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Amazon boss Jeff Bezos made the announcement himself, revealing that the company has already ordered 100,000 electric delivery vehicles which will come into use in 2021.

Despite the pledge, 1,500 Amazon workers are expected to walkout because they believe the company is not doing enough to tackle the climate crisis.

Google chief executive Sundar Pichai announced what he described as "biggest corporate purchase of renewable energy in history", amounting to $2 billion worth of solar panels and wind turbines.

In a blog making the pledge, Mr Pichai said: "Once all these projects come online, our carbon-free energy portfolio will produce more electricity than places like Washington DC or entire countries like Lithuania or Uruguay use each year."

Elsewhere, Swedish home retailer IKEA and global news service Reuters also pledged increased spending on renewable energy initiatives.

Earlier this week, 16-year old Greta Thunberg and a group of young climate activists were invited to speak in front of the US Senate to call for greater action. Instead of delivering a personal statement to Senators, Ms Thunberg submitted a copy of a major report on climate change, stressing "I don't want you to listen to me. I want you to listen to the science". She also told Senators "I know you are trying, but just not hard enough, sorry".