Cutting greenhouse gas emissions via land-use change is essential to meet climate targets

Protecting and restoring natural ecosystems in Latin America and the Caribbean not only helps communities adapt to climate change but also benefits biodiversity and enhance food and water security, according to the participants in a webinar hosted by FAPESP.

By Elton Alisson  |  Agência FAPESP – Greenhouse gas emissions by agriculture, forestry and other land uses in Brazil and the rest of Latin America and the Caribbean must be cut in the next eight years if global warming is to be limited to 1.5 °C above the pre-industrial average temperature by 2030.

As well as helping communities adapt to climate change, the reduction will afford other advantages, such as benefiting biodiversity, maintaining ecosystem services, assuring subsistence, and enhancing food and water security.

These were some of the key points stressed by researchers who took part in a webinar held on April 6 by the FAPESP Research Program on Global Climate Change (RPGCC). The purpose of the event was to discuss the latest report of the Intergovernmental Panel on Climate Change (IPCC), issued on April 4, especially its implications for Brazil.

According to the report, without immediate deep cuts in greenhouse gas (GHG) emissions in all sectors and regions of the world, the 2015 Paris Agreement’s goal of limiting global warming to 1.5 °C by 2030 cannot be met.

“The report shows that a 50% cut in emissions is required by 2030 and the planet must become carbon neutral by 2050. For this to happen, we need to build a new society that’s more sustainable and has much more economic and social equality,” said Paulo Artaxo, a professor at the University of São Paulo’s Physics Institute (IF-USP) and a member of RPGCC’s steering committee.

The next three years will be critical to efforts to achieve these goals, according to the participants in the webinar. GHG emissions must peak by 2025, after which they must steadily fall if they are to correspond to half the 2019 level by 2030. Recent global GHG inventories have shown that this will be no trivial task.

“Emissions reached the highest level ever in the past decade, although they’re rising at a slower rate. Unfortunately, GHG emissions are still increasing, despite all the promises,” said Mercedes Bustamante, a professor at the University of Brasília (UnB) and a lead author for two chapters of the report.

The emissions are highly uneven across regions, sectors and income groups. In Latin America and the Caribbean, the main source is what the report calls the agriculture, forestry and other land-use sector, which accounts for 22% of total GHG emissions, including methane and nitrous oxide as well as carbon.

This sector is particularly relevant to efforts to mitigate the climate crisis because it can both reduce GHG emissions and remove and store large amounts of carbon dioxide (CO₂), Bustamante explained.

“If the mitigation options for this sector are well designed and implemented, they should not only reduce GHG emissions but also produce a number of other co-benefits,” she said.

Among the carbon removal options for this sector are protecting and restoring natural ecosystems such as forests, peatlands, wetlands, savannas and grasslands.

“It’s important to bear in mind that the sector can also contribute to a reduction in emissions by other economic segments,” Bustamante said. “The use of wood in construction as a substitute for more carbon-intensive materials is booked as a contribution by the construction industry, for example, while substituting biofuels for fossil fuels contributes to a reduction in emissions by the energy sector.”

Available solutions

The report stresses that technological solutions are available right now for all economic segments to reduce GHG emissions by half in the required timeframe. These options cost less than USD 100 per ton of CO₂ equivalent. Over half cost less than USD 20 per tCO₂e, it notes.

“The report says the cost of cutting GHG emissions is high but the cost of not doing so is at least three times higher,” Artaxo said. “That’s a very high price for our society to pay. We must reduce the damage as much as possible.”

The cost of low-carbon technologies has fallen sharply in recent years, the report also shows. “Solar, photovoltaic and wind power generating costs have dropped significantly, as have battery prices,” said Gilberto Jannuzzi, a professor at the University of Campinas (UNICAMP) and one of the report’s review editors.

Battery prices fell 85% in the period 2010-19, while the number of electric vehicles in circulation increased by a factor of 100, said Suzana Kahn, a professor at the Federal University of Rio de Janeiro (UFRJ). Kahn was a lead author of three chapters and a review editor of two. 

The supply of electric vehicles is highly uneven globally. “Electric vehicles have huge potential and are growing strongly, but the requisite infrastructure isn’t universal. It’s basically available only in the wealthiest countries,” Kahn said. “We need this infrastructure and an industry that produces low-carbon electricity not just for transportation but also for homes and manufacturers, among other sectors.”

In contrast with solar, photovoltaic and wind power, nuclear power is one of the energy options that is increasingly expensive to produce. This is because it is becoming safer, according to Roberto Schaeffer, a professor at UFRJ and a lead author of five chapters.

“Safety comes at a price,” he said. “Because of the high cost of generating nuclear power, it doesn’t play a major role in any of the scenarios for reducing GHG emissions.”

The climate crisis cannot be addressed only in terms of technological solutions, the researchers stressed. Habits and cultural standards will also have to change. Even for these changes to happen at the level of individuals, however, it will also be necessary to have the right infrastructure, public policies and funding.

“Climate change is the most daunting problem our planet faces at this time. The solutions are complex, and will certainly be less effective unless we have the right knowledge base to make decisions on the requisite actions,” said Luiz Eugênio Mello, FAPESP’s Scientific Director.

A recording of the webinar can be watched at: www.youtube.com/watch?v=n42y0A7y1Gc.