climate change

Planting Trees, Search Engines, and Climate Change

Written by César Palacios-González

The other day I went down an internet rabbit hole when researching about planting trees and climate change. I came out the other side concluding (among other things) that there were good reasons to change my search engine to Ecosia[1]. So I did, and, other things being equal, you should too. If you have never heard of Ecosia this is the main gist: it is a search engine that uses its profits from search ad revenue to help fund tree planting projects around the world. Now let me explain how I came to this conclusion. But before I begin, I think it’s important to clarify something. Climate change is a political problem that requires a political solution. But I think this is no way negates that individual actions matter in terms of fighting its effects.

Climate change is one of the most (if not the most) serious emergencies that humanity faces right now. It is not only that the poor will suffer the most because of it.  In the words of the UN, climate change is ‘the defining issue of our time and we are at a defining moment’. Climate change, among other things, speeds the spread of infectious diseases like malaria, increases the frequency and severity of weather-related disasters such as heatwaves and floods, and creates the conditions that lead to potentially fatal malnutrition and diarrhoea (read more here and here). The World Health Organization ‘estimates that the warming and precipitation trends due to anthropogenic climate change of the past 30 years [up to 2005] already claim over 150,000 lives annually’. And according to the WHO climate change is expected, between 2030 and 2050, to cause 250,000 additional deaths per year. And it is not only humans who suffer, wildlife devastation is already happening (for example, see here and here).

Consumption in the developed world (from food to air travel, to mostly anything in between) generates greenhouse gases. And these gases trap heat in the atmosphere:

The planet’s average surface temperature has risen about 1.62 degrees Fahrenheit (0.9 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. Most of the warming occurred in the past 35 years, with the five warmest years on record taking place since 2010

In 2017, for example, the UK per capita emission of CO2 equivalent was of 7.7 tonnes (CO2 equivalent, henceforth CO2e, is a standard way of measuring carbon footprint[2]). You can answer this questionnaire from the WWF to know how big your environmental impact is. So, we know that our consumption generates a lot of greenhouse gases, that these gases contribute significantly to climate change, and that climate change harms and kills people and wildlife.

Given that the total amount of human CO2e emissions is radically different from your personal CO2e emissions it is natural to ask if your emissions (and your lifetime emissions) cause any of the previously mentioned harms. In a recent article, John Broome has shown that ‘individual’s emissions may do harm, and that they certainly do expected harm’. In other words, any one of your emissions may or may not do actual harm (for example, it could be the case that your emission was the one which triggered the drought), but they certainly create an expectation of harm (an expectation that wouldn’t be there if you hadn’t produced the emission). Here it is important to note that unless doing otherwise would greatly affect our interests, morality requires avoiding doing expected harm. Think about the following case: suppose that you can walk down road A or B. The roads are identical and lead you to the exact same place, but for the fact that if you walk down road B you might trigger an avalanche which will kill some people in a nearby village. Morality requires that you walk down road A.

What should we do regarding this expectation of harm? The first thing is carrying out lifestyle changes that will cancel or reduce some of our emissions; for example cutting meat from your diet and changing our light bulbs to LEDs, among many other things. Making such changes reduces the expected harm from your CO2e emissions. I say “reduce” because you would still likely be producing greenhouse gases in other areas of your life. The best outcome in this regard is not only to reduce one’s carbon footprint to zero, but to live a life where your carbon footprint is negative.

The second thing one should do is carbon offsetting. Carbon offsetting can be understood as a compensatory action for carbon emissions whose aim is to increase CO2 absorption or prevent its generation (for more on offsetting see here). The idea is that you balance out your emissions, and this can be done in different ways. For example: planting trees or funding clean energy technologies.

Most people in the developed world will still end up generating emissions even after a major lifestyle change, and these emissions create an expectation of harm (these emissions could come, for example, from commuting via train to work). It could be the case that you have enough resources (economic or otherwise) to offset all the emissions that you were not able to cancel through your lifestyle change. If this were the case, and you used your resources in such way, then it seems that you would no longer create an expectation of harm. It could also be the case, and I think this is the most likely scenario, that you do not have the resources (economic or otherwise) to offset all of your emissions after your lifestyle changes. What are you to do if you were in such a situation where no other lifestyle changes are possible? For example, you are stuck with your 10-year-old car and you need to drive to work due to the lack of public transportation. Here is where Ecosia comes into play.

Ecosia, as any other search engine, generates revenue from your clicking on advertisements (in this case the ads come via Bing who pays Ecosia a share, click here for more information). But importantly, Ecosia uses its profits from search ad revenue for tree planting. And according to recent research, substantive tree planting is among the best climate change solutions to date (click here for the paper).

Now, when you make a purchase on the internet you can use two different types of search engines to look for the stuff that you want to buy: 1) search engines that do not use their profits from search ad revenue for tree planting, and 2) search engines that do use their profits from search ad revenue for tree planting. As mentioned above, if you are like most people in the developed world then even after your lifestyle changes you have net positive emissions. And given that you cannot cancel out your emissions, the next best thing to do when online buying is to use a search engine that uses its profits from search ad revenue to help fund tree planting projects around the world.


[1] I guess here is where I say two things. First, I only talk about this search engine because, as far as I know, there are no others like it. Second, I am in not in any way paid nor do I receive any kind of economic benefit, or otherwise, from said company.

