The House Speaker is leading a delegation of 14 other House and Senate Democrats to this year's U.N. Framework Convention on Climate Change (COP25) in an effort to assuage concerns of the U.S.'s scheduled withdrawal from the Paris climate agreement.
"It will be more hard for the world to stop climate change by reducing the annual emissions effectively to zero without the United States", said Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics and Political Science. A path where more fossil fuels remain where they should be-in the ground-and where we are on the way to carbon neutrality by 2050.
"By coming here we want to say to everyone, we're still in", Pelosi said of the U.S.'s commitment to tackling global warming.
In an impassioned appeal, the United Nations chief worked through a long list of worrying signs, including new figures released Tuesday by the World Meterological Organisation (WMO).
Except for the European Union's newly sworn-in leadership, which was due to begin a five-year term by paying a visit to the summit, the rest of the world's largest carbon emitters - the United States, China and India - are sending ministerial or lower-level officials to the meeting.
"The last time there was a comparable concentration", Guterres said, "the temperature was two to three degrees Celsius warmer, and sea levels were 10 to 20 metres higher than today".
The opening ceremony began with a warning from Hoesung Lee, chair of the Intergovernmental Panel on Climate Change (IPCC): "If we continue as we are doing, we run the risk of increasing the temperature of the planet and that will have an effect and bad consequences for humanity and threaten our existence".
That involves creating a functioning global emissions-trading system and compensating poor countries for losses they suffer from rising sea levels and other consequences of climate change.
President Hilda Heine of the Marshall Islands warned that breaching the 1.5C barrier would spell the end of her water-bound homeland.
The report found, while an increasing number of countries have set net zero emission targets domestically, only a few long-term strategies have committed to a timeline for net zero emissions.
"In 2018, climate did not feature in the top words typically used to modify emergency, instead the top types of emergencies people wrote about were health, hospital, and family emergencies", said the selection committee of the Oxford Dictionaries.
"We have watched a string of United Nations climate conferences unfold", they continued.
"Big polluters must be rubbing their hands in glee that carbon market mechanisms, which further dilute the already weak and inadequate Paris emissions targets, are back on the agenda", said Dipti Bhatnagar, Climate Justice and Energy Program coordinator for Friends of the Earth International (FOEI), in a statement.
"Extinction Rebellion calls on Rebels Without Borders to come to Madrid", the group said in a tweet, using the hashtag #UltimatumCOP25. "Extinction Rebellion reminds leaders they can not flee the climate and ecological emergency", the group said in a press release.
"Civil disobedience and direct nonviolent actions coordinated by global rebels will fill Madrid's streets and squares".