Once fire-proof Amazon rainforests have become flammable, thanks to climate change

A forest fire in the Amazon. Image: Getty.

The Amazon rainforest is described as the planet’s lungs for good reason. So much carbon is locked up in its trees that protecting the forest is a must if we want to do something about global warming. However, reducing the CO₂ that is emitted when a tropical forest is destroyed depends not only on stopping the actual deforestation, but also on fighting wildfires within the forest.

In a new study published in Nature Communications we show that forest fires are responsible for a huge portion of the carbon emitted from the Brazilian Amazon. During drought years, these fires can emit around a billion tonnes of CO₂. That alone is double the amount of carbon effectively emitted through deforestation in the Amazon.

Humans are throwing vast amounts of CO₂ into the planet’s atmosphere. While in developed countries such as the US and UK most of the emissions come from industrial activities, in developing tropical countries such as Brazil, most come from forests being chopped down and burnt.

Yet while deforestation is already recognised as an important driver of carbon emissions, wildfires under the forest canopy present a less visible but still pernicious threat. To figure out just how bad the problem is, we combined satellite data on the current climate, atmospheric carbon content and the health of forest ecosystems. Our work revealed that emissions from tropical forest fires are growing, even though they are still not normally accounted for in estimates of national emissions.

Wildfires – but not natural fires

Wildfires in the Amazon are not natural events, but are instead caused by a combination of droughts and human activities. Both anthropogenic climate change and regional deforestation are linked to increases in the intensity and frequency of droughts over Amazonia.

Fires spreads into the forest during the 2015 drought. Image: Erika Berenguer/author provided.

This kicks off a nasty cycle: as trees have less water during such droughts, their growth slows and they’re less able to remove CO₂ from the atmosphere through photosynthesis. Trees then shed extra leaves or even die, which means more wood and leaves are ready to burn on the forest floor and, without a dense canopy to retain moisture, the forest loses some of the humidity which acted as natural fire prevention.

These changes are exacerbated by “selective logging” of specific tree species, which opens up the canopy and further dries out the understory and forest edges, which are drier than the interiors. The result: normally fire-proof rainforests become flammable.

A fiery future?

The resulting wildfires have reached a worrying level, burning millions of hectares during the recent El Niño. But the worst could still be to come, as the unusually warm conditions in the Atlantic or Pacific oceans that have caused previous droughts are expected to intensify.

So far this century the Amazon has already experienced three “droughts of the century”, in 2005, 2010, 2015-2016. If the climate science is accurate, and if no action is taken to efficiently predict and avoid fires occurring, we expect that carbon emissions from forest fires would be sustained even if deforestation ended overnight.

Smouldering tree trunk after a forest fire during the 2015 drought in eastern Amazonia. Image: Erika Berenguer/author provided.

As one of the signatories to the Paris agreement on climate change, Brazil is committed to reducing its emissions to 37 per cent below 2005 levels by 2025. A major reduction in deforestation rates over the past decade is a great start. However, deforestation policy doesn’t help reduce forest fires and consequently isn’t fully efficient in mitigating carbon emissions from the Amazon.

Brazil has made substantive advances in reporting emissions from deforestation. It now needs urgently to focus on incorporating CO₂ losses from wildfires into its estimates. After all, those fire emissions are expected to increase in future, thanks to more extreme droughts, an expansion of selective logging, and the ongoing use of fire to manage pasture or to remove regrowing vegetation on farmlands.

Kilometres of burned forests (magenta) spread across old-growth forests (green) in eastern Amazonia. White patches are clouds. Image: Celso Silva-Junior/USGS/author provided.

Given that fire is an essential part of many smallholders’ livelihoods, it is critically important to implement sustainable and socially-just policy responses. Brazil should start by reversing the budget cut to the organisation that oversees its only existing fire-prevention programme. It should also avoid selective logging in regions that are prone to fires, and ensure forest management always factors in long-term fire-prevention.

The ConversationIn summary, these findings are not only critical for policymakers in Brazil to strengthen the efforts of effectively quantifying and limiting carbon emissions from forest fires in the years ahead, but also to other tropical nations to tackle the potential impacts of drought-induced fires on their carbon budget. These new findings bring critical information for nations to help prepare for urgent actions aiming to mitigate the potential increase of fire emissions in response to the intensification of droughts in tropical ecosystems.

