And that works out to somewhere between 130 and 140 parts per million equivalent in the last, say, two decades. So this darkening of the Earth is very very important. It's very very significant. It's a large effect. And for the first time a paper actually examined- well it reported that the hemispheres are acting differently. So the darkening is actually more significant in the northern hemisphere than it is in the southern hemisphere.
So in this video I'm doing a deep dive into this darkening effect of the Earth, this albedo effect, and I'll be providing lots of references and papers that you can have a look at if you want to get more information on what's happening.
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But it's a very significant change to the overall Earth climate system, air circulation, ocean circulation, all the rest of it. So this is a an article in phys dot org that just came out just over a week ago. The Earth is reflecting less and less sunlight, study reveals. Okay.
So from 2001 to 2024 the Earth has become darker meaning that it reflects less sunlight.
So therefore more sunlight is absorbed on the surface causing heating of the planet.
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This was a research scientific report published in the journal PNAC Proceedings of the National Academy of Sciences. They found that the darkening is more pronounced in the northern hemisphere compared to the southern hemisphere. and this previously known inequality between the northern and southern hemispheres was determined- discovered after analyzing satellite data. So analyzing observations.
So in general, the southern hemisphere has been gaining radiative energy at the top of the atmosphere, meaning that the albedo is larger and the there's a net loss at the top of the atmosphere in radiative energy in the northern hemisphere, meaning that the albedo is lower. The Earth is darkening there.
Now normally in previous studies this imbalance has been offset by atmospheric and oceanic circulation. It transports energy across the equator from the southern hemisphere to the northern hemisphere. But this declining albedo effect in the northern hemisphere at a much faster rate than in the southern hemisphere now means that the atmospheric and oceanic circulations haven't been able to fully compensate.
So if we talk about an average energy intake from solar radiation of about 240 to 243 watts per square meter. A few decades ago it was closer to 240. Now it's closer to 243, but there's been a divergence or a northern hemisphere minus southern hemisphere difference of 0.34 watts per square meter per decade.
Now that doesn't seem like very much, but it's statistically significant and it has significant impacts on global circulation.
And why is this happening? The difference between the northern and southern hemisphere in albedo's reflectivity is attributed to changes in water vapor which traps heat. Water vapor is a powerful greenhouse gas. Also clouds which reflect sunlight. Also there's been lots of changes to the albedo or reflectivity of the surfaces at the Earth's surface. Like ice and snow of course reflect more solar radiation than rock or water. So the decrease in sea ice concentration and snow cover in the northern hemisphere has contributed to this darkening. And I'll talk about these images within the paper itself because because they're it's hidden at the bottom and the scale is hidden when I click here and open it up. So anyway, I'll talk about those in the paper.
A couple things that have been affecting the southern hemisphere in the last few years. There were massive bush fires in Australia around or so which added a lot of soot and ash caused a darkening and a cooling in that region in the southern hemisphere. Also, there was a massive volcanic eruption in the South Pacific in 2022 . The volcanic eruption was meters under the water. So, not only did it send up sulfur dioxide, which generally causes cooling, it also sent up water vapor, huge amounts of water vapor into the upper atmosphere, which caused warming. Okay, so those two effects were competing with each other. the
the aerosols of course that are sent up, the tiny suspended particles, they make the largest contribution to this difference between the hemispheres. They act as cloud condensation nuclei which then reflect sunlight. So in the northern hemisphere in the last few number of years the fine particulate pollution has significantly decreased due to environmental protection measures cleaning up the air in Europe, the US and China. But in the southern hemisphere the bush fires and the eruption of the Hunga Tonga volcano. in the South Pacific in 2021. The bush fires, the volcano, more aerosols in the southern hemisphere, and of course, what it doesn't mention is, of course, the great number of aerosols in the northern hemisphere from the Canadian wildfires in 2923.
