My graph this week is by Max Roser and shows the drop in deforestation for both tropical and temperate forests from pre 1700 to 2010. Yes, some good news.
But of course this is not enough because deforestation rates are still high. Bush and Englemann’s “The Future of Forests: Emissions from Tropical Deforestation with and without a Carbon Price, 2016-2050” show that unless something is done, 289 million hectares of tropical forest — that’s the size of India — will be lost in the coming 35 years. This matters for many reasons including because deforestation is a big contributor to climate change: “burning down one square mile of rainforest releases as much carbon pollution as driving a car to the sun and back twice”. The paper goes on to show that deforestation could be avoided with an appropriate carbon price and that reducing tropical deforestation is one of the cheapest ways to reduce carbon emissions. The paper is dense but here you’ll find a summary, a (weird) video and a short interview.
And now we know how many trees there are in the world thanks to Crowther and al’s “Mapping tree density at a global scale”: 3 trillion! That is eight times more than we thought we had. [Here is a short video]. This new data and its uses have implications for forest management policies, biodiversity promotion efforts, payment for ecosystem services schemes etc. But what caught my attention was in the methodology. I am not talking about the modelling part which I tried to understand, to no avail. I am talking about the data collection part. The previous (underestimated) number was based on data collected via remote sensing, i.e., satellite imagery of forest cover. The new data use “ground truth measurements of tree density”, i.e., actual information from the land collected by many through the years, which the model then uses with remote sensing information. That reminded me of the Google Flu Trends saga: first a hyped-success story about “superior” real-time flu-tracking services using big data analytics, followed by a couple of false alerts, followed by an improved and more accurate service using big data with traditional surveillance data. “Something old with something new” seems like a good recipe for SDG progress monitoring.
My quote of the week is from Warsan Shire’s powerful poem Home: “You have to understand, that no one puts their children in a boat unless the water is safer than the land.”