Oct 20th 2015

Despite decades of deforestation, the Earth is getting greener

by Yi Liu, Albert Van Dijk, and Pep Canadell

Yi Liu is ARC DECRA Fellow in Earth Observation, UNSW Australia Albert Van Dijk is Professor of Water Science and Management, Fenner School of Environment & Society, Australian National University Pep Canadell is Executive director, Global Carbon Project, CSIRO
While the news coming out of forests is often dominated by deforestation and habitat loss, research published today in Nature Climate Change shows that the world has actually got greener over the past decade.

Despite ongoing deforestation in South America and Southeast Asia, we found that the decline in these regions has been offset by recovering forests outside the tropics, and new growth in the drier savannas and shrublands of Africa and Australia.

Plants absorb around a quarter of the carbon dioxide that people release into the atmosphere by burning fossil fuels. With a greening globe, more plants may mean more absorption of carbon dioxide. If so, this will slow but not stop climate change.

However, questions remain over how long plants can keep pace with our increasing emissions in a warmer climate.

Measuring carbon in plants

We studied how plants and vegetation are faring by determining the amount of carbon stored in living plant mass (or “biomass”) above the ground.

We developed a new technique to map changes in vegetation biomass using satellite measurements of changes in the radio-frequency radiation emitted from the Earth’s surface, a technique called passive microwave remote sensing. The radiation varies with temperature, soil moisture and the shielding of water in vegetation biomass above the ground.

We extracted this vegetation information from several satellites and merged them into one time series covering the last two decades. This allowed us to track global changes in biomass from month to month, something that was not possible before.

For the period 2003-12, we found that the total amount of vegetation above the ground has increased by about 4 billion tonnes of carbon.

Still losing rainforests, but gaining forests elsewhere

Our global analysis shows losses of vegetation in many regions, particularly at the frontiers of deforestation in the tropics of South America and Southeast Asia.

As expected, the greatest declines have been in the so-called “Arc of Deforestation” on the southeastern edge of the vast Amazon forests. In Southeast Asia we found the most widespread declines in the Indonesian provinces of Sumatra and Kalimantan - the Indonesian part of Borneo.

However, we found that these rainforest losses have been offset by increases in biomass in other parts of the world.

For example, forests have spontaneously regrown on farmland abandoned after the fall of communism in Russia and neighbouring countries, while large-scale tree planting projects in China have measurably added to the global biomass. This roughly offset half of the carbon loss by tropical deforestation.

We also found unexpectedly large vegetation increases in savannas and shrublands of Australia, Africa, and South America. Previous analyses have focused on closed forests and did not measure this increase.

Is Australia getting greener?

On average, Australia is “greener” today than it was two decades ago. This is despite ongoing land clearing, urbanisation and the recent droughts in some parts of the country.

However, the increase in vegetation has not been uniform. The largest increases are in northern Australia, with lesser increases in southern Australia and a small decrease in southeastern Australia.

Mean annual change in vegetation biomass between 1993 and 2012. Blue represents an increase; red a decrease. Image modified from Liu et al., 2015

These vegetation trends seem to be mainly explained by rainfall patterns: northern Australia has been getting wetter and southeast Australia dryer. This pattern is predicted to continue according to the most recent climate change projections from the CSIRO and the Bureau of Meteorology.

Australian vegetation growth generally responds strongly to rainfall variations. More variability and an apparently increasing frequency of extreme El Niño and La Niña events due to climate change would create stronger boom-bust cycles in Australia’s vegetation.

Apart from the effect of rainfall patterns, our study also agreed with other studies observing a gradual greening trend for the past two decades, even where there was no change or even a small decrease in rainfall.

This has been ascribed mainly to the increasing number of trees and shrubs growing on semi-arid grasslands. These plants are more efficient water users than other plants such as grasses. With the increased atmospheric concentration of carbon dioxide from fossil fuel emissions, they are able to absorb more carbon from the atmosphere without using more water.

More vegetation will slow but not prevent climate change

The world’s vegetation plays an important role in slowing down climate change. About a quarter of all carbon emissions from human activities are removed by terrestrial vegetation, with the size of the carbon land sink increasing over time.

However, it remains to be seen how the increased climate variability that accompanies climate change will affect this terrestrial “carbon sink” in future. This is particularly true for seasonally dry ecosystems that experience fires, such as Australia’s savannas, where a single fire event can easily remove the carbon stored in plant biomass over many previous years. The future interaction between climate variability, vegetation and fire is difficult to predict and remains the focus of intense research.

