Between 30 and 50 percent of all the food that's produced on the planet is lost and wasted without ever reaching human stomachs. That's the stunning takeaway from a new report (pdf) from the Institution of Mechanical Engineers.

We've covered food waste before on this blog, but those figures seemed staggering to the point of absurdity. So I thought I'd comb through the report and pull out some of the concrete details that help illustrate just how the world can actually waste this much food. A sampling:

--"A [survey] in India showed that at least 40% of all its fruit and vegetables is lost between grower and consumer due to lack of refrigerated transport, poor roads, inclement weather and corruption."

--"In mature, developed economies such as the UK and USA ... entire crops, or portions of crops, can be rejected prior to harvest on the grounds of physical appearance. As a result of these factors, up to 30% of the UK vegetable crop is never harvested."

--"Grain wastage in store varies widely with the type of crop and the region. In a developed country such as Australia, wastage of 0.75% in stored grain is at the upper end of acceptability ... [In] Pakistan, losses amount to about 16% of production, or 3.2 million tonnes annually, where inadequate storage infrastructure leads to widespread rodent infestation problems."

--"Many of the grain stores in the former Soviet Republics were engineered and constructed in the 1930s, and cold-storage warehouses and food processing facilities date back to the 1950s. As a result they are inefficient by modern engineering standards, and frequently both insanitary and unsafe."

--"[M]any less-developed nations are located in the warmer, hotter regions of the world, such as India and Africa where post harvest losses of fruit and vegetables can range between 35–50% annually, and these countries lack the engineered infrastructure required to facilitate such post-harvest cooling."

And so on.

After a few pages of this, it doesn't seem so absurd to think that the world really does squander up to half its food. And all that rubbishing has major consequences. Not only is it a waste of energy and water and land, but it's a tragedy in its own right, given that some 870 million people suffer from chronic malnourishment.

On the plus side, this is a problem that can be tackled. For poorer countries, simply building better food-storage buildings could cut down massively on waste in places like Pakistan or Ghana (which lost 50 percent of its stored maize in 2008). Better harvesting technology and techniques could also help, although the report suggests that some nations like India will need more sweeping societal and political changes to cut down on waste.

Meanwhile, wealthier regions like the United States and Europe will need to think harder about not throwing out so much perfectly good food — see this old post for more on that. One small step, which Britain has been exploring of late, is to rethink their use of food labels, which often encourage supermarkets to toss out food long before it actually goes bad.

That may not seem like a pressing task right this second, but these issues are likely to get more attention in the years ahead. Scientists say it's going to be a challenge feeding the world as the population soars past 7 billion and climate change deals a blow to crop yields in the decades ahead. Apart from advanced farming techniques and better land management, we'll also need to figure out how to tamp down on food waste. See this essay (pdf) by the University of Minnesota's Jonathan Foley for more on the big picture here.