Joe Biden and Boris Johnson agree on one key point. Solar, wind power and other renewable energies will play a vital role in the battle against climate change. With other world leaders, the pair are pledging to move towards 'net zero' – the cherished goal of a balance between the amount of carbon emitted into the atmosphere by the fossil fuels we burn – coal, gas and oil – and the amount that can be removed from it. For investors, it has gained added urgency after Big Oil this week suffered a big backlash. A court in the Netherlands ordered Shell to slash its carbon emissions at a faster rate than it planned and Exxon shareholders defied the management and elected two new board members from a hedge fund who have warned against its dependence on fossil fuels.