Environment

Increased CO2 levels are greening the Earth

Rising levels of atmospheric carbon dioxide in the atmosphere has meant that large parts of the Earth have shown significant greening over the last 35 years
Rising levels of atmospheric carbon dioxide in the atmosphere has meant that large parts of the Earth have shown significant greening over the last 35 years
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Rising levels of atmospheric carbon dioxide in the atmosphere has meant that large parts of the Earth have shown significant greening over the last 35 years
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Rising levels of atmospheric carbon dioxide in the atmosphere has meant that large parts of the Earth have shown significant greening over the last 35 years
The increase in leaf coverage on the Earth in the past 35 years is equivalent to an area twice the size of the continental United States
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The increase in leaf coverage on the Earth in the past 35 years is equivalent to an area twice the size of the continental United States
CO2 levels in the atmosphere have not been this high in more than 500,000 years
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CO2 levels in the atmosphere have not been this high in more than 500,000 years

Researchers studying NASA satellite data on the Earth's vegetation coverage have discovered that plants have significantly increased their leaf cover over the last 35 years to the point that new growth across the planet is equivalent to an area twice as large as the continental United States. According to the study, the largest contributor to this greening is the growing level of carbon dioxide (CO2) in the atmosphere.

Using data collected from instruments such as NASA's Moderate Resolution Imaging Spectrometer mounted on the AquaProbe satellite and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer (such as that deployed on NOAA's DSCOVR satellite), an international team of researchers has determined that CO2 fertilization explains fully 70 percent of the greening effect observed.

Of the approximately 10 billion tons of carbon spewed into the atmosphere from human-created sources every year, about 50 percent is stored for the short-term in the oceans and in plants. Generally, this has been shared relatively evenly between vegetation and the seas acting as carbon sinks. Now, with an increased level of uptake in plants, as demonstrated by their increased leaf growth, there may be a slight shift in that storage towards the vegetation on land.

"While our study did not address the connection between greening and carbon storage in plants," said research participant Shilong Piao of the College of Urban and Environmental Sciences at Peking University. "Other studies have reported an increasing carbon sink on land since the 1980s, which is entirely consistent with the idea of a greening Earth."

The increase in leaf coverage on the Earth in the past 35 years is equivalent to an area twice the size of the continental United States
The increase in leaf coverage on the Earth in the past 35 years is equivalent to an area twice the size of the continental United States

As is well known, CO2 is vital for the biological process of photosynthesis in plants where leaves harness energy from sunlight to combine CO2 with water and minerals from the soil to create sugars. So increasing the available CO2 simply spurs growth by providing more of the gas required to feed the plant.

However, CO2 fertilization isn't the only factor involved; it may be a large proportion, but nitrogen deposition is responsible for almost a further 10 percent of the observed greening, according to the researchers. Nitrogen deposition is the movement of reactive nitrogen from the atmosphere to the ground, where it is absorbed by plants. Much of the gases responsible for nitrogen deposition are produced as a result of exhaust emissions of oxidised nitrogen (NO, HNO3 and NO2) from the burning of fossil fuels.

"The second most important driver is nitrogen, at 9 percent," said professor Ranga Myneni, from Boston University. "So we see what an outsized role CO2 plays in this process."

Adding to CO2 and nitrogen's role in the process is also land cover use change by humans, climate change influenced by increases in global temperature, and subsequent alterations to rainfall and sunlight patterns all brought about by global warming. In this way, all aspects contributed to the greening effect and, though CO2 was by far the largest contributor, it is predicted that its influence can only improve plant growth so far before increasing levels can no longer be absorbed by vegetation.

"Studies have shown that plants acclimatize, or adjust, to rising carbon dioxide concentration and the fertilization effect diminishes over time," said Dr. Philippe Ciais, associate director of the Laboratory of Climate and Environmental Sciences, Gif-suv-Yvette, France.

CO2 levels in the atmosphere have not been this high in more than 500,000 years
CO2 levels in the atmosphere have not been this high in more than 500,000 years

As a result, whilst the increasing CO2 concentrations in the atmosphere may be beneficial to plants in the short term, it still remains the major contributor to rapid climate change. Keeping heat in the Earth's atmosphere by reducing longwave heat radiation into space, CO2 has been on the rise since the dawn of the industrial era, and continues to increase as we burn more fossil fuels for energy production.

