Global warming is endangering more than we think. World problem? THE WORLD’S climate depends on a global aquatic “conveyor belt” system that snakes around the oceans, taking heat from some places and redistributing it elsewhere. It is this system that keeps Europe relatively warm despite its northern latitudes, underpins major fisheries and drives key weather patterns across continents. Global warming may be endangering this crucial circulation. Scientists are accumulating evidence that climate change is disrupting a major section of the conveyor belt, running from the tropics up to the North Atlantic and back south, slowing this piece of the system to its weakest pace in more than 1,000 years, according to a study published in the journal Nature Geoscience. By changing the atmosphere’s chemistry at a breakneck pace, humanity is conducting a massive, unprecedented experiment on finely tuned planetary systems, with consequences that range from predictable to speculative, and what experts know about Earth history offers little comfort for what awaits. The study’s authors warn that climate change may further destabilize the Atlantic circulation over coming decades. The consequences are hard to predict with precision, in part because warming air might offset some of the cooling associated with slower circulation. But previous research suggests that the last time the circulation was severely destabilized, some 12,000 years ago, Europe was slammed with bitter winters and, because of how the circulation interacts with air, severe summer heat and droughts. Climate change is not some isolated change in the air temperature. It encompasses sea-level rise, heavy storms, heat waves, droughts, wildfires, acidifying oceans and disruptions in the sensitive planetary rhythms on which human society developed. Scientists know some things for sure — the planet will warm because of greenhouse gas emissions, with a variety of negative results. But they have not catalogued all the consequences. Some are only just coming clearly into view, and some remain obscure. The longer we humans fail to adjust our behavior, the worse the consequences are likely to be.