{"id":366312,"date":"2026-04-06T13:33:10","date_gmt":"2026-04-06T13:33:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/366312\/"},"modified":"2026-04-06T13:33:10","modified_gmt":"2026-04-06T13:33:10","slug":"faster-detection-of-forest-loss","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/366312\/","title":{"rendered":"Faster Detection of Forest Loss"},"content":{"rendered":"

Tropical forests span 1.6 billion hectares<\/a> (6.2 million square miles) of Earth. These ecosystems support a majority of the planet\u2019s animal and plant species and contain plants that contribute to over a quarter of modern medicine<\/a>. But over the past two decades, an average of 10 million hectares<\/a> (nearly 40,000 square miles) of these forests\u2014roughly the size of Kentucky\u2014have been lost each year, according to the United Nations Environment Programme, affecting the ecosystems and communities that depend on them.<\/p>\n

NASA scientists recently developed a new method<\/a> for tracking tropical forest loss that delivers deforestation alerts more than three months faster than current methods. Although the technique was designed for the Amazon rainforest, data from a recently launched<\/a> satellite are expected to expand its application globally.<\/p>\n

Because tropical forests are so vast, local communities, conservationists, and policymakers rely on satellite data to manage them. Images acquired by satellites with optical sensors provide highly accurate alerts. For instance, the image above, acquired as part of the Harmonized Landsat and Sentinel-2<\/a> (HLS) project, shows newly cleared land in southwest Brazil in July 2020. Images from NASA-USGS Landsat satellites have revolutionized land management for over 50 years<\/a>. In 1988, Brazil developed one of its first satellite-based monitoring systems<\/a> using Landsat data, which remains in use today.<\/p>\n

Though Landsat is an invaluable tool for Earth observation, it has a critical limitation: clouds. As an optical satellite, it relies on reflected light and cannot observe the ground through cloud cover. This creates data gaps that are especially limiting in tropical regions, which are cloudy most of the year. In some areas, months can pass without acquiring a cloud-free image<\/a>, hindering efforts to track and curb unregulated forest clearing.<\/p>\n

To address Landsat\u2019s cloud challenge, researchers at NASA\u2019s Marshall Space Flight Center tuned into a different wavelength. Led by Africa Flores-Anderson, associate program manager for NASA\u2019s Ecosystem Conservation Program, the team piloted a system for the Amazon<\/a> that combines existing satellite-based approaches with cutting-edge radar data. The approach builds upon a platform developed by the Cardille Lab at McGill University.<\/p>\n

Synthetic aperture radar (SAR)<\/a> doesn\u2019t require daylight or clear skies. To generate an image, SAR instruments beam radar signals at a surface and measure the signals that bounce back. SAR satellites use various ranges of radar wavelengths, or \u201cbands,\u201d to measure features on Earth\u2019s surface. Over forests, the shorter wavelengths of the C-band scatter off treetops, but the longer wavelengths of the L-band can make it down to the ground.<\/a><\/p>\n

This L-band is central to Flores-Anderson\u2019s approach. Similar efforts favored C-band because it was more readily available than other SAR data. But when felled trees\u2014along with their branches and leaves\u2014are not removed right away, C-band\u2019s shorter wavelengths are scattered by remaining debris, obscuring evidence of destruction. In contrast, L-band\u2019s longer wavelengths can penetrate this material and reveal the damage. The new method is the first of its kind to automatically combine the user-friendly, intuitive images from Landsat and the consistent, detailed insights from L-band SAR data.<\/p>\n

These visuals show\u00a0the benefit of combining\u00a0optical images and L-band SAR data.\u00a0The patch of deforested land in\u00a0southwest Brazil\u00a0(top row)\u00a0is overlaid with\u00a0colors that\u00a0represent\u00a0the\u00a0month that deforestation was detected\u00a0(bottom row).\u00a0<\/p>\n

The left map shows that SAR detected two patches of forest loss in January (purple), three months earlier than optical sensors (middle map). The patches appear small because deforestation happens gradually, Flores-Anderson explained. At that point in January, only those areas had been cleared.<\/p>\n

By April (green), optical sensors had detected forest loss across a wider area, shown in the middle map. These sensors collect images every few days, while the SAR data used in this study captured the area only once or twice a month. In this case, the optical satellites observed the change during a break in the cloud cover.<\/p>\n

The map on the right shows how the new algorithm combines information from both types of observations. To increase accuracy, this algorithm confirms deforestation only if there are multiple, consecutive observations of forest loss. This view confirms deforestation as early as February, up to two months earlier than optical-only, and with much more certainty than the optical- or SAR-only approaches.<\/p>\n

On average, the\u00a0new\u00a0method for\u00a0monitoring\u00a0forests\u00a0spots felled trees within 16 days with exceptional accuracy, nearly\u00a0eliminating\u00a0false alarms.\u00a0These detections\u00a0can identify deforestation\u00a0in very cloudy regions up to\u00a0100 days\u00a0sooner than\u00a0optical-only systems. \u00a0<\/p>\n

