The Intergovernmental Panel on Climate Change is an intergovernmental scientific body established to provide the best science on climate change. Its reports tell us how bad the problem is and what we need to do to solve it, and inform both national policy and international negotiations. But there's a problem: those reports are systematically too conservative:
Across two decades and thousands of pages of reports, the world's most authoritative voice on climate science has consistently understated the rate and intensity of climate change and the danger those impacts represent, say a growing number of studies on the topic.A comparison of the projections vs reality is here. And the reason for it is simple: the IPCC operates by consensus, and includes representatives of denier-nations such as the US and Saudi Arabia in its deliberations. They downplay as much as possible, tilting the consensus away from reality - and in the process stripping out the urgent need for action. OTOH, the fear that this is having an effect on policy is overstated, for the simple reason that governments are already doing far less than the IPCC's underestimate. Still, it is a problem, and one the IPCC needs to solve if it is to effectively fulfil its mandate.
This conservative bias, say some scientists, could have significant political implications, as reports from the group – the U.N. Intergovernmental Panel on Climate Change – influence policy and planning decisions worldwide, from national governments down to local town councils.
A comparison of past IPCC predictions against 22 years of weather data and the latest climate science find that the IPCC has consistently underplayed the intensity of global warming in each of its four major reports released since 1990.