Now scientists have previously assumed that the differences in darkening between the two hemispheres would be compensated by changes in cloud cover but the role of clouds in maintaining the symmetry if you like between the hemispheres says it might be limited. So we'll have a look at the actual peer-reviewed paper first. Okay. So there's a link in this article to it. All the links are in the description.
So this is the peer-reviewed paper. We're seeing an emerging hemispheric asymmetry of the Earth's radiation and the Earth's albedo effectively. So we've got 24 years of satellite observations that are in this study. It's from the instrumentation called series CERES clouds and Earth's radiant energy system. It's the acronym.
So it shows a northern hemisphere minus southern hemisphere trend difference of . watts per square meter per decade in absorbed solar radiation ASR. Okay. So the northern hemisphere is getting .34 darker relative to the southern hemisphere. So it's absorbing watts per square meter more solar radiation. Right? darker surfaces absorb more solar radiation. That's sunlight.
And then the outgoing longwave radiation is also significantly different. It's not quite as large. It's .21 watts per square meter per decade. So this darkening of the northern hemisphere relative to the southern hemisphere, it's associated with changes in the differences in the aerosol radiation interactions, the surface albedo and also water vapor changes. Cloud changes also contribute to a greater absorb solar radiation, hemispheric contrast, but the magnitude is small. So I'll look at all the different this paper looks at all the different components that are leading to this hemispheric asymmetry and radiation absorbed solar radiation albedo and so on.
and before like I mentioned we thought that the clouds compensated for these hemispheric asymmetries but it's not they're not able to to to cover it all basically. Okay. So, so this is a very fascinating and interesting and important paper for the overall climate system. Of course, the Earth radiation budget is a key driver of atmospheric and oceanic circulation. On average, the southern hemisphere gains radiative energy at the top of the atmosphere while there's been a net loss in the northern hemisphere. This imbalance is compensated by combining atmospheric and oceanic circulations that transport energy across the equator from the southern hemisphere to the northern hemisphere.
This hemispheric imbalance arises because the war warmer northern hemisphere emits more thermal infrared radiation to space or longwave radiation compared to the southern hemisphere. Because you know look look at the there's a lot more land in the northern hemisphere than in the southern. The water absorbs a lot more solar radiation very dark surfaces and therefore and you know, the heating of the planet heat is going into the ocean. So of course the southern hemisphere is you know moderated kept cooler in general than the northern hemisphere. So there's definite hemispheric differences, but the the southern hemisphere and northern hemisphere average incoming solar radiation is almost identical. So both hemispheres must have nearly the same albedo,
but we're finding that nearly is the key word because it's changing. So hemispheric albedo symmetry, it's been a topic of fascination since it was first observed from satellites. Um, okay. So the this series instrumentation on the satellites it's finding key differences. So let's have a look at the the results basically. Okay. So this is the this is the average in watts per square meter radiative forcing absorbed shortwave radiation. So sunlight comes on the Earth, dark surfaces absorb more, light surfaces reflect more, absorb less. This is the northern hemisphere is the red. Southern hemisphere is the blue. And you can see first of all, you know, this is watts per square meter back in . Now the the absorbed solar radiation is significantly higher and it's been trending upward.
So the Earth has been darkening since 2001 and it's been darkening in the northern hemisphere and se he southern hemisphere sort of equally here but there's been an asymmetry it's now darkening more rapidly in the northern hemisphere than the southern hemisphere you know the gap is getting is quite large here
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this is the outgoing longwave radiation, so when you when you get this absorbed solar radiation shortwave radiation heating the Earth's surface and the Earth radiates heat back out. This heat is infrared radiation, longwave radiation, and then it goes up and out of the Earth's system. Some of it's trapped by water vapor and greenhouse gases of course, but the outgoing longwave radiation has been increasing more in the northern hemisphere than in the southern hemisphere. And the net, if you look, if you smash these two together, you can get the net effect. And you can see that the net effect is the net effect is larger in the southern hemisphere than the northern hemisphere.
If you take the difference between the northern hemisphere and southern hemisphere, the difference between these two curves, you can plot them as like this. Okay? So you can see, you know, the scale you know, watts per square centimeter and you can see you know how how they're trending upward.
