A Nigerian bank's own operations are not trivial. Hundreds of branches, a data centre, a substantial fleet, and — because this is Nigeria — a very large diesel generation estate keeping all of it running. Measuring it is real work and it takes a quarter to do properly.
Then the portfolio screening runs, and the operational footprint turns out to be somewhere under five per cent of the total.
This is the moment most bank sustainability programmes actually begin, and it reframes everything that came before it.
Why the loan book dominates
Every facility extended to a cement producer, every mortgage, every trade finance line to an importer of steel — the emissions of those activities are attributed back to the financier in proportion to their share of the financing. That is Scope 3 category 15, and for a financial institution it is not one category among fifteen. It is the disclosure.
The standard method is PCAF: an attribution factor, broadly your outstanding exposure divided by the borrower's total equity plus debt, applied to that borrower's emissions, summed across the portfolio.
The thing that makes it tractable
The obvious objection is that almost no Nigerian borrower reports emissions, so the calculation cannot run. PCAF anticipates exactly this.
It provides a scored data quality scale running from verified borrower-reported data at score 1 down to sector-average estimates from exposure alone at score 5. You are expected to use the best data available, disclose the weighted score, and improve it over time — not to wait until every borrower reports.
A Nigerian portfolio starting at a weighted average of 4 or 5 is entirely normal. What is read is the trajectory, not the starting point.
Where the data already is
Exposure by counterparty
In the core banking system. The numerator of every attribution factor.
Sector classification
Already maintained for prudential reporting, and it drives sector intensities where borrower data is absent.
Borrower financials
Credit files hold revenue and balance sheet data, which is what score 4 requires.
Relationship access
Adding two questions about energy consumption to an annual review is the cheapest data quality improvement available to any bank.
Do not start with the whole book
A first cycle that tries to measure every exposure produces a number nobody trusts and a team that will not do it again. Start where emissions concentrate — power, oil and gas, cement, manufacturing, transport — which is usually a minority of exposure and the majority of financed emissions.