Animation shows Earth ‘breathing’ carbon

Global warming will reduce the amount of carbon stored in forests, according to a 2019 study in Nature Communications.

Scientists said it’s because trees tend to “live quickly and die young” in the world’s constantly warming climate.

The research team, led by scientists from Cambridge University, said rising temperatures stimulate annual tree growth, but shorten their lifespan.

The overall result, they said, is a reduction in the amount of carbon stored in forests, as it returns to the environment when they die.

Warm temperatures provide ideal growing conditions for trees that the researchers believe don’t prepare the plant for adversity.

They say the lack of ‘surfacing’ often results in the trees dying if trees grown in cooler climates were to survive.

The researchers said their findings have implications for the dynamics of the global carbon cycle and ultimately for the amount of CO2 in the atmosphere.

As the Earth’s climate continues to warm, they say tree growth will continue to accelerate, but the length of time that trees store carbon — the so-called “carbon residence time” — will decrease.

During photosynthesis, trees and other plants absorb CO2 from the atmosphere and use it to build new cells.

The research team explained that long-lived trees, such as high-altitude pines and other conifers found in forests in high northern latitudes, can store carbon for many centuries.

Lead author of the study, Professor Ulf Büntgen, of the Department of Geography at the University of Cambridge, said: ‘As the planet warms, it causes plants to grow faster, so the thinking is that planting more trees will lead to more carbon is removed from the atmosphere.

“But that’s only half the story. The other half has not been considered: that these fast-growing trees retain carbon for a shorter period of time.’

Professor Büntgen uses the information in tree rings to study past climatic conditions.

He explained that growth rings are as distinctive as fingerprints: The width, density and anatomy of each ring contains information about what the climate was like in that particular year.

By taking core samples from living trees and disk samples from dead trees, scientists can reconstruct how Earth’s climate system behaved in the past and understand how ecosystems responded and respond to temperature variations.

For the study, Professor Büntgen and colleagues took more than 1,100 live and dead mountain pines from the Spanish Pyrenees and 660 Siberian larch samples from the Russian Altai. Both are high-altitude forests that have been undisturbed for thousands of years.

The researchers used the samples to reconstruct the overall lifespan and juvenile growth rates of trees growing during both industrial and pre-industrial climate conditions.

They found that harsh, cold conditions slow tree growth, but they also make trees stronger so that they can reach old age.

But trees that grow faster in the first 25 years die much earlier than their slow-growing relatives.

The negative relationship remained “statistically significant” for samples from both living and dead trees in both regions, according to the findings.


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