The woman, who has only given her name as 'Beth', sat in Castle Street on Saturday morning, holding a sign that read: "I am terrified because of the climate crisis."
Saturday's demonstration began at around 11am, leading to buses being backed up along the one-way Castle Street in Shrewsbury town centre until around 12pm.
Her protest led to buses being backed up and police being called, although traffic was monitored to ensure no emergency vehicles were delayed as a result of her campaign.
'Beth', an Extinction Rebellion protester, said she was appreciated the people who stopped to thank her, sit with her or offer her food and drink.
She said some also intervened with people who became angry with her, and that the support she received was unexpected.
"I think it goes to show there is a groundswell of concern about the climate situation and many people recognise the need for change," she said.
Speaking on Saturday, 'Beth' also said: "I wish I didn’t feel it was necessary to cause this disruption. But I am sitting here today because I want to raise awareness of a greater disruption that is happening to us all.
"I am terrified about the changes I am witnessing to our climate, and the lack of government action to limit the effects we humans are having on the ecosystem on which we depend. We have to demand action for the sake of our children.
"Locally Shropshire Council declared a climate emergency, yet it continues to build the North West Road which will generate 70,000 tonnes of CO2.
"I want to be able to look my children and grandchildren in the eye and say: 'I spoke up, I acted'."
Saturday's protest was part of coordinated national action by Extinction Rebellion to mark two years since the Government declared a climate emergency.
Other protesters blocked traffic in Manchester, Ipswich, Nottingham, Birmingham, Oxford, Bradford, Newcastle and Swansea, as well as at Tower Bridge, Blackfriars Bridge and Kings Cross in London.