The US on Friday formally re-entered the Paris Agreement, a global deal to cut carbon emissions and halt temperature rises, almost one month after US President Joe Biden reversed his predecessor Donald Trump’s decision to exit the pact. US Secretary of State Antony Blinken called the 2015 agreement an “unprecedented framework for global action” and promised the US would “do more” to tackle climate change after a four-year stall under the Trump administration. Mr Biden informed the UN that the US was rejoining the deal hours after his inauguration on January 20, kick-starting a 30-day re-entry process. Former president Donald Trump exited the pact in 2017, calling climate change an economy-draining “hoax”. “The Paris Agreement is … both simple and expansive: to help us all avoid catastrophic planetary warming and to build resilience around the world to the impacts from climate change we already see,” Mr Blinken said in a statement. “Now as momentous as our joining the agreement was in 2016 — and as momentous as our rejoining is today — what we do in the coming weeks, months and years is even more important.” His comments came amid the latest example of headline-making weather: <a href="https://www.thenationalnews.com/world/the-americas/no-end-in-sight-as-millions-in-texas-brave-record-cold-without-power-and-water-1.1168281">a winter storm across the southern US</a> that brought freezing winds, snow and ice to areas that seldom see such frigid conditions. UN Secretary General Antonio Guterres and Mr Biden’s new climate chief John Kerry will on Friday hold a virtual conversation about the threat of climate change to mark America’s formal re-entry into the accord. Mr Biden has pledged to put the US on track to net-zero emissions by 2050 to match the swift and steep global cuts that climatologists say are needed to avoid the worst impacts of global warming, using curbs on fossil fuels and investments in clean energy. The administration must now release its new emissions reduction targets, which are known in the deal as Nationally Determined Contributions, before a global leaders summit that Mr Biden will host on April 22. These moves will not be easy. The Biden administration already faces stiff opposition from climate-sceptical Republicans, labour unions and fossil fuel firms, especially over the revocation of permits for TC Energy’s Keystone XL oil pipeline project. The US policy switch means that the countries producing two thirds of global carbon emissions are pursuing carbon neutrality by 2050, the UN says. China, the world’s biggest polluter, aims to become carbon neutral by 2060. Activists complain that progress on global emissions cuts was largely derailed by the four-year Trump administration. Mr Guterres said this week that there had been “no contribution from the US” with Mr Trump in the White House. Still, the UN head described "<a href="https://www.thenationalnews.com/business/technology/amazon-s-climate-pledge-initiative-signs-up-20-more-companies-1.1168508">fantastic mobilisation of the private sector</a>, of the cities, of some states, of civil society as a whole" that kept the US on track for cutting carbon emissions in spite of Mr Trump. Under the 2015 Paris Agreement, most world governments have pledged to keep global warming “well below” 2°C above pre-industrial times and to strive to limit temperature rises to 1.5°C. The planet has so far warmed by 1.2°C and is headed for at least 3°C this century — raising the risk of wildfires, droughts, floods, hurricanes and other extreme weather that will claim lives and ravage economies, the UN says. British Prime Minister Boris Johnson will on February 23 chair virtual UN Security Council talks on the links between climate change and war. The UK will in November host the review conference of the Paris Agreement in Glasgow, known as Cop26. A <a href="https://www.thenationalnews.com/world/mankind-s-war-on-nature-driving-3-c-heat-spike-un-warns-1.1168712">UN report released on Thursday said mankind's "war on nature"</a> was wiping out whole species, polluting the atmosphere, raising temperatures and giving rise to Covid-19 and other so-called zoonotic diseases.