Luiz Aragão, Senior Lecturer in Earth Systems Sciences, University of Exeter; Jos Barlow, Professor of Conservation Science, Lancaster University, and Liana Anderson, Research Associate in Land Cover Dynamics and Carbon Emissions, University of Oxford.

This article was originally published on The Conversation. Read the original article.



Here’s how Copenhagen puts cyclists at the top of the social hierarchy

A cyclist in Copenhagen, obviously. Image: Red Bull/Getty.

Have you ever wondered why Britain is not a nation of cyclists? Why we prefer to sit in traffic as our Dutch and Danish neighbours speed through the city on bikes?

Forget about hills, rain, and urban sprawl: the real reason we aren’t cycling is much closer to home. It is not just lack of infrastructure, or lack of fitness, the reason that 66 per cent of Brits cycle less than once a year, is because of status.

An obsession with social status is hard-wired into our brains. As we have built a society that relies on cars, the bicycle has slipped to the periphery, and gone from being regarded as a sensible mode of transport, to a deviant fringe-dwellers choice.

Even though cycling to work has been shown to be one of the most effective things an individual can do to improve health and longevity, researcher David Horton thinks that there are a set of collective anxieties that are stopping us getting in the saddle. These include not just an unwillingness to be made vulnerable, but fear of being thought of as poor.

A quick look over the North Sea shows that there is an alternative. Danish culture has elevated cycling to the point of reverence, and the social status of cyclists has followed. As we have busied ourselves building infrastructure that testifies to the dominance of the car, Denmark has been creating magnificent architectural features, aimed specifically at bike users. The Cycle Snake, or Cykelslangen, literally suspends the cyclist above the city, metaphorically elevating the cyclist and creating a sense of ceremony.

In doing so, they are subtly persuading people of all backgrounds to see past their prejudices or fears and take it up as the clearly better choice. This means there are more women cycling, more older people cycling, and more ethnic minorities cycling. The activity is less dominated by comfortably middle class white males: there are cyclists from every side of the community.  

The Cykelslangen, under construction in 2014. Image: Ursula Bach and Dissing+Weitling architecture.

Despite abstract motivations like getting ripped and conquering global warming, it is only when the bike path becomes the obviously better choice that people will start to cycle. It can take years of traffic jams before people try an alternative, but if you make motorists jealous of cyclists, then the tables can quickly turn.

Another way that Copenhagen has done this is by taking privileges normally afforded only to the motorcar, and given them to the bike. The city has ensured that cycle routes do not include blind corners or dark tunnels, and that they form a complete, coherent network, and a steadily flowing system – one that allows cyclists to maintain a reasonable pace, and minimises the amount of times you have to put your foot down.

The ‘Green Wave’, for example, is a co-ordinated traffic light system on some of the main thoroughfares of the capital that helps minimise the amount of cycle congestion during peak times. It maintains a steady flow of cycle traffic, so that there is no need to stop at any point.

Small measures of prioritisation like this one increase the sense of safety and consideration that cyclists experience, making it natural for the citizens of a city to act in their own self-interest and get on their bike.

As well as redefining the streets around the bicycle, the Copenhagen Cycle Chic blog positively fetishises cyclists. The tagline “dress for your destination, not your journey” depicts the social fashion life of the cycle lane as a “never ending flow of happy people heading from A to B”. Its writers are  literally making cycling sexy, dispelling the idea that going anywhere by bike is odd, and helping the world to see that the bicycle is actually the ultimate fashion accessory.

So unlike in London, where cycling is still a predominantly male pursuit, Copenhagen sees a more even split between men and women. Not just because they feel safer on the roads, but because culturally they are comfortable with their appearance as part of a highly visible group.

So while our low level of cycling is partly due to our physical infrastructure, it is also due to our cultural attitudes. The mental roadblocks people have towards cycling can be overcome by infrastructure that is not only safe, but also brings old-fashioned notions of dignity and grace into the daily commute.

Of course, office shower facilities might stop cyclists being ostracised, too.