Overall, our study provides more direct evidence of the global increase of vegetation growth and the terrestrial carbon sink than previous studies, with unprecedented geographical attribution and year-to-year changes.

With terrestrial vegetation removing about a quarter of the carbon emissions from human activities and the global oceans removing another quarter, this means that half of our CO2 emissions remains in the atmosphere. Therefore, stabilising concentration of CO2 in the atmosphere and the consequent impact on the climate system will still require large reductions of global fossil fuel emissions.

This article was originally published on The Conversation. Read the original article.

Browse articles by author

More Essays

Jun 17th 2021
EXTRACT: "Confronting our complex history and ultimately embracing a more equitable, balanced, and humble culture may be a tall order in these fractious times. But that makes it even more imperative that we fully reckon with who we are and who we are capable of becoming."
Jun 11th 2021
EXTARCT: "A further health benefit of hiking is that it’s classed as “green exercise”. This refers to the added health benefit that doing physical activity in nature has on us. Research shows that not only can green exercise decrease blood pressure, it also benefits mental wellbeing by improving mood and reducing depression to a greater extent than exercising indoors can."
Jun 10th 2021
EXTRACT: "“The greatness of a nation and its moral progress,” Mahatma Gandhi said, “can be judged by the way its animals are treated.” If we apply that test to the world as a whole, how much moral progress have we made over the past two millennia? ...... That question is suggested by The Golden Ass, arguably the world’s earliest surviving novel, written around 170 CE, when Emperor Marcus Aurelius ruled the Roman Empire. Apuleius, the author, was an African philosopher and writer, born in what is now the Algerian city of M’Daourouch."
Jun 4th 2021
EXTRACT: "Research we’ve done, which looked at 37 adults with type 2 diabetes, found that over two weeks, prolonged sitting was associated with high blood sugar levels. But we also found that when people stood up or walked around between periods of sitting, they had lower blood sugar levels. Other studies have also had similar results."
May 28th 2021
EXTRACT: "Paul Van Doren's legacy lies in a famous company, and in his advice to young entrepreneurs to get their hands dirty, and to know what goes into making what they are selling."
May 19th 2021
EXTRACT: "May 7th marked three hundred and ten years since the philosopher David Hume was born. He is chiefly remembered as the most original and destructive of the early modern empiricists, following John Locke and George Berkeley." .... " Shocking as it may (and should) sound, Hume is implying nothing less than that the next time you turn the key in your car ignition, you are as justified to expect the engine will start as you are in believing it will turn into a pumpkin. For there is a radical contingency that pervades all our experience. We could wake up tomorrow to a world that looks and behaves very differently to the one we are in now. Matters of fact are dependent on experience and can never be known a priori — they are purely contingent, and could always turn out different than what we expect."
May 1st 2021
EXTRACT: " The sad reality is that the Mizrahim (Jews of Middle Eastern and North African descent) were discriminated against from the day of Israel’s inception, whose Ashkenazi (European Jewish) leaders viewed them as intellectually inferior, “backward,” and “too Arab,” and treated them as such, largely because the Ashkenazim agenda was to maintain their upper-class status while controlling the levers of power, which remain prevalent to this day." ..... " The greatest heartbreaking outcome is that for yet another generation of Israelis, growing up in these debilitating conditions has a direct effect on their cognitive development. A 2015 study published in Nature Neuroscience found that “family income is significantly correlated with children’s brain size…increases in income were associated with the greatest increases in brain surface area among the poorest children.” "
Apr 25th 2021
EXTRACT: "We all owe Farah Nabulsi an enormous debt of gratitude. In a short 24-minute film, The Present, she has exposed the oppressive indecency of the Israeli occupation while telling the deeply moving story of a Palestinian family. What is especially exciting is that after winning awards at a number of international film festivals​, Ms. Nabulsi has been nominated for an Academy Award for this remarkable work of art. " 
Apr 25th 2021
EXTRACT: "When I crashed to the floor of my home in Bordeaux recently after two months of Covid-19 dizziness, I was annoyed. The next day I collapsed again. Now I was worried. What I didn’t know was that my brain was sloshing around inside my skull, causing a mild concussion. Nor did I know that I was in for a whole new world of weird and wonderful hallucinations."
Apr 13th 2021
EXTRACT: "Overall, our review has found that there isn’t evidence to back up the claims that veganism is good for your heart. But that is partly because there are few studies ....... But veganism may have other health benefits. Vegans have been found to have a healthier weight and lower blood glucose levels than those who consume meat and dairy. They are also less likely to develop cancer, high blood pressure and diabetes. "
Apr 8th 2021
EXTRACT: "Pollock’s universe, the universe of Mural, cannot be said to be a rational universe. Nor is it simply devoid of all sense. It is not a purely imaginary world, although in it everything is in a constant state of flux. Mural invokes one of the oldest questions of philosophy, a question going back to the Pre-Socratic philosophers Parmenides and Heraclitus – namely, whether the nature of Reality constitutes unchanging permanence or constant movement and flux. For Pollock, the only thing that is truly unchanging is change itself. The only certainty is that all is uncertain."
Apr 8th 2021
EXTRACT: "Many present day politicians appear to have psychopathic and narcissistic traits too. It’s easy to spot such leaders, because they are always authoritarian, following hardline policies. They try to subvert democracy, to reduce the freedom of the press and clamp down on dissent. They are obsessed with national prestige, and often persecute minority groups. And they are always corrupt and lacking in moral principles."
Apr 6th 2021
EXTRACT: "This has led some to claim that not just half, but perhaps nearly all advertising money is wasted, at least online. There are similar results outside of commerce. One review of field experiments in political campaigning argued “the best estimate of the effects of campaign contact and advertising on Americans’ candidates choices in general elections is zero”. Zero!"
Mar 30th 2021
EXTRACT: "The Father is an extraordinary film, from Florian Zeller’s 2012 play entitled Le Père and directed by Zeller. I’m here to tell you why it is a ‘must see’." EDITOR'S NOTE: The official trailer is attached to the review.
Mar 28th 2021
EXTRACT: "Picasso was 26 in 1907, when he completed the Demoiselles; de Kooning was 48 in 1952, when he finished Woman I.  The difference in their ages was not an accident, for studies of hundreds of painters have revealed a striking regularity - the conceptual painters who preconceive their paintings, from Raphael to Warhol, consistently make their greatest contributions earlier in their careers than experimental painters, from Rembrandt to Pollock, who paint directly, without preparatory studies."
Mar 26th 2021
EXTRACT: "Mental toughness levels are influenced by many different factors. While genetics are partly responsible, a person’s environment is also relevant. For example, both positive experiences while you’re young and mental toughness training programmes have been found to make people mentally tougher."
Mar 20th 2021