So the northern hemisphere, southern hemisphere difference has been trending up at an increasing level. very high in the last couple of years. This is the absorbed shortwave radiation again outgoing longwave radiation and the net radiation. So the Earth is darkening. It's tra it's absorbing more heat. This is a very interesting very telling set of figures here because this is the trend.
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this is the overall trend in the southern hemisphere for absorb solar- absorb solar radiation or absorb shortwave radiation. You can see the southern hemisphere here and then the northern hemisphere of course is it's getting darker more quickly. It's absorbing a lot more. So that's the white bar here higher than than the southern hemisphere.
And this shows you. So this is a total. This is the the IRF is the instantaneous radiative forcing the very rapid radiative forcing. And then this is the response. This is the the longer term response. you can see it for you can so so this is the net here and you can see the various components in both the southern hemisphere and the northern hemisphere. the two sets of bar graphs. So, so you can see what the biggest components are from. Um, this is the total. This is the aerosol effect here. Okay. So, it's generally small. This is solar plus trace gas effects. Um, this is clouds. Clouds is having the biggest effect. Okay. And then this is the surface albedo changes. It's having also a significant effect. Next largest of the clouds, right? This is the loss of sea ice and snow cover and the darkening of the Earth from surface albedo effects and then you get this is the temperature effect and this is the water vapor effect.
So the biggest components of these changes are the clouds followed by the surface albedo followed by the water vapor in the atmosphere. those three things. These are the effects for outgoing longwave radiation and the net effects. Now this is also very interesting. This is a northern hemisphere minus southern hemisphere the trend. So if you do the subtraction, right? The northern hemisphere. Okay, so notice that they're all the northern hemisphere is definitely changing much more quickly than the southern in all of these, you know, the aerosol effect, solar plus trace gas effect, cloud effect, surface albedo effect, temperature, and then water vapor. Okay, so those are all above zero. Northern hemisphere trending faster and this is the outgoing longwave radiation.
So this this is really showing the darkening effect of the Earth and the various components of that overall darkening based on you know is it the aerosols is is the solar energy changing trace gases causing the effect clouds the albedo like loss of snow and ice for example in the Arctic darkening of the snow cover temperature effect and then the water vapor effect. So, so it's all there.
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this is showing the instantaneous radiative forcing anomaly short the shortwave effect. So, what we're seeing is because the northern hemisphere is darkening this effect is is in the red on the red side. So, there's basically there's more red since about . You can see it's taken off. There's a lot more red in the northern hemisphere. There's more blue in the southern. Okay. So the the this is because the northern hemisphere is darkening more. So it's absorbing more solar radiation. The radiation the instantaneous radiative forcing anomaly in watts per square meter is is larger in the northern hemisphere than the southern hemisphere. This is a cloud response. Okay.
So we're getting fewer and fewer clouds, more and more warming watts per square meter just from the cloud effect. We're actually getting warming from the clouds in both hemispheres. It's only near the equator. You know, we're getting intertropical convergence zone shifts and stuff and we're getting less the the response of the cloud. We're getting more clouds which are causing more cooling, you know, to try to compensate the huge increase of temperatures in the tropics here. Okay. so we're getting more and more differences in the hemisphere.
This is the of course the northern hemisphere minus southern hemisphere temperature difference. So global warming is happening more quickly in the northern hemisphere by 0.16° C per decade. You can see the trend. Again, this is the difference between northern hemisphere and southern hemisphere. We're getting much more warming where people, you know, where the land surfaces are. Of course, you know, the oceans tend to try to moderate the and keep the the warming on, you know, lower because there's a huge heat capacity of water. So, it's absorbing that heat and that heat isn't staying in the air causing temperature rises.
