From the FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO and the “worse than we thought” department.
In a Nature Communications article, international group of scientists affirms the prolongation of an annual deforestation of 7,000 square km can nullify the efforts for reducing GHG emissions
The global warming process may be even more intense than originally forecast unless deforestation can be halted, especially in the tropical regions. This warning has been published in Nature Communications by an international group of scientists.
“If we go on destroying forests at the current pace – some 7,000 km² per year in the case of Amazonia – in three to four decades, we’ll have a massive accumulated loss. This will intensify global warming regardless of all efforts to reduce greenhouse gas emissions,” said Paulo Artaxo, a professor at the University of São Paulo’s Physics Institute (IF-USP).
Reaching the conclusion
The group reached the conclusion after having succeeded in the mathematical reproduction of the planet’s current atmospheric conditions, through computer modeling that used a numerical model of the atmosphere developed by the Met Office, the UK’s national meteorological service.
Such model included meteorological factors like levels of aerosols, anthropogenic and biogenic volatile organic compounds (VOCs), ozone, carbon dioxide, methane, and other items that influence global temperature – the surface albedo among them. Albedo is a measure of the reflectivity of a surface. The albedo effect, when applied to Earth, is a measure of how much of the Sun’s energy is reflected back into space. The fraction absorbed changes according to the type of surface.
The work coordinated by University of Leeds (UK) researcher Catherine Scott was also based on years of analyses and survey over the functioning of tropical and temperate forests, the gases emitted by vegetation, and their impact on climate regulation. Collection of data regarding tropical forests was coordinated by Artaxo, as part of two Thematic Projects supported by the São Paulo Research Foundation – FAPESP: “GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia“, and “AEROCLIMA: direct and indirect effects of aerosols on climate in Amazonia and Pantanal“. Data on temperate forests was obtained in Sweden, Finland, and Russia. Collection was coordinated by Erik Swietlicki, a professor at Lund University in Sweden.
Understanding how tropical forests control temperature
“After adjusting the model to reproduce the current conditions of Earth’s atmosphere and the rise in surface temperatures that has occurred since 1850, we ran a simulation in which the same scenario was maintained but all forests were eliminated,” Artaxo said. “The result was a significant rise of 0.8 °C in mean temperature. In other words, today the planet would be almost 1 °C warmer on average if there were no more forests.”
The study also showed that the difference observed in the simulations was due mainly to emissions of biogenic VOCs from tropical forests.
“When biogenic VOCs are oxidized, they give rise to aerosol particles that cool the climate by reflecting part of the Sun’s radiation back into space,” Artaxo said. “Deforestation means no biogenic VOCs, no cooling, and hence future warming. This effect was not taken into account in previous modeling exercises.”
Temperate forests produce different VOCs with less capacity to give rise to these cooling particles, he added.
The article notes that forests cover almost a third of the planet’s land area, far less than before human intervention began. Huge swathes of forest in Europe, Asia, Africa and the Americas have been cleared.
“It’s important to note that the article doesn’t address the direct and immediate impact of forest burning, such as emissions of black carbon [considered a major driver of global warming owing to its high capacity for absorbing solar radiation]. This impact exists, but it lasts only a few weeks. The article focuses on the long-term impact on temperature variation,” Artaxo said.
Deforestation, he stressed, affects the amount of aerosols and ozone in the atmosphere definitively, changing the atmosphere’s entire radiative balance.
“The urgent need to keep the world’s forests standing is even clearer in light of this study. It’s urgent not only to stop their destruction but also to develop large-scale reforestation policies, especially for tropical regions. Otherwise, the effort to reduce greenhouse gas emissions from fossil fuels won’t make much difference,” Artaxo said.
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The paper: https://www.nature.com/articles/s41467-017-02412-4
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The Brazilian professors statement about biogenic VOCs is partly wrong. Tropical rainforests produce isoprenes. But So do temperate hardwood forests—the smoke in the Great Smokey mountains of SE US Appalachians. Coniferous boreal forests produce turpenes. And ocean algae produce dimethylsulfides. All aerosols, and all cloud condensation nuclei.
It’s about time somebody spoke up in the mono-messaging world of CO2 and its blame game political strategy.
