Good Morning Britain's Richard Madeley told an Insulate Britain campaigner 'I don't like being patronised' during a fiery argument.
It came as Insulate Britain warned that the M25 will become a "place of non-violent civil resistance" today.
The road-blocking climate group urged motorists to avoid the motorway from 7am or cut their speed to 20mph "to minimise the risk of accidents".
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It said this is in response to Government-owned National Highways securing a new court injunction banning activities that obstruct traffic on its 4,300-mile network of motorways and major A-roads in England.
This is the fourth injunction taken out in response to Insulate Britain's protests.
Activists have blocked roads on 15 days since September 13, causing misery for drivers stuck in long queues of traffic.
Protesters have frequently targeted the M25, which is the UK's busiest motorway.
Appearing as a representative, Insulate Britain campaigner Tracey Mallaghan spoke about the road blocking protests.
She was asked by Richard about the consequences of her and the groups' actions after a mum was left paralysed from a stroke after eco-protesters blocked the M25 and delayed her son as he rushed her to hospital.
Tracey said: "If it was my mum of course at the time I would be furious and heartbroken.
"But when you then go home, you then have to look at the reality, three to four years to save the future of humanity, do you know what that means for my children?"
Richard said: "So you'd allow your own mother a near-fatal stroke?"
Tracey responded: "Three to four years before my kids face an unimaginable future."
Richard said: "You're not answering the question are you?"
Tracey said: "And you're not asking the right questions."
Richard responded: "Well, that's my decision to be honest with you."
Tracey said: "Is it because you're heartless or too scared to look at the reality of our situation."
Throughout the argument, Tracey repeatedly asked if Richard was 'too heartless', 'too scared' or 'stupid'.
Unhappy with her reply, Richard said: "I don't like being patronised."
Richard finished the interview and said: "Thank you for not answering a single question."
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