This article is part one of a two-part series on the unintended negative consequences of fighting climate change. You can find part two here.
The area of leaves on the planet is growing rapidly, as well as the biomass of plants, and with it, the entire animal world. According to the accumulated observational data, people are to blame for this, that is, the carbon dioxide emitted by civilization. And this may mean that the fight against global warming will have unexpected consequences: by reducing carbon dioxide emissions, humanity will “reduce” the Earth’s biomass. But, at the same time, the area of deserts will increase. Unintentionally, global landscaping of the Earth put an exceedingly difficult choice before our species.
Usually, when it comes to the influence of nature and man, it is understood that he can only harm her: plastic islands in the Pacific Ocean (which do not exist), rising levels of the oceans (although it’s mostly dry land that rises on the rising sea) and the like.
Of course, plastic garbage in the ocean is a real problem, as is the rise in sea levels. Fish suffer from plastic in their bodies, and rising sea levels will in the distant future begin to flood countries. Only the first one should not wait for the appearance of mythical islands. And from the second — the disappearance of inhabited islands in the XXI century (the current rate of sea rise is not large enough for this). However, there are reverse stories. Sometimes anthropogenic impact on Earth life leads to an increase in biomass on the planet.
The most objective parameter of the “well-being” of vegetation as a whole is the leaf area index (LAI), equal to the area of the upper half of the leaves or, in the case of conifers, needles. It is the upper half of the green part of the plant that is most easily fixed on satellite images. Already in 2017, a cross-analysis of images obtained from various satellites showed that, at least since the 1980s, this index has been growing, and quite quickly.
Thus, from 1982 to 2011, an increase in the leaf area index was observed in 46% of the total land area covered by vegetation, and a decrease — only by 4% of the same area, mainly due to deforestation.
One of the reasons for this is warming, leading to an increase in LAI in the tundra, and the other is still a minor increase in precipitation in arid regions (an increase in temperature means an increase in evaporation from the surface of the oceans). But researchers note that these factors are responsible only for a smaller part of global gardening, but an increase in the concentration of CO2 for 70% of this process.
Plants build their tissues mainly from carbon dioxide and water. The more CO2 in the atmosphere, the less the plants need to open their stomata for “breathing”, which means they also spend less water on it. That is, the more carbon dioxide in the air the more plants get one and the other. That is why, in greenhouse farms in the West, the concentration of CO2 is artificially maintained at 800 parts per million (twice as much as in the air we breathe).
Mankind throws 37 billion tons of CO2 per year. In total, the atmosphere contains 3.2 trillion tons of carbon dioxide, that is, every year people add 1.15% of this substance. Although most of these emissions are absorbed by the ocean, plants, and rocks, about 5 billion tons per year remain. Therefore, at the end of the 18th century, CO2 in the air was 280 parts per million, and today it is 410, and another 2.45 parts per million are added annually.
This is the same greenhouse gas that leads to global warming. Water vapor plays a subordinate role in this process since its concentration in air is highly dependent on temperature. At the same time, CO2, unintentionally on the part of humanity producing it, led to the global greening observed today.
Annual CO2 emissions in billions of tons from the processing of natural resources (top to bottom): coal, oil, gas, cement
Successes of the largest countries
Recent work by Chinese researchers has shown how exactly man-made gardening has affected terrestrial vegetation. To do this, scientists have calculated the growth index of leaf area for the largest countries in the world.
The authors of this work analyzed the leaf surface index for 11 major countries of the world in satellite images from 2000 to 2017. As expected, an increase in LAI was observed in all of them. Most of all, the index rose in two countries: China and India.
The successes of China and India are not accidental. In these countries, the largest tree-planting program in the history of mankind is being implemented, and the total forest area in China only grew by 32% from 2000 to 2015. In 2018, trees were planted in an area roughly equal to that of Ireland.
In India, the situation is similar: economic and demographic growth has forced local farmers to expand their acreage, including in previously arid areas (through irrigation). Accordingly, 82% of the landscaping in India falls on arable land.
Unintentional man-made landscaping is slower, but its numbers are impressive. A significant part of the post-Soviet countries’ growth was due to the overgrowing of arable land by forest after the collapse of the planned economy in 1991. But if you take a country where there were no economic upheavals, then there and gardening goes on as usual. During the same years, the leaf area in Australia increased by 5.62%, and in the USA — by 4.55%.
The EU and Canada are planting faster (LAI increases by 7.78% and 7.13%, respectively), but higher humidity contributes to the increase there since the most intensive gardening takes place under conditions when rainfall exceeds 500 millimeters per year.
But such countries as Russia or Canada, with their cold climate, due to which a significant part of the countries’ territory is occupied by tundra and northern taiga, do not receive such a quantity of precipitation. A similar picture is observed in Australia, 70% of the territory of which is occupied by deserts and semi-deserts, and even in the USA, where there are also plenty of lush areas. But so far: the situation is gradually changing, and increased precipitation is falling, which already affects the climate of Australia, and in northern countries.
But the increase in precipitation (plus two percent for the entire twentieth century) lags far behind the growth in leaf area, which is much more affected by the increase in atmospheric CO2 (0.5% per year).
Bad good news
The overgrowing process of the rest of the world will continue until the CO2 introduced by people into the atmosphere begins to actively “wash out” it. This will not happen in the 21st century: not enough time. That is, the effect of man-made gardening will be extremely long.
Russian and Australian 5–7% growth in leaf area over 17 years is not very much at first glance. The continuation of this trend, unchanged until 2100, will increase the area of green leaves by 1.5 times, that is, many millions of square kilometers only for our country. More humid Canada and the EU countries will undergo even greater overgrowth.
In other large countries, which are even warmer and more humid, where especially dense equatorial forests grow, will not be easy to grow the area of leaves: there it already exceeds the area of these countries themselves (for Indonesia and Congo — 2–4 times). However, in these countries, the leaf area will grow somewhat, as satellite observations grow all the time.
This may seem like good news. But not really. The fight against global warming is on the agenda of the Western world, and serious measures are being taken in this area. The rapid development of renewable energy, the production of electric cars, and much more are just the beginning. In the future, many scientists and politicians of the West are sure that geoengineering and the fixation and removal of CO2 from the atmosphere cannot be dispensed with, or else global warming cannot be stopped. But the fight against CO2 will inevitably turn into the fight against the anthropogenic landscaping of the planet.
But the most important thing about the very fact of global man-made gardening and its scale has become known recently. The effect of global gardening has long remained outside the purview of the modern scientific community. If the phrase “global warming” has been systematically used in the scientific literature since the 1970s, then global greening in the twentieth century was practically absent in scientific circulation, and in popular science publications, it appeared in recent years.
Only in 2016–2017, the colossal scale of global landscaping was established: following the traces of carbonyl sulfide in the Antarctic ice, it turned out that plants in the XX century increased their biomass faster than ever in the last 54,000 years. The rate of growth of green biomass on Earth in the past century was 31% more than before the beginning of the industrial revolution — and it increased precisely because of it. More precisely, because of the additional carbon dioxide emissions it generated.
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