Nut Case Science. Proposing that he world would be different if we removed all the forests is a pretty safe bet. The world would be different if we dried up all the fresh water lakes, disappeared the oceans, killed all the animals or all the grasses or all the shrubs…..just plain nutty.
The idea that one could MODEL such a massive ecological change as removal of all forests (which cover today about 31 % of all the land surface of Earth) is scary — I find it terrifying that educated men and women, holding important scientific and educational positions, could believe such an obviously impossible idea.
oops — some formatting error above.– kh
I always have trouble remembering whether it’s the backslash or the forward slash to cancel an HTML tag.
MarkW ==> This one / Leave out the spaces in the following and you’d have a link in a blockquote:
MarkW ==> Dang …too efficient an html editor here — ignores the spaces.
Anyway the keyboard rule is this: use the slash under the question mark on your keyboard. (If you “question”…that’s it!)
Proof (within the limits of known science) that CO2 has no significant effect on climate is at http://energyredirect3.blogspot.com .
At this rate, Amazonia will be fully deforested in ~785 years. Probably a while before any impacts are evident.
Seven thousand square kilometers a year is not that much forest loss on a global or even continental scale (compared to the total forest area of Amazonia). Many of the wildfires observed in the USA every summer burn hundreds or thousands of square kilometers.
But, in many areas of the USA, Canada, and Europe, the land area covered by forests is increasing, as forests re-grow on former farmland which was abandoned as marginally productive, and logging companies plant trees so that harvested areas can be productive in future decades. If the climate is warmer now than during the Little Ice Age a few centuries ago, the forests can also grow further north or higher up on mountains than before.
There is also evidence that a wetter climate in equatorial Africa is enabling forests to expand northward toward the edge of the Sahara desert.
Have the authors of the study considered that the loss of 7,000 km2 per year of forest in Amazonia could be compensated by increases in forest area in other parts of the world?
Don’t include Canada. Canada is still removing vast areas of forest in many areas, especially in eastern Ontario and the prairies. Take a drive someday in central SK and MB, you will be astounded at the extent of brushpiles waiting to be burned. But I agree with the rest of your post.
“the land area covered by forests is increasing, as forests re-grow on former farmland which was abandoned as marginally productive”
In the US my guess is that most farms going to forest was due to farmer’s children getting an education and jobs, and not wanting to work or maintain the farms once their parents passed on.
If the land is needed to produce crops, it will be farmed, by somebody. Even if it has to be bought up by a conglomerate.
The reason why farmland is being abandoned is because technology allows us to grow more crops on less land. Which means that the now excess cropland gets abandoned.
No, it’s because hundreds of thousands (millions?) no longer have to grow their own food or raise tobacco to survive. I’ve known a number of people who worked tobacco and crops on their family farm when they were young (morning, evening, summer farm work; school during the day). They got an education and good jobs, and now the last thing they want to do is farm. The only thing they want now that even remotely resembles farming is mowing a lawn.
Growing your own food doesn’t matter. Eating food does.
What matters is how much land is needed to grow the food we all eat. That amount has gone down, even as the population has gone up.
I don’t know how many total acres was used to grow tobacco, but I doubt it was all that much, not compared to the land needed to grow crops. Just think of the volume of food eaten by the average person in a day, now compare that to the total volume of cigarettes smoked by an average person in a day. (Note, I said average person, not average smoker. Everybody eats, not everybody smokes.)
It’s pretty basic really. If we aren’t growing enough food, then the price of food goes up. This causes farmers to try and grow more food. First they use their own land, then they try to buy any vacant land near by. This continues to the point where you can no longer earn enough by growing crops to cover the cost of buying more land.
The opposite is equally true, if we are growing more food than is optimal, the price of food will drop. This will decrease the income of farmers, some farmers will stop farming their least productive acres, other marginal farms may go out of business completely.
Thus the amount of land used as farms will always reflect the amount of food needed.
“This effect was not taken into account in previous modeling exercises.” Unsettling, but
I would also like to know what effects are not going to be taken into account in future modeling exercises.
So what is it? Are the rain forests being stripped faster than they are regrowing? You hear both sides of the equation. Sounds like much of the data for this study is based on computer models. Well, that automatically makes it suspect.
The Amazon rainforest is about 7,000,000 km². Do they think that none of it will grow back in 1,000 years?
Caused it, not will “intensify it”… it caused it.