The tropical precipitation index is also shifting is also different here. it's been increasing in the tropics we're getting more and more you know higher temperatures more water evaporation from oceans more rainfall in the tropics and this is the the absorb solar radiation cloud contribution difference in the two hemispheres and then the extra in in this is in the tropics and this is in the extratropics. So the cloud effect is causing a reduction of absorbed solar radiation in the tropics. We're getting more clouds in the tropics, but we're getting far fewer in the extrraopics which covers a wider r you know surface area over the planet. So this effect is dominating if you look at the overall planetary effect. Okay.
So this is a very significant and key paper. Now I want to talk about some other things that are changing the hemispheric asymmetry and one of those is the so I mentioned the Australian wildfires also the hunga volcano eruptions unexpected southern hemisphere cooling effect challenges geoengineering assumptions well you know it's a bit misleading the title basically there's there when this volcano went off the sulfur causes a cooling the water vapor causes a warming So, it throws a monkey wrench into the situation. This underwater volcano went off near Tonga in the South Pacific in 2022. It spewed enough water vapor into the stratosphere to push global temperatures higher past 1.5 set by the Paris Accords.
but it caused a reduction of temperature over the southern hemisphere, the sulfur effect. So, you know, why was this so significant? Because the Hunga Tonga volcano erupted January th, from a vent just m below the ocean surface. So it shot up an enormous amount of water vapor along with a moderate amount of sulfur dioxide into the stratosphere, the upper atmosphere. Sulfur dioxide converted to sulfate aerosols that reflect sunlight back into space. So cooled that region.
But the water vapor has a heating effect. So these two effects were opposing. Sulfur sulfate aerosols lead to cooling in the atmosphere. Like pinatubo massive volcano cooled the climate but but water vapor is a powerful greenhouse gas. When it's up in the stratosphere it cools the stratosphere but it it warms the Earth's surface because it traps the infrared radiation. But that effect is what's very important is the the altitude of the water vapor. The higher into the stratosphere it goes, the greater the warming effect on Earth. Okay. So, so that caused the overall global warming. Okay. So, those were two competing things.
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And there's a peer-reviewed paper which is excellent on this particular topic. Um, and I've got the it's open source. The peer-reviewed paper is here and you can look at all of the the details. the southern hemisphere had a radiated forcing of negative at the top of the atmosphere. and these values decreased by about a year later. But the overall warming you know from water vapor you know was a huge compensating factor for that. So there's a lot of detail in this paper about that particular event and it's really a fascinating and interesting paper and I think I've discussed it previously because this this paper is from a while well I think it's from it's from the beginning of the year I believe it doesn't say the the date I don't see the date on there I'm looking for a date but it just says the year I guess that's the six Okay.
So anyway, I don't want to dwell on that. Let's have a look more at some more general albedo discussions here. So what are the major factors changing the albedo of the Earth? Well, these the the major factors are variations in ice and snow cover, variations in cloud abundance and cover, land use changes like deforestation, urbanization, and then atmospheric pollutants like soot and aerosols. Okay, so this on the surface, the snow and ice, right? We if we get more melting of sea ice, glaciers, snow cover, seasonal snow cover, the darker surfaces underneath are exposed. They absorb more sunlight, lowers the overall Earth albedo, increases warming via a self-reinforcing feedback because the warmer it gets, the more melting there is.
The vegetation and land use, right? deforestation, desertification, agricultural activities, alter the the reflect the ground the reflectivity or albedo of the ground. Okay. urbanization introduces darker surfaces like asphalt and for you know roads and roofs and stuff. The atmospheric factors are cloud cover right and then you need to know the altitude of the clouds. So changes in low altitude clouds have a major impact. Fewer clouds mean less sunlight's reflected. More is absorbed by the Earth's surface. So that reduces the planetary albedo. It drives additional warming. And then aerosols and soot. Aerosols reflect sunlight can temporarily increase albedo. but soot deposits in snow and ice darken these surfaces. It can temporarily increase albedo by acting as cloud condensation nuclei. So more clouds, but soot deposits darken the surfaces, amplify warming, and then of course the feedbacks, the ice albedo feedback, the cloud feedback, um, and so on.
