As coal, gas, and oil production continues, "climate-related natural disasters are becoming more frequent, more deadly, more destructive, with growing human and financial costs", Guterres pointed out.
Spain's acting Prime Minister Pedro Sanchez - whose Government stepped in to host the summit after unrest erupted in Chile, the original venue - urged delegates to be bold.
COP25 was supposed to take place in Chile, but anti-government protests and police repression there spurred Chile's government to bow out. According to the United Nations Framework Convention on Climate Change (UNFCCC), around 30,000 participants have been accredited to the event.
In an interview with The Associated Press, the United Nations chief hoped that stricter goals in Europe would allow European Union leaders to convince fellow big polluters "to understand that this must be a collective effort and that they all will have to correct their policies in order to drastically be able to reduce the emissions".
The conference comes as global efforts to mitigate climate change are on the brink of failure.
Every year, air pollution, associated to climate change, kills seven million people.
Trump says complying with the accord would hurt the US economy, restricting domestic producers while other big polluters such as China increase emissions. In 2018, emissions totaled 55 gigatonnes of Carbon dioxide equivalent.
Cuts in emissions of greenhouse gases - mostly from burning carbon-based fossil fuels - that have been agreed so far under the Paris deal are not enough to limit temperature rises to a goal of between 1.5 and 2 degrees Celsius above pre-industrial levels.
Key meetings will centre on how landmark 2015 Paris Climate Change Agreement becomes fully operational, in particular mechanisms for trading carbon, as well as the groundwork needed for fresh climate pledges due to be made by all Paris signees before the end of 2020.
Chile's environment minister, Carolina Schmidt, said that the December 2-13 meeting in Madrid needs to lay the groundwork for moving toward carbon neutral economies while being sensitive to the poorest and those most vulnerable to rising temperatures - something that policymakers have termed "just transition".
This 25th annual global summit on climate change has had a rocky start; last year, initial host country Brazil withdrew its offer to host the conference, then replacement host country Chile did the same in October of this year.
"Guterres supports Turkey's reasonable position in the climate change negotiations", Murat Kurum told reporters following his meeting with Guterres in the Spanish capital of Madrid.
"One of the most important points is that China opposes any kind of unilateralism and safeguards the authority of multilateralism", said Lu, adding that China will work with other parties to help make the conference a success.