SCIENCE DISCUSSION ONLY
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We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System—biosphere, climate, and societies—and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values.
Temperature Anomalies by Country 1880-2017
Temperature Anomalies by Country 1880-2017 based on NASA GISTEMP data.
What happens to infrared radiation emitted by the Earth's surface? As it moves up layer by layer through the atmosphere, some is stopped in each layer. (To be specific: a molecule of carbon dioxide, water vapor or some other greenhouse gas absorbs a bit of energy from the radiation. The molecule may radiate the energy back out again in a random direction. Or it may transfer the energy into velocity in collisions with other air molecules, so that the layer of air where it sits gets warmer.) The layer of air radiates some of the energy it has absorbed back toward the ground, and some upwards to higher layers. As you go higher, the atmosphere gets thinner and colder. Eventually the energy reaches a layer so thin that radiation can escape into space.
The bonds within molecules all vibrate at temperatures above absolute zero. There are several types of vibrations that cause absorptions in the infrared region. Probably the most simple to visualise are bending and stretching, examples of which are illustrated below using a molecule of water.
If the vibration of these bonds result in the change of the molecule’s dipole moment then the molecule will absorb infrared energy at a frequency corresponding to the frequency of the bond’s natural vibration. This absorption of energy resulting in an increase in the amplitude of the vibrations is known as resonance.
Plain Language Summary
Global temperature is rapidly approaching the 1.5°C Paris target. In this study, we find that in the absence of external cooling influences, such as volcanic eruptions, the midpoint of the spread of temperature projections exceeds the 1.5°C target before 2029, based on temperatures relative to 1850–1900. We find that the phase of the Interdecadal Pacific Oscillation (IPO), a slow‐moving natural oscillation in the climate system, will regulate the rate at which global temperature approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative phase, however, the projections are centered on reaching the target around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent climate model predictions suggestive of a turnaround in the IPO, a sustained period of rapid temperature rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists.
Macdoc wrote:Okay - I see what you are after and I certainly could not have answered it ....but I think this does nicely
https://www.scribd.com/document/3791196 ... ck-ENGLISH
Infrared Spectroscopy_Teacher resource pack_ENGLISH.pdf
SnipThe bonds within molecules all vibrate at temperatures above absolute zero. There are several types of vibrations that cause absorptions in the infrared region. Probably the most simple to visualise are bending and stretching, examples of which are illustrated below using a molecule of water.
If the vibration of these bonds result in the change of the molecule’s dipole moment then the molecule will absorb infrared energy at a frequency corresponding to the frequency of the bond’s natural vibration. This absorption of energy resulting in an increase in the amplitude of the vibrations is known as resonance.
Tero: Yes it's roughly the same area of chemistry. Will read to see what else is there.
More detail here
http://www.umsl.edu/~orglab/documents/IR/IR2.html
referred to in this which might be of interest to you
http://www.realclimate.org/index.php/ar ... nt-page-2/
Macdoc wrote:2040 - 1.5C Paris target ??
Wishful thinkingPlain Language Summary
Global temperature is rapidly approaching the 1.5°C Paris target. In this study, we find that in the absence of external cooling influences, such as volcanic eruptions, the midpoint of the spread of temperature projections exceeds the 1.5°C target before 2029, based on temperatures relative to 1850–1900. We find that the phase of the Interdecadal Pacific Oscillation (IPO), a slow‐moving natural oscillation in the climate system, will regulate the rate at which global temperature approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative phase, however, the projections are centered on reaching the target around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent climate model predictions suggestive of a turnaround in the IPO, a sustained period of rapid temperature rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists.
https://agupubs.onlinelibrary.wiley.com ... 17GL073480
American Geophysical Union
Nonprofit organization
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The American Geophysical Union is a 501 nonprofit organization of geophysicists, consisting of over 62,000 members from 144 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international field of geophysics. Wikipedia
Climate scientists debate a flaw in the Paris climate agreement | Dana ...
https://www.theguardian.com/.../climate ... mate-agr...
Mar 29, 2018 - But HadCRUT4 has some significant flaws. First, it only covers 84% of Earth's surface. There are large gaps in its coverage, mainly in the Arctic, Antarctica, and ...
Another complication is that most estimates of how far we’ve come are based on the global temperature from the Hadley Centre/Climate Research Unit in the U.K. It’s a fine choice but possibly not the best, because by omitting the Arctic (the fastest-warming region on earth) it may underestimate the total temperature increase.
Gavin Schmidt’s response
Gavin Schmidt at RealClimate says of the IPCC Special Report on 1.5°C that responding to climate change is far more like a marathon than a sprint. He addresses directly the question Can we avoid going through 1.5°C?:
So my answer is… no.
However, David Spratt cites research by Benjamin Henley
and Andrew King showing that the 1.5°C target could be reached by between 2026 and 2031 depending on the phases of the Interdecadal Pacific Oscillation (IPO).
The difference here is that the IPCC follows the pack, whereas Spratt cites quality recent research. There is a risk that the new research is right. However, policy makers will blithely ignore it until it is incorporated perhaps in the next IPCC report years down the track.
OlivierK wrote:Perhaps the easiest way to work out why we disagree is for you to state:
(1) what you think the current trend warming over pre-industrial temperatures is
(2) what you think the current decadal trend warming rate is
(3) what you think the trend warming rise is likely to be over the coming decade, and
(4) an explanation for the difference between (2) and (3) if there is one
That would help me analyse why you draw such different conclusions from the same data.
Could you see your way to answering these fairly straightforward questions, without namecalling, please?
OlivierK wrote:OlivierK wrote:Perhaps the easiest way to work out why we disagree is for you to state:
(1) what you think the current trend warming over pre-industrial temperatures is
(2) what you think the current decadal trend warming rate is
(3) what you think the trend warming rise is likely to be over the coming decade, and
(4) an explanation for the difference between (2) and (3) if there is one
That would help me analyse why you draw such different conclusions from the same data.
Could you see your way to answering these fairly straightforward questions, without namecalling, please?
I would have thought that an expert like yourself would have the knowledge required to churn out an answer to these pretty basic questions at your fingertips. Seems I thought wrong.
How much has the planet warmed in the industrial period (leaving out short-term fluctuations)?
At what rate is it warming (leaving out short-term fluctuations)?
What rate of warming can we expect in the near future?
If the expectation is for the future rate to be markedly different from the current rate, what's the cause?
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