  The current emissions from computing are almost 4% of the world total. This
is already more than emissions from the airline industry and are projected to
rise steeply over the next two decades. By 2040 emissions from computing alone
will account for more than half of the emissions budget to keep global warming
below 1.5$^\circ$C. Consequently, this growth in computing emissions is
unsustainable. The emissions from production of computing devices exceed the
emissions from operating them, so even if devices are more energy efficient
producing more of them will make the emissions problem worse. Therefore we must
extend the useful life of our computing devices. As a society we need to start
treating computational resources as finite and precious, to be utilised only
when necessary, and as effectively as possible. We need frugal computing:
achieving our aims with less energy and material.
