Their revision incorporates the impact of previously neglected physical properties in ice.
As global temperatures rise due to human-induced climate change, precise computerized climate models will be crucial in shedding light on how our climate will continue to evolve in the coming years.
In a study published in the Journal of Geophysical Research: Atmospheres, a team led by researchers from the UC Irvine Department of Earth System Science and the University of Michigan Department of Climate and Space Sciences and Engineering reveal how a climate model commonly used by geoscientists currently overestimates a key physical property of Earth’s climate system called albedo, which is the degree to which ice reflects planet-warming sunlight into space.
Albedo is a measure of the reflectivity of a surface, expressed as the fraction of incoming solar radiation that is reflected by that surface back into space. It is a critical factor in determining the Earth’s climate and energy balance. Surfaces with high albedo, such as snow and ice, can reflect a large portion of incoming solar energy, whereas darker surfaces like forests or oceans absorb more solar energy.
“We found that with old model versions, the ice is too reflective by about five percent,” said Chloe Clarke, a project scientist in UC Irvine professor Charlie Zender’s group. “Ice reflectivity was much too high.”
The amount of sunlight the planet receives and reflects is important for estimating just how much the planet will warm in the coming years. Previous versions of the model, called the Energy Exascale Earth System Model (E3SM), overestimated albedo because they did not account for what Clarke described as the microphysical properties of ice in a warming world.
Those properties include the effects things like algae and dust have on albedo. Dark-colored algae and dust can make snow and ice less reflective and less able to reflect sunlight.
Analysis Using Satellite Data
To do the analysis, Clarke and her team studied satellite data to track the albedo of the Greenland Ice Sheet. They found that E3SM reflectivity overestimates the reflectivity of the ice sheet, “meaning the model estimates less melt than what would be expected from the ice microphysical properties,” said Clarke.
But with the new ice reflectivity incorporated into the model, the Greenland Ice Sheet is melting at a rate of about six gigatons more than in older model versions. This is based on albedo measurements that are more consistent with satellite observations.
Clarke hopes her team’s study stresses the importance of the seemingly minuscule properties that can have far-reaching consequences for the overall climate. “I think our work is going to help models do a much better job of helping us capture snow and ice-related climate feedbacks,” she said.
Next, Clarke wants to study different icy parts of the planet to gauge how widespread the albedo discrepancy is in E3SM. “Our next steps are to get it so it is functional globally and not just valid over Greenland,” said Clarke, who also intends to compare the new Greenland Ice Sheet melt rates to observations to measure how much more accurate the new ice albedo is. “It would be useful to apply it to glaciers in places like the Andes and Alaska.”
Reference: “The Effect of Physically Based Ice Radiative Processes on Greenland Ice Sheet Albedo and Surface Mass Balance in E3SM” by C. A. Whicker-Clarke, R. Antwerpen, M. G. Flanner, A. Schneider, M. Tedesco and C. S. Zender, 8 April 2024, Journal of Geophysical Research: Atmospheres.
DOI: 10.1029/2023JD040241
Additional authors include Raf Antwerpen (Lamont-Doherty Earth Observatory), Mark G. Flanner (University of Michigan), Adam Schneider (National Oceanic and Atmospheric Administration), Marco Tedesco (Lamont-Doherty Earth Observatory) and Charlie S. Zender (UC Irvine). Funding information is listed in the study.
21 Comments
Strictly speaking, albedo is only applicable to diffuse reflectors, primarily clouds, fresh snow, particulate surfaces such as sand, and particles suspended in water. The 71% of Earth covered by water, primarily reflects by specular reflectance, which increases with the angle of incidence, as characterized by Fresnel’s Equations ( https://en.wikipedia.org/wiki/Fresnel_equations ), leading to 100% reflectance at a grazing angle (90 degrees). Typically, the Global Circulation Models use an ocean ‘albedo’ that is a combination of the effects of diffuse reflectance of sediment and plankton, plus the specular reflection at the water surface, which is a lower-bound for water.
https://wattsupwiththat.com/2016/09/12/why-albedo-is-the-wrong-measure-of-reflectivity-for-modeling-climate/
At the next level of refinement, even rough surfaces are not reflecting at a single value of reflectance, but have a complex reflectance called the hemispherical, bi-reflectance distribution function (BRDF) that varies with the angle of incidence of sunlight and the viewing position. It is why people sometimes experience ‘snow blindness’ if not wearing eye protection and look in the direction of the sun for extended periods because, as is typical, there is a strong forward lobe in the BRDF. Even the stubble in a harvested corn field will display very high reflectance off the stalks and clods when the sun is low on the horizon. Observations from a nadir-viewing platform, which is typical for most imaging satellites, only reveal the back (retro)reflectance and not the forward reflectance away from the sun.
