The main carbon store in the planet’s soil is peat, a deposit of plant origin found in water-saturated areas called peat bogs or peatlands. In total, peatlands contain over 550 gigatons of carbon in the form of partially decomposed plant matter, representing 42% of all soil carbon worldwide. There are peat bogs everywhere from the tropics to the polar icecaps, but polar peatlands are particularly important because of the large expanse of the Earth’s surface they cover and the fact that they often lie in areas of permafrost, i.e. perennially frozen ground. Permafrost immobilizes carbon in peat, helping prevent it from being released into the atmosphere in the form of greenhouse gases, such as carbon dioxide (CO2) or methane (CH4). There is permafrost under approximately 25% of the surface of the Northern Hemisphere. Permafrost immobilizes carbon in peat, helping prevent it from being released into the atmosphere in the form of greenhouse gases, such as carbon dioxide or methane. CREAF researchers Olga Margalef, Oriol Grau and Sergi Pla-Rabés have recently returned from an expedition to northern Alaska (Toolik, 68º N), which they undertook to gain an insight into what will happen if global warming causes the permafrost in peat bogs to melt. Understanding the key role peatlands play in the functioning of the planet is vital and urgent, not only because they act as a carbon sink but also because they contain a large quantity of essential nutrients, such as nitrogen and phosphorus, whose cycle in such ecosystems has been the subject of very little study. “Permafrost degradation is occurring because rising temperatures are melting the ice it contains”, says Olga Margalef. “Southern permafrost boundaries are receding northwards and have fallen back by 30 to 80 km over the last few decades”, she notes. “It’s crucial that we study the effects of the thawing of permafrost to understand how biogeochemical cycles could change worldwide”, she continues. “We expect that huge amounts of CO2 will be emitted into the atmosphere, and that large quantities of phosphorus and nitrogen will be released into water and made available to organisms.” Southern permafrost boundaries are receding northwards and have fallen back by 30 to 80 km over the last few decades. This was the researchers’ second field campaign, following a previous expedition to the province of Lappland in Sweden. Both campaigns received funding from INTERACT (a European initiative for giving young researchers access to remote research stations) through the P-PEAT and P-PEAT 2 projects. The samples taken in Sweden shed light on 9,000 years of the region’s history In 2018, the researchers sampled plants and soil at a range of depths in Sweden, where the permafrost is discontinuous and the ice forms small, lentil-like spots. Their goal was to compare areas in which the permafrost had remained intact and others in which it had recently thawed. “Frozen soil isn’t easy to sample – it’s as hard as rock – and you have to use a drilling machine”, remarks Oriol Grau. “The one we used was designed specifically for our work and was fitted with a motor”, he explains. The goal was to compare areas in which the permafrost had remained intact and others in which it had recently thawed. The researchers also took a continuous sample of soil spanning a vertical distance of more than a metre to enable them to study the layers of peat that had been built up over time and which the permafrost had preserved like the pages of a book. The sample will be used to reconstruct environmental conditions in the distant past. “The sample contains more than 9,000 years of the region’s history, so it will help us understand the dynamics of permafrost formation and degradation in the Holocene”, says Sergi Pla-Rabés. Alaska’s permafrost is melting too In Alaska, in contrast, the permafrost is continuous. Even so, the researchers observed permafrost zones where warming had already caused degradation, both at the edges and in the middle of peat bogs. They did so by taking peat samples at different depths in the unfrozen, living surface layer and the frozen part alike. They also sampled plants and carried out exhaustive sampling on water to study its chemistry and the abundance of diatoms (a type of microscopic algae) in it. The researchers reported that colder temperatures, heavy rain and snow, and a two-and-a-half-hour slog from the research station to the sampling area made the second campaign a great deal harder than the first. "The researchers observed permafrost zones where warming had already caused degradation, both at the edges and in the middle of peat bogs." Comparing the findings of the two campaigns will help further our understanding of the effects of the thawing of continuous and discontinuous permafrost.
According to an article by CREAF researchers Benjamin Stocker and Josep Peñuelas published in Nature Geoscience, drought impact studies based on satellite data do not factor in the effects of soil moisture.
A study led by CREAF shows that decreases in pollutant deposition and the increase in atmospheric CO2 have stimulated photosynthesis and carbon sequestration in forests. Therefore, it is crucial to understand how carbon circulates in the atmosphere, in living organisms, oceans, and soils in order to anticipate the effects of climate change.
The Global Carbon Budget 2017 has analyzed carbon emission sources and sinks worldwide. This year the researcher Benjamin Stocker from CREAF has collaborated in the report contributing and preparing data about how the change in the use we give to the territory has affected CO₂ emissions.
A new study led by Josep Peñuelas and published in Nature Ecology and Evolution reveals that CO2 abundance in the atmosphere no longer has a powerful fertilizing effect on vegetation. The greening that has been observed in recent years is slowing and this will cause CO2 levels in the atmosphere to rise, thus increasing temperatures and leading to increasingly severe changes in climate.
A new study has concluded that, universally, trees that have died from drought are unable to transport water to their leaves. The findings also highlight trees that have drained their carbon reserves since they are not able to carry out photosynthesis. The results of the study will permit the creation of more precise models for predicting the effects of climatic changes on vegetation.
The COP21 set the maximum temperature increase for 2100 at 1.5° C. The only scenario which would allow achievement of this goal would require vastly reducing human CO2 emissions, significantly increasing the prominence of renewable energies, and the use of some type of artificial carbon sequestration technology.
An international team of researchers co-led by Josep Peñuelas (CSIC and CREAF) has developed a new method for monitoring changes in the photosynthetic activity of perennial conifers throughout the year. This new technique, based on the analysis of remote sensing images captured by satellites, will improve global models of atmospheric carbon capture and permit more precise predictions about climate change.
The journal Nature has today published a study which had the participation of CSIC scientists at CREAF, Marc Estiarte and Josep Peñuelas, which demonstrates the relationship between the release of carbon from soils and the acceleration of climate change.
Since 1982, Earth has become greener in an area covering 36 million km2, close to two times the size of the United States. Above all, this seems to be the result of a fertilizing effect of atmospheric carbon dioxide (CO2) on plants. The study was carried out with satellite images which can capture this increase in terrestrial leaf area.
CREAF researchers uncover how climate change-provoked substitutions of pines with holm oak affect soil respiration10 de March 2016Albert Naya i Díaz
Scots pine is the tree species with the greatest latitudinal distribution between Siberia and the Iberian Peninsula. The death of these pines due to drought does not affect CO2 emissions from forest soil.
The worst scenario occurs when NAO and EA are in opposite phases. This ocurred in the first few years of the previous decade and during this period, the CO2 uptake was below average. Recently, NAO and EA were in the same phase and ecosystems have been able to remove more carbon from the atmosphere.
A study carried out by researchers from CREAF and the UAB shows that restoring degraded land with sewage sludge aids carbon sequestration in the soil. These organic wastes improve soil structure and the growth of plants, and these are eventually incorporated into the soil as soil carbon.
Researchers from the UAB, CREAF and the National Museum of Natural Sciences (MNCN-CSIC) have analysed how the deterioration of woods caused by droughts associated to global warming are affecting the microbial composition of the soil and modifying carbon cycles.
Nightime temperatures on the planet have increased 1.4 times faster than daytime temperatures. This asymmetry alters carbon fluxes and plant growth in the northern hemisphere, according to a study in which the CREAF is participating.