John Kerry says current goals under Paris climate agreement 'inadequate' to reduce Earth's temperature

"The goals thus far have been inadequate ... The goal of achieving a 1.5˚(C) limitation on the rise of Earth's temperature is absolutely the appropriate goal, but the current promises of countries through the Paris Agreement, are insufficient to get the job done," Kerry told CNN's Fareed Zakaria on "GPS."

But, the former US secretary of state said, there was still time to do more when it comes to climate change.

Shortly after taking office, President Joe Biden took several executive actions aimed at the climate crisis and rejoined the Paris Climate Accord, the landmark 2015 agreement the US abandoned under former President Donald Trump. The pact, signed by nearly all the world's countries, seeks to limit global warming to well below 2°C and pursue efforts to limit it to 1.5°C. On the campaign trail, Biden announced a goal of the US achieving net-zero emissions by 2050 and climate experts say the goal is aggressive but achievable.

Kerry on Sunday again signaled his own approval of a carbon tax as an option to take on the climate crisis, something Biden said he would support during the 2020 presidential campaign, when asked if he thought the US could go down that route.

"Well, we could do it. It is one option of many things we're going to have to consider and may wind up doing," Kerry said, adding that he agrees with the idea that it is one of the most significant things that can be done to have a rapid impact.