Joe Biden's plan to tackle climate change has been described as the most ambitious of any mainstream US presidential candidate yet. Our environment correspondent Matt McGrath considers what he wants to do, and how he might get it done. Much will be made about Joe Biden's pledge to re-join the Paris climate agreement, the international pact designed to avoid dangerous warming of the Earth. President Trump pulled out of the deal after the Obama administration had signed up in 2016, and during the drawn-out election count, Mr Biden confirmed that reversing the decision would be one of his first acts as president. But key to his credibility on the international stage will be his domestic policies on cutting carbon emissions. More radical Democrats such as congresswoman Alexandria Ocasio Cortez have put forward a proposal called the Green New Deal, which would eliminate carbon emissions from most sources over a decade. The Biden climate plan is more moderate. However, if enacted, it would still be the most progressive climate strategy the US has ever attempted. Net zero by 2050 Mr Biden is proposing to make US energy production carbon-free by 2035 and to have the country achieve net zero emissions by the middle of the century. Reaching net zero requires that any carbon emissions are balanced by absorbing an equivalent amount from the atmosphere by, for example, planting trees. Once in office, Joe Biden wants to spend $2 trillion over four years to drive down emissions by upgrading four million buildings to make them more energy efficient. He wants to spend heavily on public transport, to invest in electric vehicle manufacturing and charging points and give consumers financial incentives to trade up to cleaner cars. All of these options have one additional component apart from cutting carbon: they put people back to work. Andrew Light, a former senior climate official in the Obama administration, says Mr Biden is focused on what lowers emissions and increases jobs at the same time. "There will be a big push on electric vehicles, a big push on efficient buildings, both residential and offices, a big push on creating a new kind of civilian conservation corps and doing a lot of nature-based solutions on climate change. "You've got a really good menu to choose from in all of these different sectors." Mr Biden has also said he will not allow fracking on federal land. Fracking is a drilling process in which chemicals are injected into rocks to liberate natural gas and oil, and is controversial because of its environmental impact. However, since about 90% of it occurs on state or private land, the vast majority of fracking will be unaffected.