Some of his closest rivals were greeted more like rock stars.
The Sunrise Movement - which has pressured candidates to take the pledge - has now called on Biden to cancel the event.
Biden's latest slip of the tongue came during his speech to the 1,227 delegates in the state that holds the first primary in the Democratic presidential nomination process.
Biden's team insists such optics are overrated as indicators of a candidate's strength. If Inslee's experience is any indication of the role for amiable wannabes with slightly unusual ideas, candidates will start campaigning on a platform of love soon enough should self-help author Marianne Williamson drop out of the running.
"If you believe that God is watching as poison is being belched into the air of creation, and people are being harmed by it, countries are at risk in low-lying areas- what do you suppose God thinks of that?" he said.
But after the 2016 campaign, enthusiasm is on the minds of Democrats. Cory Booker, as the crowd erupted in cheers. Hillary Clinton, meanwhile, headlined smaller events and ultimately struggled to match Republican enthusiasm.
What's more, coal, oil and gas companies, along with investor-owned utilities, have spent millions of dollars to mislead the public about the existence of the climate crisis and blocking policies to curb it at every level of government.
Sanders declined to support a full end to the filibuster, asserting that he could get climate change legislation through Congress without needing to eliminate the Senate's 60-vote requirement for many bills by using a procedural maneuver that the GOP most recently used in 2017 to pass massive tax legislation. Rival campaigns grumbled privately that Warren, who represents neighbouring MA, was benefiting from home field advantage.
Sanders, a veteran politician on the left of the Democratic party, promised to reduce domestic emissions by at least 71% by 2030 and achieve full decarbonisation by 2050. But since announcing his campaign in April, Biden has made four campaign trips to the state with sometimes-uneven results. Supporters of the major candidates gathered outside the arena in the early morning hours, waving signs and chanting campaign slogans.
Democrats in New Hampshire have been slow to endorse so far this election system. They were not a significant presence at the partisan convention.
New Hampshire is not accustomed to playing the role of the undercard.
"And everywhere along the way - for example, I've argued and pushed for us suing those executives who are engaged in pollution, those companies engaged in pollution", he added.
"There would be no empty chair", Biden said.
The former vice president also mixed up the timeline around the Marjory Stoneman Douglas High School in Parkland, Florida in February of 2018.
And Biden was not exactly snubbed at the convention.
In a series of 10-minute speeches, the contenders accused Trump of sowing hate and threatening democracy, calling the 2020 election a referendum on what kind of country the United States would be. "And I'm challenging every other candidate for President to do the same". Last month in Iowa, the California Democrat dedicated five days in August alone to a bus tour. Bernie Sanders and 37-year-old Pete Buttigieg, who has urged voters to elevate a new generation of leaders. The rest of the democratic world recognizes that President Trump is erratic, self-serving and corrupt, and this is damaging the entire world order as well as hurting our nation. In the last few weeks you've confused New Hampshire for Vermont, said Bobby Kennedy and MLK were assassinated in the late '70s, assured us, 'I'm not going nuts.' Follow up question: Are you going nuts?'