He later told reporters that realities about global climate are "worse than expected, but the political will is relatively faded after Paris" and is not matching the challenges.
Two weeks of talks began yesterday in Poland to tackle deep political divisions at the most important United Nations meeting on global warming since the landmark 2015 Paris deal to shift away from fossil fuels.
Negotiators from around the world opened the United Nations' annual climate change conference Sunday in a Polish city built around mining coal, widely seen as a main culprit behind global warming.
Host country Poland is expected to propose what it calls a "just transition" for the oil, gas, and coal industries to ease the financial blow from the move away from such polluting sources of energy.
UN Secretary-General Antonio Guterres warned nations that their plan to chart a route away from runaway global warming was "way off course".
Guterres also urged negotiators not to forget that the challenges they face pale in comparison to the difficulties climate change already is causing millions of people around the world whose homes and livelihoods are threatened by rising sea levels, drought and more powerful storms.
The United States, meanwhile, reiterated at the G20 summit in Argentina on Saturday its decision to withdraw from the Paris accord and a U.S. commitment to all energy sources.
Schwarzenegger also insisted that the United States was "still in" an worldwide accord to curb global warming despite U.S. President Donald Trump's decision to walk away from the agreement.
Citing a recent scientific report on the dire consequences of letting average global temperatures rise beyond 1.5 degrees, Guterres urged countries to cut their emissions 45 per cent from 2010 levels by 2030 and aim for net zero emissions by 2050.
Pompeo says USA will suspend arms pact over Russia's 'cheating'
President Donald Trump had threatened in late October that he would leave the treaty. "Russia's violation of the INF Treaty erodes the foundations of effective arms control and undermines Allied security".
"The rest of the G-20 have not only understood the science, they are taking actions to both prevent the major impacts and strengthen their economies", said Figueres, who now works with Mission 2020, a group that campaigns to reduce greenhouse gas emissions.
"The impacts of climate change are increasingly hard to ignore", said the statement, a copy of which was obtained by AFP.
The meeting in Katowice is regarded as a key test of countries' willingness to back their lofty but distant goals with concrete measures, some of which are already drawing fierce protests.
"In short, we need a complete transformation of our global energy economy, as well as how we manage land and forest resources", Guterres said.
The UN negotiations got off to a chaotic start in the Polish mining city of Katowice Sunday, with the opening session delayed almost three hours by a series of last-ditch submissions.
Arnold Schwarzenegger says he wishes he could travel back in time like the cyborg he played in "The Terminator" so he could stop fossil fuels from being used. "It's what I think you could call a distributed leadership, where you have a number of countries - some of them small or medium-sized - really making headway and doing it in tandem with cities and states and businesses".
Not far from the meeting venue, Polish anti-coal activists held a small protest Sunday.
Marches aimed at showing support for ending the use of coal-fired power plants and other efforts to limit climate change drew thousands of people over the weekend in Brussels, Berlin and Cologne.