Stefan

The amount of freshwater found on our planet has dropped significantly in the last decade, NASA satellites have found.

An international team of scientists reviewed observations taken by the Gravity Recovery and Climate Experiment (GRACE) satellites operated by NASA, the German Aerospace Center and the German Research Center for Geosciences. The data collected by GRACE revealed that beginning in May 2014, there was a plunge in Earth’s freshwater supply, and the planet has still not recovered. The researchers suggest that this evidence could also mean Earth is undergoing a drier phase than normal.

New research shows plants absorb 31% more CO2 than previously estimated, raising the global Terrestrial Gross Primary Production (GPP) to 157 petagrams^* per year. Using carbonyl sulfide as a proxy for photosynthesis, this study highlights tropical rainforests’ critical role as carbon sinks and stresses the importance of accurate photosynthesis modeling for climate predictions.

^* One petagram equals 1 billion metric tons, which is roughly the amount of CO2 emitted each year from 238 million gas-powered passenger vehicles.

https://www.nature.com/articles/s41586-024-08050-3

Here is the result of the publication entitled “Assessing the cooling potential of climate change adaptation measures in rural areas“, which indicates that there are large potentials for cooling the landscapes with water retention measures and increased vegetation.

“Our studies show that targeted land use changes can achieve significant cooling of up to 3.5 °C in the Elbe-Elster district. This would be an important contribution to adapting the region to climate change,” explains Prof. Dr. Claas Nendel, co-head of the Data Analysis and Simulation research platform at ZALF and one of the authors of the study. “We can see from our data that more trees and wetlands in the region in particular can reduce the negative effects of heat waves and droughts.”

Using high-resolution satellite data and statistical models, the researchers simulated various scenarios to analyze the potential cooling effects of different measures. Tree populations and wetlands in particular play an important role in the Elbe-Elster district. These landscape elements release water into the atmosphere through evaporation. This creates a cooling effect that can greatly influence the regional climate of a region. Instead of flowing out of the region via the rivers, the water is kept in the regional water cycle.

The study’s methodology can also be used to evaluate climate adaptation measures in other regions. This could support spatial planning and the allocation of funding to identify sensible measures for a specific area. The EU Renaturation Act promotes measures to restore and preserve natural habitats and ecosystems in Europe. The adaptation measures examined in the study, such as the rewetting of wetlands and afforestation, are central elements of this law and contribute to its goal of promoting biodiversity and counteracting climate change. The next step is to implement the provisions into national law. Against this background, the importance of the study results for practical implementation is once again underlined.

https://www.sciencedirect.com/science/article/pii/S0301479724015810

Very interesting study: Continents as sponge landscapes versus deserts. What happens climatically and atmospherically when there is no more water available for evaporation over the continents?

• temperatures rise (due to reduced evaporative cooling)
• precipitation decreases (because evaporation is greatly reduced)
• continental cloud cover decreases (due to lower evaporation)
• this causes the land surface to heat up more
• the residence time of atmospheric water vapor increases by about 50 percent (presumably because there is too little water available for regular cloud formation?)

Abstract:

When we suppress evaporation to create a desert-like planet, we find that temperatures increase and precipitation decreases in the global mean. We find an increase in atmospheric water vapor over both land and ocean in the DesertLand simulation. Suppressing evaporative cooling over the continents reduces continental cloud cover, allowing more energy input to the surface and increasing surface moist static energy over land. The residence time of atmospheric water vapor increases by about 50 percent. Atmospheric feedbacks such as changes in air temperatures and cloud cover contribute larger changes to the terrestrial surface energy budget than the direct effect of suppressed evaporation alone. Without the cloud feedback, the land surface still warms with suppressed land evaporation, but total atmospheric water vapor decreases, and the anomalous atmospheric circulations over the continents are much shallower than in simulations with cloud changes; that is, the cloud feedback changes the sign of the water vapor response. This highlights the importance of accounting for atmospheric feedbacks when exploring land surface change impacts on the climate system.

This extreme experiment raises the question of how real-world changes to the land surface (e.g. land use, agriculture) may be contributing to climate change by altering atmospheric water vapor and cloud cover, and how terrestrial evaporation modulates climate on other planets or in past continental configurations of Earth’s history.

https://iopscience.iop.org/article/10.1088/1748-9326/acdbe1

That’s an important paper and message: Leipzig researchers have found that large-scale deforestation has a greater warming effect on the climate than previously assumed. The cooling effect of cloud cover is reduced by almost half as a result.

Experts led by Hao Luo and Johannes Quaas from the Institute of Meteorology at the University of Leipzig demonstrated a reduction in clouds in these deforested areas by analyzing computer simulations and observations. Deforestation has a warming effect by releasing carbon dioxide, but at the same time forests are darker than the areas after deforestation. This leads to a cooling effect because less sunlight is absorbed. The new study was able to prove that the reduction of cloud cover reduces this cooling effect by almost half.

“We found that as a result of deforestation, low-lying clouds are decreasing globally, and in the tropics, high-lying clouds are also decreasing,” explains Luo. “Low-lying clouds have a cooling effect on the climate because they reflect a lot of sunlight,” adds Quaas. The scientists analyzed idealized deforestation simulations using climate models and reanalyses and, on this basis, provided insights into a local decrease in global low-lying clouds and tropical high-lying clouds as a result of large-scale deforestation.