[2]The idea is to express the impact of each different greenhouse gas in terms of the amount of CO2 that would create the same amount of warming. That way, a carbon footprint consisting of lots of different greenhouse gases can be expressed as a single number’.

Cross Post: How psychology can help us solve climate change

Time to cooperate. Hands by Shutterstock


The Paris agreement on climate change calls for a global responsibility to cooperate. As we are often reminded, we urgently and drastically need to limit our use of one shared resource – fossil fuels – and its effect on another – the climate. But how realistic is this goal, both for national leaders and for us? Well, psychology may hold some answers.

Psychologists and economists have long explored the conflict between short-term individual and long-term collective interests when dealing with shared resources. Think of the commons dilemma: the scenario in which a field for grazing cattle works well when everyone cooperates by sticking to one cow each, but which leads to the so-called “tragedy of the commons” if more selfish drives take over.

It is useful to think about overuse of fossil fuels and its effect on the climate as a similar dilemma. If we were to think of this from a purely economic perspective, we would likely act selfishly. But psychological research should make us more optimistic about cooperation. Continue reading

Vagueness and Making a Difference

Do you make the world a worse place by purchasing factory-farmed chicken, or by paying for a seat on a transatlantic flight?  Do you have moral reason to, and should you, refrain from doing these things?  It is very unlikely that any individual act of either of these two sorts would in fact bring about a worse outcome, even if many such acts together would.  In the case of factory-farming, the chance that your small purchase would be the one to signal that demand for chicken has increased, in turn leading farmers to increase the number of chickens raised for the next round, is very small.  Nonetheless, there is some chance that your purchase would trigger this negative effect, and since the negative effect is very large, the expected disutility of your act is significant, arguably sufficient to condemn it.  This is true of any such purchasing act, as long as the purchaser is ignorant (as is almost always the case) of where she stands in relation to the ‘triggering’ purchase.

Continue reading

Do we have a moral obligation protect the climate?

On 6 December, Prof. Dr. Bernward Gesang, Chair of Philosophy and Ethics of Economy at the University of Mannheim, presented an interesting talk on “Do individuals have duties to protect the climate?” exploring if individuals have moral obligation to change their behaviours to mitigate climate change from an Act Utilitarian perspective, i.e. the view that an act is permissible if and only if no other acts bring higher overall utility. Continue reading

Après nous, le déluge: legislating science

The North Carolina senate tried to pass a bill in June banning state agency researchers from using exponential extrapolations in predictions of sea level, requiring them to just using linear extrapolations. After being generally laughed at, the legislators settled for a compromise: state agencies were forbidden to base any laws or plans on exponential extrapolations for the next three to four years. Now a new report shows that sea levels are rising faster near North Carolina than anywhere else on Earth.

Continue reading

The price of uncertainty: geoengineering climate change through stratospheric sulfate

With thanks to Clive Hamilton for his talk.

Stratospheric sulfate seems to be one of the most promising geoengineering methods to combat climate change. It involves the injection of  hydrogen sulfide (H2S), sulfur dioxide (SO2) or other sulfates, into the stratosphere. Similar to what happens after major volcanic eruptions, this would reflect off part of the sun’s energy and cool the Earth, counterbalancing the effect of greenhouse gases (see for instance the “Year without a Summer” that followed the 1815 eruption of Mount Tambora).

It is probably the best geoengineering solution to climate change, in that it’s likely to work, should be technically feasible, can be done by a single nation if need be (no need for global consensus), and is likely to be very cheap – especially in comparison with cutting emissions. But it has a few drawbacks:

  1. It will have unpredictable effects on the weather across the globe.
  2. We can’t really test it – the test would be doing it, on a global scale.
  3. We wouldn’t know if it worked until we’d had about a decade of temperature measurements.
  4. Once started, it’s extremely dangerous to stop it – especially if carbon emissions keep rising.

So, should we do it? Narrow cost-benefit analysis suggests yes, but that doesn’t take into account the uncertainty, the unknown unknowns – the very likely probability that things will not go as expected, and that we’ll have difficulty dealing with the side effects. This includes the political side effects when some areas of the globe suffer more than others from this process.

How bad does global warming have to get before we consider this type of nearly irreversible geoengineering? If we had to choose between this and cutting emissions, how high would the cost of cutting have to go before we sprang for this instead? In short, what price do we put on avoiding uncertainty on the global scale? Can we estimate a dollar amount, or some alternative measure of the cost – quality-adjusted life years, or some other human-scale estimate? Or is this an illusionary precision, and do our intuitions and qualitative arguments (precautionary principle?) give us a better estimate of whether we should go ahead with this?

Planet of the (Little) Apes

The Daily Mail has recently published an article entitled ‘Planet of the (little) apes: Save the world by genetically engineering humans to be smaller, suggests NYU philosopher.’ (

 It is always good to see the Daily Mail covering philosophy and covering issues in applied ethics in particular. The NYU philosopher in question is former Uehiro Centre researcher S. Matthew Liao. His co-authors, Anders Sandberg and Rebecca Roache are both affiliated with the Future of Humanity Institute here at Oxford and the paper under discussion is called ‘Human Engineering and Climate Change’ and is forthcoming in Ethics Policy and the Environment, an interdisciplinary academic journal which specialises in environmental policy and ethics.

  Continue reading


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