One third of the world’s new vegetation is in India and China, data shows

China and India are “leading the world” in “greening” the landscape, a study finds, with the two countries accounting for one-third of the new forests, croplands and other types of vegetation observed globally since 2000.

The results, published in Nature Sustainability, also show that China alone accounts for a quarter of the human-caused greening observed since 2000 – despite containing only 6.3% of the world’s landmass.

In China, 42% of the greening comes from the expansion of forests while 32% comes from cultivated farmlands, the study finds. In India, 82% of the greening comes from new croplands.

However, it is important to note that greening observed in China and India is “not enough to offset” the loss of the world’s tropical rainforests, particularly in Brazil, a scientist tells Carbon Brief.

The findings also suggest that the “CO2 fertilisation effect” – where increasing CO2 levels in the atmosphere bolster the growth of plants – could be a “less prominent” driver of “global greening” than previously thought, a study author tells Carbon Brief.

This is because human-driven land-use change – through the planting of croplands, forests and other types of vegetation – could be having a larger impact on global greening than previously recognised, the author says.

Green planet

Across the world, the rate of plant growth appears to be increasing. Scientists who study this phenomenon call it “global greening”.

One reason that plants could be growing faster is that humans are releasing billions of tonnes of CO2 into the atmosphere every year – and plants use CO2 to carry out photosynthesis. The process whereby increasing CO2 levels boosts plant growth is known as the “CO2 fertilisation effect”.

However, humans can also have a direct impact on the amount of vegetation found on Earth through the way in which they manage land.

The new study examines how both human-driven land-use change and the natural growth of vegetation have contributed to greening across the world over 2000-16.

To do this, the researchers made use of data taken by the Moderate Resolution Imaging Spectroradiometer (Modis) – a key sensor onboard NASA’s Terra and Aqua satellites.

The high-resolution sensor captures “greening” – net gain of leaf-covered area – and “browning” – net loss of leaf-covered area – across the globe, explains study lead author Chi Chen, a PhD student at Boston University. He tells Carbon Brief:

Leafy landscape

The map below shows the results, with green representing regions of net greening and yellow, red and purple showing regions with net browning. On the map, white areas depict barren land, permafrost, ice, wetlands and built-up areas.

The map identifies seven “greening clusters” circled in red – including (1) across central North America, (2) southern Brazil, (3) the European Union, (4) Central Africa, (5) India, (6) China and (7) south Australia.

More information on the regional breakdown of new vegetation growth is offered in the table below. The table ranks the 11 largest countries by leaf-covered area in 2000 (left), net change in leaf-covered area from 2000-16 (middle) and this net change as a percentage of the total leaf-covered area (right).

The results show that “China and India stand out”, Chen says:

China alone accounts for a quarter of the global net increase in leaf area from 2000-16, the study finds. This is equal to the greening observed in Russia, the US and Canada over the same time period.

Around 42% of the greening seen in China comes from the expansion of forests. The map below offers a closer look at greening from forest expansion in China over the study period. (Last year, Carbon Brief published an explainer detailing how China has, according to its government, planted 35bn trees since the 1990s.)

India, meanwhile, accounts for 6.8% of the global net increase in leaf area, the study finds. This is roughly equal to that in the US or Canada – which both had three times more vegetated area in 2000.

While these greening trends are significant, it is important to note that they cannot make up for the loss of natural rainforests in the world’s tropical regions, says Prof Anja Rammig, a researcher of land-surface interactions from the Technical University of Munich, who was not involved in the study. She tells Carbon Brief:

This is also noted by the researchers of the study, who say in their paper:

(It is worth noting that the study did not look at how much natural forest has been converted into croplands.)

Fertilisation effect

Another key finding of the research paper is that “human land-use” has been “a dominant driver” of global greening since 2000, the authors say.

One reason for this conclusion is that the study shows that cropland expansion has contributed the most to greening over the study period, they say. Six out of seven “greening clusters” (shown on the first map) “overlap” with regions known to have highly intensive agriculture. Rammig says:

The expansion of agriculture over the time period can “be attributed to quick-growing hybrid cultivars [plant varieties], multiple cropping, irrigation, fertiliser use, pest control, better quality seeds, farm mechanisation, credit availability and crop insurance programmes”, the authors say.

In other words, much of the greening observed on Earth has had more to do with direct human interference than the indirect effect of climate change or the CO2 fertilisation effect, says study co-author Prof Ranga Myneni, a research of vegetation remote sensing from Boston University. He tells Carbon Brief:

The designations employed and the presentation of material on these maps do not imply the expression of any opinion on the part of the World Economic Forum concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.