So there's all of these factors. The Earth albedo has changed significantly in the last few decades. The Earth albedo has decreased noticeably over the past few decades, leading to a measurable increase in global warming. Since the s, the Arctic albedo has dropped. Globally, the planetary albedo has decreased.
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Okay. So the Earth overall if you measure the reflect reflectance of the Earth overall from satellites look at Earth Earth shine measurements the Earth reflects about 30% of incoming solar radiation but this proportion shrinking. So it's less than 30% and that's changed most quickly in the last years by a huge amount. In 2023 Earth's albedo was possibly at its lowest since 1940. So, the record heat was worsened. And the reduction in reflectivity albedo has led to an increase in absorbed solar over the past two decades. The recent decline in albedo, it can explain up to to ° C of the high temperature we saw in 2023. And this is substantial compared to other warming factors like greenhouse gases and the El Nino.
Okay, so it's a huge effect. The albedo is- the Earth's diminishing albedo. It's becoming darker over recent decades. It's a significant and growing contributor to global warming causing extra heating that's now well documented and quantified by recent scientific studies. Okay, so there you have it. and they talk about more things the contributions and so on. Okay. So it's all and and I I asked some additional questions major factors affecting the the albedo of the Earth and this is looking at the sources right all the different sources a lot of peer-reviewed papers and so on in various journals and in the last few months the most important key papers on albedo they did reanalysis data so Gossling at al 2025 science this would they found that the record low albedo of the Earth was a key driver behind the missing point two Celsius of recent global warming.
the large cloud feedbacks are confirming high climate sensitivity. This is a Hansen and Karishia paper so James Hansen. So years of satellite data shows a marked decline in Earth's albedo mostly from cloud changes supporting the case of high climate sensitivity to greenhouse gas forcing. A paper in Nature they looked at land surface albedo changes so increased land albedo providing radiative cooling but not enough to counter overall warming. decreased albedo in snow covered regions due to less snow, increase in some snow-free areas. So, globe, right? so, they looked at all kinds of different effects. the observed albedo drop in 2023 may be the lowest since at least 1940 So, all of these things are in various scientific papers and so on.
And I looked at a couple other papers. this was a 20-year daily surface albedo along a transsect in Antarctica. And so the surface albedo in Antarctica was seen to be decreasing. Okay. There's an ongoing darkening process of the ice in Antarctica and that's caused. So this is ice on the land. We know of the drop from lack- the vanishing sea ice. But this is but the land is also darkening. Okay. And because it's darkening, we're getting a progressive darkening of the surface snow in Antarctica. Okay. More melt lowers the albedo and so on. the surface snow from coast to dome a the summit of the east Antarctic ice sheet was going dark during 2002 to 2023. So a significant darkening of the ice. another drop of another albedo effect.
We see similar things in the Arctic. This was the Helm Holtz article. The planet's lower reflectivity is causing a sharp increase in global warming which we saw in 2023. Okay. recent global temperature surge intensified by record low planetary albedo. right, there's lots of stuff being coming out on this. you know how the temperatures are skyrocketing because the lower albedo and I just want to look at the albedo of some of the surface of the Earth.
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So this is albedos of different surfaces of the Earth. This is a Colorado University of Colorado Boulder quick bite albedo comparison. So the whole Earth 30%. fresh snow of course 80 to 90% reflectivity sea ice 50 to 70% right depending on if there's snow on top of the sea ice or if the sea if there's water infusion slush versus snow etc. Desert sand typical 40%. Green grass reflects 25% of incoming solar radiation from the sun. Bare soil 17%. Conifer forest pretty dark 8 to 15% reflectance. Open ocean the average is about 6%. Right? Depends a lot on the angle of the incident light. And fresh ashalt 4%. Right? Very very dark. The moon by the way is about 6%. It's not on this particular image but it is on.
