But the speech threatens to be overshadowed by country-wide demonstrations called by Navalny's supporters, who fear the life of Putin's best-known critic is in grave danger.
"The Russian president once said that if a fight is inevitable, you need to hit first. But every leader needs to understand that a fight must not be inevitable when it concerns a real war and millions of human lives."
As the European Union's 27 foreign ministers held virtual talks Monday, EU foreign policy chief Josep Borrell said the bloc held the Russian authorities responsible for Navalny's health.
Biden has invited 40 world leaders to the climate summit, part of his effort to make the fight against global warming a top priority.
Putin, in his speech, will "outline Russia's approaches in the context of forging broad international cooperation aimed at overcoming the negative effects of global climate change," the Kremlin said.
Navalny, 44, a prominent opponent of Russian President Vladimir Putin, started refusing food on March 31 in protest at what he said was the refusal of prison authorities to treat him properly for acute back and leg pain.
"His condition is indeed critical," said Alexandra Zakharova, a representative of the Doctors Alliance trade union - a group that Russian authorities regard as opposition activists.
There is a strong push in the United States to cripple the project with sanctions and prevent its completion, out of fear that it will give Moscow a dangerous grip on the energy supplies of US allies in Europe.
She said the United States believes a summit would be a good step forward toward "the development of a stable and predictable relationship" between the two countries.
The US secretary of state also met with EU foreign policy chief Josep Borrell, both of whom expressed deep concern over Russian troop movements, according to a European statement.
Ukraine has raised the alarm over an increase in Russian forces near its eastern border as violence has risen along the line of contact separating its troops from Russia-backed separatists in its Donbass region.
"The Chancellor demanded that this build-up be unwound in order to de-escalate the situation," Germany's government said in a readout of a telephone call between Merkel and Putin.