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.



To build its emerging “megaregions”, the USA should turn to trains

Under construction: high speed rail in California. Image: Getty.

An extract from “Designing the Megaregion: Meeting Urban Challenges at a New Scale”, out now from Island Press.

A regional transportation system does not become balanced until all its parts are operating effectively. Highways, arterial streets, and local streets are essential, and every megaregion has them, although there is often a big backlog of needed repairs, especially for bridges. Airports for long-distance travel are also recognized as essential, and there are major airports in all the evolving megaregions. Both highways and airports are overloaded at peak periods in the megaregions because of gaps in the rest of the transportation system. Predictions for 2040, when the megaregions will be far more developed than they are today, show that there will be much worse traffic congestion and more airport delays.

What is needed to create a better balance? Passenger rail service that is fast enough to be competitive with driving and with some short airplane trips, commuter rail to major employment centers to take some travelers off highways, and improved local transit systems, especially those that make use of exclusive transit rights-of-way, again to reduce the number of cars on highways and arterial roads. Bicycle paths, sidewalks, and pedestrian paths are also important for reducing car trips in neighborhoods and business centers.

Implementing “fast enough” passenger rail

Long-distance Amtrak trains and commuter rail on conventional, unelectrified tracks are powered by diesel locomotives that can attain a maximum permitted speed of 79 miles per hour, which works out to average operating speeds of 30 to 50 miles per hour. At these speeds, trains are not competitive with driving or even short airline flights.

Trains that can attain 110 miles per hour and can operate at average speeds of 70 miles per hour are fast enough to help balance transportation in megaregions. A trip that takes two to three hours by rail can be competitive with a one-hour flight because of the need to allow an hour and a half or more to get to the boarding area through security, plus the time needed to pick up checked baggage. A two-to-three-hour train trip can be competitive with driving when the distance between destinations is more than two hundred miles – particularly for business travelers who want to sit and work on the train. Of course, the trains also have to be frequent enough, and the traveler’s destination needs to be easily reachable from a train station.

An important factor in reaching higher railway speeds is the recent federal law requiring all trains to have a positive train control safety system, where automated devices manage train separation to avoid collisions, as well as to prevent excessive speeds and deal with track repairs and other temporary situations. What are called high-speed trains in the United States, averaging 70 miles per hour, need gate controls at grade crossings, upgraded tracks, and trains with tilt technology – as on the Acela trains – to permit faster speeds around curves. The Virgin Trains in Florida have diesel-electric locomotives with an electrical generator on board that drives the train but is powered by a diesel engine. 

The faster the train needs to operate, the larger, and heavier, these diesel-electric locomotives have to be, setting an effective speed limit on this technology. The faster speeds possible on the portion of Amtrak’s Acela service north of New Haven, Connecticut, came after the entire line was electrified, as engines that get their power from lines along the track can be smaller and much lighter, and thus go faster. Catenary or third-rail electric trains, like Amtrak’s Acela, can attain speeds of 150 miles per hour, but only a few portions of the tracks now permit this, and average operating speeds are much lower.

Possible alternatives to fast enough trains

True electric high-speed rail can attain maximum operating speeds of 150 to 220 miles per hour, with average operating speeds from 120 to 200 miles per hour. These trains need their own grade-separated track structure, which means new alignments, which are expensive to build. In some places the property-acquisition problem may make a new alignment impossible, unless tunnels are used. True high speeds may be attained by the proposed Texas Central train from Dallas to Houston, and on some portions of the California High-Speed Rail line, should it ever be completed. All of the California line is to be electrified, but some sections will be conventional tracks so that average operating speeds will be lower.

Maglev technology is sometimes mentioned as the ultimate solution to attaining high-speed rail travel. A maglev train travels just above a guideway using magnetic levitation and is propelled by electromagnetic energy. There is an operating maglev train connecting the center of Shanghai to its Pudong International Airport. It can reach a top speed of 267 miles per hour, although its average speed is much lower, as the distance is short and most of the trip is spent getting up to speed or decelerating. The Chinese government has not, so far, used this technology in any other application while building a national system of long-distance, high-speed electric trains. However, there has been a recent announcement of a proposed Chinese maglev train that can attain speeds of 375 miles per hour.

The Hyperloop is a proposed technology that would, in theory, permit passenger trains to travel through large tubes from which all air has been evacuated, and would be even faster than today’s highest-speed trains. Elon Musk has formed a company to develop this virtually frictionless mode of travel, which would have speeds to make it competitive with medium- and even long-distance airplane travel. However, the Hyperloop technology is not yet ready to be applied to real travel situations, and the infrastructure to support it, whether an elevated system or a tunnel, will have all the problems of building conventional high-speed rail on separate guideways, and will also be even more expensive, as a tube has to be constructed as well as the train.

Megaregions need fast enough trains now

Even if new technology someday creates long-distance passenger trains with travel times competitive with airplanes, passenger traffic will still benefit from upgrading rail service to fast-enough trains for many of the trips within a megaregion, now and in the future. States already have the responsibility of financing passenger trains in megaregion rail corridors. Section 209 of the federal Passenger Rail Investment and Improvement Act of 2008 requires states to pay 85 percent of operating costs for all Amtrak routes of less than 750 miles (the legislation exempts the Northeast Corridor) as well as capital maintenance costs of the Amtrak equipment they use, plus support costs for such programs as safety and marketing. 

California’s Caltrans and Capitol Corridor Joint Powers Authority, Connecticut, Indiana, Illinois, Maine’s Northern New England Passenger Rail Authority, Massachusetts, Michigan, Missouri, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Texas, Vermont, Virginia, Washington, and Wisconsin all have agreements with Amtrak to operate their state corridor services. Amtrak has agreements with the freight railroads that own the tracks, and by law, its operations have priority over freight trains.

At present it appears that upgrading these corridor services to fast-enough trains will also be primarily the responsibility of the states, although they may be able to receive federal grants and loans. The track improvements being financed by the State of Michigan are an example of the way a state can take control over rail service. These tracks will eventually be part of 110-mile-per-hour service between Chicago and Detroit, with commitments from not just Michigan but also Illinois and Indiana. Fast-enough service between Chicago and Detroit could become a major organizer in an evolving megaregion, with stops at key cities along the way, including Kalamazoo, Battle Creek, and Ann Arbor. 

Cooperation among states for faster train service requires formal agreements, in this case, the Midwest Interstate Passenger Rail Compact. The participants are Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, and Wisconsin. There is also an advocacy organization to support the objectives of the compact, the Midwest Interstate Passenger Rail Commission.

States could, in future, reach operating agreements with a private company such as Virgin Trains USA, but the private company would have to negotiate its own agreement with the freight railroads, and also negotiate its own dispatching priorities. Virgin Trains says in its prospectus that it can finance track improvements itself. If the Virgin Trains service in Florida proves to be profitable, it could lead to other private investments in fast-enough trains.

Jonathan Barnett is an emeritus Professor of Practice in City and Regional Planning, and former director of the Urban Design Program, at the University of Pennsylvania. 

This is an extract from “Designing the Megaregion: Meeting Urban Challenges at a New Scale”, published now by Island Press. You can find out more here.