If anything, the climate models probably underestimate the so-called albedo variable because the models don’t take into account the rapidly increasing reflectance with angles of incidence over about 60 degrees, up to a maximum of 100% where the limb of the illuminated surface of Earth is water, and instead use averages for small angles of incidence.
This is yet another example of the poor quality of research being done in climatology. I think that this group needs to add someone to their team who is an expert in optical physics.
the very first statement in this article shows the bias of this rag “As global temperatures rise due to human-induced climate change,” the earth is constantly emitting megatons of gases etc. as well as heating of the oceans via floor vents. Curioiusly the article forgets all the other aspects of global heating in favor of once again trying to convince the public that the whole problem is generated by human activity.
The 2nd aspect of this article is that in examining the “science” they found errors affecting the calculations SURPRISE. How many other errors have been made in support of the “human caused” global meltdown. When science begins to objectively examine what is going on, people may listen, until then squeek squeek squeek
The Scitechdaily site reports on science, it is not a “rag”.
Meanwhile, man made global warming and climate science is not in doubt and the current work show that there is no ‘bias’. The model result were still consistent with observations, despite a 5 % [!] error in a model parameter (that will be fixed now). Meanwhile you are 100 % erroneous on the science.
It’s so funny the way the elite scientists have claimed that global warming will kill us. Some of the people purporting our demise suggested it should have happened by now. But it hasn’t and it won’t. If you all can recall, if you were an adult in the 1970’s, we were supposed ot all be dead by 2020 due to Global Cooling. Ha! Here we are,
I remember those documentaries in the 1970s about global cooling. They were dramatic. I also remember that a hand calculator was huge advanced technology and there were only a few computers that had similar power to a poker chip. Don’t you think that with the advances in computing power in the past 50 years that we might be able to narrow in on the issues a little better now?
Computing faster with the wrong numbers doesn’t provide the right answer. The problem is whether or not the theory behind the calculations is correct.
That is a tired old saw: only TWO papers mentioned global cooling in the 1970s, global cooling ending up on TIME Magazine over fears of nuclear war.
Hypocritically, environmental skeptics are the sort of people who would fearmonger about nuclear war: i.e. the Heartland and Fraser Institutes are anti-socialist, and the 1950s had nuclear sirens.
NOTHING happened.
The “elite” scientists? I don’t like the poor quality of education since the Late Middle Ages but anyone who claims they are being persecuted by the academic elite is just a anti-intellectual crank (not pseudo-intellectual per se, but anti-intellectual, as they imply the very concept of science is bad).
“…, only TWO papers mentioned global cooling in the 1970s, …”
Only two that you are aware of, or are willing to admit you are aware of. From the paper to be found at the link immediately following:
“1. Of the 190 papers in the database, the respective number of papers are 86 cooling, 58 neutral and 46 warming. In percentage terms, this equates to 45% cooling papers, 31% neutral papers and 24% warming papers, if we use all of the data.”
https://wattsupwiththat.com/2018/11/19/the-1970s-global-cooling-consensus-was-not-a-myth/
You might also find the following to be of interest:
https://www.climatedepot.com/2021/12/22/watch-the-1970s-cooling-scare-was-real/
What evidence justifies you lumping all skeptics with the Heartland and Fraser Institutes? It sounds to me like a personal political bias that fell out of your pocket when you tried to do a handstand. Yes, the 1950s had “nuclear sirens” and CONELRAD alerts; however, we are discussing the 1970s here.
That is not what the science says, before a consensus formed there was a lack of consensus into the 1970s. But scientific (not denialist) reviews show a strong majority of papers on warming. So yes, it is a is a tired old saw, and has little to do with today’s climate science.