\u201cIn the tropics, it\u2019s important to detect deforestation as soon as it occurs,\u201d Flores-Anderson said. \u201cIf an image of a cleared forest isn\u2019t available until the following year, the area may already be regrown, and deforestation will be missing from our data.\u201d<\/p>\n

For experts like Sylvia Wilson, the chief forest and climate scientist at Wilpa Capacity Development with nearly 20 years of global forest monitoring experience with the U.S. Geological Survey, adding L-band SAR to optical is a scientific game changer. \u201cL-band SAR gives us the opportunity to see what optical doesn\u2019t,\u201d Wilson said. \u201cBut it\u2019s not one sensor versus the other; the future is SAR plus optical.”<\/p>\n

The NISAR<\/a> (NASA-ISRO Synthetic Aperture Radar) satellite, launched in July 2025, will drastically increase the feasibility of systems like Flores-Anderson\u2019s by providing more frequent and comprehensive L-band SAR data. L-band data has been relatively scarce, with limited images only available in a few areas like the Brazilian Amazon. Once more NISAR data become publicly available, they will provide free, global L-band SAR every 12 days. Flores-Anderson\u2019s system is already prepared to incorporate this data.<\/p>\n

\u201cIt doesn\u2019t matter which sensor we get data from\u2014whether it\u2019s optical or SAR\u2014it automatically adds to our model,\u201d Flores-Anderson explained. \u201cAs more NISAR data become available, we will have more accurate, faster detection of change.\u201d<\/p>\n

NASA Earth Observatory images by Michala Garrison, using MODIS data from NASA\u00a0EOSDIS LANCE<\/a>\u00a0and\u00a0GIBS\/Worldview<\/a>, the\u00a0Harmonized Landsat and Sentinel-2<\/a>\u00a0(HLS) product, and model data provided by Flores-Anderson et al<\/a>. Story by Lena Pransky (EarthRISE) with Jake Ramthun (EarthRISE) and Madeleine Gregory (Landsat Project Science Support).<\/p>\n

\t\t\t\t\t\"Satellite\t\t\t\t<\/p>\n

\t\t\t\t\t\"Figure\t\t\t\t<\/p>\n

Cardille, J. A. et al. (2022) Multi-sensor change detection for within-year capture and labelling of forest disturbance<\/a>. Remote Sensing of Environment, 268 (112741).<\/p>\n

Flores-Anderson, A.I. et al. (2026) On the sensitivity of SAR C- and L-band dual-polarized data for detection of early deforestation in the tropics<\/a>. Remote Sensing of Environment, 333 (115133).<\/p>\n

Flores-Anderson, A.I. et al. (2025) Early Deforestation Detection in the Tropics using L-band SAR and Optical multi-sensor data and Bayesian Statistics<\/a>. International Journal of Applied Earth Observation and Geoinformation, 143 (104831).<\/p>\n

INFOAMAZONIA (2022, February 15) Prodes and Deter: get to know these strategic systems in the fight against deforestation in the Amazon<\/a>. Accessed April 2, 2026.<\/p>\n

NASA (2025, July 25) Get to Know SAR \u2013 Overview<\/a>. Accessed April 2, 2026.<\/p>\n

Pelletier, F. et al. (2024) Inter- and intra-year forest change detection and monitoring of aboveground biomass dynamics using Sentinel-2 and Landsat<\/a>. Remote Sensing of Environment, 301 (113931).<\/p>\n

Springer Nature (2023, August 24) Behind the Paper<\/a>. Accessed April 2, 2026.<\/p>\n

United Nations Climate Action (2025) Forests – nature\u2019s solution to carbon pollution<\/a>. Accessed April 2, 2026.<\/p>\n

United Nations Environment Programme (2025, October) High-risk Forests, High-value Returns and the State of Finance for Forests: Key Messages<\/a>. Accessed April 2, 2026.<\/p>\n

National Park Service (2019, March 8) Wildlife of the Tropical Rainforests<\/a>. Accessed April 2, 2026.<\/p>\n

United Nations Foundation (2023, January 4) Biodiversity Explained: Facts, Myths, and the Race to Protect It<\/a>. Accessed April 2, 2026.<\/p>\n","protected":false},"excerpt":{"rendered":"Tropical forests span 1.6 billion hectares (6.2 million square miles) of Earth. These ecosystems support a majority of…\n","protected":false},"author":2,"featured_media":366313,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[121856,104562,117340,35950,142229,139397,192320,111,139,69,147,392,23440],"class_list":{"0":"post-366312","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-aqua","9":"tag-earth-observatory","10":"tag-earth-visualization-mapping","11":"tag-land-use","12":"tag-landsat-8-ldcm-landsat-data-continuity-mission","13":"tag-landsat-9","14":"tag-marshall-earth-sciences","15":"tag-new-zealand","16":"tag-newzealand","17":"tag-nz","18":"tag-science","19":"tag-space","20":"tag-vegetation"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/366312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=366312"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/366312\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/366313"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=366312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=366312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=366312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}