Did wealth decide how much CFC the grace period released?

Find your issue, and check it is measured

An environmental issue: something happening, to something, because of something, with proof that somebody measures it.

CFCs released at the surface drift up to the stratosphere and destroy ozone there for decades. Developing countries were allowed to keep using them until 2010, so every tonne used in those years went into a store that holds it for decades.

Proof it is measured

Ozone-depleting substances, country by country, opened: each party's own annual returns to the UN, 1986 to 2022, in ODP tonnes. Joined to Our World in Data's GDP per person and population.

In the news

UN News, 9 January 2023: nearly 99% of banned ozone-depleting substances phased out, and the ozone layer on track to recover over the Antarctic by around 2066.

The system

Input: CFCs consumed, then released. Store: chlorine in the stratosphere, where it stays for decades. Output: slow breakdown and removal. Effect: less ozone, more ultraviolet reaching the surface. The treaty can act only on the input.

Write your research question

One sentence naming the indicator and its units, the years and the places. No strategy in it.

What is the relationship between GDP per person (1995 to 1997 average) and total CFC consumption per million people, 1996 to 2009, across the Article 5 parties to the Montreal Protocol?

Independent variable

GDP per person, averaged over 1995 to 1997, in constant 2021 international dollars (adjusted for inflation and for price differences between countries).

Dependent variable

Total CFC consumption from 1996 to 2009, in ODP tonnes (tonnes weighted by how much ozone each chemical destroys) per million people.

The environmental side

An amount of ozone-depleting chemical, weighted by the ozone it destroys: the input to the stratospheric store. GDP alone against a policy date would be economics with no environment in it.

Why these years

1995 to 1997 are the treaty's baseline years for developing countries' freeze. 1996 to 2009 are the years they could still use CFCs after developed countries had to stop.

Find a real-world strategy and its tensions

One real-world strategy people are genuinely arguing about, two named positions, and what the tension does.

The Multilateral Fund for the Implementation of the Montreal Protocol.

The strategy

Set up by the London Amendment in June 1990. Industrialised parties pay in; Article 5 parties draw on it to meet the extra cost of switching away from the controlled chemicals. The fund is replenished by negotiation every three years.

Position 1 · economic, political

The United States, in William Reilly's opening statement at London (June 1990): it would pay its share, likely twice as much as the next largest donor. But the cost had to be limited and predictable, and paying must not become the rule for other environmental problems.

Position 2 · social, political

Maneka Gandhi, India's environment minister, at London (UPI, 30 June 1990): "You have made the mess, and now you can pay to clean it up." India won a promise that developing countries could renegotiate what they had agreed to if the money or technology did not arrive.

The tension

Who pays for a problem mostly caused by others. Donors wanted a limit on the cost. Developing countries would not give up cheap refrigeration without help.

What it does

Delay: a fourteen-year grace period for Article 5 parties. Uneven costs: the donors pay, and the size of the fund is argued over every three years.

For the environment

Every tonne used during the grace period is chlorine in a store that holds it for decades. That is what the dependent variable measures.

Link to the question

The fund exists so that a poorer country can afford to stop. The question tests whether poorer countries used more CFCs per person while they were allowed to.

Select and document your data

A dataset you can defend: counted, documented, and cut to a rule fixed before you looked.

Sources

Ozone-depleting substance consumption (UNEP), GDP per capita and population, all via Our World in Data. Each downloads by adding .csv to the chart address. Joined on the three-letter country code. The ozone file arrived as 5,642 rows, 177 entities, 1986 to 2022.

Article 5

Article 5 parties are the developing countries the treaty gave extra time. That is every country in the file except 22 developed ones: the eighteen named in the worked example, plus Andorra, Palestine, San Marino and the Vatican. EU member states are not in the file as countries.

Inclusion rule

A country must have used CFCs at some point, and reported in every year from 1996 to 2009 (a total needs every year). It must also have GDP for all of 1995, 1996 and 1997. Aggregate rows (blank code or OWID_) are removed.

Derived quantities

Mean GDP per person for 1995 to 1997. Total CFC consumption 1996 to 2009, divided by mean population over the same years, times one million.

How the numbers were made

CFC figures are each government's own report to the UN, weighted by ozone-depleting potential. Consumption is production plus imports minus exports, so it is not the same as emission (release into the air). Singapore's total is below zero. GDP and population are modelled estimates.

Credit

UNEP and Our World in Data (CC BY), with the date downloaded.

Treat your data

Run a statistical test, leading to figures you built and a statistical result.

Spearman's rank correlation, two-tailed, at p = 0.05.

Why this test

A relationship between two measurements on the same 132 countries. Both are strongly skewed (a few large users and many small ones), so use a rank test rather than Pearson's.

Decided before running it

Critical value about 0.170 for n = 132 (check it in the table you cite). With this many countries even a weak relationship can be significant, so report the strength of the coefficient, not only p.