The United Nations' Climate Change Conference, COP26, could be postponed or radically changed due to the COVID-19 pandemic, Sky News reported on Wednesday, citing unnamed government sources.
The November summit was originally due to be held in 2020, but was postponed due to COVID-19.
Sky said two government sources suggested the Glasgow summit might have to be delayed for a second time amid signs the pandemic is worsening in parts of the world.
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Sky also quoted Prime Minister Boris Johnson's office as saying that the British leader was determined to hold the summit in person. They quoted a further unnamed source as saying that there were always uncertainties, but that they had seen nothing to suggest the summit could not go ahead.
Britain is hoping to use the summit to revitalise commitment to global climate aims after a pandemic that has pushed the environment down the global list of priorities.
The summit had been seen as a way for post-Brexit Britain to forge closer relations with the United States, who under President Joe Biden have recommitted to global accord on climate change.
The British government did not immediately respond to a request for comment on the Sky report.