Archives par mot-clé : Greening

biology+acidification, climate-debate

Past global photosynthesis reacted quickly to more carbon in the air

by University of Copenhagen, Mar 10, 2022 in ScienceDaily

Ice cores allow climate researchers to look 800,000 years back in time: atmospheric carbon acts as fertilizer, increasing biological production. The mechanism removes carbon from the air and thereby dampens the acceleration in global warming.

Even under ice age conditions will plants, plankton, and other life forms be able to increase production whenever atmospheric carbon concentrations rise. The mechanism will not prevent an ongoing trend of global warming, but at least dampen the acceleration. This conclusion stems from an international collaboration involving the Physics of Ice Climate Earth (PICE) center of Niels Bohr Institute, University of Copenhagen.

“Global biosphere production through photosynthesis is the strongest absorbing flux of atmospheric carbon dioxide. It is therefore essential to understand its natural variability for a better projection of the future carbon cycle,” says Postdoc researcher Ji-Woong Yang, PICE, continuing:

“Nowadays, as we have Earth observation satellites and other advanced equipment, the mechanism of carbon fertilization is well established. However, we were not sure that the same mechanism existed in past periods where the climate was very different and atmospheric carbon concentrations much lower. The new results confirm the existence of the strong correlation and allow us to model future developments with more confidence.”

Eight glacial cycles are covered

In collaboration with Laboratoire des Science du Climat et de l’Environnement, France, the PICE team has studied the ancient air trapped inside tiny air bubbles in an Antarctic ice core. The ice core represents the last 800,000 years of climatic development.

The scientists take advantage of the fact that the oxygen atom does not only exist in the most common form 16O with 8 protons and 8 neutrons but also as the isotopes 17O and 18O. The isotopic composition is a tracer for biosphere productivity. Uniquely, the method will show the global level of biological production in contrast to other methods which give more localized results.

Combining the air bubble measurements with modeling of oxygen behavior in both the biosphere and the stratosphere, the researchers were able to quantify the biosphere productivity evolution under both glacial periods (ice ages) and interglacial periods. In total, eight glacial cycles were covered.

“The results clearly demonstrate that productivity drops during glacial periods and increases during interglacial periods. Further, a strong correlation exists with past atmospheric carbon dioxide concentrations measured from multiple ice cores. In addition, the effect is more prominent during glacial periods where the level of carbon dioxide and the global biosphere productivity start to increase several thousand years before the ice caps begin to melt. This correlation is explained by the strong fertilization effect by atmospheric carbon dioxide,” says Ji-Woong Yang.

unclassified

New Study: Rising CO2 Drives Post-1980s Greening…Which Cools The Earth And Offsets 29% Of Human Emissions

by Haverd et al., 2020 in NoTricksZone/K. Richard

About 70% of the Earth’s post-1980s vegetative greening trend has been driven by CO2 fertilization. More greening has offset or reversed 29% of recent anthropogenic CO2 emissions. Greening also has a net cooling effect on surface temperatures.

Earlier this year we highlighted a study (Haverd et al., 2020) asserting rising CO2 and warming are the dominiant drivers of Earth’s strong post-1980s greening trend. This greening expands Earth’s carbon sink so profoundly that by 2100 the greening of the Earth will offset 17 years (equivalent) of anthropogenic CO2 emissions.

A 17% offset over 80 years, or net CO2 emissions reversal, would easily supplant the effectiveness of Paris climate accord CO2 mitigation policies.

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Now another new study (Piaoet et al., 2020) expands upon these same principles, further suggesting the net effect of more CO2-driven greening is more cooling and carbon sink expansion.

Since the 1980s, 29% of human CO2 emissions were cancelled out by the CO2-induced greening of the Earth. The post-2000 vegetative greening expansion has been so massive (5.4 million km²) its net areal increase is equivalent to a region the size of the Amazon rainforest.

“Vegetation models suggest that CO2 fertilization is the main driver of greening on the global scale, with other factors being notable at the regional scale. Modelling indicates that greening could mitigate global warming by increasing the carbon sink on land and altering biogeophysical processes, mainly evaporative cooling.”

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climate-debate

Flawed Models: New Studies Find Plants Take Up “More Than Twice As Much” CO2 Than Expected

by Fritz Vahrenholt, July 7, 2020 in NoTricksZone

First, the global mean temperature of satellite based measurements was surprisingly much higher in May 2020 than in April. In contrast, the global temperatures of the series of measurements on land and sea decreased. The difference can be explained by the fact that under warm El-Nino conditions the satellite measurements lag about 2-3 months behind the earth-based measurements.

From November 2019 to March 2020 a moderate El-Nino was observed, which has now been replaced by neutral conditions in the Pacific. Therefore, it is to be expected that also the satellite based measurements, which we use at this point, will show a decrease in temperatures within 2-3 months.

The average temperature increase since 1981 remained unchanged at 0.14 degrees Celsius per decade. The sunspot number of 0.2 corresponded to the expectations of the solar minimum.

The earth is greening

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better to know...?, climate-debate

Human Activity in China and India Dominates the Greening of Earth, NASA Study Shows

by NASA, February 11, 2019

The world is literally a greener place than it was 20 years ago, and data from NASA satellites has revealed a counterintuitive source for much of this new foliage: China and India. A new study shows that the two emerging countries with the world’s biggest populations are leading the increase in greening on land. The effect stems mainly from ambitious tree planting programs in China and intensive agriculture in both countries.

The greening phenomenon was first detected using satellite data in the mid-1990s by Ranga Myneni of Boston University and colleagues, but they did not know whether human activity was one of its chief, direct causes. This new insight was made possible by a nearly 20-year-long data record from a NASA instrument orbiting the Earth on two satellites. It’s called the Moderate Resolution Imaging Spectroradiometer, or MODIS, and its high-resolution data provides very accurate information, helping researchers work out details of what’s happening with Earth’s vegetation, down to the level of 500 meters, or about 1,600 feet, on the ground.

A world map showing the trend in annual average leaf area, in percent per decade (2000-2017)
The world is a greener place than it was 20 years ago, as shown on this map, where areas with the greatest increase in foliage are indicated in dark green. Data from a NASA instrument orbiting Earth aboard two satellites show that human activity in China and India dominate this greening of the planet.
Credits: NASA Earth Observatory

Taken all together, the greening of the planet over the last two decades represents an increase in leaf area on plants and trees equivalent to the area covered by all the Amazon rainforests. There are now more than two million square miles of extra green leaf area per year, compared to the early 2000s – a 5% increase.

“China and India account for one-third of the greening, but contain only 9% of the planet’s land area covered in vegetation – a surprising finding, considering the general notion of land degradation in populous countries from overexploitation,” said Chi Chen of the Department of Earth and Environment at Boston University, in Massachusetts, and lead author of the study.

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