As I drove with my family through a remote valley in south-western Uganda ten years ago, we turned a corner and entered a vast landscape of devastation - thousands of hectares of hillside stripped bare of indigenous forest and replanted with sterile rows of eucalyptus and conifers. In the distance we could hear chainsaws buzzing. When we reached the far side of the valley we came across a sign stating 'Funded by the European Union'.
This, of course, is what offsetting nightmares are made of. Almost since the concept was invented in the late 1980s, carbon offsetting has had a bad press, likened to buying papal indulgences, described as 'greenwash' and a licence to pollute. The kind of scheme I saw in Uganda only serves to underline the potential pitfalls.
So we need to ask ourselves 'Would Jesus offset?' Does offsetting work at all? Isn't it based on dodgy science? Can it make any realistic contribution to tackling climate change? Doesn't it cause more harm than good?
Thankfully, nowadays all reputable voluntary carbon offset projects are regulated by rigorous, independent standards which ensure not only that carbon dioxide is mitigated, but that the communities where they are situated reap the benefits and are helped to adapt to the impacts of climate change.
Tree-planting projects must be designed to bring community and environmental benefits, including sources of income from forest products, and improvements to soil and biodiversity, as well as sequestrating carbon. Projects are required to deliver permanence (through strong community relations and robust, sustainable mechanisms to deliver payments for ecosystem services), additionality (evidence that the trees would not have been planted without the scheme), and no leakage (so people don't cut down trees elsewhere to replace the land used for tree planting). Detailed baseline and monitoring surveys of a project at its outset and during its life will enable accurate calculations of carbon mitigation potential, and are tempered by risk buffers to take account of the vagaries of weather, fire and disease.
Fuel-efficient stoves and biosand water filters both result in reduced emissions from burning wood and charcoal, but can also bring multiple benefits to communities, saving people time and money collecting fuel, and bringing improvements to health as harmful emissions are reduced. Renewable energy projects should be carefully designed to be sustainable and appropriate for the communities who will be using them. Once again, careful baseline and monitoring assessments and conservative estimates of carbon savings ensure no over-counting, as real people rarely use technology in exactly the way it was designed to be used.
Carbon offsetting relies on careful use of data, robust analysis and caution at both ends of the equation. Carbon calculators, such as the one on the Climate Stewards website, are based on annually-updated emissions factors published by the government for all forms of transport, including vehicle efficiency and average occupancy. For flights, the figure includes an 8% "distance uplift" to reflect the reality that planes do not always fly on the most direct route, as well as a CO2 emissions factor of 90%, to reflect Radiative Forcing (RF) - the influence of other climate change effects of aviation, such as water vapour, contrails and nitrous oxide.
Understanding the carbon footprint of our transport choices is the first step towards making informed decisions about how to reduce it. Climate Stewards' message is 'Reduce what you can and offset the rest'. This is endorsed by Katharine Hayhoe, evangelical Christian and climate scientist, who frequently tells her Twitter followers that she reduces everything she can, and offsets the rest with Climate Stewards.
Carbon offsetting does not mean that we can appease our guilt and keep on flying; we need to reduce our demand for travel, innovate and switch to renewable sources of energy. But offsetting can be one part of the solution, reducing overall carbon dioxide levels in the atmosphere, and giving us a little more time to breathe as we transition to a clean economy, and helping communities most affected by climate change to adapt.
So would Jesus offset? I think he would!
This article first appeared on the website of The John Ray Initiative (used with permission) and Caroline is giving a seminar at their conference this month (17/3/18 in Birmingham) entitled "Transport Now and in the Future - What are the issues?".