Climate change is considered one of the greatest challenges facing humanity, with those in developing countries most likely to suffer as the planet warms. Many charities work to reduce harms due to climate change, pursuing a range of strategies, including political action, preventing deforestation, promoting clean energy, etc. Suppose you wanted to prevent climate change through your donations. How might you choose between them?

At GWWC, we've been conducting a preliminary investigation of charities that work to mitigate climate change, looking for those that provide the greatest emissions-reductions for your money. This is the first in a two-part series exploring our research. In the next post, I'll discuss our investigation and its results in more detail. Here, I want to tell you about some of the high-level arguments and considerations we've encountered, which might support focusing on some kinds of mitigation-methods over others.

Consideration #1: The 'binding budget'

Many people believe the key thing in climate change mitigation is to focus on political strategies directed at causing international agreements that limit the concentration of atmospheric greenhouse gases at a level deemed 'safe' (e.g., 2ºC of warming).

Here's one line of argument that could support this view. We might think of there as being a 'carbon budget' that humanity is entitled to spend: the aim is not to go 'overdrawn'. Suppose some day a binding international agreement will be reached: the entire 'budget' might then be spent, but we won't go above the limit. If the total 'budget' will be spent in any case, you might think any unilateral reduction in emissions you make now makes no difference: any emissions you have reduced in advance will just be extra that someone will be allowed to emit after that agreement.

This argument may sound plausible, but I'm not convinced. The argument assumes the probability of international agreement is not substantially altered by prior emissions reductions. However, agreement seems more likely if it will be cheaper for the parties to uphold, and the cost of agreeing on any particular constraint will be affected by prior reductions. The further we begin from the targets we set, the less likely we are to attain them. Overall, it seems unclear whether unilaterally reducing emissions by some amount encourages more or less abatement through future large-scale agreements. Either way, it's probably not a large effect.

Consideration #2: Market feedback

One popular strategy for mitigating climate change is to prevent deforestation. Suppose you protect a hectare of rainforest from being felled. You've decreased the supply of timber somewhat, but the people who would have bought the wood you've protected still want timber. The price of timber should increase a little. This encourages others to fell their forests a little more, cancelling some of your gains.

The big question is, how much do these feedbacks reduce the effect of your efforts? This depends on what are known as the 'price elasticity of supply' and the 'price elasticity of demand'. These measure how much more wood is harvested if the price of wood goes up by one percent, and how much more wood is wanted if the price goes down by one percent. Let's call these ES and ED, respectively. If you 'buy' one unit of forest and keep it from being logged, the reduction in logged forest is ED/(ED + ES).Supply and demand elasticities are known for many items. If we can't find these figures however, we might estimate that ES and ED are equal. On this assumption, we should estimate the real effect of reducing logging to be half of what it first seems.

Consideration #3: The 'worthless' (?) tonne

Another consideration that supports focusing on big-picture political issues is the worry that only large-scale collective action makes any real difference: the impact we can make is otherwise just too small. For example, suppose you support a project which limits deforestation, but the reduction you create is a single puny tonne. Since climate change is a very big problem, some people feel that contributing a small amount to its solution counts for virtually nothing. Other people may not contribute the rest of what's needed to really solve the issue. China might increase its emissions so much as to dwarf reduction efforts in your country. In that case, aren't your efforts wasted?

This would be true if the amount of carbon in the atmosphere didn't make much difference except at a threshold. This is not the situation we are in. As far as we know the costs from climate change don't come only at big thresholds - each extra bit of carbon dioxide in the atmosphere makes climate change a bit worse. 'Safety targets' such as 2ºC don't signify points at which we expect steep changes in harm: they're lines chosen to represent costs 'too large' by some agreed standard, largely as a focus for mitigation efforts. Even if there were steep thresholds, we don't know exactly where they are. This makes reducing emissions on the margin as good in expectation as if there weren't any thresholds, albeit more chancy. Think of it as like running for a bus which leaves at an unknown time - at many times your running won't help, but sometimes it will make all the difference. Overall, if you run a bit more you're more likely to catch the bus.

Consideration #4: Hidden help

Climate change often involves a large number of groups working together or in parallel to achieve important ends. This creates difficulty when it comes to assessing a charity's past effectiveness: it's difficult to isolate their particular contribution. Suppose a charity tries to shut down coal plants, and coal plants are indeed shut down. Other charities may also have been trying to shut down coal plants, and coal plants close for many reasons. How can you say how much good this charity has done?

I don't know of a simple answer to this question. You will want to find a way to estimate what would have happened otherwise. You will need to decide whether to credit a charity with the difference in probability of outcomes they seem to have caused, or with what actually happened. Another issue is whether to credit charities with the marginal or average value of contributing to a project. Suppose the first charity working on some issue makes a large difference, but each added charity helps less. Do you divide the gains between them, credit each with almost nothing, or credit each successive one with less?

Consideration #5: The unruly future

Here is one final concern. Suppose you reduce emissions by preventing deforestation. Even if you do a good job of this, it might be hard to protect it from being logged in fifty years: there's some probability the forest will be cut down in future. You've bought future people the option of continuing to lock up carbon in the forest, but circumstances might change and they might not take this option. If the forest is logged in fifty years, you'll basically just have delayed some climate change for that period.

This could obviously erode most or all of the value of your mitigation project. It depends, however, on where added climate change would do the most harm. Due to economic development and technological progress, we should expect future people to be better equipped to deal with negative effects from climate change. Delaying some degree of climate change by fifty years might therefore constitute a considerable benefit.

These have been some of the issues we've considered in our quest to find the best charities for turning your dollars into reduced greenhouse emissions. In our preliminary investigation, we've found a number of promising organisations. I'll be discussing these in my next post.

Continue to part 2

Katja Grace is a PhD Philosophy student at Carnegie Mellon University. Her personal website is here.

Image credit: CC BY-ND 2.0 Nathan Hayag