From the desk of editor in chief,
Meher Kashif Younis:
“Declining plant growth is linked to decreasing air moisture tied to global warming Scientists say the greening effects from rising levels of car bon dioxide might be over”. NASA
Earth is losing its greenery due to many factors including an increasing number of houses and agriculture. We need to take steps to increase forest cover to restore nature. There is a need to balance the development and restoration of the environment.
The world is gradually becoming less green, scientists have found. Plant growth is declining all over the planet, and new research links the phenomenon to decreasing moisture in the air a consequence of climate change. Since then, more than half of the world’s vegetated landscapes have been experiencing a “browning” trend, or decrease in plant growth, according to my research.
Climate records suggest the declines are associated with a metric known as vapor pressure deficit that’s the difference between the amounts of moisture the air actually holds versus the maximum amount of moisture it could be holding. A high deficit is sometimes referred to as an atmospheric drought.
Since the late 1990s, more than half of the world’s vegetated landscapes have experienced a growing deficit, or drying pattern.
The planet’s climate would also be drastically altered in the short and long term. Trees mediate the water cycle by acting as biological pumps: they suck water from the soil and deposit it into the atmosphere by transforming it from liquid to vapor. By doing this, forests contribute to cloud formation and precipitation. Trees also prevent flooding by trapping water rather than letting it rush into lakes and rivers, and by buffering coastal communities from storm surges. They keep soil in place that would otherwise wash away in rain, and their root structures help microbial communities thrive.
Without trees, formerly forested areas would become drier and more prone to extreme droughts. When rain did come, flooding would be disastrous. Massive erosion would impact oceans, smothering coral reefs and other marine habitats. Islands stripped of trees would lose their barriers to the ocean, and many would be washed away. “Removing trees means losing huge amounts of land to the ocean,” says Thomas Crowther, a global systems ecologist at ETH Zurich in Switzerland and lead author of the 2015 Nature study.
In addition to mediating the water cycle, trees have a localized cooling effect. They provide shade that maintains soil temperatures and, as the darkest thing in the landscape, they absorb heat rather than reflect it. In the process of evapotranspiration, they also channel energy from solar radiation into converting liquid water into vapor. With all of those cooling services lost, most places where trees formerly stood would immediately become warmer. In another study, Prevedello and his colleagues found that complete removal of a 25 sq. km patch of forest caused local annual temperatures to increase by at least 2C in tropical areas and 1C in temperate areas. Researchers have also found similar temperature differences when comparing forested and open areas.
On a global scale, trees combat warming caused by climate change by storing carbon in their trunks and removing carbon dioxide from the atmosphere. Deforestation already accounts for 13% of total global carbon emissions, according to an IPCC report published in August, while land use change in general accounts for 23% of emissions. With all trees on the planet wiped out, previously forested ecosystems “would become only a source of emission of carbon dioxide into the atmosphere, rather than a sink,” says Paolo D’Odorico, a professor of environmental science at the University of California, Berkeley. Over time, Crowther predicts that we would see the release of 450 gigatons of carbon into the atmosphere more than doubling the amount that humans have already contributed. For a while, this effect grasses. But while smaller plants capture carbon at a faster rate than trees, they also release it more rapidly. Eventually perhaps over a few decades these plants would no longer be able to head off the coming warming. “The timeline depends on where you are, since decomposition is much faster in the tropics than the Arctic,” D’Odorico says. “But once carbon dioxide is in the atmosphere, it doesn’t matter if it’s coming from here or from there.”
Humanity’s suffering would begin well before catastrophic global warming took place, however. The increased heat, disruption to the water cycle and loss of shade would take a deadly toll on billions of people and livestock. Poverty and death would also descend on many of the 1.6 billion people who currently rely directly on forests for their livelihoods, including for harvesting food and medicine. More people still would find themselves unable to cook or heat their homes, given the lack of firewood. Around the world, those whether as loggers or paper-makers, fruit growers or carpenters would suddenly be jobless, devastating the global economy. The timber sector alone provides employment to 13.2 million people and generates $600bn (£500bn) each year, according to the World Bank.
Agricultural systems would likewise swing wildly out of whack. Shade crops like coffee would drastically decline, as would ones that rely on tree-dwelling pollinators. Due to temperature and precipitation fluctuations, places that formerly produced crops would suddenly fail while others that were previously unsuitable might become desirable. Over time, though, soils everywhere would become depleted, requiring significant amounts of fertilizer for crops to survive. Further heating would eventually render most places uncultivatable and unlivable.
On top of these devastating changes would be health impacts. Trees clean the air by absorbing pollutants and trapping particulate matter on their leaves, branches and trunks. Researchers from the US Forest Service have calculated that trees in the US alone remove 17.4 million tons of air pollution each year, a service valued at $6.8bn (£5.6bn). At least 850 lives are saved as a result and at least 670,000 cases of acute respiratory issues are avoided.
All told, human beings would struggle to survive in a world without trees. Urbanized, Western lifestyles would quickly become a thing of the past and many of us would die from starvation, heat, drought and floods. Surviving communities, Lowman believes, would likely be those that have retained traditional knowledge about how to live in treeless environments, such as Australia’s Aboriginals. Crowther, on the other hand, suspects that life would only persist in a Mars like colony, enabled by technology and entirely divorced from the existence we have always known.
“Even if we could live in a world without trees, who would want to?” Crowther says. “This planet is unique from everything else we currently know in the universe because of this unexplainable thing called life, and without trees, almost all of it would just be screwed.” As the population is continuously increasing, there is a growing need for housing, which is resulting in the cutting of trees. WHAT ARE THE MAIN CAUSES OF DEFORESTATION?
1. INDUSTRIAL AGRICULTURE
Look no further than your dinner plate, because industrial agriculture accounts for around 85% of deforestation worldwide. While this can mostly be attributed to meat production (beef in particular), soy and palm oil plantations follow closely behind as causes for deforestation. But before you shun the tofu, let’s take a closer look: meat producers clear vast swaths of forest to graze their livestock, but beef cows don’t just eat grass in fact, 80% of all soybeans grown go directly into feed for cattle, and poultry. Palm oil, an ingredient that’s as ubiquitous as it is destructive, is a major contributor to deforestation in countries like Indonesia and Malaysia.
2. TIMBER
LOGGING Around 380,000 hectares of forest are cut every year to meet the incredible global demand for wood and wood products, accounting for around 60% of degradation. Another 25% of forest is degraded for fuelwood and charcoal. From clear cuts to massive logging roads providing access to previously untouched areas, these degraded forests are much more vulnerable to conversion to other land uses like mining, agriculture, and settlement.
3. MINING
Thanks to an ever-increasing demand for minerals, mining in tropical forests is on the rise. And because large-scale mining is an intensive, industrial undertaking, it necessitates the development of massive infrastructure, which only amplifies the degradation.
4. EXPANSION AND INFRASTRUCTURE
As the tide of human population growth washes over the land, large swaths of forest get cleared to make way for the expansion of cities and settlements. And with these settlements come even more infrastructure and expansion.
5. CLIMATE CHANGE
Climate change is a leading cause of deforestation. Extreme weather events like wildfires (which are responsible for an estimated 10% of degradation annually), droughts, and storm surges destroy millions of hectares of forest every year and their intensity is only increasing with global warming. But the trouble doesn’t stop there: after the last fire has been put out, the gates open wide to accommodate pests, diseases, and invasive species that make themselves at home, decimating whatever remains.