So you know if you just Google what's the albedo of various surface of the Earth and select images you can see all these great images of different surfaces etc. you know good examples. So they have the albedo of the moon 6% ashalt five here concrete dry concrete water bodies light roof 35% that tarp I'm going to put up on my roof to to capture to you know capture the micrometeorites which I mentioned in the last video it's also increasing the albedo of my roof so cooling my h will cool my house in the summer
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brick stone 20%, dark roofs 8%. Look, huge difference. We should all have light roofs. Grass 25%, crops, grassland 10%. Forest 10%, fresh snow . The Earth average, it says it's 80 here, in the in the other stuff. And then the Wikipedia page on albedo is is is excellent. You know, it talks all about these different factors. It shows the albedo change in Greenland here. Um, it has a similar chart to what I've already showed you. Aluminum is 85% albedo. Uh, it gives the ranges. Ocean ice, deciduous forest, coniferous forest. So, there's more detail here. New concrete 55%. Um, Warren ashalt There's different details here. Um,
and this is the Earth's albedo reflectivity from to now. You can see how the Earth is getting darker. And now we're seeing that it's getting darker faster in the southern hem in the northern hemisphere than the southern hemisphere. This drop in albedo is equivalent to a 138 part per million increase in atmospheric CO2. Okay, so the CO2 rates going up, greenhouse gases are going up, but the darkening is another effect up above and beyond that. And you can put it in a green in a CO equivalent 38 ppm. That's huge. That's in the last couple decades. And I really like this I really like this chart, this graph here, because it graphically shows the albedo in percent and it gives a range. So this is snow in this whole range. So this is old snow, you know, you get dust particles, it looks darker, grayish, right? It might only be 43% reflecting. New snow fresh, you know, 85% or so. You know, ice has a range here. Water is it depends on the angle of incidence.
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Then you can have dry sand, high albedo, wet sand, much lower. Dry soil, dark soil is darker and much wetter. And then clouds, cumulus Stratus clouds, other clouds only and under. Desert has a range. Savannah has a range. Forest can coniferous versus deciduous, etc. meadows, alto stratus clouds, very high these are cirrus clouds, very high up their albedo range and crops and so on depending on the color. So this is a really this is an excellent illustration of the different albedo ranges of different materials. And there's also this this is interesting. This is the reflectivity of smooth water versus the incident angle from incident angle from normal. Okay. and
you can see that the the angle of the light coming on the water has a huge impact on the reflectivity and whether it's horizontally or vertically polarized light or horizontally polarized light. In fact, horizontally polarized light, the reflectivity goes to zero at something called Brewster's angle here. Okay. So, the angle the reflectivity you know is huge. It's got a huge variation for for water depending on the angle of the sunlight. So, this is important to keep in mind for the albedo of water. especially if you're talking about the southern hemisphere, you need to look at the angle of the sun to calculate what the albedo will be.
And yeah, so it's a really useful site and it actually gives information on different albedos that are used in astronomy for the various planets and so on. So you know the albedo is a term here. Here's the moon. The moon reflects light. You know, Mercury, Venus, Mars, right? There's different types of asteroids and comets and so on.
So, these are the these all have albedos, which is very important for astronomy. Anyway, it's an excellent site in on albedo. So, the key thing is that the Earth is getting a lot darker. the darkness is increasing at faster rates in the northern hemisphere versus the southern is changing the overall circulation of of ocean and atmosphere circulation patterns. So it's very crucial to consider the there's massive changes underway in the overall climate system and albedo is a big and very important part of it. Anyway, thanks for listening. Please go to my website paulbeckwith.net net and donate to PayPal to support my research and videos. Or you can if you prefer Patreon, I'm on there and just search for Paul Beckwwith no space. That's my handle on threads and mastadon and you know LinkedIn and Substack and Reddit, all these other things. I post on all of these things.
So make sure you follow me on those platforms and please share my videos far and wide to help me disseminate the this information where I take peer-reviewed science and try to explain it in hopefully a manner that can educate people and teach people especially people without any science background. So, thanks for listening and bye for now.
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