LONDON — All but one of the realistic scenarios that could emerge once Britain has formally left the European Union would cause the amount of goods Britain exports to tumble, hurting the country's overall trade picture in the process, according to research from Bank of America Merrill Lynch.

Writing in a note last Friday, economists from the US banking giant cited a chart first circulated back on March 13, which illustrates just how big a battle the UK faces to keep its current export levels in the face of leaving the EU.

BAML presents seven separate scenarios, ranging from a "very hard Brexit" — where Britain drops out of the EU without a deal and has to trade using WTO rules — all the way to a "soft Brexit" that includes striking deals with every single country outside the European Economic Area. All but that final scenario would see UK exports fall.

Here is what the team, headed by Ruben Segura-Cayuela wrote when presenting the chart on March 13 (emphasis ours):

"The UK could offset some of the costs of Brexit by signing trade deals with non-EU countries. But we estimate those trade deals would offset only a small proportion of the Brexit-related decline in exports."

"... signing an FTA with the US, Australia and New Zealand (22% of UK exports) immediately upon Brexit would raise UK exports by only 4% (22% of the 47% of exports to those countries that are goods increased by 36%: 22%*47%*36%=4%)."

The bank does warn in its most recent analysis that the numbers should be taken with a pinch of salt, noting: "We would strongly caution readers against taking the numbers literally: they are very much an upper bound on Brexit effects." Regardless, they're an interesting exploration of how damaging leaving the EU will be to the UK's global trading picture.

Here is the chart: