The Paris Agreement aims for global warming contained to 1.5°C by the end of the century. IPCC estimates that this threshold will probably be crossed as early as the next decade.
Based on current global commitments to reduce emissions, the planet is heading for 3°C warming by 2100. For Europe, this equates to a 4°C rise, partly because land is warming faster than the average ocean surface. In a France at +4 °C, heat waves could last up to two months, water shortages, become the norm. The decline in GDP would be understood.