The city of Homs has been ravaged by war, leaving millions of people homeless an

Mar 20th 2021
EXTRACT: "There are two main rival models of ethics: one is based on rights, the other on duties. The rights-based model, which traces its philosophical origins to the work of John Locke in the 17th century, starts from the assumption that individuals have rights ....... According to this approach, duties are related to rights, but only in a subordinate role. My right to health implies a duty on my country to provide some healthcare services, to the best of its abilities. This is arguably the dominant interpretation when philosophers talk about rights, including human rights." ........ "Your right to get sick, or to risk getting sick, could imply a duty on others to look after you during your illness." ..... "The pre-eminence of rights in our moral compass has vindicated unacceptable levels of selfishness. It is imperative to undertake a fundamental duty not to get sick, and to do everything in our means to avoid causing others to get sick. Morally speaking, duties should come first and should not be subordinated to rights." ..... "Putting duties before rights is not a new, revolutionary idea. In fact it is one of the oldest rules in the book of ethics. Primum non nocere, or first do no harm, is the core principle in the Hippocratic Oath historically taken by doctors, widely attributed to the ancient Greek philosopher and physician Hippocrates. It is also a fundamental principle in the moral philosophy of the Roman statesman Marcus Tullius Cicero, who in De Officiis (On Duties) argues that the first task of justice is to prevent men and women from causing harm to others."
Mar 18th 2021
EXTRACT: "Several studies have recently compared the difference between antibodies produced straight after a coronavirus infection and those that can be detected six months later. The findings have been both impressive and reassuring. Although there are fewer coronavirus-specific antibodies detectable in the blood six months after infection, the antibodies that remain have undergone significant changes. …….. the “mature” antibodies were better at recognising the variants."
Mar 15th 2021
EXTRACT: "Like Shakespeare, Goya sees evil as something existing in itself – indeed, the horror of evil arises precisely from its excess. It overflows and refuses to be contained by or integrated into our categories of reason or comprehension. By its very nature, evil refuses to remain within prescribed bounds – to remain fixed, say, within an economy where evil is counterbalanced by good. Evil is always excess of evil." ....... "Nowhere is this more evident than in war. Goya offers us a profound and sustained meditation on the nature of war ........ The image of a Napoleonic soldier gazing indifferently on a man who has been summarily hanged, probably by his own belt, expresses the tragedy of war – its dehumanization of both war’s victims and victors."