Monthly Archives: March 2020

Reflective crops contribute to climate change mitigation

Albedo change can make an important contribution to the climate impact of cropping systems. Albedo is the share of solar radiation reflected back from the ground. It ranges between 5 and 30% for bare and vegetated agricultural land, and can reach up to 90% due to snow cover. The more reflective a surface, the higher its albedo and the greater the potential for radiative cooling and eventually temperature change.

Photograph by Sergio Lorenc

Albedo has increased globally due to agricultural expansion, converting forests to more reflective grass- and croplands. However, deforestation is associated with losses of crucial ecosystem functions including carbon storage and local surface cooling by evapotranspiration. Managing agricultural land to achieve higher reflectivity has the potential to mitigate local heat waves and global warming. Strategies to increase the albedo of croplands include selection of reflective species or varieties, introduction of cover crops, intercropping, residue retention, and delayed or no ploughing.

In a recently published article, we studied how cultivating abandoned land with short-rotation willow affects albedo and evaluated its potential as a climate change mitigation measure. We found that albedo increased from 16.5 to 21.5% on average when fallow land was cultivated with willow, based on three years of field-measured data. These data were subsequently combined with a time-dependent life cycle assessment (LCA) model of bioenergy produced from willow. Here, we included emissions from the production of inputs, field operations, soil, transport and energy conversion.

Simulating processes and emission along the life cycle and impacts on climate over time allowed us to compare the effect of albedo change (cooling) to that of greenhouse gas emissions (warming) and carbon sequestration in biomass and soil (cooling). In sum, the bioenergy system had a net cooling effect because albedo change and carbon sequestration outweighed emissions from the supply chain and soil. Our results over time showcase the different nature of albedo and long-lived greenhouse gases as climate forcers. Albedo change needs to be sustained for years in order to offset the temperature response to a one-off greenhouse gas emission.

The article has been published open access in GCB Bioenergy:
Sieber, P., Ericsson, N., Hammar, T., & Hansson, P.-A. Including albedo in time-dependent LCA of bioenergy. GCB Bioenergy, n/a(n/a). doi:10.1111/gcbb.12682

100 000 ton per year instead of 30 000 – updated data about food waste from Swedish retail stores

The elefant in the room in this new report http://www.naturvardsverket.se/Om-Naturvardsverket/Publikationer/ISBN/8800/978-91-620-8857-6/, was the new data on retail waste – 100000 tons instead of 30000 tons -, which now is based on figures reported directly by the retail chains via the voluntary agreement instead of statistics based on a few stores combined with the number of employees. Expressen, a Swedish tabloid newpaper, made an interview with me and choosed to put focus on how the stores try to hide the food waste data, by not including rejected fruit and vegetables and returned unsold bread and dairy products. From my perspective, this actual behaviour is true, but the incentive is probably not to hide data from the public, but to shuffle the waste to other actors for economical reasons. I also think the newpaper “scope” about this could have been that the Swedish environmental protection agency previously used a method that only catched a third of the actual waste, besides that the now published “actual” waste does not include everything arising at retail level. /Ingrid Strid, food waste researcher at SLU

https://www.expressen.se/nyheter/klimat/sa-doljs-matsvinnet-genom-livsmedelsjattarnas-kryphal/

Oranges in nets are often wasted when one fruit gets bad.

New Food waste course

If you are interested in food waste-related issues, there is an opportunity to learn more this autumn in the new course “Food waste – current situation and future opportunities.” held at SLU in Uppsala. The course starts in August and will revolve around topics covered in the new Routledge Handbook of Food waste that will also act as the course literature. Study visits and project work are also an integral part of the course to disseminate where waste occurs and what strategies need to be in place to tackle this present issue both now and tomorrow.