“The reduced cloud cover can be explained by changes in the turbulent heat flow at the surface, which reduces buoyancy and moisture to varying degrees,” says Quaas, who also works at the German Center for Integrative Biodiversity Research Halle-Jena-Leipzig (iDiv). According to the researchers, the effects of the different meteorological processes in forests and cleared areas on clouds and the associated radiation balance have not yet been sufficiently investigated.

https://www.nature.com/articles/s41467-024-51783-y

I wrote two chapters in this book “3 Degrees more” about nature based solutions to climate change – one about carbon sequestration in the soils, and the other about the potential of vegetation to cool the climate.

This open access book describes in detail what life on this planet would be like if its average surface temperature were to rise 3 degrees Celsius above the preindustrial level. On this basis, the book argues that it is imperative to keep this temperature rise below 2 degrees Celsius. It then lays out a detailed plan of what politically feasible, cost-effective measures should now be taken to achieve this goal. In this context, the book provides detailed discussions of climate finance, climate education and nature-based solutions. The book has been translated into English from the original German version published in 2022, and contains an original foreword and preface.

https://link.springer.com/book/10.1007/978-3-031-58144-1

Permaculture instructor Andrew Millison journeys to Senegal to see a movement of forest gardens which are contributing to Africa’s Great Green Wall. Andrew accompanies the organization Planet Wild to visit the excellent work of Trees for the Future. Planet Wild is funding the planting of 40,000 trees in this project so we are here to assess the system and report on the situation on the ground.

https://www.youtube.com/watch?v=1LCTVO_Y5Rs

Permaculture Instructor Andrew Millison visits the largest reforestation project in the world in the Southern Indian States of Tamil Nadu and Karnataka with the Isha Foundation, founded by Sadhguru. Andrew spent 5 days traveling around the Cauvery River watershed looking at the work of the Isha Foundations’ Cauvery Calling project, touring farms, nurseries, temples, and talking with Isha’s field agents. Andrew then went to Isha’s ashram in Tennessee and was able to directly question Sadhguru about the project.

https://www.youtube.com/watch?v=adTsC7RPlUs

Trees, forests, vegetation cools the planet! We have stated that again and again. Here is another very interesting study, underlining the function of vegetation for the climate:

In the course of global warming due to climate change, temperatures in North America have risen by an average of 0.7 degrees Celsius. Except on the US East Coast, which cooled by around 0.3 degrees Celsius between 1900 and 2000, which scientists refer to as a “warming hole”.

The forests on the US East Coast cooled the surface temperatures of the ground by 1 to 2 degrees Celsius each year. Weather stations surrounded by forests were up to 1 degree cooler than locations that were not reforested. The reforestation program of the 20th century was therefore a gigantic success story for the climate.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023EF003663

Permaculture instructor Andrew Millison journeys with the UN World Food Programme to the Northern border of Senegal to see an innovative land recovery project within the Great Green Wall of Africa that is harvesting rainwater, increasing food security, and rehabilitating the ecosystem.

https://www.youtube.com/watch?v=WCli0gyNwL0

The last post on heat extremes in soils states (from the press release of the scientific publication):

When the temperature in the soil is higher than in the air, additional heat is released to the lower atmosphere – causing temperatures in the atmosphere to rise. “Soil temperature acts as a factor in the feedback loop between soil moisture and temperature and can thus intensify heat waves in certain regions”.

I find this sentence particularly interesting because I suspect that the explanation behind it is the effect of the Stefan-Boltzmann law, and thus the role that land destruction has on the climate.

Of course we know that when nature is destroyed there is an important switch between the production of latent energy (LE; energy bound in water vapor) and sensible heat (“hot air”). Nature produces a lot of LE that can rise vertically into higher parts of the atmosphere without being impeded by naturally occurring or anthropogenic greenhouse gases, where condensation allows some of this released energy to escape into space.

Here is a drawing of mine that shows this:

The Stefan-Boltzmann law describes the intensity of thermal radiation emitted by matter as a function of the temperature of the matter. For an ideal absorber/radiator or black body, the Stefan-Boltzmann law states that the total energy emitted per unit area per unit time is directly proportional to the fourth power of the temperature of the black body, T:

If an area with a forest is 20°C warm, a vegetated field is 35°C warm and an open field is 50°C warm [the three have equal distances of 15°C], the difference in radiant power in W/m2 is 95 for forest/vegetated field and 110 for vegetated field/open field [so not equal, but “exponentially” increasing], see my graph below:

What does this mean now? The natural (as well as the anthropogenic) GHG effect is based on the “reflection” of incoming short-wave solar radiation into outgoing long-wave radiation by GHGs and clouds. If we now create warm surfaces on vast landscapes instead of water vapor that would pass through the greenhouse gases in the atmosphere, which emit long-wave radiation with its fourth power, which is reflected by the greenhouse gases and largely held in the lower part of the atmosphere, we increase the warming of the atmosphere enormously.

Question: How high would the warming effect of anthropogenic greenhouse gases in the atmosphere be without “land use change” as opposed to “land use change”? What role does the altered energy cycle – linked to the water cycle – play in anthropogenic climate change?

In my opinion, 4th power energy radiation and its influence on (naturally occurring, but also anthropogenically added) greenhouse gases is the key to the argument that greened versus ungreened/open/concreted areas are to be distinguished. And have not yet been taken into account in the climate change debate.