“Scientists increasingly predict warming, 1970s
In the early 1970s, evidence that aerosols were increasing worldwide and that the global temperature series showed cooling encouraged Reid Bryson and some others to warn of the possibility of severe cooling. The questions and concerns put forth by Bryson and others launched a new wave of research into the factors of such global cooling.[59] Meanwhile, the new evidence that the timing of ice ages was set by predictable orbital cycles suggested that the climate would gradually cool, over thousands of years. Several scientific panels from this time period concluded that more research was needed to determine whether warming or cooling was likely, indicating that the trend in the scientific literature had not yet become a consensus.[69][70][71] For the century ahead, however, a survey of the scientific literature from 1965 to 1979 found 7 articles predicting cooling and 44 predicting warming (many other articles on climate made no prediction); the warming articles were cited much more often in subsequent scientific literature..[59] Research into warming and greenhouse gases held the greater emphasis, with nearly six times more studies predicting warming than predicting cooling, suggesting concern among scientists was largely over warming as they turned their attention toward the greenhouse effect.[59]” [“History of climate change science”, Wikipedia]
No one has said man made global warming will kill “us”!, only that the rapid change will kill many as we can already see from e.g. increased extreme heat events and increased death from it. The damage is not killing as much as the destruction of nature, society and economy due to the rapid changes.
Consider the earth as a kitchen match. The wood is the earth, the red blob is methane, the white bit at the end is carbon dioxide. All is well till the methane is set off. That happened in 2023. The earth is now doomed to burn-up. It would take a world wide wartime economy to save us now. Are you ready?
Poor analogy. CO2 is measured in ‘parts per million,’ while methane is measured in ‘parts per billion.’ Short term, methane has more warming potential than carbon dioxide. However, when compared on a parts per million basis and a 100-year integrated effect, methane is only about one order of magnitude more powerful on a molecule-to-molecule basis, which hardly makes up for the nearly four orders of magnitude greater abundance of carbon dioxide.
https://wattsupwiththat.com/2023/03/06/the-misguided-crusade-to-reduce-anthropogenic-methane-emissions/
I take the OP to mean that the observation that the paleosol now has net methane emissions will significantly increase the effect of man made global warming.
The world is a small boat in a vast sea of nothing. The boat is sinking with every rich nation refusing to fix its hole till every other nation fixes its hole. We are all acting like 3 year-olds. I guess we deserve what we get. SUNK!
Too much thought here. The earth will self correct anything we temp to do to it. Just remember, the only reason we are allowed to live on this earth is that the earth needed plastic, once it has enough, it will get rid of us… we are very close.
Any correction now will take centuries, if it will ever correct fully. But that is not the problem, the problem is that man made global warming is orders of magnitude faster than natural climate variation.
I like the holistic approach. Keep it up!
I’d suggest factoring in with this finding the tendency of solar-flaring impacts across predisposed regions on Earth, e.g., “The South Atlantic Anomaly”. The point here is that environmental change may not be happening gradually anymore, but in some cases, exponentially. There probably is a sum there to be added up.
An obvious observation over the past 10 years would show how apparently “dirty” snow and ice have generally become. Could this “coloring” phenomenon, if it grew worse over time, turn ice and snow into a heat sink, switching the “accepted” cooling effect into a “new” heating effect?
“… environmental change may not be happening gradually anymore …”
The word “may” is a very holistic word. 🙂
From the linked abstract: “These algae present a positive feedback, as they darken the surface of the ice sheet with their photoprotective pigments, leading to increased surface melt, …”
Increased surface melt is only true if there is high thermal conductivity between the top of the algae and the underlying ice. If the thermal conductivity is low, then the algae will be warmed, which they will find beneficial, and the shaded ice will be cooler than bare ice. Unfortunately, the researchers say nothing about the thermal conductivity as if they didn’t measure it — or even consider that anything but accelerated melting might be possible.
There are numerous examples of large pebbles and cobbles shading the ice immediately under them and producing ice pedestals that leave the stone sitting above the surrounding ice.
The whole series of comments from you is referencing a man made climate change denial site, for no good reason. The new work speaks for itself, and as UofM press release describes it is the first time scientists could work out the contributing mechanism consistency with models. The model outcomes were consistent, just “toward the higher end of climate model estimates.” That is what the 5 % [!] fix will correct.
Meanwhile, man made global warming and climate science is not in doubt and your unquantified personal opinion responses do not change that.
“”When we use climate simulations to quantify how melting sea ice affects climate, we typically simulate a full century before we have an answer,” said Mark Flanner, professor of climate and space sciences and engineering and the corresponding author of the study published in Geophysical Research Letters. “We’re now reaching the point where we have a long enough record of satellite data to estimate the sea ice climate feedback with measurements.””
[“Sea ice’s cooling power is waning faster than its area of extent, new study finds”, by Derek Smith, University of Michigan]