Concentrations haven't been as high as they are today for at least the past 500,000 years, and climate change is increasing the temperature of the planet, forcing sea levels to rise, glaciers and sea ice to melt, and adversely increasing severe weather patterns and increasing storm strength.

"[The extent of the greening over the past 35 years] has the ability to fundamentally change the cycling of water and carbon in the climate system," said lead Zaichun Zhu, a researcher from Peking University, China, a lead author on the climate study.

So, whilst the favorable effects of CO2 on plants may both improve the capacity and production of vegetation on Earth, it is almost certainly only a short-term beneficial by-product of a much greater problem, particularly when plants can no longer absorb any more and oceans are full to capacity with this gas. At that point we will have a much, much greater problem on our hands, no matter how green our trees may be.

The research paper was recently published in the journal Nature Climate Change.

The video below is NASA's short take on the research.

Source: NASA

Update May 2, 2016: This story originally referred to nitrogen as a greenhouse gas when referring to nitrogen deposition. While nitrous oxide is a greenhouse gas, nitrogen is not. We apologize for the error and have modified the text accordingly.

Rising CO2 Levels Greening Earth

17 comments
MarkJones8bb2ceed5bee4b24
That's why I go for long drives,
VincentWolf
So if the CO2 is increasing and plant life is flourishing--wouldn't then the oxygen concentration in our atmosphere being to slowly rise as well since trees produce oxygen as a byproduct of their chlorophyll derived energy process? "On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four." - Environment Canada, Canada's national environmental agency So do we risk not only dying from overheating our atmosphere but also from having a too rich oxygen concentration (which can be a poison to us) at some point in the future if we never stop using gas and oil? Thus returning our atmosphere to a point not seen for billions of years before single cell organism harnished that oxgyen to support their live (algae).
JanetCarsonhopper
been saying for 35 years my trees are growing faster, walnuts growing 3 feet or more a year. used to grow about 2 feet a year.
amazed W1
The article seems to be unnecessarily pessimistic. Surely if we don't cut down the increased vegetation the beneficial effect of greening continues - more carbon is sequestrated before we reach saturation. Obviously it isn't the solution to the total problem but it should have a useful super-marginal effect on the growth of renewable fuel sources. The fascinating thing is that it illustrates what we were taught at school as "Le Chatelier's principle", basically that there is a reaction to every action that tends to counter the said action.
Fretting Freddy the Ferret pressing the Fret
@VincentWolf No, you don't need to worry about trees. You need to worry about algae, since they are responsible for producing most of Earth's oxygen by far.
CliffG
Watch the fossil fuel apologists glom onto this piece of information. But the point is CO2 levels continue to rise along with global temperatures. Maybe a useful analogy is one tends to bail faster as the boat sinks. Not mentioned here is that plant growth in many places is not constrained by CO2 or nitrogen, but by water availability. As climates change under AGW the distribution of precipitation changes, further screwing up the system that enables life.
Robert in Vancouver
The article again tells us that sea levels are rising due to man made climate change. That's a just another pile of climate change scaremongering BS! I have lived 50 metres from the Pacific Ocean for 27 years and cannot see any change to high tide marks on piers, sea walls, or beaches. No change whatsoever. None.
kisu1492
Didn't it take algae scores of millions of years to increase atmospheric oxygen concentrations from around 0 to around 20%? Also, the article says nitrogen is a greenhouse gas. It isn't.
Joe Maxwell
The latest research I read shows that the earth is not warming but cooling at this time. Greenhouse gases have almost no effect on climate change. Cloud cover has much greater impact. Normal cycles that we have no control over effect us in many ways including the stock market and the economies as well as climate change. Adding more people to this planet, is our biggest problem. We have only so much area to grow food and only so much space for people to live. China's experiment of limiting the number of children turned out to be a desaster. Maybe we should eat a lot more algae and insects
piperTom
From the article: "... another greenhouse gas produced as a by-product of human activities, nitrogen, is responsible for [something]". Nitrogen?!?! Surely, you meant to say nitrates or nitrites or... anything but just "nitrogen" which is already 78% of the air. It's hard to see how any human production could influence the over 4 quadrillion tons of nitrogen already in the air.