CO2 levels could trigger clouds 'tipping point' and 8C of global warming Carbon Brief11:11 Mon, 25 Feb
Fluffy clouds may disappear by 2100, causing 8 degree warming i News06:12
Global warming imperils clouds that deter hothouse Earth GMA News02:46
Global warming imperils stratocumulus clouds that deter hothouse Earth: scientists The Japan Times14:30 Mon, 25 Feb
High CO2 levels can destabilize marine layer clouds Phys.org11:01 Mon, 25 Feb
If climate change makes the clouds disappear, we're screwed Grist Magazine19:07 Mon, 25 Feb
If Carbon Dioxide Levels Get High Enough, They'll Break Up Planet-Cooling Clouds IFLScience11:05 Mon, 25 Feb
I've Got to Admit I Didn't See the Death of Clouds Coming Esquire14:39 Mon, 25 Feb
Striking study finds a climate tipping point in clouds Ars Technica18:16 Mon, 25 Feb
Study finds increasing carbon dioxide levels threaten marine stratus clouds Slashgear09:13
The loss of clouds could add another 8°C to global warming MIT Technology Review07:43
Very high carbon dioxide could suppress cooling clouds, climate change model warns The Washington Post11:12 Mon, 25 Feb
We Could Be On The Verge Of Killing Off Clouds And Returning To A 'Hothouse Earth' Forbes16:24 Mon, 25 Feb
Isn't it impressive how Climate Crisis Central can blanket the world with a scary message, with enough variety in titles to disguise the robotic repetition? Yet just reading the headlines already suggests to anyone with critical intelligence what is false about this alarm. Let me list some of the obvious flaws before digging into this issue.
1. It's a projection from a climate model, not a finding from observations.
2. It is based on highly uncertain supposed mechanisms.
3. It presupposes CO2 concentrations 3 times the present level.
4. The possible effect will occur after almost all readers will be dead of natural causes.
5. It claims a runaway warming "tipping point" which the earth has suppressed until now.
6. It contradicts the logic of a warmer world increasing the hydrology cycle with more clouds and precipitation.
7. It stokes fear of "hothouse earth" when presently we are slowly emerging from "severe icehouse earth."
The above image comes from esteemed paleoclimatologist Christopher Scotese. It shows the range of earth's climate history, and that we are presently slowly emerging from Severe Icehouse. It also shows that the world warms by rising temperatures at higher latitudes toward the poles, while the equator remains the same, thus reducing the gradient. Tossing around the word "Hothouse" is nonsensical in today's situation. See also: Fact: Future Will be Flatter Not Hotter
As it happens, the first article in the list is the most informative: A World Without Clouds Excerpts in italics with my bolds
A state-of-the-art supercomputer simulation indicates that a feedback loop between global warming and cloud loss can push Earth's climate past a disastrous tipping point in as little as a century.
Clouds currently cover about two-thirds of the planet at any moment. But computer simulations of clouds have begun to suggest that as the Earth warms, clouds become scarcer. With fewer white surfaces reflecting sunlight back to space, the Earth gets even warmer, leading to more cloud loss. This feedback loop causes warming to spiral out of control.
Climate physicists at the California Institute of Technology performed a state-of-the-art simulation of stratocumulus clouds, the low-lying, blankety kind that have by far the largest cooling effect on the planet. The simulation revealed a tipping point: a level of warming at which stratocumulus clouds break up altogether. The disappearance occurs when the concentration of CO2 in the simulated atmosphere reaches 1,200 parts per million — a level that fossil fuel burning could push us past in about a century, under "business-as-usual" emissions scenarios. In the simulation, when the tipping point is breached, Earth's temperature soars 8 degrees Celsius, in addition to the 4 degrees of warming or more caused by the CO2 directly.
The huge range in the models' predictions chiefly comes down to whether they see clouds blocking more or less sunlight in the future. As Marvel put it, "You can fairly confidently say that the model spread in climate sensitivity is basically just a model spread in what clouds are going to do."
The problem is that, in computer simulations of the global climate, today's supercomputers cannot resolve grid cells that are smaller than about 100 kilometers by 100 kilometers in area. But clouds are often no more than a few kilometers across. Physicists therefore have to simplify or "parameterize" clouds in their global models, assigning an overall level of cloudiness to each grid cell based on other properties, like temperature and humidity.
But clouds involve the interplay of so many mechanisms that it's not obvious how best to parameterize them. The warming of the Earth and sky strengthens some mechanisms involved in cloud formation, while also fueling other forces that break clouds up. Global climate models that predict 2 degrees of warming in response to doubling CO2 generally also see little or no change in cloudiness. Models that project a rise of 4 or more degrees forecast fewer clouds in the coming decades.
But vastly more important and more challenging than high clouds are the low, thick, turbulent ones — especially the stratocumulus variety. Bright-white sheets of stratocumulus cover a quarter of the ocean, reflecting 30 to 70 percent of the sunlight that would otherwise be absorbed by the dark waves below.
Suppositions: First, when higher CO2 levels make Earth's surface and sky hotter, the extra heat drives stronger turbulence inside the clouds. The turbulence mixes moist air near the top of the cloud, pushing it up and out through an important boundary layer that caps stratocumulus clouds, while drawing dry air in from above. Entrainment, as this is called, works to break up the cloud.
Secondly, as the greenhouse effect makes the upper atmosphere warmer and thus more humid, the cooling of the tops of stratocumulus clouds from above becomes less efficient. This cooling is essential, because it causes globs of cold, moist air at the top of the cloud to sink, making room for warm, moist air near Earth's surface to rise into the cloud and become it. When cooling gets less effective, stratocumulus clouds grow thin.
On the Other Hand:
Joel Norris is one of the world experts in studying clouds in relation to climate, and he has published findings in partnerships with Martin Wild of ETH Zurich, where the global dimming and brightening database is located. See: Nature's Sunscreen for background.
Norris provides an informative context in this pdf presentation Observed Cloud Cover Trends and Global Climate Chang
He notes these Uncertainties in Feedbacks
• general theories do not exist for quantifying most individual climate feedbacks
• observations lack sufficient detail and comprehensiveness
• competing climate processes cannot be distinguished using observations
• global climate models have insufficient spatial resolution to simulate climate processes
From analyzing the data, Norris concludes that Total Cloud Cover has been Net Cooling:
• satellite radiation and surface cloud data have been combined to produce the first-ever multidecadal estimation of radiation variability due to clouds
• the role of clouds in the climate system is one of the biggest uncertainties in understanding future climate change
• upper-level cloud cover has decreased and outgoing LW radiation has increased over most of the global ocean
• low-level stratiform cloud cover and reflected SW radiation have increased over midlatitude oceans
• cloud changes since 1952 have had a net cooling effect on the Earth
See also: No GHG Warming Fingerprints in the Sky
from Climate Change Skeptic Blogs via hj on Inoreader https://ift.tt/2tEC3n2
No comments:
Post a Comment